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Physiology > Exam 2 – Cardio Ch 18 > Flashcards

Exam 2 – Cardio Ch 18 Flashcards

(63 cards)

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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
What is the neurotransmitter for vasoconstrictor nerves?
Norepinephrine
26
What does the adrenal medulla secrete?
Epinephrine and norepinephrine which constricts blood vessels via alpha adrenergic receptors (circulates in blood)
27
What can epinephrine also dilate?
Vessels through a potent Beta2 receptor
28
LOOK AT VASOVAGAL SYNCOPE
LOOK AT VASOVAGAL SYNCOPE
29
What are baroreceptors?
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
What does carotid sinus transmit?
Via hering's nerve to the glossopharyngeal nerves and then to the nucleus tractus solitarius (NTS) to medulla
31
What does the arch of the aorta transmit?
Via vagus to nucleus tractus solitarius
32
LOOK AT ANATOMY OF BARORECEPTORS
LOOK AT ANATOMY OF BARORECEPTORS
33
What is the arterial baroreceptor reflex?
Short term regulation of arterial pressure
34
What is the arterial baroreceptor reflex initiated by?
Baroreceptors in walls of large systemic arteries
35
How does a ride in pressure affect baroreceptors?
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
What pressures do carotid sinus baroreceptors response to?
Between 60 and 180 mmHg
37
What pressure does baroreceptors respond to changes in?
Arterial pressure
38
What pressure is baroreceptor reflex most sensitive at?
100 mmHg
39
As pressure increases the number of impulses from carotid sinus increases, which results in what?
1. Inhibition of vasoconstrictor | 2. Activation of vagal center
40
LOOK AT BARORECEPETOR PICTURE SLIDES
LOOK AT BARORECEPETOR PICTURE SLIDES
41
How do baroreceptors reduce daily variations in arterial pressure?
By opposing increases or decreases in arterial pressure
42
Why are baroreceptors unimportant in long term control of arterial pressure?
Because they adapt
43
What are chemoreceptors?
Chemosensitive cells sensitive to oxygen lack, CO2 excess or H+ ion excess
44
Where are chemoreceptors located?
In carotid bodies near the carotid bifurcation and on the arch of the aorta
45
What does activation of chemosensitive receptors result in?
Excitation of vasomotor center
46
When are secondary chemoreceptors stimulated?
Not stimulated until pressure falls below 80mmHg
47
LOOK AT CAROTID AND AORTIC CHEMORECEPTORS CHART
LOOK AT CAROTID AND AORTIC CHEMORECEPTORS CHART
48
What is CNS ischemic response activated by?
Cerebral ischemia
49
What does reduced cerebral blood flow elevate?
CO2 and pH which activates VMC to increase arterial pressure
50
What is one of the most powerful activators of the sympathetic vasoconstrictor system?
VMC ischemic response
51
Look at CNS ischemic response chart
Look at CNS ischemic response chart
52
When is CNS ischemic response activated?
When pressure falls below 60 mmHg
53
When is CNS ischemic response maximized?
At pressures of 15-20 mmHg
54
What effect does prolonged CNS ischemia have?
A depressant effect on the vasomotor center
55
What do low pressure receptors in atria and pulmonary arteries minimize?
Arterial pressure changes
56
What do artial and pulmonary artery reflexes try to do to pressure?
Keep pressure within a lower range
57
What does increases in blood volume activate?
Low pressure receptors which in turn lower arterial pressure
58
Activation of low pressure receptors enhances Na and water excretion by?
Decreasing rate of ADH Increasing glomerular filtration rate Decreasing Na reabsorption
59
What does the bainbridge reflex prevent?
Damming of blood in veins, artia, and pulmonary circulation
60
What does an increase in atrial pressure in bainbridge reflex cause?
Increases heart rate
61
In bainbridge reflex, what does stretching of atria cause?
Sending signals to VMC via vagal afferents to increase heart rate and contractility
62
Look at bainbridge reflex chart
Look at bainbridge reflex chart
63
Look at atrial and pulmonary artery reflexes
Look at atrial and pulmonary artery reflexes

Physiology (70 decks)

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