Nervous Regulation of the Circulation and Rapid Control of Arterial Pressure

Question 1

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

Answer 1

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

Question 2

Sympathetic nerves fibers innervate all vessels except

Answer 2

capillaries, precapillary, precapillary sphincters and some metarterioles

Question 3

Sympathetic nerves release what hormone and activates what receptor?

Answer 3

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

Question 4

Adrenal medulla

Answer 4

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

Question 5

Sympathetic vasoconstrictor especially effect

Answer 5

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

Question 6

Sympathetic stimulation increases or decreases arterial pressure?

Answer 6

Increases

Question 7

Sympathetic stimulation causes 3 things to increase arterial pressure

Answer 7

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.

Question 8

Vasomotor Center

Answer 8

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

Question 9

3 Important areas of the vasomotor center

Answer 9

Vasoconstrictor region
Cardiac region
Sensory region

Question 10

Vasoconstrictor area tones

Answer 10

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

Question 11

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

Answer 11

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

Question 12

Cardiac centers

Answer 12

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.

Question 13

T/F There are parasympathetic nerves to the heart

Answer 13

True

Question 14

Sensory area

Answer 14

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

Question 15

Reflex control of circulatory

Answer 15

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

Question 16

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

Answer 16

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

Question 17

Baroreceptors

Answer 17

Located in walls of carotid sinus and aortic arch

Sensory afferents (aortic, herings nerve, glossopharyngeal nerve)

Terminate in NTS

Question 18

Baroreceptors response to changes in pressure

Answer 18

Blood pressure increase= increase impulses to brain

Blood pressure decreases= decreases impulses to brain

Question 19

Baroreceptor reflex overview

Answer 19

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

Question 20

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

Answer 20

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.

Question 21

What would happen when arterial pressure is increased?

Answer 21

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

Reflex bradycardia.

Question 22

Body posture and baroreceptors

Answer 22

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

Question 23

Buffer function of the baroreceptors

Answer 23

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

Question 24

Carotid and Aortic Chemoreceptors monitor chemicals if pressure is…

Answer 24

BELOW NORMAL

decrease O2, increase CO2, decrease pH

Question 25

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

Answer 25

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

Question 26

carotid and aortic chemoreceptors controls

Answer 26

Minor control with baroreceptors

MAJOR control with respiration

Question 27

CNS Ischemic Response

Answer 27

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.

Question 28

Atrial reflex that activate the kidneys

Answer 28

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.

Question 29

Atrial stretch does what to heart rate

Answer 29

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

Question 30

Vasovagal Syncope

Answer 30

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.