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2.1 Control and Integrative Physiology > Mairead - ANS and the Heart > Flashcards

Mairead - ANS and the Heart Flashcards

1
Q

What affects does sympathetic activity have on the heart?

A

Increases heart rate

Increases force of contraction of the ventricles

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2
Q

What mediates increase of hr and force of contraction via sympathetic activity?
(3)

A

This is mediated by direct innervation of the heart and by the release of the hormones adrenaline and noradrenaline from the adrenal medulla

The sympathetic activation has a positive ionotrophic effect, acting on beta1 receptors of cardiac muscle

The hormones also stimulate ventricular muscle metabolism and perfusion of the myocardium

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3
Q

What receptors are found in cardiac muscle?

A

Beta1 receptors

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4
Q

What affect does adrenaline and noradrenaline have on the heart
(2)

A

They stimulate ventricular muscle metabolism and perfusion of the myocardium

They have a positive ionotrophic effect

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5
Q

What is the net effect of sympathetic activity on the heart?
(4)

A

Increased force

Increased in SV

Decrease in ESV

Increase in heart rate

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6
Q

What affect does the parasympathetic system have on the heart

A

Parasympathetic slows the heart rate and has a small decreasing effect on contractility

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7
Q

What mediates the effect of the parasympathetic system on the heart

A

Mediated through the vagus nerve

Negative ionotrophic effect

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8
Q

What does adrenaline and noradrenaline do to the heart?

A

Positive ionotrophic effect

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9
Q

What does glucagon do to the heart?
(2)

A

It’s released by the pancreas to increase glucose levels in blood

It has a positive ionotrophic effect

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10
Q

What affect do thyroid hormones have on the heart?

A

Thyroid hormones have a positive ionotrophic effect

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11
Q

Comment on the adjustment of heart rate

A

Heart rate is continually adjusted as circulatory system demands changes

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12
Q

What makes adjustments in heart rate?

A

ANS

Circulating hormones

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13
Q

ANS and circulating hormones have a chronotrophic effect, what is meant by this?

A

They have the ability to alter the heart rate

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14
Q

Where does the sympathetic and parasympathetic division innervate the heart?

A

The SA and AV nodes

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15
Q

Describe the ANS activation in the heart at rest?

A

There is resting autonomic tone

Both divisions are active at rest

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16
Q

At rest which division is slightly more dominant?

A

Parasympathetic

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17
Q

How does the ANS adjust cardiovascular function

A

By adjusting both the sympathetic and parasympathetic divisions

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18
Q

How exactly does ANS alter the HR?
(2)

A

Parasympathetic and sympathetic alter the HR by changing the permeability of the conducting system cells

This is done by altering SA node firing and altering the conduction time

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19
Q

What affect does altering SA node firing have?

A

It changes the permeability of the conducting system cells

20
Q

What affect does increasing parasympathetic firing of SA node have on HR

A

Results in slower HR

21
Q

How does increasing parasympathetic firing result in slowing heart rate?

A

By increasing the K+ permeability and hyperpolarizing the membrane

This Ach/Muscarinic action is a negative chronotrophic effect

22
Q

What does increasing the sympathetic firing of the SA node do?
(4)

A

Releases noradrenaline at the B1 receptors

This increases the Na+ and Ca++ entry

This increases the rate of depolarisation and shortens repolarisation

This is a positive chronotrophic effect

23
Q

What does a release of noradrenaline at B1 receptors do?

A

Increases the Na+ and Ca++ entry

24
Q

What does increased Na+ and Ca++ entry do

A

This increases the rate of depolarisation and shortens repolarisation

25
Q

What is another name for the Bainbridge reflex?

A

Atrial reflex

26
Q

What activates the Bainbridge reflex

A

As the venous return increases, the walls of the right atrium are stretched

27
Q

What does the Bainbridge reflex do?
(3)

A

It activates the ANS

Results in increased sympathetic activation i.e. increases SA node firing

The increase in HR matches the increase in venous return

28
Q

What hormones affect the heart rate and what do they do?
(2)

A

Adrenaline, noradrenaline and thyroid hormones

They increase the heart rate and contractility of the heart

29
Q

When is adrenaline or noradrenaline released
(2)

A

Sympathetic activation in a flight or flight response

Stimulates release of adrenaline and noradrenaline from the adrenal gland

30
Q

How does adrenaline and noradrenaline increase the heart rate?

A

They increase the rate of depolarisation of the SA node and decrease the duration of repolarisation

31
Q

What is the equation for cardiac reserve?

A

Max CO - resting CO

32
Q

What may cause an increase in demand on the heart?

A

May increase due to muscle damage, valve damage or hypertension

33
Q

What affects does increased demand on the heart have on the heart?

A

Cardiac output may be inadequate

Pulmonary pressures increase

34
Q

What happens when CO may be inadequare

A

This may lead to poor perfusion, and therefore fatigue and poor exercise tolerance

35
Q

What happens when pulmonary pressures increase?

A

This may lead to oedema in the lung tissue and poor O2 exchange, which results in breathlessness

36
Q

What is it called if K+ is high?

A

Hyperkalemia

37
Q

What is it called if K+ is low?

A

Hypokalemia

38
Q

What happens if K+ is really high?

A

it’s life threatening

39
Q

Write a note on high K+

A

Depolarisation normal

K+ movement inhibited as K+ channel opens

Therefore, repolarisation is inhibited

Muscle becomes weak

40
Q

Write a note on low K+

A

Hyperpolarisation of muscle cells

Muscle more difficult to excite

Hyperpolarisation of nodal cells: hr down, blood pressure down

41
Q

What is high calcium called?

A

Hypercalcemia

42
Q

What is high Ca++?
(4)

A

EC Ca++ increased, SR Ca++ increased

Cells extremely excitable

More powerful and prolonged contractions

May be fatal

43
Q

Write about low Ca++

A

Contractions weak

May stop

44
Q

Write about low temperature

A

Slows SA depolarisation

Lowers HR

Reduced strength of contraction

45
Q

Write about high temperature

A

Increased hr and force

46
Q

What effects does caffeine have on the heart?

A

Caffeine, increased rate of depolarisation of the SA node

47
Q

What effects does nicotine have on the heart?

A

Sympathetic neurons

2.1 Control and Integrative Physiology (21 decks)

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