Lecture 10 Kidneys and osmoregulation

Question 1

fish kidneys (3)

Answer 1

paired structures, often fused
dorsal to body cavity, ventral to vertebrae
anterior and posterior portions

Question 2

anterior portion (pronephros) (3)

Answer 2

reproductive in male elasmobranchs, chimeras, and non-teleost bony fishes

lymphotic and hemopoietic function (makes white and red blood cells) in teleosts - also contains chromaffin and interrenal tissues

ciliated nephrostome opens to coelom

Question 3

posterior portion (opisthonephros) (2)

Answer 3

for execratory purposes
lacks nephrostome

Question 4

kidney blood flow (3 steps)

Answer 4

dorsal Aorta - glomerulus - cardinal vein

Question 5

hyperosmotic definition

Answer 5

to face osmotic pressure greater than the physiological norm

Question 6

osmoregulation in freshwater fish (4)

Answer 6

-fish hyperosmotic environments tend to gain H20
-filtration at glomerulus where H20 & small molecules reabsorb glucose & ions in tubules (ions in bladder)
-Na+, Cl- lost in urine due to amount of H2O passed (highly dilute)
-gills absorb most H2O, salts and excrete most urea, ammonia

Question 7

osmoregulation in saltwater fish (4)

Answer 7

-hypoosmotic: H2O diffuses out lose up to 30-60% intake

-drink seawater as H2O source: 7-35% body wt. per day absorbed in alimentary canal

-monovalent ions excreted from chloride cells found on gills and also mouth, operculum, head

-kidneys have reduced/lost glomeruli to minimize renal H2O loss

Question 8

Osmoregulation In Marine Elasmobranchs (4)

Answer 8

-elasmobranchs retain nitrogenous wastes
-urea and trimethylamine oxide (TMAO) are reabsorbed in kidney
-excrete H2O and salts (Mg++, PO4) in urine and Na+ in rectal gland
-in freshwater bull sharks increase urine flow and lose rectal gland function