physiology exam questions

Question 1

sequence of events involved in the transmission of information across synapse
pt1

Answer 1

1. membrane is depolarised by arrival of action pot
2. calcium channels open
3. Calcium enter cell and triggers release of neurotransmitter by exocytosis

Question 2

sequence of events involved in the transmission of information across synapse
pt2

Answer 2

4. Neurotransmitter diffuses across synaptic cleft and some of it binds to receptors on postsynpatic cell membrane
5. response is produced in post synpatic cell

Question 3

sequence of events involved in the transmission of information across synapse
pt3. (what happens to neurotransmitters )

Answer 3

1. degraded by enzymes
2. taken up by presynaptic cell
3. NT or products of degradation diffuses away from synaptic cleft

Question 4

Summation can be either temporal or spatial depending on whether

Answer 4

postsynaptic potentials being summed, arise at the same or different synapses

Question 5

what is temporal summation

Answer 5

SINGLE pre-synaptic neurons that fires many times in succession , causing post synaptic neurons to reach threshold and fire

Question 6

spatial summation

Answer 6

when excitatory potential from MANY DIFFERENT pre synaptic nuerons cause post synaptic neurons to reach its threshold and fire

Question 7

Stroke Volume depend on

Answer 7

ventricular contractability
EDV
afterload

Question 8

Ventricular contractility

Answer 8

• sympathetic nerves ⇧ force of contraction
• ↑contractility ↓ESV
• tf more blood ejected
• tf ↑ stroke volume
• also under control by hormones eg adrenalin

Question 9

EDV (end-diastolic volume)

Answer 9

starlings law = force of ventricular contraction ↑or↓ as EDV ↑or ↓

↑venous return ↑EDV

WHEN EDV ↑ so is sv

Question 10

factors effecting EDV

Answer 10

(1) filling time which depends on HR

(2) atria pressure which is determined by venous return and the force of atria contraction

Question 11

Afterload

depends on

Answer 11

• depends on arterial pressure
• pressure in aorta during ejection, forces heart to pump against force at which ventricles contract
• Increased aortic pressure > the more ventricles need to contract

↑ atria pressure cause SV ↓

Question 12

Afterload is commonly related to

Answer 12

myocardial wall stress during systolic ejection.

Question 13

contractability describes

Answer 13

forcefulness of the heart’s contraction

Question 14

Factors affecting force/tension

Answer 14

Frequency of stimulant
fibre diameter
fibre length
recruitment

Question 15

Frequency of stimulant

Answer 15

Treppe
Summation
Tetanus

Question 16

Fibre diameter

Answer 16

larger = ↑ of filaments , cross bridge and sacromeres

tf more force

Question 17

Fibre length

Answer 17

Resting can develop most tension

max overlap of thick & thin filaments

Question 18

Recruitment

Answer 18

more fibres contracting more tension due to more motorneurons being excited