Osmoregulation

Question 1

what is osmoregulation? what does it balance?

Answer 1

it is the regulation of solute concentrations

-balances water loss and gain (maintains homeostasis)

Question 2

what kind of environment do the physiological systems of animals operate in?

Answer 2

fluid environment

Question 3

what is excretion?

Answer 3

the removal of metabolic/toxic waste products from the

body

Question 4

what organs handle the excretion of waste products? what waste products do they deal with?

Answer 4

gills/lungs –> Carbon dioxide
excretory organs such as kidneys –> Nitrogenous wastes
kidneys/gills –> water

Question 5

what are excretory organs are often involved in both: …

3 main duties include:

Answer 5

• excretion and osmoregulation
  1. Removal of toxic wastes
  2. Maintaining solute ion concentration
  3. Maintaining water balance

Question 6

what is diffusion?

Answer 6

movement of solutes down their concentration gradient, from an area of higher solute concentration to an area of lower solute concentration

Question 7

what is osmosis?

Answer 7

movement of water through a semi-permeable membrane, from an area of low solute concentration to an area of higher solute concentration

Question 8

what is osmolarity? what does it determine?

Answer 8

• the solute concentration of a solution

- determines the direction of movement of water across a selectively permeable membrane

Question 9

what is a hyperosmotic solution?

Answer 9

• solution with higher solute concentration

- same as hypertonic solution

Question 10

what is a hypoosmotic solution?

Answer 10

• solution with a lower solute concentration

- same as hypotonic solution

Question 11

freshwater animals have adaptations to … water and … solutes. therefore freshwater is a ….. solution

Answer 11

1. reduce water uptake
2. conserve solutes
3. hypoosmotic solution

Question 12

marine animals have adaptations to … water and … solutes. therefore marine water is a … solution

Answer 12

1. increase, and conserve water uptake
2. reduce/limit solutes
3. hyperosmotic solution

Question 13

what are osmoconformers? give example

Answer 13

are organisms that are isoosmotic to their external environment, meaning that they do not have to regulate their osmolarity
eg. many marine invertebrates

Question 14

what are osmoregulators? give example

Answer 14

are organisms whose internal environment differs from their external one (hypoosmotic or hyperosmotic), and therefore expend energy to control water uptake and loss
eg. freshwater and marine vertebrates

Question 15

what challenges do marine fish face in osmoregulation?

Answer 15

1. gaining of salt ions from food and seawater (diffusion into gills)
2. water loss through osmosis from gills and other body parts

Question 16

what adaptations do marine fish have for osmoregulation?

Answer 16

1. drinking seawater –> because they’re actively losing water to the environment, they take up more water by drinking (but also gain salt)
2. actively excreting salt ions from gills (active transport)
3. excretion of salt ions from kidneys -> very little urine produced, very salt concentrated

Question 17

what challenges do freshwater fish face in osmoregulation?

Answer 17

1. loses salt by diffusion
2. gains water by osmosis through gills and other body parts
3. has to take in more water when eating

Question 18

what adaptations do freshwater fish have for osmoregulation?

Answer 18

1. does not drink water
2. active uptake of salt ions via gills (active transport)
3. excretes large amounts of urine, very dilute

Question 19

what are stenohaline animals?

Answer 19

• animals that cannot tolerate substantial changes in external osmolarity (ie. cannot survive in fluctuating salt environments)
• most fish

Question 20

what are euryhaline animals?

Answer 20

• animals that can survive large fluctuations in external osmolarity (ie. can survive large fluctuations of salt environments)
• salmon –> live in ocean, go to freshwater to spawn

Question 21

what is the major regulatory problem that terrestrial animals face?

Answer 21

dehydration

Question 22

what are behavioral adaptations of land animals to reduce water loss?

Answer 22

1. Being nocturnal
2. Hiding under vegetation
3. Living underground

Question 23

what structural adaptations do land animals have to reduce water loss?

Answer 23

-have body coverings
1. exoskeletons (insects)
2. shells (land snails)
3. layers of dead, keratinized skin cells (most
terrestrial vertebrates)

Question 24

what causes land animals considerable water loss?

Answer 24

1. loss from moist surfaces in their gas exchange organs
2. loss from urine and feces
3. loss across the skin.

Question 25

how do land animals typically mange water budgets?

Answer 25

1. by drinking/eating moist foods

2. using metabolic water produced by cellular respiration