Osmoregulation in Animals

Question 1

What are freshwater fish at risk of? (relating to water content)

Answer 1

Inundation of water and loss of salts

Question 2

What is the osmotic pressure of freshwater?

Answer 2

5 mOsm

Question 3

Are freshwater fish hyperosmotic or hypo-osmotic to their environment?

Answer 3

Hyperosmotic

Question 4

What does a ‘diluting’ kidney refer to in a freshwater fish?

Answer 4

Produces a large quantity of very dilute urine

Question 5

Are loops of Henle present in freshwater fish?

Answer 5

No

Question 6

What methods are used in freshwater fish to reabsorb salt?

Answer 6

-Additional salts are taken up by the gills
-Salts are reabsorbed in the proximal tubules of the nephrons

Question 7

Do freshwater fish drink?

Answer 7

NO

Question 8

Are saltwater bony fish hyperosmotic or hypo-osmotic to their environment?

Answer 8

hypo-osmotic

Question 9

What are saltwater bony fish at risk of? (relating to water content)

Answer 9

in danger of gaining salts and dehydrating

Question 10

Do marine fish drink seawater?

Answer 10

Yes, constantly

Question 11

How do marine fish desalinate?

Answer 11

excreting monovalent ions (eg Na+,Cl-) at the gills. The gills perform more osmoregulation than the kidneys

Question 12

What do marine fish nephrons lack?

Answer 12

glomeruli and Bowman’s capsules

Question 13

What are the main functions of the nephrons in marine fish?

Answer 13

produce small volume of urine to regulate divalent ions Ca2+, Mg2+

Question 14

What is the osmotic pressure of saltwater?

Answer 14

1100 mOsm

Question 15

What is the osmotic pressure in marine fish bodies?

Answer 15

600 mOsm

Question 16

What is the osmotic pressure in freshwater fish bodies

Answer 16

500 mOsm

Question 17

What is the stimulus for the control system for dehydration in mammals?

Answer 17

rise in osmolarity of plasma

Question 18

Where are the receptors and control centre for the dehydration control system in mammals?

Answer 18

The hypothalamus and the carotid artery

Question 19

What is the effector for dehydration control in mammals?

Answer 19

Antidiuretic Hormone (ADH) which is released from the posterior pituitary gland

Question 20

What is the ADH equivalent in reptiles, birds, fish and amphibians?

Answer 20

arginine vasotocin

Question 21

Where does ADH binds to in the Kidney?

Answer 21

receptors on the basal membrane of the collecting ducts

Question 22

What protein insertion does ADH trigger?

Answer 22

aquaporins (from vesicles which deliver info from host cells to recipient cells) onto the apical membranes. These serve as water channels and lead to formation of hyperosmotic urine.

Question 23

What is the apical membrane

Answer 23

wall of the tubule to the lumen

Question 24

What is the dehydration regulatory system in mammals called? And what kind of feedback does it use?

Answer 24

-Thirst Control Centre
-Negative feedback loop

Question 25

How do reptiles conserve water?

Answer 25

At the epithelium of cloaca (urogenital opening) water is reabsorbed and a concentrated uric paste is secreted

Question 26

What kind of urine do reptiles have?

Answer 26

Isosmotic

Question 27

What nephrons do reptiles have?

Answer 27

Only cortical nephrons

Question 28

What are the specific features of nephrons in desert mammals?

Answer 28

Only juxta-medullary nephrons to produce very concentrated urine. Have thick medullas. Very long loops of Henle - lots of NaCl pumps

Question 29

What is the osmotic pressure of kangaroo rat urine?

Answer 29

5500 mOsm

Question 30

What are some features of desert animals to help them not overheat?

Answer 30

-Most animals gain water in food and are nocturnal -Kangaroo rat lives in burrows to combat the heat – often seal the entrances -Long eared jerboas and fennec foxes have large ears to help dump heat -Long loops of Henle aid in water retention in desert mammals

Question 31

How do vampire bats use their kidneys after feeding?

Answer 31

-After feeding they are then so heavy that they need to produce a lot of dilute urine to reduce their weight so they can fly. -produce concentrated urine - 4,600mOsm/L.