text:
Renin
From Wikipedia, the free encyclopedia
Jump to: navigation, search
For the places in Iran, see Renin, Iran.
Not to be confused with rennin, the active enzyme in rennet.
REN
Available structures
PDB
Ortholog search: PDBe RCSB
[show]List of PDB id codes
4XX4, 1BBS, 1BIL, 1BIM, 1HRN, 1RNE, 2BKS, 2BKT, 2FS4, 2G1N, 2G1O, 2G1R, 2G1S, 2G1Y, 2G20, 2G21, 2G22, 2G24, 2G26, 2G27, 2I4Q, 2IKO, 2IKU, 2IL2, 2REN, 2V0Z, 2V10, 2V11, 2V12, 2V13, 2V16, 2X0B, 3D91, 3G6Z, 3G70, 3G72, 3GW5, 3K1W, 3KM4, 3O9L, 3OAD, 3OAG, 3OOT, 3OQF, 3OQK, 3OWN, 3Q3T, 3Q4B, 3Q5H, 3SFC, 3VCM, 3VSW, 3VSX, 3VUC, 3VYD, 3VYE, 3VYF, 4AMT, 4GJ5, 4GJ6, 4GJ7, 4GJ8, 4GJ9, 4GJA, 4GJB, 4GJC, 4GJD, 4PYV, 4Q1N, 4RYC, 4RYG, 4RZ1, 4S1G, 4XX3
Identifiers
Aliases
REN, HNFJ2, renin
External IDs
OMIM: 179820 MGI: 97898 HomoloGene: 20151 GeneCards: REN
[hide]Gene location (Human)
Chr.
Chromosome 1 (human)[1]
Band
1q32.1
Start
204,154,819 bp[1]
End
204,190,324 bp[1]
[show]Gene location (Mouse)
Chr.
Chromosome 1 (mouse)[2]
Band
1 E4|1 57.91 cM
Start
133,350,510 bp[2]
End
133,360,325 bp[2]
[show]Gene ontology
Molecular function
• insulin-like growth factor receptor binding
• aspartic-type endopeptidase activity
• endopeptidase activity
• peptidase activity
• receptor binding
• hydrolase activity
• protein binding
Cellular component
• cytoplasm
• membrane
• plasma membrane
• intracellular
• extracellular region
• extracellular space
• apical part of cell
Biological process
• response to immobilization stress
• regulation of blood volume by renin-angiotensin
• male gonad development
• regulation of MAPK cascade
• kidney development
• renin-angiotensin regulation of aldosterone production
• cell maturation
• amyloid-beta metabolic process
• response to organic substance
• angiotensin maturation
• proteolysis
• mesonephros development
• regulation of blood pressure
• response to lipopolysaccharide
• cellular response to drug
• protein catabolic process
• drinking behavior
• hormone-mediated signaling pathway
• response to cGMP
• response to cAMP
• response to drug
Sources:Amigo / QuickGO
Orthologs
Species
Human Mouse
Entrez
5972
19701
Ensembl
ENSG00000143839
ENSMUSG00000070645
UniProt
P00797
P06281
RefSeq (mRNA)
NM_000537
NM_031192
RefSeq (protein)
NP_000528
NP_112469
Location (UCSC)
Chr 1: 204.15 – 204.19 Mb Chr 1: 133.35 – 133.36 Mb
PubMed search
[3] [4]
Wikidata
View/Edit Human View/Edit Mouse
renin
Identifiers
EC number
3.4.23.15
CAS number
9015-94-5
Databases
IntEnz
IntEnz view
BRENDA
BRENDA entry
ExPASy
NiceZyme view
KEGG
KEGG entry
MetaCyc
metabolic pathway
PRIAM
profile
PDB structures
RCSB PDB PDBe PDBsum
Gene Ontology
AmiGO / QuickGO
[show]Search
PMC
articles
PubMed
articles
NCBI
proteins
Renin (etymology and pronunciation), also known as an angiotensinogenase, is a serine protease protein and enzyme secreted by the kidneys that participates in the body's renin-angiotensin aldosterone system (RAAS)—also known as the renin-angiotensin-aldosterone axis—that mediates the volume of extracellular fluid (blood plasma, lymph and interstitial fluid), and arterial vasoconstriction. Thus, it regulates the body's mean arterial blood pressure.
Renin can be referred to as a hormone even though it has no peripheral receptors and rather has an enzymatic activity with which it hydrolyzes angiotensinogen to angiotensin I.
Contents
[hide]
1 Biochemistry and physiology
1.1 Structure
1.2 Secretion
1.3 Renin-angiotensin system
2 Function
3 Genetics
3.1 Model organisms
4 Clinical applications
4.1 Measurement
5 Discovery and naming
6 See also
7 References
8 External links
Biochemistry and physiology[edit]
Structure[edit]
The primary structure of renin precursor consists of 406 amino acids with a pre- and a pro-segment carrying 20 and 46 amino acids, respectively. Mature renin contains 340 amino acids and has a mass of 37 kDa.[5]
Secretion[edit]
The enzyme renin is secreted by pericytes (mural cells) (1) in vicinity of the afferent arterioles and similar microvessels of the kidney from specialized cells of the juxtaglomerular apparatus—the juxtaglomerular cells, in response to three stimuli:
A decrease in arterial blood pressure (that could be related to a decrease in blood volume) as detected by baroreceptors (pressure-sensitive cells). This is the most direct causal link between blood pressure and renin secretion (the other two methods operate via longer pathways).
A decrease in sodium load delivered to the distal tubule. This load is measured by the macula densa of the juxtaglomerular apparatus.
Sympathetic nervous system activity, which also controls blood pressure, acting through the β1 adrenergic receptors.
Human renin is secreted by at least 2 cellular pathways: a constitutive pathway for the secretion of the precursor prorenin and a regulated pathway for the secretion of mature renin.[6]
Renin-angiotensin system[edit]
Main article: Renin–angiotensin system
The renin-angiotensin system, showing role of renin at bottom.[7]
The renin enzyme circulates in the blood stream and hydrolyzes (breaks down) angiotensinogen secreted from the liver into the peptide angiotensin I.
Angiotensin I is further cleaved in the lungs by endothelial-bound angiotensin-converting enzyme (ACE) into angiotensin II, the most vasoactive peptide.[8][9] Angiotensin II is a potent constrictor of all blood vessels. It acts on the smooth muscle and, therefore, raises the resistance posed by these arteries to the heart. The heart, trying to overcome this increase in its 'load', works more vigorously, causing the blood pressure to rise. Angiotensin II also acts on the adrenal glands and releases aldosterone, which stimulates the epithelial cells in the distal tubule and collecting ducts of the kidneys to increase re-absorption of sodium, exchanging with potassium to maintain electrochemical neutrality, and water, leading to raised blood volume and raised blood pressure. The RAS also acts on the CNS to increase water intake by stimulating thirst, as well as conserving blood volume, by reducing urinary loss through the secretion of vasopressin from the posterior pituitary gland.
The normal concentration of renin in adult human plasma is 1.98–24.6 ng/L in the upright position.[10]
Function[edit]
Renin activates the renin-angiotensin system by cleaving angiotensinogen, produced by the liver, to yield angiotensin I, which is further converted into angiotensin II by ACE, the angiotensin-converting enzyme primarily within the capillaries of the lungs. Angiotensin II then constricts blood vessels, increases the secretion of ADH and aldosterone, and stimulates the hypothalamus to activate the thirst reflex, each leading to an increase in blood pressure. Renin's primary function is therefore to eventually cause an increase in blood pressure, leading to restoration of perfusion pressure in the kidneys.
Renin is secreted from juxtaglomerular kidney cells, which sense changes in renal perfusion pressure, via stretch receptors in the vascular walls. The juxtaglomerular cells are also stimulated to release renin by signaling from the macula densa. The macula densa senses changes in sodium delivery to the distal tubule, and responds to a drop in tubular sodium load by stimulating renin release in the juxtaglomerular cells. Together, the macula densa and juxtaglomerular cells comprise the juxtaglomerular complex.
Renin secretion is also stimulated by sympathetic nervous stimulation, mainly through beta-1 adrenergic receptor (β1 adrenoreceptor) activation.
Renin can bind to ATP6AP2, which results in a fourfold increase in the conversion of angiotensinogen to angiotensin I over that shown by soluble renin. In addition, renin binding results in phosphorylation of serine and tyrosine residues of ATP6AP2.[11]
The level of renin mRNA appears to be modulated by the binding of HADHB, HuR and CP1 to a regulatory region in the 3' UTR.[12]
Genetics[edit]
The gene for renin, REN, spans 12 kb of DNA and contains 8 introns.[13] It produces several mRNA that encode different REN isoforms.
Mutations in the REN gene can be inherited, and are a cause of a rare inherited kidney disease, so far found to be present in only 2 families. This disease is autosomal dominant, meaning that it is characterized by a 50% chance of inheritance and is a slowly progressive chronic kidney disease that leads to the need for dialysis or kidney transplantation. Many—but not all—patients and families with this disease suffer from an elevation in serum potassium and unexplained anemia relatively early in life. Patients with a mutation in this gene can have a variable rate of loss of kidney function, with some individuals going on dialysis in their 40s while others may not go on dialysis until into their 70s. This is a rare inherited kidney disease that exists in less than 1% of people with kidney disease.[14]
Model organisms[edit]
Ren1 knockout mouse phenotype
[show]Characteristic
Phenotype
Homozygote viability Normal
Fertility Normal
Body weight Normal
Anxiety Normal
Neurological assessment Normal
Grip strength Normal
Hot plate Normal
Dysmorphology Normal
Non-Invasive Blood Pressure Abnormal[15]
Indirect calorimetry Normal
Glucose tolerance test Normal
Auditory brainstem response Normal
DEXA Normal
Radiography Normal
Body temperature Normal
Eye morphology Normal
Clinical chemistry Normal
Haematology Normal
Micronucleus test Normal
Heart weight Normal
Skin Histopathology Normal
Brain histopathology Normal
Salmonella infection Normal[16]
Citrobacter infection Abnormal[17]
All tests and analysis from[18][19]
Model organisms have been used in the study of REN function. A knockout mouse line, called Ren1Ren-1c Enhancer KO was generated.[20] Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.[18][21] Twenty four tests were carried out on mutant mice and two significant abnormalities were observed. Homozygous mutant animals had a decreased heart rate and an increased susceptibility to bacterial infection.[18] A more detailed analysis of this line indicated plasma creatinine was also increased and males had lower mean arterial pressure than controls.[20]
Clinical applications[edit]
Main article: Renin inhibitor
An over-active renin-angiotension system leads to vasoconstriction and retention of sodium and water. These effects lead to hypertension. Therefore, renin inhibitors can be used for the treatment of hypertension.[22][23] This is measured by the plasma renin activity (PRA).
In current medical practice, the renin-angiotensin-aldosterone system's overactivity (and resultant hypertension) is more commonly reduced using either ACE inhibitors (such as ramipril and perindopril) or angiotensin II receptor blockers (ARBs, such as losartan, irbesartan or candesartan) rather than a direct oral renin inhibitor. ACE inhibitors or ARBs are also part of the standard treatment after a heart attack.
The differential diagnosis of kidney cancer in a young patient with hypertension includes juxtaglomerular cell tumor (reninoma), Wilms' tumor, and renal cell carcinoma, all of which may produce renin.[24]
Measurement[edit]
Further information: Plasma renin activity
Renin is usually measured as the plasma renin activity (PRA). PRA is measured specially in case of certain diseases that present with hypertension or hypotension. PRA is also raised in certain tumors.[25] A PRA measurement may be compared to a plasma aldosterone concentration (PAC) as a PAC/PRA ratio.
Discovery and naming[edit]
The name renin = ren + -in, "kidney" + "compound". The most common pronunciation in English is /ˈriːnɪn/ (long e); /ˈrɛnɪn/ (short e) is also common, but using /ˈriːnɪn/ allows one to reserve /ˈrɛnɪn/ for rennin. Renin was discovered, characterized, and named in 1898 by Robert Tigerstedt, Professor of Physiology, and his student, Per Bergman, at the Karolinska Institute in Stockholm.[26][27]
See also[edit]
Angiotensin-converting enzyme
Plasma renin activity
Renin inhibitor
Renin stability regulatory element (REN-SRE)
References[edit]
^ Jump up to: a b c GRCh38: Ensembl release 89: ENSG00000143839 - Ensembl, May 2017
^ Jump up to: a b c GRCm38: Ensembl release 89: ENSMUSG00000070645 - Ensembl, May 2017
Jump up ^ "Human PubMed Reference:".
Jump up ^ "Mouse PubMed Reference:".
Jump up ^ Imai T, Miyazaki H, Hirose S, Hori H, Hayashi T, Kageyama R, Ohkubo H, Nakanishi S, Murakami K (Dec 1983). "Cloning and sequence analysis of cDNA for human renin precursor". Proceedings of the National Academy of Sciences of the United States of America. 80 (24): 7405–9. doi:10.1073/pnas.80.24.7405. PMC 389959  . PMID 6324167.
Jump up ^ Pratt RE, Flynn JA, Hobart PM, Paul M, Dzau VJ (Mar 1988). "Different secretory pathways of renin from mouse cells transfected with the human renin gene". The Journal of Biological Chemistry. 263 (7): 3137–41. PMID 2893797.
Jump up ^ Boulpaep EL, Boron WF (2005). "Integration of Salt and Water Balance; The Adrenal Gland". Medical physiology: a cellular and molecular approach. St. Louis, MO: Elsevier Saunders. pp. 866–867, 1059. ISBN 1-4160-2328-3.
Jump up ^ Fujino T, Nakagawa N, Yuhki K, Hara A, Yamada T, Takayama K, Kuriyama S, Hosoki Y, Takahata O, Taniguchi T, Fukuzawa J, Hasebe N, Kikuchi K, Narumiya S, Ushikubi F (Sep 2004). "Decreased susceptibility to renovascular hypertension in mice lacking the prostaglandin I2 receptor IP". The Journal of Clinical Investigation. 114 (6): 805–12. doi:10.1172/JCI21382. PMC 516260  . PMID 15372104.
Jump up ^ Brenner & Rector's The Kidney, 7th ed., Saunders, 2004, pp. 2118-2119 Full Text with MDConsult subscription
Jump up ^ Hamilton Regional Laboratory Medicine Program - Laboratory Reference Centre Manual. [deadlink]
Jump up ^ Nguyen G, Delarue F, Burcklé C, Bouzhir L, Giller T, Sraer JD (Jun 2002). "Pivotal role of the renin/prorenin receptor in angiotensin II production and cellular responses to renin". The Journal of Clinical Investigation. 109 (11): 1417–27. doi:10.1172/JCI14276. PMC 150992  . PMID 12045255.
Jump up ^ Adams DJ, Beveridge DJ, van der Weyden L, Mangs H, Leedman PJ, Morris BJ (Nov 2003). "HADHB, HuR, and CP1 bind to the distal 3'-untranslated region of human renin mRNA and differentially modulate renin expression". The Journal of Biological Chemistry. 278 (45): 44894–903. doi:10.1074/jbc.M307782200. PMID 12933794.
Jump up ^ Hobart PM, Fogliano M, O'Connor BA, Schaefer IM, Chirgwin JM (Aug 1984). "Human renin gene: structure and sequence analysis". Proceedings of the National Academy of Sciences of the United States of America. 81 (16): 5026–30. doi:10.1073/pnas.81.16.5026. PMC 391630  . PMID 6089171.
Jump up ^ Zivná M, Hůlková H, Matignon M, Hodanová K, Vylet'al P, Kalbácová M, Baresová V, Sikora J, Blazková H, Zivný J, Ivánek R, Stránecký V, Sovová J, Claes K, Lerut E, Fryns JP, Hart PS, Hart TC, Adams JN, Pawtowski A, Clemessy M, Gasc JM, Gübler MC, Antignac C, Elleder M, Kapp K, Grimbert P, Bleyer AJ, Kmoch S (2009). "Dominant renin gene mutations associated with early-onset hyperuricemia, anemia, and chronic kidney failure". Am. J. Hum. Genet. 85 (2): 204–13. doi:10.1016/j.ajhg.2009.07.010. PMC 2725269  . PMID 19664745.
Jump up ^ "Non-Invasive Blood Pressure data for Ren1". Wellcome Trust Sanger Institute.
Jump up ^ "Salmonella infection data for Ren1". Wellcome Trust Sanger Institute.
Jump up ^ "Citrobacter infection data for Ren1". Wellcome Trust Sanger Institute.
^ Jump up to: a b c Gerdin AK (2010). "The Sanger Mouse Genetics Programme: High throughput characterisation of knockout mice". Acta Ophthalmologica. 88: 925–7. doi:10.1111/j.1755-3768.2010.4142.x.
Jump up ^ Mouse Resources Portal, Wellcome Trust Sanger Institute.
^ Jump up to: a b Adams DJ, Head GA, Markus MA, Lovicu FJ, van der Weyden L, Köntgen F, Arends MJ, Thiru S, Mayorov DN, Morris BJ (Oct 2006). "Renin enhancer is critical for control of renin gene expression and cardiovascular function". The Journal of Biological Chemistry. 281 (42): 31753–61. doi:10.1074/jbc.M605720200. PMID 16895910.
Jump up ^ van der Weyden L, White JK, Adams DJ, Logan DW (2011). "The mouse genetics toolkit: revealing function and mechanism". Genome Biology. 12 (6): 224. doi:10.1186/gb-2011-12-6-224. PMC 3218837  . PMID 21722353.
Jump up ^ Presentation on Direct Renin Inhibitors as Antihypertensive Drugs
Jump up ^ Ram CV (Sep 2009). "Direct inhibition of renin: a physiological approach to treat hypertension and cardiovascular disease". Future Cardiology. 5 (5): 453–65. doi:10.2217/fca.09.31. PMID 19715410.
Jump up ^ Méndez GP, Klock C, Nosé V (Feb 2011). "Juxtaglomerular cell tumor of the kidney: case report and differential diagnosis with emphasis on pathologic and cytopathologic features". International Journal of Surgical Pathology. 19 (1): 93–8. doi:10.1177/1066896908329413. PMID 19098017.
Jump up ^ Hamilton Regional Laboratory Medicine Program - Laboratory Reference Centre Manual. Renin Direct.
Jump up ^ Phillips MI, Schmidt-Ott KM (Dec 1999). "The Discovery of Renin 100 Years Ago". News in Physiological Sciences. 14: 271–274. PMID 11390864.
Jump up ^ Tigerstedt R, Bergman PG (1898). "Niere und Kreislauf" [Kidney and Circulation]. Skandinavisches Archiv für Physiologie [Scandinavian Archives of Physiology] (in German). 8: 223–271. doi:10.1111/j.1748-1716.1898.tb00272.x.
(1) Human kidney pericytes produce renin ; Stefanska A, Kenyon C, Christian HC, Buckley C, Shaw I, Mullins JJ, Péault B. Kidney Int. 2016 Dec; 90(6):1251-1261
External links[edit]
GeneReviews/NCBI/NIH/UW entry on Familial Juvenile Hyperuricemic Nephropathy Type 2
OMIM entries on Familial Juvenile Hyperuricemic Nephropathy Type 2
The MEROPS online database for peptidases and their inhibitors: A01.007
Renin at the US National Library of Medicine Medical Subject Headings (MeSH)

