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w:2017 - Medsci 1/2 > Cardiovascular system: Initiation and regulation > Flashcards

Cardiovascular system: Initiation and regulation Flashcards

1
Q

Where does the action potential start from?

A

The sinoatrial node

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2
Q

What action potential is produced by the SA node?

A

~1.5mV

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3
Q

How does the sinoatrial node control its depolarise?

A

It has an unstable resting potential

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4
Q

How do the myocytes of the atria, ventricle and conduction system have different action potentials from myocytes?

A

They all have the same initial depolarisation, however mysocytes in the heart have a plateau phase of depolarisation

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5
Q

What causes the plateau phase of depolarisation?

A

The inward movement of calcium ions

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6
Q

What does the calcium influx ensure?

A

It ensures that the AP lasts almost as long as the contract of the cell

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7
Q

What does the long plateau phase ensure?

A

The unidirectional excitation of the myocardium (i.e. muscles of the heart)

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8
Q

When does re-polarisation of the myocardial cells occur?

A

When the voltage dependent calcium channels inactivate

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9
Q

Label the diagram, what is this showing?

A

Showing an electrocardiogram (i.e. ECG)

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10
Q

What does an ECG show?

A

The electrical activity of the heart from the front (FYI electrical activity is different at different orientations)

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11
Q

What does the relative size of the ECG waves indicate about the heart?

A

The relative size of the heart

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12
Q

What creates the P wave? What does it cause?

A

the depolarisation of the atrium causes atrial systole

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13
Q

When there is a plateau in the ECG, what does this indicate?

A

Diastole of the entire heart (if there is any contraction in the heart then it causes an AP to be produced)

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14
Q

What creates the QRS complex? What does it cause?

A

The depolarisation of the ventricle causes ventricular systole

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15
Q

What causes the T wave?

A

The depolarisation of the ventricular myocytes

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16
Q

What part of the brain can influence the heart rate?

A

The cardiovascular centre

17
Q

What parts of the brain connect to the cardiovascular system

A

Higher brain centres (i.e. cerebral cortex, limbic system, hypothalamus) and sensory receptors (proprioceptors, chemoreceptors and baroreceptors)

18
Q

In what situations can the higher brain centres influence increased heart rate without exercise?

A

Stress, anxiety etc.

19
Q

What do the proprioceptors monitor?

A

Monitor movement

20
Q

Label the diagram, what is it showing?

A

It is showing how the heart delivers and receives information to and from the brain

21
Q

What do the chemoreceptors monitor?

A

Monitor blood chemistry

22
Q

What do the baroreceptors monitor?

A

Monitor blood pressure

23
Q

What are the output nerves from the cardiovascular centre?

A

Sympathetic nerve and parasympathetic nerve

24
Q

What does the sympathetic nerve do to the heart?

A

It cause an increase in the rate of spontaneous depolarisation in the SA and AV node increasing heart rate and it increase the contractility of the ventricles and atria

25
Q

How is the sympathetic nerve able to cause its increase in heart activity?

A

It increases the amount of norepinephrine actin on ß1 receptors

26
Q

What does the parasympathetic nerve do to the heart?

A

Decreases the rate of spontaneous depolarisation in the SA and AV node decreasing heart rate

27
Q

How does the parasympathetic nerve cause the decrease in heart activity?

A

It lengthen the plateau period of depolarisation

28
Q

What nerve runs into the heart from the cardiovascular centre?

A

The vagus nerve (contains the parasympathetic system FYI)

29
Q

Where does the vagus nerve run through the body? What kind of nervous system is transferred in the vagus nerve?

A

Runs down next to the artery (not in the spinal cord)

The parasympathetic system

30
Q

What is information coming into and out of the CNS called?

A

Into = Afferent information

Out = Efferent information

31
Q

How is the sympathetic nerve connected to the heart?

A

It is connected to the heart b the cardiac accelerator nerve which runs through the spinal cord

w:2017 - Medsci 1/2 (19 decks)

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