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5 Cards in this Set
- Front
- Back
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Overview of descending limb for water reabsorption |
High permeable H2O AQP-1 channel always open No Na+ reabsorption |
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Overview of ascending limb for water reabsorption |
Actively transports NaCl from lumen into interstitial fluid 200 mOsm/l Impermeable to H2O |
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What is the point of concentrating the fluid and then diluting it? |
Vertical gradient in medullary interstitial fluid that collecting ducts use to concentrate tubular fluid further so a urine more concentrated than body fluid can be excreted Fluid is hypotonic in distal part can excrete a urine more dilute than normal body fluids |
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Where does vasopressin-controlled variable H2O reabsorption occur? |
Final tubular segments Obligatory H2O reabsorption proximal tubule (65 % filtered H2O) loop of Henle (15 % filtered H2O) |
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What is the stimulus for ADH release?
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1) Most Potent: Osmolarity. Greater than 280 mOsM Hypothalamic osmoreceptors Interneurones in hypothalamus - synthesise AD. Released from pituitary. Collecting duct epithelium. 2) Low blood volume Decreased atrial stretch detected by stretch receptors. Sensory neuron to hypothalamus. 3) Decreased blood pressure. Carotid and aortic baroreceptors. Sensory neuron to hypothalamus. |
