Control Of Heart Rate Flashcards

1
Q

What is the autonomic nervous system?

A

A division of the nervous system that controls involuntary movement of cardiac/smooth muscles, glands

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2
Q

What is the autonomic nervous system divided into?

A

Sympathetic nervous system
Parasympathetic nervous system
Both include various neurones that control involuntary action of muscles and glands that works antagonistically against each other

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3
Q

Parasympathetic nervous system

A

Involving rest

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4
Q

Sympathetic nervous system

A

Involving fight/flight responses

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5
Q

What type of muscle is the heart composed of?

A

Cardiac muscle

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6
Q

Myogenic

A

Muscle contraction is initiated by the muscle itself instead of the neurone

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7
Q

Cardiac muscle is….

A

Myogenic

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8
Q

What is the main cause behind cardiac muscle contraction in the cardiac cycle?

A

A wave of electrical activity

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9
Q

What triggers the atria to contract in atrial systole?

A

SAN sends a wave of electrical activity across atria causing atrial contraction

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10
Q

What carries the wave of electrical activity across the atria?

A

Special cardiac muscle tissue

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11
Q

what prevents wave of electrical activity reaching ventricle?

A

Non conducting tissues between atria and ventricles stops wave of electrical activity passing down outer walls of ventricles

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12
Q

Why do we want to prevent wave of electrical activity immediately passing to ventricles?

A

Because we need a delay before the ventricles contract so blood can fill atria and Atrioventricular valves close
Prevents backflow of blood in ventricles

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13
Q

Where in the atria muscles does the wave of electrical activity join together?

A

In the Atrioventricular node (AVN)

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14
Q

What happens before AVN sends a wave of electrical activity?

A

AVN delays

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15
Q

Where does AVN send a wave of electrical activity down?

A

Down the bundle of His- down the apex of the heart
followed y purkyne tissue

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16
Q

What is the Bundle of His composed of

A

Purkyne tissue

17
Q

How does the Bundle of His branch off?

A

Into individual Purkyne tissue that crawl up the sides of the ventricle walls

18
Q

Wave of electrical activity up the purkyne tissue?

A

Causes ventricles to contract from the base up

19
Q

What part of the brain controls how fast the heart rate is?

A

The medulla

20
Q

Why would we need to increase heart rate?

A

During exercise to deliver oxygen and glucose faster to respiring muscles

21
Q

Faster heart rate is a problem because,,,,

A

Leads to too high blood pressure which damages blood vessels

22
Q

Lower heart rate is a problem because,,,,,,,,,,

A

Blood moves too slowly so not enough oxygen is delivered to tissues

23
Q

Main theory on how the autonomic nervous system controls heart rate?

A

By increasing/decreasing aerobic respiration so increasing/decreasing CO2 conc in blood so more or less dissolving in water in blood to produce a more or less acidic solution

24
Q

What else can controlling heart rate lead to?

A

Changes in blood pressure

25
Q

High heart rate leads to

A

High blood pressure since more blood is pumped per unit time

26
Q

Low heart leads to

A

Low blood pressure since less blood is pumped per unit time

27
Q

How does increase in respiration lead to increase in heart rate

A

Chemoreceptors in aorta detect rise in CO2 of blood
chemoreceptors send more impulses to medulla
Medulla sends more impulses to SAN;
By sympathetic neurones