Homeostasis

Question 1

why does phased seperation occur

Answer 1

contact is minimised between polar and non-polar components by grouping polar together so they can have as many polar interactions as possible

Question 2

why does phased separation occur

Answer 2

contact is minimised between polar and non-polar components by grouping polar together so they can have as many polar interactions as possible

Question 3

what is added to the phospholipid bilayer to prevent it freezing at body temperature

Answer 3

cholesterol

Question 4

which kind of molecules cannot cross the lipid bilayer

Answer 4

hydrophilic

Question 5

examples of what can pass through the phospholipid bilayer

Answer 5

CO2, steroids (testosterone), some drugs

Question 6

4 types of diffusion transport

Answer 6

direct free diffusion
uniporter
co-transporter
antiporter

Question 7

where are high sodium levels found? where are high potassium levels found?

Answer 7

sodium - outside cell
potassium - inside cell

Question 8

what does the Na+/K+ ATPase do

Answer 8

3Na+ out, 2K+ in

Question 9

example on how the NA+/K+ ATPase can be used

Answer 9

lower concentrations of Na+ in cell cause it to diffuse in through other receptors, providing energy for eg glucose to enter with it

Question 10

4 classifications of paths?

Answer 10

autocrine
juxtacrine
paracrine
endocrine

Question 11

autocrine?

Answer 11

signalling to itself

Question 12

signalling in general to another cell

Answer 12

paracrine

Question 13

juxtacrine

Answer 13

signalling to an immediate neighbour

Question 14

endcrine?

Answer 14

passing via blood to otherc ells

Question 15

are steroids hydrophobic or hydrophilic

Answer 15

hydrophobic

Question 16

how do steroid signals alter gene expression?

Answer 16

pass through lipid bilayer, bind to transcription factor, affects transcription of DNA

Question 17

what are steroids generally used for? examples?

Answer 17

long term things:
sex determination
menstrual cycles and puberty
stress
inflammation
etc

Question 18

signals which cannot pass through the cell membrane (too hydrophilic)

Answer 18

neurotransmitters, peptide hormones

Question 19

two ways hydrophilic signalling molecules pass on their signals into the cell?

Answer 19

binds to receptor causing conformational change

dimerization - each half of signal holds together two receptors which act on each other if held together long enough

Question 20

G-protein signalling? - example for calcium

Answer 20

G-protein coupled receptor activates, binds G-protein which is activated then can activate another enzyme - phospholipase, which breaks many phospholipids (amplification) which bind to calcium channels in the ER releasing Ca2+ down conc gradient and calcium activates various proteins

Question 21

how can calcium blood concentration levels be raised

Answer 21

PTH from parathyroid gland causes reabsorption from urine and reabsorption called bone.

Question 22

integral control?

Answer 22

how far wrong something is and for how long - more and more active the longer something is in error

Question 23

proportional control?

Answer 23

looks at how far wrong something is

Question 24

differential control?

Answer 24

how quickly things are changing

Question 25

what kind of control for PTH control of renal absorption and intestinal absorption

Answer 25

intestinal absorption - integrational control
renal absorption - proportional control

Question 26

what physiological changes are anticipative

Answer 26

signalling via sympathetic nervous system - brain recognises danger, adrenaline kicks in

Question 27

anticipatory signalling common in what

Answer 27

fleeing, fighting mating

Question 28

damage to effectors solution

Answer 28

substitute artificial version of effector

Question 29

damage to control systems solution

Answer 29

use drug that mimics missing signal or blocks pathways that shouldn’t be active