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Flashcards in HRV + dyslipidaemia Deck (84)
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1

What are the neurotransmitters of the SNS and PNS?

SNS:
presynaptic - acetylcholine
postsynaptic - noradrenaline

PNS:
presynaptic - acetylcholine
postsynaptic - acetylcholine

2

HR is a balance between ... and ... activity

PNS
SNS

3

Additional SNS pathway:

Adrenal pathway with adrenaline released from adrenal medulla

4

Which parts of the heart does the PNS innervate?

Atria
SAN
AVN

5

Which parts of the heart does the SNS innervate?

SAN
AVN
Atria
Ventricles (inotropic effect)

6

Name the 2 receptors involved in the PNS pathway

Presynaptic - nicotinic
Postsynaptic - muscarinic

7

5 effectors of autonomic nervous system

Smooth muscle
Cardiac muscle
Exocrine glands/cells
Some endocrine glands/cells
Some adipose tissue

8

Post synaptic receptors of SNS include ... and ...-receptors

alpha
beta

9

Pacemaker cells of heart have membrane potentials ... than that of cardiac muscle cells with naturally ... membranes allowing ... depolarisation to threshold producing an AP

lower
leaky
spontaneous

10

SNS ... HR and increases ...

increases
strength of contraction

11

Pacemaker membrane potential is usually ...

-60mV (versus -80 to -90mV for other cardiac cells)

12

Describe the process of SNS increasing HR

1. Increased SNS tone
2. Increased adrenaline and NA
3. activation of beta-receptors and increased calcium (and Na+) influx into myocardial cells
4. Depolarisation threshold reached quicker --> increased HR
5. Increased calcium availability --> increased contraction force

13

The ... of calcium from ... is important for the speed of contraction

undocking
troponin

14

The SNS causes a ... forceful contraction with a ... duration

more
shorter

15

With a slower HR (predominantly PNS), there is a ... depolarisation with ...

slower
hyperpolarisation

16

With a faster HR (predominantly SNS), there is a ... depolarisation with ... repolarisation

rapid
reduced

17

Describe the process of PNS decreasing HR

1. Increased vagal tone
2. Increased ACh release
3. Increased outflow of K+ from cells and decreased calcium influx leading to hyperpolarisation of myocardial cells
4. Depolarisation threshold reached more slowly
5. decreased HR

18

Beta-1 receptor main location and effects:

Myocardium:
Increases HR, increases contractility

19

Beta-2 receptor main locations and effects:

Bronchiolar and arterial smooth muscle:
Relaxation of bronchial smooth muscle
Arteriolar dilation

20

Differential effect of cardiac SNS fibres: left fibres have a greater effect on ...; right fibres have a greater effect on increasing ...

contractility
HR

21

The intrinsic HR of the heart is ...

100bpm

22

As exercise intensity increases, there is more ... control of HR

sympathetic

23

In a study, participants were given propranolol (Beta-blocker) then atropine and vice versa: what HR response would you see?

Initial HR decrease with propranolol, then increase with atropine to reach intrinsic HR (as both receptors blocked)

Initial increase of HR with atropine, then decrease to intrinsic HR with propranolol as both SNS and PNS receptors blocked

24

Mean HR is an ... rate over one minute, sometimes the HR will be faster and other times are slower

average

25

Demands of the body for HR response:

Respiration
BP control
Temperature control
Delivery of O2 and removal of wastes
Hormonal influences

26

HR variability on breathing:

Breathe out: slows down HR (PNS nerves inhibited)
Breathe in: speeds up HR (PNS nerves fire)

27

During a slower HR with more ... influence, there is ... variation between heart beats

PNS
more

28

During a quicker HR with more ... influence, there is ... variation between heart beats

SNS
less

29

Advantages of greater HR variability (3)

So the body can vary HR with all the demands

Variation reflects a healthy vagal system

Lack of variation indicates SNS predominance - hyperpolarised membrane with increased arrhythmia risk

30

3 ways neurotransmitters are usually removed from synapse

Enzymes break them down

Diffusion away from cell

Transport into cells