[show]
v
t
e
PDB gallery
2bks: CRYSTAL STRUCTURE OF RENIN-PF00074777 COMPLEX
2g24: Ketopiperazine-Based Renin Inhibitors: Optimization of the ""C"" Ring
2ren: STRUCTURE OF RECOMBINANT HUMAN RENIN, A TARGET FOR CARDIOVASCULAR-ACTIVE DRUGS, AT 2.5 ANGSTROMS RESOLUTION
2iko: Crystal Structure of Human Renin Complexed with Inhibitor
2g1y: Ketopiperazine-Based Renin Inhibitors: Optimization of the ""C"" Ring
2g20: Ketopiperazine-Based Renin Inhibitors: Optimization of the C Ring
2g26: Ketopiperazine-Based Renin Inhibitors: Optimization of the ""C"" Ring
2g1n: Ketopiperazine-based renin inhibitors: Optimization of the ""C"" ring
1bil: CRYSTALLOGRAPHIC STUDIES ON THE BINDING MODES OF P2-P3 BUTANEDIAMIDE RENIN INHIBITORS
2iku: Crystal Structure of Human Renin Complexed with Inhibitors
2g1o: Ketopiperazine-Based Renin Inhibitors: Optimization of the ""C"" Ring
2g1r: Ketopiperazine-Based Renin Inhibitors: Optimization of the C Ring
1bim: CRYSTALLOGRAPHIC STUDIES ON THE BINDING MODES OF P2-P3 BUTANEDIAMIDE RENIN INHIBITORS
2fs4: Ketopiperazine-Based Renin Inhibitors: Optimization of the C ring
2il2: Crystal Structure of Human Renin Complexed with Inhibitor
1hrn: HIGH RESOLUTION CRYSTAL STRUCTURES OF RECOMBINANT HUMAN RENIN IN COMPLEX WITH POLYHYDROXYMONOAMIDE INHIBITORS
2bkt: CRYSTAL STRUCTURE OF RENIN-PF00257567 COMPLEX
2g27: Ketopiperazine-Based Renin Inhibitors: Optimization of the ""C"" Ring
1rne: THE CRYSTAL STRUCTURE OF RECOMBINANT GLYCOSYLATED HUMAN RENIN ALONE AND IN COMPLEX WITH A TRANSITION STATE ANALOG INHIBITOR
2g21: Ketopiperazine-Based Renin Inhibitors: Optimization of the ""C"" Ring
1bbs: X-RAY ANALYSES OF PEPTIDE INHIBITOR COMPLEXES DEFINE THE STRUCTURAL BASIS OF SPECIFICITY FOR HUMAN AND MOUSE RENINS
2g1s: Ketopiperazine-Based Renin Inhibitors: Optimization of the C Ring
2i4q: Human renin/PF02342674 complex
2g22: Ketopiperazine-Based Renin Inhibitors: Optimization of the ""C"" Ring
[show]
v
t
e
Hormones
Endocrine
glands
Hypothalamic-
pituitary
Hypothalamus
GnRH
TRH
Dopamine
CRH
GHRH
Somatostatin (GHIH)
MCH
Posterior pituitary
Oxytocin
Vasopressin
Anterior pituitary
FSH
LH
TSH
Prolactin
POMC
CLIP
ACTH
MSH
Endorphins
Lipotropin
GH
Adrenal axis
Adrenal cortex
aldosterone
cortisol
cortisone
DHEA
DHEA-S
androstenedione
Adrenal medulla
epinephrine
norepinephrine
Thyroid
Thyroid hormone
T3
T4
Calcitonin
Thyroid axis
Parathyroid
PTH
Gonadal axis
Testis
testosterone
AMH
inhibin
Ovary
estradiol
progesterone
activin and inhibin
relaxin
Placenta
hCG
HPL
estrogen
progesterone
Pancreas
glucagon
insulin
amylin
somatostatin
pancreatic polypeptide
Pineal gland
melatonin
N,N-dimethyltryptamine
5-methoxy-N,N-dimethyltryptamine
Other
Thymus
Thymosins
Thymosin α1
Beta thymosins
Thymopoietin
Thymulin
Digestive system
Stomach
gastrin
ghrelin
Duodenum
CCK
Incretins
GIP
GLP-1
secretin
motilin
VIP
Ileum
enteroglucagon
peptide YY
Liver/other
Insulin-like growth factor
IGF-1
IGF-2
Adipose tissue
leptin
adiponectin
resistin
Skeleton
Osteocalcin
Kidney
renin
EPO
calcitriol
prostaglandin
Heart
Natriuretic peptide
ANP
BNP
[show]
v
t
e
Arteries and veins
Vessels
Arteries
Nutrient artery
Arteriole
Metarteriole
Capillaries
Types
Continuous
Fenestrated
Sinusoidal
Precapillary sphincter
Precapillary resistance
Veins
Vena comitans
Superficial vein
Deep vein
Emissary veins
Venous plexus
Venule
Lymph
Lymphatic vessel
Lymph
Lymph capillary
Circulatory system
Systemic
Left heart → Aorta → Arteries → Arterioles → Capillaries → Venules → Veins → Vena cava → (Right heart)
Pulmonary
Right heart → Pulmonary arteries → Lungs → Pulmonary vein → Left heart
Microanatomy
Microcirculation
Tunica intima
Endothelium
Internal elastic lamina
Tunica media
Tunica externa
Vasa vasorum
Vasa nervorum
Vascular nerves
Rete mirabile
Circulatory anastomosis
[show]
v
t
e
Physiology of the kidneys and acid-base physiology
Renal function
Secretion
clearance
Pharmacokinetics
Clearance of medications
Urine flow rate
Reabsorption
Solvent drag
sodium
chloride
urea
glucose
oligopeptides
protein
Renal function
Glomerular filtration rate
Creatinine clearance
Renal clearance ratio
Urea reduction ratio
Kt/V
Standardized Kt/V
Measures of dialysis
Hemodialysis product
PAH clearance (Effective renal plasma flow
Extraction ratio)
Filtration
Renal blood flow
Ultrafiltration
Countercurrent exchange
Filtration fraction
Hormones
Antidiuretic hormone
Aldosterone
Atrial natriuretic peptide
Renin
Erythropoietin
Calcitriol
Prostaglandins
Acid-base balance
Fluid balance
Darrow Yannet diagram
Body water: Intracellular fluid/Cytosol
Extracellular fluid
(Interstitial fluid
Plasma
Transcellular fluid)
Base excess
Davenport diagram
Anion gap
Arterial blood gas
Winters' formula
Buffering
Bicarbonate buffer system
Respiratory compensation
Renal compensation
Other
Fractional sodium excretion
BUN-to-creatinine ratio
Tubuloglomerular feedback
Natriuresis
Urine
[show]
v
t
e
Proteases: aspartate proteases (EC 3.4.23)
Vertebrate
Pepsin
Chymosin
Renin
Signal peptide peptidase
Beta secretase
1
2
Pathogenic
Plasmepsin
HIV-1 protease
Plant
Nepenthesin
Cathepsin
D
E
[show]
v
t
e
Enzymes
Activity
Active site
Binding site
Catalytic triad
Oxyanion hole
Enzyme promiscuity
Catalytically perfect enzyme
Coenzyme
Cofactor
Enzyme catalysis
Regulation
Allosteric regulation
Cooperativity
Enzyme inhibitor
Classification
EC number
Enzyme superfamily
Enzyme family
List of enzymes
Kinetics
Enzyme kinetics
Eadie–Hofstee diagram
Hanes–Woolf plot
Lineweaver–Burk plot
Michaelis–Menten kinetics
Types
EC1 Oxidoreductases (list)
EC2 Transferases (list)
EC3 Hydrolases (list)
EC4 Lyases (list)
EC5 Isomerases (list)
EC6 Ligases (list)
[show]
v
t
e
Angiotensin receptor modulators
ATR
Agonists: Angiotensin II
Angiotensin III
Angiotensin IV
Saralasin
Antagonists: Abitesartan
Azilsartan
Azilsartan medoxomil
Candesartan
Elisartan
Embusartan
Eprosartan
EXP-3174
Fimasartan
Forasartan
Irbesartan
Losartan
Milfasartan
Olmesartan
Olmesartan medoxomil
Olodanrigan
PD123319
Pomisartan
Pratosartan
Ripisartan
Saprisartan
Sparsentan
Tasosartan
Telmisartan
Valsartan
Zolasartan
ACE inhibitors: Alacepril
Benazepril
Captopril
Cilazapril
Delapril
Enalapril
Enalaprilat
Fosinopril
Gemopatrilat
Imidapril
Lisinopril
Moexipril
Omapatrilat
Perindopril
Quinapril
Quinaprilat
Ramipril
Rentiapril
Rescinnamine
Spirapril
Spiraprilat
Temocapril
Trandolapril
Zofenopril
Zofenoprilat
Renin inhibitors: Aliskiren
Ciprokiren
Ditekiren
Enalkiren
Pepstatin
Remikiren
Terlakiren
Zankiren
Propeptides: Angiotensinogen
Angiotensin I
See also
Receptor/signaling modulators
Signaling peptide/protein receptor modulators
Molecular and Cellular Biology portal
Retrieved from "https://en.wikipedia.org/w/index.php?title=Renin&oldid=815387368"
Categories:
Genes on human chromosome 1
EC 3.4.23
Hormones of the kidneys
Peptide hormones
Renal physiology
Genes mutated in mice
Hidden categories:
CS1 German-language sources (de)
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
Languages
العربية
Български
Bosanski
Català
Čeština
Deutsch
ދިވެހިބަސް
Eesti
Español
فارسی
Français
Gaeilge
Galego
한국어
Հայերեն
Hrvatski
Bahasa Indonesia
Italiano
עברית
Magyar
Nederlands
日本語
Norsk
Polski
Português
Română
Русский
Shqip
Simple English
Српски / srpski
Suomi
Svenska
தமிழ்
Українська
中文
Edit links
This page was last edited on 14 December 2017, at 14:58.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

