Control of Heart Rate Flashcards

1
Q

what is the heart innverated by

A

the heart is innervated by both divisions of the autonomic nervous system and contraction is not required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is bradycardia and tachycardia

A

Increased activity in the sympathetic nerves to the heart increases HR - tachycardia
Increased activity in the parasympathetic nerves to the heart decreases HR - bradycardia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what do tachycardia and bradycardia

A

Tachycardia and bradycardia affect heart rate by changing slope of the pacemaker potential changes in the rate are the chronotropic effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what neurotransmitters does parasymapethic and symapethic nervous sytem

A

parasympathetic nervous system releases ACh while the sympathetic nervous system releases noradrenaline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are ACH and NorAd coupled to

A

ACH is coupled to an inhibitory G protein that reduces activity of the cAMP pathway
NorAd is coupled to a stimulatory G protein that accelerates the cAMP pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Parasympathetic NS decreases heart rate through 2 effects on pacemaker tissue

A

Parasympathetic NS decreases heart rate through 2 effects on pacemaker tissue
Hyperpolarisation of the SA node membrane (takes longer to reach threshold)
Decreases the rate of spontaneous depolarisation
ACH increases K permeability by G proteins coupled inwardly rectifying potassium channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Other effects of parasympathetic stimulation on heart activity

A

Parasympathetic stimulation decreases the AV node excitability which prolongs the transmission of impulses to the ventricles.
Shortens the plateau phase of the AP in atrial contractile cells, weakening atrial contraction.
Parasympathetic stimulation has little effect on ventricular contraction
decrease in HR, the time between atrial and ventricular contraction is increased and atrial contraction is weaker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

effects of sympathetic stimulation on the SA node

A

Sympathetic NS speeds up heart rate through its effect on pacemaker tissue
main effect is to speed up depolarisation so threshold is reached more rapidly - NorAd augments If and T type channel activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Other effects of sympathetic stimulation of heart activity

A

Sympathetic stimulation of the AV node reduces AVnodal delay by increasing conduction velocity.
Speeds up spread of the AP throughout the specialised conduction pathway.
Increased contractile strength of the atrial and ventricular contractile cells (heart beats more force fully and squeezes out more blood)
Increased Ca2+permeability through prolonged opening of L-type Ca2+channels.*Speeds up relaxation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Sympathetic stimulation of the heart is to improve its effectiveness as a pump

A

increase heart rate
decreasing the delay between atrial and ventricular contraction
Decreasing conduction time through the heart
increasing the force of contraction and speeding up the relaxation process so that more time is available for filling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is antagonist

A

Parasymapethic and sympathetic effects on heart rate are antagonistic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is heart rate determined by te balance of what

A

Heart rate is determined by the balance of the SA node (vagus) and stimulation (sympathetic nerves)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Heart rate can be altered by what

A

Heart rate can be altered by shifting the balance of autonomic nervous stimulation.
HR is increased by simultaneously increasing sympathetic and decreasing parasympathetic activity
Conversely, HR is decreased by simultaneously increasing parasympathetic. and decreasing sympathetic. activity
The activity of the autonomic nervous system is co-ordinated by the cardiovascular control centre, located in the brain stem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the primary mena by which HR is rgualted

A

autonomic innervation is the primary means by which HR is regualted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly