Nervous Regulation of the Circulation and Rapid Control of Arterial Pressure Flashcards

1
Q

T/F parasympathetic plays a major role in regulation of circulation

A

False. Plays a minor role but important role in regulating heart function.

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2
Q

Sympathetic nerves fibers innervate all vessels except

A

capillaries, precapillary, precapillary sphincters and some metarterioles

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3
Q

Sympathetic nerves release what hormone and activates what receptor?

A

Noepinephrine on alpha adrenergic receptors on smooth muscle cells in blood vessels.

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4
Q

Adrenal medulla

A

Holds/releases noepinephrine and epinephrine that’ll be transmitted to blood vessels.

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5
Q

Sympathetic vasoconstrictor especially effect

A

Kidneys, gut, spleen, and skin but less potent in skeletal muscle and brain.

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6
Q

Sympathetic stimulation increases or decreases arterial pressure?

A

Increases

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7
Q

Sympathetic stimulation causes 3 things to increase arterial pressure

A

1-Constricting almost all arterioles of body to increase total peripheral resistance (alpha receptor)

2-Constrict large veins which increases venous return and cardiac output. DECREASES COMPLIANCE (alpha receptor)\
3-Stimulating heart to increase heart rate and contractility (beta receptors)

THESE THREE THINGS ALWAYS HAPPEN WHEN SYMPATHETIC STIMULATON.

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8
Q

Vasomotor Center

A

Collection of cell bodies in medulla oblongata (brain stem cell) that regulates blood pressure and cardiac function primarily through the ANS.

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9
Q

3 Important areas of the vasomotor center

A

Vasoconstrictor region
Cardiac region
Sensory region

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10
Q

Vasoconstrictor area tones

A

Transmits signals CONTINUOUSLY to sympathetic nerve fibers. Sympathetic tone (think how SA node fires continuously)

These impulses maintain partial state of contraction in smooth muscle cells in blood vessels=VASOMOTOR TONE

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11
Q

If you cut sympathetic tone to blood vessels what would happen?

A

No constriction of blood vessels. So atrial pressure would fall, No noepinephrine would be released to stimulate constriction in blood vessels.

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12
Q

Cardiac centers

A

1-Cardiac accelerator area: increases HR. Transmits signals to regulate sympathetic nerves to the heart. Noepinephrine activating beta receptors.

2-Cardioinhibitory area: decrease HR. Dorsal motor nuclei of vagus nerve. Transmits parasympathetic impulses to heart through vagus nerve. Acetylcholine actiating muscarinic receptors.

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13
Q

T/F There are parasympathetic nerves to the heart

A

True

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14
Q

Sensory area

A

Located in nucleus tractus solitarius (NTS)

Receives sensory input from baroreceptors located in body

Output controls activity of: vasoconstrictor area. cardiac inhibitory area, cardiac accelerator area

REFLEX CONTROL OF CIRCULATORY FUNCTION

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15
Q

Reflex control of circulatory

A

Reflex= what happens after increase/decrease of blood pressure.

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16
Q

Negative feedback mechanisms (for reflex) for maintaining normal arterial pressure (4)

A

1-Baroreceptor reflex
2-Chemoreceptor reflec
3-Atrial and pulmonary reflex
4-CNS ischemic response

17
Q

Baroreceptors

A

Located in walls of carotid sinus and aortic arch

Sensory afferents (aortic, herings nerve, glossopharyngeal nerve)

Terminate in NTS

18
Q

Baroreceptors response to changes in pressure

A

Blood pressure increase= increase impulses to brain

Blood pressure decreases= decreases impulses to brain

19
Q

Baroreceptor reflex overview

A

Senses pressure changes

Transmits info to sensory area (NTS)

Symp and parasymp activity altered to bring pressure back to set point. POINT SET BY KIDNEYS

20
Q

What would happen if there was a decrease in arterial pressure? (dog hit by car or hemorrhaging)

A

Decreased blood volume causes decrease in arterial pressure

Heart rate increased. Blood pressure decreased.

Reflex tachycardia

Cardiac accelerator area increases nerve firing (sympathetic). Blood vessels constrict in kidneys, GI. Blood flow to kidneys would decrease and resistance to kidneys would increase.

Vasoconstrictor center would increase.

Parasympathetic regulation would decrease.

21
Q

What would happen when arterial pressure is increased?

A

Vasoconstrictor firing decreases. Blood vessels dilate. Tissues get more blood. Blood pressure increases, heart rate decreases.

Reflex bradycardia.

22
Q

Body posture and baroreceptors

A

Lying–>Standing
Decrease in arterial pressure in head and upper body
Fallnig pressure sensed by BR and increased sympathetic discharge maintains pressure.

23
Q

Buffer function of the baroreceptors

A
  • reduces moment to moment variations in arterial pressure (tries to keep things constant)
  • UNIMPORTANT IN LONG TERM CONTROL OF ARTERIAL PRESSURE (Kidneys job)
24
Q

Carotid and Aortic Chemoreceptors monitor chemicals if pressure is…

A

BELOW NORMAL

decrease O2, increase CO2, decrease pH

25
Q

When carotid and aortic chemoreceptors detect below pressure, what happens?

A

Excitation of vasomotor center (VC) and there’s an increase in sympathetic activity.

26
Q

carotid and aortic chemoreceptors controls

A

Minor control with baroreceptors

MAJOR control with respiration

27
Q

CNS Ischemic Response

A

Emergency pressure control system

Direct activation of VC

Only operated when arterial pressure is WELL BELOW NORMAL.

Sympathetic actvity is at 100%

Increase in CO2 signals 100% symp activity and blood flow to parallel organs stop to try to get blood to brain and heart.

28
Q

Atrial reflex that activate the kidneys

A

Volume reflex

Low pressure receptors in atria and pulmonary arteries (R side of heart)

Minimize arterial pressure changes in response to changes in BLOOD VOLUME.

Increase in blood volume=increase in sodium and water excretion.

29
Q

Atrial stretch does what to heart rate

A

INCREASE

Atrial stretch influences VC and there’s increase in heart rate contractility BUT NO EFFECT ON BLOOD VESSELS. This is called the Bainbridge Reflex

30
Q

Vasovagal Syncope

A

Emotional stress can mess up connections between cortex and hypothalamus.

Medulla decreases release in sympathetic output and increase in vagal output

TPR decreases and CO and Venous return

Arterial pressure decreases

Cerebral blood flow decreases

FAINT.