values: mw-page-base noprint

values: mw-head-base noprint

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

values:
/wiki/Renin,_Iran_(disambiguation)
mw-redirect mw-disambig
Renin, Iran (disambiguation)

values:
note
hatnote navigation-not-searchable

values: /wiki/Rennin mw-redirect Rennin

values:
/wiki/Mendelian_Inheritance_in_Man
mw-redirect
Mendelian Inheritance in Man

values:
nofollow
external text
https://omim.org/entry/179820

values:
/wiki/File:HSR_1996_II_3.5e.svg
image
Genomic location for REN

values: position: absolute; left: 235.82266589903px; top: 2px; padding: 0;

attrs: alt src width height data-file-width data-file-height

values:
/wiki/File:Red_rectangle_2x18.png
image
Genomic location for REN

values: position: absolute; left: 241.8px; top: 19px; padding: 0;

values:
center
position: relative; width: 300px;

values: position: absolute; left: 195.26434837663px; top: 2px; padding: 0;

values: position: absolute; left: 201.3px; top: 19px; padding: 0;

values:
nofollow
http://amigo.geneontology.org/
external text

values:
nofollow
https://www.ebi.ac.uk/QuickGO/
external text

values:
nofollow
external text
http://www.uniprot.org/uniprot/P00797

values:
nofollow
external text
http://www.uniprot.org/uniprot/P06281

values:
/wiki/CAS_registry_number
mw-redirect
CAS registry number

values:
nofollow
external text
http://www.expasy.org/enzyme/3.4.23.15

values:
/wiki/PRIAM_enzyme_specific_profiles
mw-redirect
PRIAM enzyme specific profiles

values:
/wiki/Gene_Ontology
mw-redirect
Gene Ontology

values:
nofollow
external text
//www.ebi.ac.uk/QuickGO/term/GO:0004195

values: background-color: #e7dcc3; border:#fafafa 2px solid; border-width:3px 2px 0 0;

values: background-color: #eee; border:#fafafa 2px solid; border-width:3px 0 0 2px;

values: National Center for Biotechnology Information

values: width:22em;float:none; clear:none; margin:0; border-width:0; border-collapse:collapse; text-align:left; width:100%

values:
/wiki/Interstitial_fluid
mw-redirect
Interstitial fluid

values:
/wiki/Angiotensin_I
mw-redirect
Angiotensin I

values: Edit section: Biochemistry and physiology

values:
/wiki/Atomic_mass_unit
mw-redirect
Atomic mass unit

values:
/wiki/Renin-angiotensin_system
mw-redirect
Renin-angiotensin system

values:
/wiki/Angiotensin_II
mw-redirect
Angiotensin II

values:
/wiki/Antidiuretic_hormone
mw-redirect
Antidiuretic hormone

values:
/wiki/Distal_tubule
mw-redirect
Distal tubule

values: Renin stability regulatory element (REN-SRE)

values:
headerSort
0
columnheader button
Sort ascending

values:
/wiki/Open_Field_(animal_test)
mw-redirect
Open Field (animal test)

values: wikitable sortable collapsible collapsed jquery-tablesorter

values:
/wiki/Phenotypic_screen
mw-redirect
Phenotypic screen

values:
/wiki/Bacterial_infection
mw-redirect
Bacterial infection

values:
/wiki/Arterial_pressure
mw-redirect
Arterial pressure

values:
/wiki/PRA_(Medical)
mw-redirect
PRA (Medical)

