osmoreglation and ion regulation

Question 1

what 2 types of gradient can result in diffusion

Answer 1

ionic and concentration

Question 2

are cations positively or negatively charged

Answer 2

positive

Question 3

what is osmosis

Answer 3

movement of a solvent (water) passively across a semi-permeable membrane

Question 4

what is osmolarity

Answer 4

concentration of all particles in a solution

Question 5

how is osmolarity measured

Answer 5

osmols / Litre

Question 6

what is the osmolarity of 1 mol/L CaCl2

Answer 6

= 1 Osm/L Ca+ and 2 Osm/L of Cl-
= 3 Osm/L

Question 7

what is tonicity

Answer 7

solute concentration that directly affects water movemnt by osmosis

Question 8

what particles does tonicity refer to

Answer 8

only solute particles that cannot cross the membrane

Question 9

what happens if a normal cell is placed in to a hypotonic solution

Answer 9

water diffuses into cell causing it to swell

Question 10

what happens when a cell is placed in a hypotonic solution for a long duration

Answer 10

hemolysis - burst

Question 11

what occurs if a cell is continuously in a hypertonic solution

Answer 11

crenation

Question 12

what molecules are transported via facilitated diffusion

Answer 12

polar molecules and larger ions

Question 13

what are the transporters used in secondary active transport

Answer 13

symporter and antiporter

Question 14

how do molecules move in secondary active transport

Answer 14

ion pumps create elctrochemical gradient driving secondary movement

Question 15

what transporter increases the rate of water movement

Answer 15

aquaporin

Question 16

what 2 things often control ion channels

Answer 16

ligands or voltage

Question 17

name a well known use of active transport

Answer 17

Na+ / K+
sodium potassium pumps

Question 18

2 osmotic challenges

Answer 18

ingestion and excretion,
external environment

Question 19

what is an osmoconformer

Answer 19

body fluid and cellular osmolarity similar to that of external environment

Question 20

what types of animal are osmoconformers

Answer 20

invertebrates and some marine vertebrates

Question 21

how do elasmobranchs maintain extracellular fluid osmolarity

Answer 21

urea and NaCl secretion

Question 22

what is an osmoregulator

Answer 22

body fluid osmolarity is homeostatically regulated different to that of external environment

Question 23

what are the boundaries of osmolarity for an osmoregulator

Answer 23

290 - 400 mOsm / L

Question 24

in a hyper-osmoregulator, does the body fluid or external media have higher osmolarity

Answer 24

body fluid is higher

Question 25

what does euryhaline mean

Answer 25

they tolerate a large range of salinities

Question 26

what does stenohaline mean

Answer 26

only tolerate a narrow range of salinities

Question 27

what type of cell is used for epithelial transport in teleosts

Answer 27

ionocytes - mitochondria rich cells

Question 28

3 ways freshwater teleosts fight against water gain and salt loss

Answer 28

produce alot of dilute urine, reabsorbing urine salts,
gain salts from diet,
active uptake of salts from water via gills

Question 29

how do freshwater teleosts carry out active salt uptake

Answer 29

Na+ / K+ ATPase lowers cellular NA+
H+ ATPase creates local membrane potential driving NA+ uptake
Cl- uptake by apical HCO3- exchange
Cl- enters blood against conc gradient

Question 30

4 ways marine teleosts defend themselves against water loss and salt gain

Answer 30

low urine flow rates,
drink seawater to replace lost volume and active water uptake in gut,
don’t reduce permeability,
active excretion of salts via gills

Question 31

explain the process of active salt excretion in marine teleosts

Answer 31

Na+ / K+ ATPase lowers cellular Na+ and increases basolateral Na+
Na+ gradient drives Cl- entry via co-transporter
Cl- excreted via apical channels#
Na+ excreted by passive paracellular diffusion due to electrochemical gradient
K+ ions must recycle

Question 32

explain the process of active water uptake in marine teleosts

Answer 32

oesophagus and stomach - passive NaCl diffusion from seawater to blood
intestine - active salt uptake followed by water uptake

Question 33

what teleosts are euryhaline and why

Answer 33

salmonids and eels
have freshwater to saltwater migrations

Question 34

what is the name for migration from freshwater to saltwater

Answer 34

smoltification

Question 35

what changes occur in a salmonid when undergoing smoltification

Answer 35

acclimation induced by growth hormone and cortisol
apical proton pump is down regulated
proliferation of gill ionocytes
increased Na+ / K+ ATPase activity
increase NaCl secretion
silvering up and changes in body shape

Question 36

how do marine birds and reptiles cope with drinking sea water

Answer 36

secrete salt into salt gland