chapter 18- Exam 3

Question 1

how do the nerves regulate the circulation

Answer 1

• Redistribution of blood flow
• Increasing pumping activity of the heart
• Rapid control of arterial pressure
• Regulates via the autonomic nervous system

Question 2

what is apart of the autonomic nervous system

Answer 2

Sympathetic nervous system

Parasympathetic nervous system

Question 3

what does the Sympathetic nervous system control in circulation

Answer 3

is important in control of circulation

Question 4

what does the Parasympathetic nervous system control in circulation

Answer 4

is important in regulating heart function

Question 5

what is the Parasympathetic nervous system main control in circulation

Answer 5

mainly controls heart rate via the vagus nerve

Question 6

what does the Sympathetic nervous system innervate

Answer 6

Innervate Most vessels

• small arteries,
• arterioles,
• large veins
• heart

Question 7

what doesNT the Sympathetic nervous system innervate

Answer 7

Do Not Innervate

• capillaries
• Precapillary sphincters
• some metarterioles

Question 8

what does the Sympathetic nervous system do for the circulation

Answer 8

Increase vascular resistance

Question 9

where are the sympathetic vasoconstrictor systems located

Answer 9

Vasoconstrictor fibers are distributed throughout all segments of the circulation

Question 10

where is the sympathetic vasoconstrictor systems in the MOST

Answer 10

Distribution is greater in kidneys, gut, spleen, and skin

Question 11

where is the sympathetic vasoconstrictor systems in the LEAST

Answer 11

Less potent in coronary circulation and the brain

Question 12

what equals arterial pressure

Answer 12

Q x total peripheral resistance

Question 13

what can increase arterial pressure

Answer 13

=constricting arterioles
=constricting veins
=directly increasing Q

Question 14

what does constricting arterioles do for increasing arterial pressure

Answer 14

which increases total peripheral resistance

Question 15

what does constricting veins do for increasing arterial pressure

Answer 15

(mostly veins, but some other large vessels) increasing venous return and cardiac output

Question 16

what does directly increasing Q do for increasing arterial pressure

Answer 16

by increasing heart rate and contractility

Question 17

what does the vasomotor center do

Answer 17

VMC transmits impulses downward through the cord to almost all blood vessels

Question 18

where is the VMC located

Answer 18

is located bilaterally in the reticular substance of the medulla and the lower third of the pons

Question 19

what is the VMC composed of

Answer 19

• vasoconstrictor area
• vasodilator area, and
• sensory area

Question 20

what does the vasoconstrictor area of the VMC do

Answer 20

Transmits signals continuously to sympathetic nerve fibers → sympathetic vasoconstrictor tone

***This maintains partial state of contraction in blood vessels called vasomotor tone

Question 21

Look at slide

Answer 21

9 there is a flow chart

Question 22

how does the nervous system increase the arterial pressure

Answer 22

via the VMC

Question 23

how does the VMC increase arterial pressure in seconds

Answer 23

• constricting arterioles
• constricting veins
• directly increases Q

Question 24

when can rapid increase in arterial pressure occur

Answer 24

during exercise or with a fright

Question 25

look at slide

Answer 25

10 there is a flow chart at the bottom

Question 26

when is the arterial baroreceptor reflex important

Answer 26

in short term regulation of arterial pressure

Question 27

how is the baroreceptor reflex initiated

Answer 27

Reflex is initiated by stretch receptors called baroreceptors or pressoreceptors located in the walls of the large systemic arteries

Question 28

what does the rise in pressure in the arterial do

Answer 28

A rise in pressure stretches baroreceptors and causes them to transmit signals to the VMC and feedback signals are sent via the automonic nervous system to the circulation to reduce AP back to normal

Question 29

where are the Baroreceptors located

Answer 29

Baroreceptors are located in the walls of the carotid bifurcation called the carotid sinus and in the walls of the aortic arch

Question 30

how are signals form the carotid sinus transmitted

Answer 30

Signals from the carotid sinus are transmitted by the Hering’s nerve to the glossopharyngeal nerves and then to the nucleus tractus solitarius (NTS) of the medulla

Question 31

how are the signals from the arch of the aorta transmitted

Answer 31

Signals from the arch of the aorta are transmitted through the vagus into the NTS

Question 32

when do the carotid sinus receptors respond

Answer 32

baroreceptors respond to pressures between 60 and 180 mmHg

Question 33

what do the Baroreceptors respond to

Answer 33

respond to changes in arterial pressure

Question 34

when are the Baroreceptors the most sensitive

Answer 34

is most sensitive at a pressure of 100mmHg

Question 35

what happens when a pressure increases and the number of impulses from the carotid sinus increase

Answer 35

1) Inhibition of the vasoconstrictor | 2) Activation of the vagal center

Question 36

what are the fx of the Baroreceptors

Answer 36

**Maintains relatively constant pressure despite changes in body posture **Opposes either increases or decreases in arterial pressure thereby reducing daily variations in arterial pressure **They are unimportant in long term control of arterial pressure because the baroreceptors adapt

Question 37

Look at slides

Answer 37

14, 15

Question 38

what are chemoreceptors

Answer 38

Chemoreceptors are chemosensitive cells sensitive to oxygen lack, CO2 excess, or H ion excess

Question 39

where are chemoreceptors located

Answer 39

are located in carotid bodies near the carotid bifurcation and on the arch of the aorta

Question 40

what does the activation of chemosensitive receptors result in

Answer 40

in excitation of the vasomotor center

Question 41

when are chemoreceptors stimulated

Answer 41

they will not stimulated until pressure falls below 80mmHg | -- look at slide 16 at pic and chart

Question 42

when is the CNS ischemic response activated

Answer 42

in response to cerebral ischemia

Question 43

what happens when there is reduced cerebral blood flow

Answer 43

causes CO2 buildup which stimulates vasomotor center thereby increasing arterial pressure

Question 44

what is the most powerful activators of the sympathetic vasoconstrictor system

Answer 44

CNS Ischemic response --look at slide 17 at the pic and the flow chart at the bottom

Question 45

when will the CNS ischemic response be activated

Answer 45

CNS Ischemic response is not activated until pressure falls below 60mmHg; Greatest activation occurs at pressures of 15-20mmHg

Question 46

what is a special type of CNS ischemic response

Answer 46

cushing reaction

Question 47

what effect does a prolonged CNS ischemia response have

Answer 47

Prolonged CNS ischemia has a depressant effect on the vasomotor center

Question 48

what do the low pressure receptor in the atria and the pulmonary arteries do

Answer 48

minimize arterial pressure changes in response to changes in blood volume

Question 49

what activates the low pressure receptors

Answer 49

Increases in blood volume activates low pressure receptors which in turn lower arterial pressure

Question 50

what does the activation of the low pressure receptors enhances

Answer 50

Na and water

Question 51

how does the activation fo the low pressure receptors enhances NA and water

Answer 51

- Decreasing rate of antidiuretic hormone - Increasing glomerular filtration rate - Decreasing Na reabsorption