values:
nofollow
external text
//doi.org/10.1073%2Fpnas.80.24.7405

values:
/wiki/PubMed_Identifier
mw-redirect
PubMed Identifier

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/6324167

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/2893797

values:
nofollow
external text
//doi.org/10.1172%2FJCI21382

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/15372104

values:
nofollow
external text
//doi.org/10.1172%2FJCI14276

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/12045255

values:
nofollow
external text
//doi.org/10.1074%2Fjbc.M307782200

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/12933794

values:
nofollow
external text
//doi.org/10.1073%2Fpnas.81.16.5026

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/6089171

values:
nofollow
external text
//doi.org/10.1016%2Fj.ajhg.2009.07.010

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/19664745

values:
nofollow
http://www.sanger.ac.uk/mouseportal/
external text

values:
nofollow
external text
//doi.org/10.1074%2Fjbc.M605720200

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/16895910

values:
nofollow
external text
//doi.org/10.1186%2Fgb-2011-12-6-224

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/21722353

values:
nofollow
external text
//doi.org/10.2217%2Ffca.09.31

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/19715410

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/19098017

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/11390864

values: -moz-column-width: 33em; -webkit-column-width: 33em; column-width: 33em; list-style-type: decimal;

values: 2bks: CRYSTAL STRUCTURE OF RENIN-PF00074777 COMPLEX

values: min-height:6.1em;width:187px;line-height:1.3em;padding:2px 6px 1px 6px;margin:0px;border:none;border-width:0px

values: 2iko: Crystal Structure of Human Renin Complexed with Inhibitor

values: 2iku: Crystal Structure of Human Renin Complexed with Inhibitors

values: 2il2: Crystal Structure of Human Renin Complexed with Inhibitor

values: 2bkt: CRYSTAL STRUCTURE OF RENIN-PF00257567 COMPLEX

values:
/wiki/File:PDB_2i4q_EBI.png
image
2i4q: Human renin/PF02342674 complex

values: nowraplinks collapsible collapsed navbox-inner

values:
/wiki/Hypothalamic-pituitary_hormone
mw-redirect
Hypothalamic-pituitary hormone

values:
/wiki/Growth_hormone_releasing_hormone
mw-redirect
Growth hormone releasing hormone

values:
/wiki/Melanin_concentrating_hormone
mw-redirect
Melanin concentrating hormone

values:
/wiki/Thyroid_hormone
mw-redirect
Thyroid hormone

values: nowraplinks hlist collapsible collapsed navbox-inner

values: nowraplinks collapsible autocollapse navbox-inner

values:
/wiki/Acid-base_physiology
mw-redirect
Acid-base physiology

values:
/wiki/Clearance_(medicine)
mw-redirect
Clearance (medicine)

values:
/wiki/Glomerular_filtration_rate
mw-redirect
Glomerular filtration rate

values:
/wiki/Creatinine_clearance
mw-redirect
Creatinine clearance

values:
/wiki/Measures_of_dialysis
mw-redirect
Measures of dialysis

values:
/wiki/Acid-base_homeostasis
mw-redirect
Acid-base homeostasis

values:
/wiki/Arterial_blood_gas
mw-redirect
Arterial blood gas

values:
/wiki/Fractional_sodium_excretion
mw-redirect
Fractional sodium excretion

values:
/wiki/Aspartate_protease
mw-redirect
Aspartate protease

values:
/wiki/Catalytically_perfect_enzyme
mw-redirect
Catalytically perfect enzyme

values:
/wiki/Enzyme_superfamily
mw-redirect
Enzyme superfamily

values:
/wiki/Enzyme_family
mw-redirect
Enzyme family

values: Template talk:Angiotensin receptor modulators

values:
/wiki/Angiotensin_receptor
mw-redirect
Angiotensin receptor

values:
/wiki/Angiotensin_III
mw-redirect
Angiotensin III

values:
/wiki/Azilsartan_medoxomil
mw-redirect
Azilsartan medoxomil

values:
/wiki/Olmesartan_medoxomil
mw-redirect
Olmesartan medoxomil

values: Template:Signaling peptide/protein receptor modulators

values: Category:CS1 German-language sources (de)

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values:
/wiki/Renin
View the content page [ctrl-alt-c]
c

values: Discussion about the content page [ctrl-alt-t]

values: p-namespaces navigation vectorTabs p-namespaces-label

values:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

values:
/w/index.php?title=Renin&action=edit
Edit this page [ctrl-alt-e]
e

values: Past revisions of this page [ctrl-alt-h]

values: p-views navigation vectorTabs p-views-label

values:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

values:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

values:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

values: Featured content – the best of Wikipedia

values: Find background information on current events

values:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

values: portal navigation p-navigation p-navigation-label

values: Guidance on how to use and edit Wikipedia

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values:
uls-settings-trigger
Language settings
0
button
true

values: رينين – Arabic

values:
https://bs.wikipedia.org/wiki/Renin
Renin – Bosnian
bs
bs
interlanguage-link-target

values:
https://ca.wikipedia.org/wiki/Renina
Renina – Catalan
ca
ca
interlanguage-link-target

values:
https://cs.wikipedia.org/wiki/Renin
Renin – Czech
cs
cs
interlanguage-link-target

values:
https://de.wikipedia.org/wiki/Renin
Renin – German
de
de
interlanguage-link-target

values: ރީނިން – Divehi

values:
https://et.wikipedia.org/wiki/Reniin
Reniin – Estonian
et
et
interlanguage-link-target

values:
https://es.wikipedia.org/wiki/Renina
Renina – Spanish
es
es
interlanguage-link-target

values: رنین (آنزیم) – Persian

values:
https://gl.wikipedia.org/wiki/Renina
Renina – Galician
gl
gl
interlanguage-link-target

values:
https://hr.wikipedia.org/wiki/Renin
Renin – Croatian
hr
hr
interlanguage-link-target

values:
https://id.wikipedia.org/wiki/Renin
Renin – Indonesian
id
id
interlanguage-link-target

values:
https://it.wikipedia.org/wiki/Renina
Renina – Italian
it
it
interlanguage-link-target

values:
https://hu.wikipedia.org/wiki/Renin
Renin – Hungarian
hu
hu
interlanguage-link-target

values:
https://nl.wikipedia.org/wiki/Renine
Renine – Dutch
nl
nl
interlanguage-link-target

values:
https://no.wikipedia.org/wiki/Renin
Renin – Norwegian
no
no
interlanguage-link-target

values:
https://pl.wikipedia.org/wiki/Renina
Renina – Polish
pl
pl
interlanguage-link-target

values:
https://pt.wikipedia.org/wiki/Renina
Renina – Portuguese
pt
pt
interlanguage-link-target

values:
https://sq.wikipedia.org/wiki/Renina
Renina – Albanian
sq
sq
interlanguage-link-target

values:
https://simple.wikipedia.org/wiki/Renin
Renin – Simple English
simple
simple
interlanguage-link-target

values:
https://fi.wikipedia.org/wiki/Reniini
Reniini – Finnish
fi
fi
interlanguage-link-target

values:
https://sv.wikipedia.org/wiki/Renin
Renin – Swedish
sv
sv
interlanguage-link-target

values: ரெனின் – Tamil

values: /static/images/wikimedia-button-1.5x.png 1.5x, /static/images/wikimedia-button-2x.png 2x

values: /static/images/poweredby_mediawiki_132x47.png 1.5x, /static/images/poweredby_mediawiki_176x62.png 2x

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Renin rootpage-Renin skin-vector action-view


