Homeostasis

Question 1

what is homeostasis?

Answer 1

process of keeping the internal conditions within the body at an optimal point, allowing optimal performance.

Question 2

what is entropy

Answer 2

measure of level of disorder

external environment = high entropy

Question 3

what are the variations in ph in different cellular compartments?

Answer 3

mitochondrial matrix =7.7 
lysosomal and endosomes = 4.6 -6 
secretory vesicles = 5-6 
extracellular Fluid = 7.4 
cytosol = 7.1

Question 4

what are the ion concentrations in intracellular and extracellular Fluid?

Answer 4

intracellular 
Na= 10-15 
cl= 20-30 
k= 120-150 
HCO3= 12-16 
Ca2+= ionised (10^-7) 
pi = ionised (0.5-0.7) 

extracellular 
Na =135-147 
cl=95-105 
k=3.5-5 
HCO3= 22-28 
CA2+= total (2.1-2.8) ionised (1.1-1.4)
pi = total (1.0-1.4) ionised (0.5-0.7)

Question 5

what is the permeability coefficient?

Answer 5

J = P x (c1 - c2)

J = nate rate of solute movement

Question 6

name the different types of membrane transport

Answer 6

pores , channels, solute carriers, pumps, vesicular transport

Question 7

structure of aquaporins

Answer 7

4 subunits
6 alpha helical TM regions
pore diameter= 2.8 Å
12 different subtypes

Question 8

solute carriers characteristics

Answer 8

bind solute on one side, conformational change, release of solute on the other side

Example - GLUT 1-4 (glucose transporter)

Question 9

2 forms of active transport

Answer 9

primary - uses ATP hydrolysis directly
secondary - movement of one solute down its concentration gradient is used to drive movement of another solute against it’s concentration gradient

Question 10

types of ATPase transporters

Answer 10

P type - ATP hydrolysis for phosphorylation
V type - vacuolar, contributes to setup of pH gradient
F type - uses proton gradient for ATP synthesis

Question 11

Na+/k+ ATPase pump 4 main domains

Answer 11

N- nucleotide binding domain
P- phosphorylation domain
A-actuator domain
M- transmembrane domain

Question 12

what is osmotic pressure?

Answer 12

minimum pressure needed to be applied to a solution to prevent inward flow of water across a semipermeable membrane- measure of tendency of a solution to take in water by osmosis.

Question 13

osmotic pressure formula?

Answer 13

pi = nCRT

n- number of dissociate particles
C- total concentration
R- gas constant
T- temperature in k

Question 14

what is osmolaLity?

Answer 14

concentration of solute expressed as total number of solutes per kilogram.

Question 15

what is osmolaRity?

Answer 15

concentration of solutes expressed as number of solutes per Litre

Question 16

what is tonicity?

Answer 16

the ability of an extracellular solution to make water move into or out of a cell by osmosis.

Question 17

what is an acid extruder?

Answer 17

Na/H exchanger- transports hydrogen out of cell in exchange for sodium.

Question 18

what is a Base extruder?

Answer 18

anion exchanger e.g HCO3/Cl exchanger- transports HCO3 out in exchange for chloride ions.

Question 19

systems that help to control resting calcium concentrations.

Answer 19

plasma membrane Ca2+ ATPase, SERCA

Na+/Ca2+ exchanger