13061809
Description
Flashcards by J yadonknow, updated more than 1 year ago
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Created by J yadonknow
about 6 years ago
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| Question | Answer |
| Function of CC multiplier | Concentrate urine in LOH |
| Initial concentration of CCM | Walls of AL impermeable to water Walls of DL permeable Osmotic gradient |
| Single effect generation | A.T./Diffusion of NaCl out of AL to ISF Dilutes tubule fluid, conc.'s ISF H2O from DL to hyperosmotic ISF Diffusion of Na/Cl to DL |
| The single effect | Dif in OSP and [Nacl] btw. ALF/DLF/ISF H2O moves out of DL to ISF until = |
| How does OSP' change in nephron | OSP' increases as depth into medulla increases |
| What does length of LOH determine? | OSP' size and conc. of urine |
| What is the vasa recta? | Specialised capillary of juxtamedullary nephron |
| What is the function? | Creates a hyperosmotic ISF to draw as much water out of nephron as possible Especially during antidiuresis |
| Salt diffusion from VR | DVR: plasma ~300 mOsm Encounters ^ osmotic ISF as it descends Salt diffuses from ISF to plasma, ^ its conc AVR: Conc. blood flows towards cortex from papilla loses salt to increasingly dilute medullary ISF |
| Summary | Salt reabsorbed from LOH trapped+recycled within medulla by CC flow of blood in vasa recta |
| Water reabsorption in VR | DVR: Dilute blood flow into medulla loses H2O to ^ conc. medullar ISF AVR: Conc. blood flow from tip of papilla towards cortex gains H2O from ^ dilute medullary ISF |
| Summary | Water tends to short circuit from DVR-> AVR helps preserve conc. of medullary ISF |
| Diagram of urea movement | ah |
| Where is [urea] high | interstitium of inner medulla |
| Why does inner medulla have a steep osmotic '? | Facilitate constant reabsorption of H2O from DL This maintains a high conc. of tubular fluid in DCT/CD, concentrating urine |
| Urea Uniporters | Expressed in CD facilitates diff of urea from intertubular -> ISF Further ^ OSP of ISF of inner medulla Further ^ H2O reabsorption |
| Hormonal control Vasopressin (ADH) | Upregulates urea uniporter expression of UT-A1/UT-A3 |
| UT-A2 | Expressed in LOH, passes urea from ISF to intertubular fluid |
| Vasopressin | Produced in hypothalamus Released by pituitary gland ^ H2O permeability of DCT/CD ^ BP as more h2o reabsorped Decreases blood plasma osmolarity |
| How does ADH do this? | Upregulates translocation of AQP channels to apical PCM of DCT/CD cells |
| What happens when dehydrated | When dehydrated less H2O available to be reabsorbed, urine more conc., more ADH released to ^ H2O reabsorption |
| Renin | Creates Angiotensin I from angiotensin Converted to Angiotensin II Stimulates adrenal cortex to produce aldosterone Aldosterone ^ Na+ reabsorption Angiotensin II also stimulates General Systemic Vasoconstriction |
| Stimulators of renin secretion | Low BP Low Na+ in DCT, sensed by Maculla Densa SNS |
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