text:
Lens (anatomy)
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Lens
Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens.
Schematic diagram of the human eye.
Details
Identifiers
Latin
lens crystallin
MeSH
Crystalline+lens
Dorlands
/Elsevier
12483326
TA
A15.2.05.001
FMA
58241
Anatomical terminology
[edit on Wikidata]
The lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a sharp real image of the object of interest to be formed on the retina. This adjustment of the lens is known as accommodation (see also below). Accommodation is similar to the focusing of a photographic camera via movement of its lenses. The lens is more flat on its anterior side than on its posterior side.
The lens is also known as the aquula (Latin, a little stream, dim. of aqua, water) or crystalline lens. In humans, the refractive power of the lens in its natural environment is approximately 18 dioptres, roughly one-third of the eye's total power.
Contents
[hide]
1 Structure
1.1 Histology
1.1.1 Lens capsule
1.1.2 Lens epithelium
1.1.3 Lens fibers
1.2 Development
1.3 Variation
2 Function
2.1 Accommodation
2.2 Crystallins and transparency
2.3 Nourishment
3 Clinical significance
4 Additional images
5 See also
6 References
7 External links
Structure[edit]
The lens is part of the anterior segment of the human eye. In front of the lens is the iris, which regulates the amount of light entering into the eye. The lens is suspended in place by the suspensory ligament of the lens, a ring of fibrous tissue that attaches to the lens at its equator[1][2] and connects it to the ciliary body. Posterior to the lens is the vitreous body, which, along with the aqueous humor on the anterior surface, bathes the lens. The lens has an ellipsoid, biconvex shape. The anterior surface is less curved than the posterior. In the adult, the lens is typically circa 10 mm in diameter and has an axial length of about 4 mm, though it is important to note that the size and shape can change due to accommodation and because the lens continues to grow throughout a person's lifetime.[3]
Histology[edit]
The lens has three main parts: the lens capsule, the lens epithelium, and the lens fibers. The lens capsule forms the outermost layer of the lens and the lens fibers form the bulk of the interior of the lens. The cells of the lens epithelium, located between the lens capsule and the outermost layer of lens fibers, are found only on the anterior side of the lens. The lens itself lacks nerves, blood vessels, or connective tissue.[4]
Lens capsule[edit]
The lens capsule is a smooth, transparent basement membrane that completely surrounds the lens. The capsule is elastic and is composed of collagen. It is synthesized by the lens epithelium and its main components are Type IV collagen and sulfated glycosaminoglycans (GAGs).[3] The capsule is very elastic and so allows the lens to assume a more globular shape when not under the tension of the zonular fibers, which connect the lens capsule to the ciliary body. The capsule varies from 2 to 28 micrometres in thickness, being thickest near the equator and thinnest near the posterior pole.[3]
Lens epithelium[edit]
The lens epithelium, located in the anterior portion of the lens between the lens capsule and the lens fibers, is a simple cuboidal epithelium.[3] The cells of the lens epithelium regulate most of the homeostatic functions of the lens.[5] As ions, nutrients, and liquid enter the lens from the aqueous humor, Na+/K+-ATPase pumps in the lens epithelial cells pump ions out of the lens to maintain appropriate lens osmotic concentration and volume, with equatorially positioned lens epithelium cells contributing most to this current. The activity of the Na+/K+-ATPases keeps water and current flowing through the lens from the poles and exiting through the equatorial regions.
The cells of the lens epithelium also serve as the progenitors for new lens fibers. It constantly lays down fibers in the embryo, fetus, infant, and adult, and continues to lay down fibers for lifelong growth.[6]
Lens fibers[edit]
The lens fibers form the bulk of the lens. They are long, thin, transparent cells, firmly packed, with diameters typically 4–7 micrometres and lengths of up to 12 mm long.[3] The lens fibers stretch lengthwise from the posterior to the anterior poles and, when cut horizontally, are arranged in concentric layers rather like the layers of an onion. If cut along the equator, it appears as a honeycomb. The middle of each fiber lies on the equator.[6] These tightly packed layers of lens fibers are referred to as laminae. The lens fibers are linked together via gap junctions and interdigitations of the cells that resemble "ball and socket" forms.
The lens is split into regions depending on the age of the lens fibers of a particular layer. Moving outwards from the central, oldest layer, the lens is split into an embryonic nucleus, the fetal nucleus, the adult nucleus, and the outer cortex. New lens fibers, generated from the lens epithelium, are added to the outer cortex. Mature lens fibers have no organelles or nuclei.
Development[edit]
Development of the human lens begins at the 4 mm embryonic stage. Unlike the rest of the eye, which is derived mostly from the neural ectoderm, the lens is derived from the surface ectoderm. The first stage of lens differentiation takes place when the optic vesicle, which is formed from outpocketings in the neural ectoderm, comes in proximity to the surface ectoderm. The optic vesicle induces nearby surface ectoderm to form the lens placode. At the 4 mm stage, the lens placode is a single monolayer of columnar cells.
As development progresses, the lens placode begins to deepen and invaginate. As the placode continues to deepen, the opening to the surface ectoderm constricts and the lens cells forms a structure known as the lens vesicle. By the 10 mm stage, the lens vesicle has completely separated from the surface ectoderm.
After the 10 mm stage, signals from the developing neural retina induces the cells closest to the posterior end of the lens vesicle begin to elongate toward the anterior end of the vesicle.[7] These signals also induce the synthesis of crystallins.[7] These elongating cells eventually fill in the lumen of the vesicle to form the primary fibers, which become the embryonic nucleus in the mature lens. The cells of the anterior portion of the lens vesicle give rise to the lens epithelium.
Additional secondary fibers are derived from lens epithelial cells located toward the equatorial region of the lens. These cells lengthen anteriorly and posteriorly to encircle the primary fibers. The new fibers grow longer than those of the primary layer, but as the lens gets larger, the ends of the newer fibers cannot reach the posterior or anterior poles of the lens. The lens fibers that do not reach the poles form tight, interdigitating seams with neighboring fibers. These seams are readily visible and are termed sutures. The suture patterns become more complex as more layers of lens fibers are added to the outer portion of the lens.
The lens continues to grow after birth, with the new secondary fibers being added as outer layers. New lens fibers are generated from the equatorial cells of the lens epithelium, in a region referred to as the germinative zone. The lens epithelial cells elongate, lose contact with the capsule and epithelium, synthesize crystallin, and then finally lose their nuclei (enucleate) as they become mature lens fibers. From development through early adulthood, the addition of secondary lens fibers results in the lens growing more ellipsoid in shape; after about age 20, however, the lens grows rounder with time and the iris is very important for this development[3]
Several proteins control the embryonic development of the lens: among these, primarily, PAX6, considered the master regulator gene of this organ[8]. Other effectors of proper lens development include the Wnt signaling components BCL9 and Pygo2.[9]
Variation[edit]
In many aquatic vertebrates, the lens is considerably thicker, almost spherical, to increase the refraction. This difference compensates for the smaller angle of refraction between the eye's cornea and the watery medium, as they have similar refractive indices.[10] Even among terrestrial animals, however, the lens of primates such as humans is unusually flat.[11]
In reptiles and birds, the ciliary body touches the lens with a number of pads on its inner surface, in addition to the zonular fibres. These pads compress and release the lens to modify its shape while focusing on objects at different distances; the zonular fibres perform this function in mammals. In fish and amphibians, the lens is fixed in shape, and focusing is instead achieved by moving the lens forwards or backwards within the eye.[11]
In cartilaginous fish, the zonular fibres are replaced by a membrane, including a small muscle at the underside of the lens. This muscle pulls the lens forward from its relaxed position when focusing on nearby objects. In teleosts, by contrast, a muscle projects from a vascular structure in the floor of the eye, called the falciform process, and serves to pull the lens backwards from the relaxed position to focus on distant objects. While amphibians move the lens forward, as do cartilaginous fish, the muscles involved are not homologous with those of either type of fish. In frogs, there are two muscles, one above and one below the lens, while other amphibians have only the lower muscle.[11]
In the most primitive vertebrates, the lampreys and hagfish, the lens is not attached to the outer surface of the eyeball at all. There is no aqueous humor in these fish, and the vitreous body simply presses the lens against the surface of the cornea. To focus its eyes, a lamprey flattens the cornea using muscles outside of the eye and pushes the lens backwards.[11]
Function[edit]
Accommodation[edit]
An image that is partially in focus, but mostly out of focus in varying degrees.
The lens is flexible and its curvature is controlled by ciliary muscles through the zonules. By changing the curvature of the lens, one can focus the eye on objects at different distances from it. This process is called accommodation. At short focal distance the ciliary muscle contracts, zonule fibers loosen, and the lens thickens, resulting in a rounder shape and thus high refractive power. Changing focus to an object at a greater distance requires the relaxation of the lens and thus increasing the focal distance.
The refractive index of human lens varies from approximately 1.406 in the central layers down to 1.386 in less dense layers of the lens.[12] This index gradient enhances the optical power of the lens.
Aquatic animals must rely entirely on their lens for both focusing and to provide almost the entire refractive power of the eye as the water-cornea interface does not have a large enough difference in indices of refraction to provide significant refractive power. As such, lenses in aquatic eyes tend to be much rounder and harder.
