Cell Homeostasis

Question 1

What are the normal intracellular and extracellular conditions for sodium

Answer 1

high extracellular, low intracellular

Question 2

What is the function of the thick ascending limb in the loop of Henle

Answer 2

reabsorption of Na+ and Cl-

Question 3

What are the properties of the apical membrane of the thick ascending limb

Answer 3

impermeable to water, ammonia and protons

Question 4

What does the reabsorption of NaCl across the TAL create

Answer 4

trans-epithelial osmotic gradient

Question 5

What is the trans-epithelial osmotic gradient responsible for

Answer 5

counter current multiplication

Question 6

Activity of what transporter depends on the inward Na gradient

Answer 6

NKCC

Question 7

What happens if intracellular sodium levels rise

Answer 7

diuresis, increased sodium and chloride in the urine

Question 8

Describe the normal chemical and electrical gradient for sodium movement

Answer 8

very large for sodium to move into the cell

Question 9

What problems occur if the sodium chemical and electrical gradient are reduced

Answer 9

action potential propagation problems, slower action potentials

Question 10

What controls intracellular Na+

Answer 10

Na/K ATPase pump

Question 11

What does Na/K ATPase require for its action

Answer 11

ATP phosphorylation

Question 12

What happens to the Na/K ATPase when 3 sodiums bind

Answer 12

phosphorylation

Question 13

What does phosphorylation of the Na/K ATPase pump trigger

Answer 13

conformational change

Question 14

What is the effect of this conformational change on the Na/K ATPase

Answer 14

shifts the binding domain from intracellular to extracellular side - moving Na+ out

Question 15

What does the function of the sodium potassium ATPase pump depend on

Answer 15

ATP, intracellular sodium and extracellular potassium

Question 16

What is the Na/K+ ATPase inhibited by

Answer 16

cardiac glycolysis, ouabain and digoxin

Question 17

What is the net effect on the membrane potential of the Na/K ATPase

Answer 17

makes inside of the cell more negative

Question 18

What does accumulation of K inside the cell create

Answer 18

driving force for potassium to leave the cell - making the cell more negative

Question 19

What are the normal intracellular and extracellular conditions for calcium

Answer 19

high extracellular calcium, low intracellular calcium

Question 20

Why is calcium regulation important

Answer 20

calcium is an important second messenger

Question 21

How does the cell maintain low intracellular calcium

Answer 21

Na/Ca exchanger, Ca ATPase

Question 22

What does the Na/Ca exchanger transport

Answer 22

exchanges extracellular sodium for intracellular calcium

Question 23

True or False - the Na/Ca exchanger is electrogenic

Answer 23

True

Question 24

What is the SLC8

Answer 24

solute co transporter type 8

Question 25

How many transmembrane spanning domains does the SLC8 have

Answer 25

10

Question 26

What is the Na/Ca exchanger a member of

Answer 26

SLC8 gene family

Question 27

How does the SLC8 gene family allow different functions in different cell types

Answer 27

changing its splice variant

Question 28

What family is the Ca ATPase a member of

Answer 28

P-Type ATPase family

Question 29

How many types of ATPases are there

Answer 29

2

Question 30

What are PMCAs

Answer 30

plasma membrane calcium pumps

Question 31

What is the function of PMCAs

Answer 31

pump Ca2+ across the plasma membrane out of the cell

Question 32

What is the function of SERCA

Answer 32

pump Ca2+ out of cytoplasm into organelles

Question 33

What is SERCA

Answer 33

calcium pumps found on sacroplasmic or ER membranes

Question 34

What are SPCA

Answer 34

Ca2+ pumps on golgi apparatus

Question 35

How does calcium signalling move calcium

Answer 35

across PM into cytoplasm, or out of storage organelle into cytoplasm

Question 36

Where are voltage operated Ca chanels found (VOCC)

Answer 36

excitable cells

Question 37

What are VOCCs activated by

Answer 37

depolarisation

Question 38

Where are receptor operated Ca channels (ROCC) found

Answer 38

secretory cells and nerve terminals

Question 39

What are ROCCs activated by

Answer 39

binding of agonist

Question 40

Example of a ROCC

Answer 40

NMDA receptor

Question 41

Where are mechanically activated Ca channels found

Answer 41

many cells

Question 42

What do mechanically activated Ca channels respond to

Answer 42

cell deformation

Question 43

What is an example of mechanically activated Ca channels

Answer 43

stretch activated channels

Question 44

What activates store operated calcium channels

Answer 44

depletion of calcium stores

Question 45

What are the two classes of calcium channels in store membranes

Answer 45

IP3 receptors, ryanodine receptors

Question 46

What receptors involved in calcium signalling are associated with excitable cells

Answer 46

ryanodine

Question 47

Which receptor involved in calcium signalling is biphasic

Answer 47

ryanodine

Question 48

What happens to the SOCCs when IP3 is formed

Answer 48

open and calcium moves out into the cytoplasm

Question 49

How are the calcium levels restored

Answer 49

SOCCs open and allow calcium to move in and refill the store

Question 50

Name another protein involved with calcium movement

Answer 50

Stim and Orai channels