ch 40 - exam 3

Question 1

What is osmoregulation?

Question 2

What are electrolytes?

Answer 2

salts, ions (Cl-, K+) important for

Question 3

What are the rules to diffusion and osmosis/ how do they work?

Question 4

What is active vs passive vs secondary active transport?

Answer 4

• active: requires an energy source (ATP), moves molecules against gradient
• passive: based on diffusion down a gradient, no ATP, need a channel or carrier to help
• 2º: cotransport; driven by energy from gradient, something goes down conc. gradient and something goes against

Question 5

What are osmoconformers vs omoregulators?

Answer 5

osmoconformers: match surrounding fluid, ocean animals

osmoregulators: control osmolarity of fluids/tissues and it is different than surrounding fluid, freshwater

Question 6

What are the osmotic challenges marine vs freshwater fish face and how do they solve it?

Answer 6

marine fish: drink a lot, don’t pee much, gain many electrolytes by diffusion, spend ATP, lose electrolytes via active transport out

freshwater fish: don’t drink water, pee a lot, have pumps, gain electrolytes through active transport in, lose electrolytes via diffusion

Question 7

What is the trade off with gills?

Answer 7

thin to allow gas exchange but also lose important water or ions

Question 8

How do sharks osmoconform and how does their rectal gland work?

Answer 8

blood osmolarity = SW osmolarity
blood composition:
- less salt, more urea, low NaCl due to salt excretion
Rectal Gland:
- active transport sets up strong gradient (Na+)
- use gradient to transport other substances w/out using more energy
- Na+ build up at Na+/Cl-/K+ costransporter

Question 9

what kinds of nitrogenous waste are there and what are costs/benefits? which is most costly to make vs least? which requires the most water vs least?

Question 10

Does water move actively?

Answer 10

no - no known pump to move water against its gradient

Question 11

What does osmoregulation in insects look like?

Answer 11

• minimize water loss:
  - spiracles
  - cuticle = wax
  malpighian tubules collect wastes (incl. water and electrolytes), direct contact with hemolymph
  hindgut has specialized cells for reuptake (reabsorption of water and electrolytes)

Question 12

how do malpighian tubules work in insects?

Question 13

how does the mammalian kidney work?

Question 14

what are the 5 parts of the kidney + function of each?

Answer 14

1. Renal Corpuscle: filtration, so large molecules and cells remain in blood
2. Proximal Tubule: reabsorption to bloodstream (Na+, glucose, Cl-, vitamins, H2O)
3. Loop of Henle: water and ion movement, water leaves and is reabsorbed by blood vessels
4. Distal Tubule: filtrate that enters is always dilute, regulates bp
5. Collecting Duct: leaks urea to maintain osmotic gradient, not permeable to water

Question 15

how does the loop of henle reabsorb water back into the body?

Answer 15

passive transport of water into body in descending limb

Question 16

what are the 3 sections of the loop of henle and how do they function?

Answer 16

• descending limb: lets water back into body but not salt or electrolytes
• thin ascending limb: expels Cl- and Na+ back into body
• thick ascending limb: uses ATP to pump electrolytes back into body to maintain outside osmolarity so that water always goes out on descending limb

Question 17

what is the collecting ducts role in moderating the urine color and outflow?

Answer 17

Leaks urea to maintain osmotic gradient, yellow= nitrogenous waste, urine concentrated

Question 18

where are aquaporins inserted? what hormone is involved? under what conditions are they added?

Answer 18

?