Crystallins and transparency[edit]
Graph showing optical density (OD) of the human crystalline lens for newborn, 30-year-old, and 65-year-old from wavelengths 300-1400 nm.
Crystallins are water-soluble proteins that compose over 90% of the protein within the lens.[13] The three main crystallin types found in the human eye are α-, β-, and γ-crystallins. Crystallins tend to form soluble, high-molecular weight aggregates that pack tightly in lens fibers, thus increasing the index of refraction of the lens while maintaining its transparency. β and γ crystallins are found primarily in the lens, while subunits of α -crystallin have been isolated from other parts of the eye and the body. α-crystallin proteins belong to a larger superfamily of molecular chaperone proteins, and so it is believed that the crystallin proteins were evolutionarily recruited from chaperone proteins for optical purposes.[14] The chaperone functions of α-crystallin may also help maintain the lens proteins, which must last a human for his/her entire lifetime.[14]
Another important factor in maintaining the transparency of the lens is the absence of light-scattering organelles such as the nucleus, endoplasmic reticulum, and mitochondria within the mature lens fibers. Lens fibers also have a very extensive cytoskeleton that maintains the precise shape and packing of the lens fibers; disruptions/mutations in certain cytoskeletal elements can lead to the loss of transparency.[15]
The lens blocks most ultraviolet light in the wavelength range of 300–400 nm; shorter wavelengths are blocked by the cornea. High intensity ultraviolet light can harm the retina, and artificial intraocular lenses are therefore manufactured to also block ultraviolet light.[16] People lacking a lens (a condition known as aphakia) perceive ultraviolet light as whitish blue or whitish-violet.[17][18]
Nourishment[edit]
The lens is metabolically active and requires nourishment in order to maintain its growth and transparency. Compared to other tissues in the eye, however, the lens has considerably lower energy demands.[19]
By nine weeks into human development, the lens is surrounded and nourished by a net of vessels, the tunica vasculosa lentis, which is derived from the hyaloid artery.[7] Beginning in the fourth month of development, the hyaloid artery and its related vasculature begin to atrophy and completely disappear by birth.[20] In the postnatal eye, Cloquet's canal marks the former location of the hyaloid artery.
After regression of the hyaloid artery, the lens receives all its nourishment from the aqueous humor. Nutrients diffuse in and waste diffuses out through a constant flow of fluid from the anterior/posterior poles of the lens and out of the equatorial regions, a dynamic that is maintained by the Na+/K+-ATPase] pumps located in the equatorially positioned cells of the lens epithelium.[5]
Glucose is the primary energy source for the lens. As mature lens fibers do not have mitochondria, approximately 80% of the glucose is metabolized via anaerobic metabolism.[21] The remaining fraction of glucose is shunted primarily down the pentose phosphate pathway.[21] The lack of aerobic respiration means that the lens consumes very little oxygen as well.[21]
Clinical significance[edit]
Cataracts are opacities of the lens. While some are small and do not require any treatment, others may be large enough to block light and obstruct vision. Cataracts usually develop as the aging lens becomes more and more opaque, but cataracts can also form congenitally or after injury to the lens. Nuclear sclerosis is a type of age-related cataract. Diabetes is another risk factor for cataract. Cataract surgery involves the removal of the lens and insertion of an artificial intraocular lens.
Presbyopia is the age-related loss of accommodation, which is marked by the inability of the eye to focus on nearby objects. The exact mechanism is still unknown, but age-related changes in the hardness, shape, and size of the lens have all been linked to the condition.
Ectopia lentis is the displacement of the lens from its normal position.
Aphakia is the absence of the lens from the eye. Aphakia can be the result of surgery or injury, or it can be congenital.
Additional images[edit]
MRI scan of human eye showing lens.
Interior of anterior chamber of eye.
The crystalline lens, hardened and divided.
Section through the margin of the lens, showing the transition of the epithelium into the lens fibers.
The structures of the eye labeled
Another view of the eye and the structures of the eye labeled
This svg file was configured so that the rays, diaphragm and crystalline lens are easily modified[22]
See also[edit]
Medical portal
Evolution of the eye, for how the lens evolved
Intraocular lenses
Iris
Lens capsule
Phacoemulsification
Visual perception
Zonules of Zinn
Crystallin
References[edit]
Jump up ^ "Equator of lens - definition from". Biology-Online.org. Retrieved 2012-11-25.
Jump up ^ "equator of the crystalline lens - definition of equator of the crystalline lens in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia". Medical-dictionary.thefreedictionary.com. Retrieved 2012-11-25.
^ Jump up to: a b c d e f John Forrester, Andrew Dick, Paul McMenamin, William Lee (1996). The Eye: Basic Sciences in Practice. London: W. B. Saunders Company Ltd. p. 28 ISBN 0-7020-1790-6
Jump up ^ Duker, Myron Yanoff, Jay S. (2008). Ophthalmology (3rd ed.). Edinburgh: Mosby. p. 382. ISBN 978-0323057516.
^ Jump up to: a b O. Candia (2004). Electrolyte and fluid transport across corneal, conjunctival and lens epithelia. Experimental Eye Research 78 (3): 527–535.
^ Jump up to: a b "eye, human". Encyclopædia Britannica from Encyclopædia Britannica 2006 Ultimate Reference Suite DVD 2009
^ Jump up to: a b c The Eye: Basic Sciences in Practice, p. 102, ISBN 0-7020-1790-6
Jump up ^ Cvekl, Aleš; Ashery-Padan, Ruth (2014-12-01). "The cellular and molecular mechanisms of vertebrate lens development". Development. 141 (23): 4432–4447. doi:10.1242/dev.107953. ISSN 0950-1991. PMID 25406393.
Jump up ^ Cantù, Claudio; Zimmerli, Dario; Hausmann, George; Valenta, Tomas; Moor, Andreas; Aguet, Michel; Basler, Konrad (2014-09-01). "Pax6-dependent, but β-catenin-independent, function of Bcl9 proteins in mouse lens development". Genes & Development. 28 (17): 1879–1884. doi:10.1101/gad.246140.114. ISSN 0890-9369. PMID 25184676.
Jump up ^ Kardong, K. (2008). Vertebrates: Comparative anatomy, function, evolution (5th ed.). (pp. 676–677). Boston: McGraw-Hill
^ Jump up to: a b c d Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 463–464. ISBN 0-03-910284-X.
Jump up ^ Hecht, Eugene. Optics, 2nd ed. (1987), Addison Wesley, ISBN 0-201-11609-X. p. 178.
Jump up ^ Hoehenwarter W.; Klose J.; Jungblut P. R. (2006). "Eye lens proteomics". Amino Acids. 30 (4): 369–389. doi:10.1007/s00726-005-0283-9.
^ Jump up to: a b Andley U (2006). "Crystallins in the eye: function and pathology". Progress in Retinal and Eye Research. 26 (1): 78–98. doi:10.1016/j.preteyeres.2006.10.003.
Jump up ^ H Bloemendal, W. de Jong, R Jaenicke, NH Lubsen, C Slingsby and A Tardieu (2004). "Aging and vision: structure, stability, and function of lens crystallins". Progress in Biophysics and Molecular Biology. 86 (3): 407–485. doi:10.1016/j.pbiomolbio.2003.11.012. PMID 15302206. CS1 maint: Uses authors parameter (link)
Jump up ^ M A Mainster (2006). "Violet and blue light blocking intraocular lenses: photoprotection versus photoreception". British Journal of Ophthalmology. 90 (6): 784–792. doi:10.1136/bjo.2005.086553. PMC 1860240  . PMID 16714268.
Jump up ^ R M Anderson (1983). "Visual perceptions and observations of an aphakic surgeon". Perceptual and Motor Skills. 57: 1211–1218. doi:10.2466/pms.1983.57.3f.1211.
Jump up ^ David Hambling (29 May 2002). "Let the light shine in". The Guardian.
Jump up ^ Whikehart, David R. (2003). Biochemistry of the Eye, 2nd ed. 2003. Philadelphia: Butterworth Heinemann, p. 107–8 ISBN 0-7506-7152-1
Jump up ^ The Eye: Basic Sciences in Practice, p. 104, ISBN 0-7020-1790-6
^ Jump up to: a b c Biochemistry of the Eye, 2nd ed, p. 107–8, ISBN 0-7506-7152-1
Jump up ^ Download and open with Inkscape 9.1. The separate components reside on different "layers" to facilitated editing.
External links[edit]
Histology image: 08001loa – Histology Learning System at Boston University
[hide]
v
t
e
Anatomy of the globe of the eye
Fibrous tunic (outer)
Sclera
Episcleral layer
Schlemm's canal
Trabecular meshwork
Cornea
Limbus
layers
Epithelium
Bowman's
Stroma
Dua's layer
Descemet's
Endothelium
Uvea/vascular tunic (middle)
Choroid
Capillary lamina of choroid
Bruch's membrane
Sattler's layer
Ciliary body
Ciliary processes
Ciliary muscle
Pars plicata
Pars plana
Iris
Stroma
Pupil
Iris dilator muscle
Iris sphincter muscle
Retina (inner)
Layers
Inner limiting membrane
Nerve fiber layer
Ganglion cell layer
Inner plexiform layer
Inner nuclear layer
Outer plexiform layer
Outer nuclear layer
External limiting membrane
Layer of rods and cones
Retinal pigment epithelium
Cells
Photoreceptor cells (Cone cell, Rod cell) → (Horizontal cell) → Bipolar cell → (Amacrine cell) → Retina ganglion cell (Midget cell, Parasol cell, Bistratified cell, Giant retina ganglion cells, Photosensitive ganglion cell) → Diencephalon: P cell, M cell, K cell, Muller glia
Other
Macula
Perifoveal area
Parafoveal area
Fovea
Foveal avascular zone
Foveola
Optic disc
Optic cup
Ora serrata
Anatomical regions of the eye
Anterior segment
Adnexa
Fibrous tunic
Anterior chamber
Aqueous humour
Iris
Posterior chamber
Ciliary body
Lens
Capsule of lens
Zonule of Zinn
Posterior segment
Vitreous chamber
Vitreous body
Retina
Choroid
Other
Keratocytes
Ocular immune system
Tapetum lucidum
Eye care professional
Eye disease
Refractive error
Accommodation
Physiological Optics
Visual perception
Authority control
LCCN: sh85034493
GND: 4003601-7
BNF: cb119648755 (data)
NDL: 00571638
BNE: XX534868
Retrieved from "https://en.wikipedia.org/w/index.php?title=Lens_(anatomy)&oldid=805893062"
Categories:
Human eye anatomy
Lenses
Hidden categories:
CS1 maint: Uses authors parameter
Medicine infobox template using GraySubject or GrayPage
Medicine infobox template using Dorlands parameter
Wikipedia articles with LCCN identifiers
Wikipedia articles with GND identifiers
Wikipedia articles with BNF identifiers
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
Languages
العربية
Bosanski
Català
Čeština
Dansk
Deutsch
Dolnoserbski
Eesti
Español
Esperanto
Euskara
فارسی
Français
Galego
한국어
Hornjoserbsce
Hrvatski
Ido
Bahasa Indonesia
Italiano
עברית
Basa Jawa
Lietuvių
Bahasa Melayu
Nederlands
日本語
Norsk nynorsk
Polski
Português
Română
Русский
Simple English
Slovenčina
Slovenščina
کوردی
Srpskohrvatski / српскохрватски
Suomi
Svenska
Татарча/tatarça
Тоҷикӣ
Українська
اردو
ייִדיש
中文
Edit links
This page was last edited on 18 October 2017, at 09:01.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

