chapter 44: osmoregulation and excretion

Question 1

What is omsmolarity?

Answer 1

solute concentration of a solution determines movement of water across a selectively permeable membrane

Question 2

What is osmoregulation?

Answer 2

controls solute concentrations and balances gain and loss of water

Question 3

What are osmoconformers?

Answer 3

are isoosmotic with their surrondings and do not regulate their osmolarity

Question 4

What are osmoregulators?

Answer 4

expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment

Question 5

What does stenohaline mean in animals?

Answer 5

they cannot tolerate substantial changes in external osmolarity

Question 6

What does euryhaline mean in animals?

Answer 6

they can survive large fluctuations in external osmolarity

Question 7

What are marine invertebrates?

Answer 7

osmoconformers

Question 8

What are marine vertebrates (and some invertebrates?)

Answer 8

osmoregulators

Question 9

How does osmoregulation balance the uptake and loss of water and solutes?

Answer 9

driving force for movement of solutes and water is a concentration gradient of one or more solutes across the plasma membrane

Question 10

What is the osmoregulation of marine animals?

Answer 10

marine fish lose water by osmosis and gain salt by diffusion from food

Question 11

What is the osmoregulation of freshwater animals?

Answer 11

salts lost by diffusion are replaced in foods and by uptake across the gills

Question 12

What is anhydrobiosis?

Answer 12

some aquatic invertebrates in temporary ponds lose most of their body water and survive in dormant state

Question 13

What helps terrestrial animals prevent dehydration?

Answer 13

body coverings

Question 14

How do desert animals get water savings?

Answer 14

nocturnal lifestyles

Question 15

What are the different factors that affect amount of energy in osmoregulators?

Answer 15

1. how different the animals osmolarity is from its surroundings
2. how easily water and solutes move across the animals surface
3. work required to pump solutes across the membrane

Question 16

What is urea?

Answer 16

excretion made by mammals, urea requaires less water than ammonia

Question 17

What is uric acid?

Answer 17

what insects, reptiles and birds excrete. it is non toxic, is is more energetically expensive to produce than urea

Question 18

What is ammonia?

Answer 18

what fish excrete

Question 19

What is the role of the excretory system?

Answer 19

regulates solute movement between internal fluids and the external environments
form urine by refining a filtrate derived from body fluids

Question 20

What are the key functions of most excretory systems?

Answer 20

1. filtration: filtering of body fluids
2. reabsorption: reclaiming valuable solutes
3. secretion: adding non essential solutes and wastes from body fluids to the filtrate
4. excretion: processed filtrate containing nitrogenous wastes released from body/

Question 21

What is a protonephridium?

Answer 21

a network of dead-end tubules connected to external openings

Question 22

What is metanephridia?

Answer 22

consists of tubules that collect coelomic fluid and produce dilute urine for excretion

Question 23

What is the role of malpighian tubules?

Answer 23

remove nitrogenous wastes from hemolymph and function in osmoregulation

Question 24

How does blood filtrate to urine?

Answer 24

1. proximal tubule: reabsorption of ions, water and nutrients, materials are excreted
2. descending limb of the loop of henle: reabsorption of water continues due to aquaporin proteins - movement driven by high osmolarity
3. ascending limb of the loop of henle: salt diffuse from tubule but not water
4. distal tubule: regulates K+ and NaCl concentrates
5. collecting duct: carries filtrate through medulla to renal pelvis

Question 25

What is the antidiuretic hormone?

Answer 25

ADH - is released into the blood when osmolarity of blood rises above set point

Question 26

What is the reaction of ADH?

Answer 26

when binding ADH to receptor molecules, temporary increase in aquaproin proteins in membrane happens, reducing urine volume and lowers blood osmolarity