Control of blood water potential
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- Created by: Rachelezy
- Created on: 19-02-20 15:24
Define osmoregulation
Control of blood water potential via homeostatic mechanisms
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Describe the gross structure of a mammalian kidney
Fibrous Capsule -protects kidney Cortex -outer region consists of Bowman's capsule, convoluted tubules, blood vessels Medulla-inner region collecting ducts, loops of Henle, blood vessels. Renal Pelvis-collects urine into ureter
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gross structure of a mammalian kidney (continued)
Ureter - tube carries urine to bladder Renal artery - supplies kidney with oxygenated blood Renal vein - returns deoxygenated blood from kidney to the heart
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Describe the structure of a nephron
Bowman's Capsule-at start,surrounds glomerulus Proximal Convoluted Tubule-series of loops surrounded by capillaries,walls made of epithelial cells Loop of Henle-from cortex to medullaDistal Convoluted Tubule-fewer capillariesCollecting Duct-to pelvis
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Describe the blood vessels associated with the nephron
*Wide afferent arterioles from renal artery enters renal capsule and forms glomerulus (brached knot of capillaries that combine to form narrow efferent arteriole) *Efferent arteriole branches to from capillary network that surround tubules.
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Explain how glomerular filtrate is formed
Ultrafilitration In Bowman's Capsule - High hydrostatic pressure in glomerulus forces small molecules out AGAINST osmotic gradient. Basement membrane acts as filter. Blood cells and large molecules remain in capillary
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How are cells of the Bowman's capsule adapted for ultrafiltration?
Fenestrations between epithelial cells of capillaries. Fluid can pass between and under folded membrane of podocytes
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State what happens during selective reabsorption and where it occurs
Useful molecules from glomerular filtrate e.g. glucose are absorbed back into the blood. Occurs in the proximal convoluted tubule
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Outline the transport processes involved in selective reabsorption
glucose form glomerular filtrate -(co-transport with Na+ ions)> cells lining PCT -(active transport)> intercellular spaces -(diffusion)> blood capillary lining tubule
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How are cells in the PCT adapted for selective reasborption?
Microvilli - large surface area for co-transporter proteins. Many mitochondria - ATP for active transport of glucose into intercellular spaces. Folded basal membrane - large surface area
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What happens in the Loop of Henle?
1)Active transport of Na+ & Cl- out of ascending limb.2)WP of interstitial fluid decreases.3)Osmosis of water out of descending limb.4)WP of filtrate decreases going down descending limb; lowest in medullory region, highest at top of ascending limb
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Explain the role of the distal convoluted tubule
Reabsorption of water via osmosis and of ions via active transport. The permeability of walls is determined by the action of hormones
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Explain the role of the collecting duct
Reabsorption of water from filtrate into interstitial fluid via osmosis through aquaporins
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Explain why it is important to maintain an Na+ gradient
Countercurrent Multiplier - filtrate in collecting duct is always beside an area of interstitial fluid that has a lower water potential. Maintains wp gradient for maximum reabsorption of water
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What might cause blood water potential to change?
*Level of water intake *Level of ion intake in diet *Level of ions used in metabolic processes or excreted *sweating
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Explain the role of the hypothalamus in osmoregulation
1)Osmosis of water out of osmoreceptors in hypothalamus causes them to shrink. 2)Triggers hypothalamus to produce more antidiuretic hormone (ADH)
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Explain the role of the posterior pituitary gland in osmoregulation
Stores and secretes ADH produced by the hypothalamus
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Explain the role of ADH in osmoregulation
Makes cells lining collecting duct more permeable to water. Binds to receptor -> activates phosphorylase ->vesicles with aquaporins on membrane fuse with cell surface membrane
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Role of ADH in osmoregulation (continued)
Makes cells lining collecting duct more permeable to urea. Water potential in interstitial decreases. More water reabsorbed = more concentrated urine
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Other cards in this set
Card 2
Front
Describe the gross structure of a mammalian kidney
Back
Fibrous Capsule -protects kidney Cortex -outer region consists of Bowman's capsule, convoluted tubules, blood vessels Medulla-inner region collecting ducts, loops of Henle, blood vessels. Renal Pelvis-collects urine into ureter
Card 3
Front
gross structure of a mammalian kidney (continued)
Back
Card 4
Front
Describe the structure of a nephron
Back
Card 5
Front
Describe the blood vessels associated with the nephron
Back
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