key: html

type: local

value: div

attrs: id class

values: mw-page-base noprint

values: mw-head-base noprint

value: a

attrs: id class lang

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

value: i

value: th

attrs: colspan style

value: tr

value: img

attrs: href class

value: td

values: Schematic diagram of the human eye en-edit.png

attrs: href title

values:
/wiki/Focal_distance
mw-redirect
Focal distance

values:
/wiki/Photographic_lens
mw-redirect
Photographic lens

values:
/wiki/Refractive_power
mw-redirect
Refractive power

values:
/wiki/Anterior_segment
mw-redirect
Anterior segment

values:
/wiki/Lens_capsule
mw-redirect
Lens capsule

values:
/wiki/Aqueous_humor
mw-redirect
Aqueous humor

values:
/wiki/Gap_junctions
mw-redirect
Gap junctions

values:
/wiki/Columnar_cells
mw-redirect
Columnar cells

values:
/wiki/Cartilaginous_fish
mw-redirect
Cartilaginous fish

attrs: alt src width height class srcset data-file-width data-file-height

values: Edit section: Crystallins and transparency

values:
/wiki/Chaperone_proteins
mw-redirect
Chaperone proteins

values:
/wiki/Cloquet%27s_canal
mw-redirect
Cloquet's canal

values:
/wiki/Anaerobic_metabolism
mw-redirect
Anaerobic metabolism

values:
/wiki/Aerobic_respiration
mw-redirect
Aerobic respiration

values: display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle

values: margin:0.5em 0 0.5em 1em;border:solid #aaa 1px

values:
/wiki/Zonules_of_Zinn
mw-redirect
Zonules of Zinn

values:
nofollow
external text
//doi.org/10.1242%2Fdev.107953

values:
nofollow
external text
//www.worldcat.org/issn/0950-1991

values:
/wiki/PubMed_Identifier
mw-redirect
PubMed Identifier

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/25406393

values:
nofollow
external text
//doi.org/10.1101%2Fgad.246140.114

values:
nofollow
external text
//www.worldcat.org/issn/0890-9369

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/25184676

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/15302206

values: Category:CS1 maint: Uses authors parameter

values:
nofollow
external text
//doi.org/10.1136%2Fbjo.2005.086553

attrs: alt src title width height srcset data-file-width data-file-height

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/16714268

values:
nofollow
external text
//doi.org/10.2466%2Fpms.1983.57.3f.1211

values: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;

attrs: alt src width height srcset data-file-width data-file-height usemap

values: 1:posterior segment 2:ora serrata 3:ciliary muscle 4:ciliary zonules 5:Schlemm's canal 6:pupil 7:anterior chamber 8:cornea 9:iris 10:lens cortex 11:lens nucleus 12:ciliary process 13:conjunctiva 14:inferior oblique muscule 15:inferior rectus muscule 16:medial rectus muscle 17:retinal arteries and veins 18:optic disc 19:dura mater 20:central retinal artery 21:central retinal vein 22:optic nerve 23:vorticose vein 24:bulbar sheath 25:macula 26:fovea  27:sclera 28:choroid 29:superior rectus muscle 30:retina

values: margin-left: 255px; margin-top: -20px; text-align: left;

values:
navbox-image
5
width:1px;padding:0px 0px 0px 2px

values: Intrinsically photosensitive retinal ganglion cells

values:
/wiki/Fibrous_tunic
mw-redirect
Fibrous tunic

values: nowraplinks hlist collapsible autocollapsed navbox-inner

values:
nofollow
external text
https://d-nb.info/gnd/4003601-7

values: Category:Medicine infobox template using GraySubject or GrayPage

values: Category:Medicine infobox template using Dorlands parameter

values: Category:Wikipedia articles with LCCN identifiers

values: Category:Wikipedia articles with GND identifiers

values: Category:Wikipedia articles with BNF identifiers

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values:
/wiki/Lens_(anatomy)
View the content page [ctrl-alt-c]
c

values: Discussion about the content page [ctrl-alt-t]

values: p-namespaces navigation vectorTabs p-namespaces-label

values:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

values: Past revisions of this page [ctrl-alt-h]

values: p-views navigation vectorTabs p-views-label

values:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

values:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

values:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

values: Featured content – the best of Wikipedia

values: Find background information on current events

values:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

values: portal navigation p-navigation p-navigation-label

values: Guidance on how to use and edit Wikipedia

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values: A list of all special pages [ctrl-alt-q]

values: Permanent link to this revision of the page

values: Link to connected data repository item [ctrl-alt-g]

values: Printable version of this page [ctrl-alt-p]

values:
uls-settings-trigger
Language settings
0
button
true

values: عدسة (تشريح) – Arabic

values: interlanguage-link interwiki-es badge-Q17437798 badge-goodarticle

values: עדשה (עין) – Hebrew

values:
https://nl.wikipedia.org/wiki/Ooglens
Ooglens – Dutch
nl
nl
interlanguage-link-target

values:
https://ro.wikipedia.org/wiki/Cristalin
Cristalin – Romanian
ro
ro
interlanguage-link-target

values: Хрусталик – Russian

values: Күз ясмыгы – Tatar

values: Ҷалидия – Tajik

values: Кришталик – Ukrainian

values: عدسہ (آنکھ) – Urdu

values:
suggestions
display: none; font-size: 13px;

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Lens_anatomy rootpage-Lens_anatomy vector-nav-directionality skin-vector action-view