- Antidiuretic Hormone (ADH) - Causes kidneys to increase water absorbtion.
- Osmoreceptors - specialized nerve cells in the hypothalamus that detect changes in the osmotic pressure of the blood and surrounding the extra-cellular fluids (ECF's)
- Aldosterone - Hormone that increases Na reabsorption from distal tubule and collecting ducts.
Balance
- Body adjusts for increased water intake by increasing urine output.
- Urine output is decreased when excercise is increased or water intake decreased.
- These adjustments involve interaction by the bodys two communication systems, the nervous system and the endocrine system.
ADH and the Nephron:
- 85% of water filtered into nephron is reabsorbed in the proximal tubule.
- Proximal tubule is permeable to water, but this permeability dosn't extend to the other parts of the nephron.
- the loop of henle is permeable to water and hydrogen ions, the ascending tubule is semipermeable to NaCl.
- Active Transport of Na ions concentrates solutes within the medula of the kidney.
- Without ADH, the tubule remains impermeable to water but still activlet transports Na ions from the tubules (oter 15%of water filtered into the nephron is lost)
-Brandon
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