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Physiology > Exam 2 – Cardio Ch 18 > Flashcards

Exam 2 – Cardio Ch 18 Flashcards

1
Q

What roles does the nervous system have in regulation of the circulation?

A

Redistribution of blood flow
increasing or decreasing pumping activity of heart
rapid control of arterial pressure
regulates via autonomic nervous system

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2
Q

What is the sympathetic nervous system important in?

A

Control of circulation

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3
Q

What is the parasympathetic nervous system important in?

A

Regulating heart function

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4
Q

What do sympathetic nerve fibers innervate?

A

All vessels except capillaries and precapillary sphincters and some metarterioles
Large veins and the heart

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5
Q

What do innervation of small arteries and arterioles allow sympathetic nerves to do?

A

Increase vascular resistance

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6
Q

What is the parasympathetic nervous system mainly important in control of?

A

Heart rate via the vagus nerve

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7
Q

Where are vasocontrictor fibers distributed?

A

Throughout all segments of circulation

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8
Q

What are the areas of greater distribution of vasoconstrictor fibers?

A

Kidneys
Gut
Spleen
Skin

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9
Q

What are the areas of less potent vasoconstrictor fibers?

A

Coronary circulation

Brain

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10
Q

What is arterial pressure?

A

Cardiac output X total peripheral resistance

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11
Q

What can arterial pressure be increased by?

A

Constricting almost all arterioles of body = increased total peripheral resistance
Constricting large vessels (veins) of circulation = increasing venous return and cardiac output
Directly increasing cardiac output by increasing heart rate and contractility

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12
Q

What is VMC?

A

Vasomotor center

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13
Q

Where does VMC transmit impulses?

A

Downward through cord to almost all blood vessels

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14
Q

Where is VMC located?

A

Bilaterally in the reticular substance of the medullar and the lower third of pons

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15
Q

What is the VMC composed of?

A

Vasoconstrictor area
Vasodilator area
Sensory area

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16
Q

What does the VMC have input to?

A

Both sympathetic and parasympathetic

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17
Q

How do many higher centers of the brain influence VMC?

A

Many higher centers of brain such as the hypothalamus can exert powerful excitatory or inhibitory effects of VMC

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18
Q

Define sympathetic vasoconstrictor tone

A

Vasoconstrictor area of VMS transmits signals continuously to sympathetic nerve fibers

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19
Q

Define vasomotor tone

A

Maintain partial state of contraction in blood vessels

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20
Q

What do large portions of VMC do?

A

Increase heart rate and contractility

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21
Q

What do medial portion of VMC do?

A

Transmit via vagus nerve to heart to decrease heart rate

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22
Q

How does VMC increase arterial pressure within seconds by?

A

Constricting almost all arterioles of the body which increases total peripheral resistance
Constricting large vessels of the circulation thereby increasing venous return and cardiac output
Directly increases cardiac output by increasing heart rate and contractility

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23
Q

When can rapid increases of arterial pressure occur?

A

During exercise or with fright

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24
Q

Look at arterial pressure chart

A

Look at arterial pressure chart

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25
Q

What is the neurotransmitter for vasoconstrictor nerves?

A

Norepinephrine

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26
Q

What does the adrenal medulla secrete?

A

Epinephrine and norepinephrine which constricts blood vessels via alpha adrenergic receptors (circulates in blood)

27
Q

What can epinephrine also dilate?

A

Vessels through a potent Beta2 receptor

28
Q

LOOK AT VASOVAGAL SYNCOPE

A

LOOK AT VASOVAGAL SYNCOPE

29
Q

What are baroreceptors?

A

Spray type nerves endings located in the walls of the carotid bifurcation called the carotid sinus and in the walls of the aortic arch

30
Q

What does carotid sinus transmit?

A

Via hering’s nerve to the glossopharyngeal nerves and then to the nucleus tractus solitarius (NTS) to medulla

31
Q

What does the arch of the aorta transmit?

