1. 7.6 Define gel electrophoresis. Briefly, describe how it works.

2.  Body adjusts for increased water intake by increasing _____________ output.  Adjustments involve the nervous and endocrine systems.

3.  ADH: antidiuretic hormone – causes kidneys to increase water reabsorption.  ADH: produced by specialized nerve cells in the hypothalamus.  Pituitary gland: stores and releases ADH into blood.  Osmoreceptors: specialized nerve receptors in the hypothalamus.  when blood solutes become more concentrated, increases blood’s osmotic pressure  osmoreceptors shrink (losing water)  nerve message sent to pituitary gland  ADH released into blood  reabsorbs more water from the nephrons  osmotic pressure regulated.

4.  Shrunken osmoreceptors  pituitary releases ADH  initiates thirst  water consumed  concentration of blood solutes decrease  lower osmotic pressure  fluids from blood to osmoreceptors  swell  nerve signal to nephrons  less water reabsorbed.

6.  Proximal tubule very permeable to water (85% of reabsorption occurs here). Descending loop of Henle is also permeable to water and ions.  Ascending loop of Henle and distal tubule is impermeable to water without ADH.  Permeable to NaCl  active transport of Na+ ions causes increase in ions in medulla (interstitual fluid).  15% of water filtered into nephron will be lost in urine if no ADH present

7.  ADH: makes upper part of distal tubule permeable to water  High [NaCl] in intercellular spaces  osmotic pressure increases  water sucked out of nephron.

8.  Kidneys adjust blood volumes  adjusts blood pressure.  Aldosterone: hormone that increases Na+ reabsorption.  Produced in the cortex or adrenal glands (right above kidneys).  As NaCl reabsorption increases, osmotic gradient increases  more water moves out of nephrons by osmosis.

10.  Reduction of oxygen and nutrients to tissues.  Juxtaglomerular apparatus: (near glomerulus)  detects low blood pressure  releases renin (enzyme that converts angiotensinogen to angiostensin)  Angiostensin: enzyme  Constriction of blood vessels  increase in blood pressure.  Stimulates the release of aldosterone from adrenal gland.

11.  Kidneys maintain pH balance  Relatively constant: b/n 7.3 & 7.4  We eat acidic/basic foods  Cellular respiration: CO2 production. ▪ Carbonic acid, weak acid, is produced. ▪ Buffer system: bicarbonate ion eliminates extra H+.

12.  Buffer system  Kidneys help restore buffer.  CO2 actively transported from peritubular capillaries (surround the ______________) into cells surrounding the nephron  CO2 + H2O  HCO3- and N+ ions.  HCO3- back into blood.  H+ recombind with phosphate ions or ammonia  excreted in urine.

15.  Page 356, # 1-8, 10.