A

Via vagus to nucleus tractus solitarius

32
Q

LOOK AT ANATOMY OF BARORECEPTORS

A

LOOK AT ANATOMY OF BARORECEPTORS

33
Q

What is the arterial baroreceptor reflex?

A

Short term regulation of arterial pressure

34
Q

What is the arterial baroreceptor reflex initiated by?

A

Baroreceptors in walls of large systemic arteries

35
Q

How does a ride in pressure affect baroreceptors?

A

Stretches baroreceptors and causes them to transmit signals to VMC and feedback signals are sent via the autonomic nervous system to the circulation to reduce arterial pressure back to normal

36
Q

What pressures do carotid sinus baroreceptors response to?

A

Between 60 and 180 mmHg

37
Q

What pressure does baroreceptors respond to changes in?

A

Arterial pressure

38
Q

What pressure is baroreceptor reflex most sensitive at?

A

100 mmHg

39
Q

As pressure increases the number of impulses from carotid sinus increases, which results in what?

A
  1. Inhibition of vasoconstrictor

2. Activation of vagal center

40
Q

LOOK AT BARORECEPETOR PICTURE SLIDES

A

LOOK AT BARORECEPETOR PICTURE SLIDES

41
Q

How do baroreceptors reduce daily variations in arterial pressure?

A

By opposing increases or decreases in arterial pressure

42
Q

Why are baroreceptors unimportant in long term control of arterial pressure?

A

Because they adapt

43
Q

What are chemoreceptors?

A

Chemosensitive cells sensitive to oxygen lack, CO2 excess or H+ ion excess

44
Q

Where are chemoreceptors located?

A

In carotid bodies near the carotid bifurcation and on the arch of the aorta

45
Q

What does activation of chemosensitive receptors result in?

A

Excitation of vasomotor center

46
Q

When are secondary chemoreceptors stimulated?

A

Not stimulated until pressure falls below 80mmHg

47
Q

LOOK AT CAROTID AND AORTIC CHEMORECEPTORS CHART

A

LOOK AT CAROTID AND AORTIC CHEMORECEPTORS CHART

48
Q

What is CNS ischemic response activated by?

A

Cerebral ischemia

49
Q

What does reduced cerebral blood flow elevate?

A

CO2 and pH which activates VMC to increase arterial pressure

50
Q

What is one of the most powerful activators of the sympathetic vasoconstrictor system?

A

VMC ischemic response

51
Q

Look at CNS ischemic response chart

A

Look at CNS ischemic response chart

52
Q

When is CNS ischemic response activated?

A

When pressure falls below 60 mmHg

53
Q

When is CNS ischemic response maximized?

A

At pressures of 15-20 mmHg

54
Q

What effect does prolonged CNS ischemia have?

A

A depressant effect on the vasomotor center

55
Q

What do low pressure receptors in atria and pulmonary arteries minimize?

A

Arterial pressure changes

56
Q

What do artial and pulmonary artery reflexes try to do to pressure?

A

Keep pressure within a lower range

57
Q

What does increases in blood volume activate?

A

Low pressure receptors which in turn lower arterial pressure

58
Q

Activation of low pressure receptors enhances Na and water excretion by?

A

Decreasing rate of ADH
Increasing glomerular filtration rate
Decreasing Na reabsorption

59
Q

What does the bainbridge reflex prevent?

A

Damming of blood in veins, artia, and pulmonary circulation

60
Q

What does an increase in atrial pressure in bainbridge reflex cause?

A

Increases heart rate

61
Q

In bainbridge reflex, what does stretching of atria cause?

A

Sending signals to VMC via vagal afferents to increase heart rate and contractility

62
Q

Look at bainbridge reflex chart

A

Look at bainbridge reflex chart

63
Q

Look at atrial and pulmonary artery reflexes

A

Look at atrial and pulmonary artery reflexes

Physiology (70 decks)

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