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S2 MAP II > Nervous Regulation of Circulation > Flashcards

Nervous Regulation of Circulation Flashcards

1
Q

what are the two theories of how local control of blood flow to the tissues occurs?

A

O2 lack theory

vasodilator theory

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2
Q

how does ANS regulation of blood flow compare with local blood flow control
-characteristics of this type of control

A

more global in effect

  • redistributes blood to different areas of body prn
  • affects heart rate
  • can rapidly change arterial blood pressure
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3
Q

which part of the ANS is the primary nervous system influence in regulating circulation
-what does the other one do?

A

SNS

PSNS assists in regulation of heart function

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4
Q

sympathetic vasomotor nerves

  • leaves spinal cord where
  • pass into…
  • continue as…
A 
leave through thoracic and 1st 1 or 2 lumbar spinal nerves
pass into sympathetic chain
continue into
-sympathetic nerves
-spinal nerves
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5
Q

SNS

-innervates which vessels

A

innervates all vessels except

  • capillaries
  • precapillary sphincters
  • metarterioles
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6
Q

SNS innervation of small arteries and arterioles

-allows…

A

allows stimulation to vasoconstrict

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7
Q

SNS influence on veins

-what occurs with blood loss

A

stimulation decreases their volume
with blood loss
-reflexes elicited from aortic bodies and carotid sinus
-stimulates sympathetic nerve impulses to the veins
-result: blood goes towards the heart

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8
Q

significant blood loss - clinical pathologies

-can result from…

A 
circulatory shock
-condition in which blood vessels are inadequately filled and blood can't circulate normally
can lead to...
-hypovolemic shock
-vascular shock
-cardiogenic shock
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9
Q

hypovolemic shock

A

loss of blood volume
can be due to burns
-partly due to edema formation
reduction in BP

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10
Q

vascular shock

A

due to massive vasodilation

  • allergic response (release of histamine)
  • septicemia (large bacterial infection that travels through the blood)
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11
Q

cardiogenic shock

A

heart failure

due to tissue damage to the heart

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12
Q

SNS control

-sympathetic nerves carry many _____ and few _____

A

many vasoconstrictor fibers and few vasodilator fibers

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13
Q

SNS vasoconstrictor fibers

  • where are they distributed
  • where is the largest distribution
  • less distributed to…
A

distributed to all segments of circulation
largest distribution to kidneys, intestines, spleen, and skin
less distributed to skeletal muscles and brain

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14
Q

SNS vasoconstriction: CNS control

A

vasomotor center

  • in the medulla
  • regulates diameter of vessels and controls blood pressure
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15
Q

vasomotor center areas

A

vasoconstrictor area
vasodilator area
sensory area

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16
Q

vasoconstrictor area of vasomotor center

-what does it do?

A

sympathetic vasoconstrictor tone

  • maintains normal vasomotor tone
  • contributes to maintenance of BP
17
Q

what can happen if sympathetic vasoconstrictor tone is lost

A

vasodilation

-can lead to vascular shock

18
Q

how does the vasoconstricor area work?

A

neurons in area secrete norepinephrine
causes excitation of SNS vasoconstrictor fibers
SNS transmits signals through the spinal cord and peripheral sympathetic nerves to almost all blood vessels of body

19
Q

vasodilator area of vasomotor center

  • neuronal fibers project towards _____
  • function
A

project up toward vasoconstrictor area

inhibit the vasoconstrictor area

20
Q

sensory area of vasomotor center

  • sensory nerve impulses received from…
  • function
A

impulses received from circulatory system via vagus and glossopharyngeal nerves
sensory area output helps control vasoconstrictor and vasodilator areas

21
Q

adrenal medulla

  • when does it receive SNS stimulation
  • result
  • function
A

receives SNS stimulation simultaneously as blood vessels
result
-medullae secrete norepinephrine and epinephrine into blood system
primarily causes vasoconstriction
epinephrine occasionally causes vasodilation in some tissues

22
Q

cardiac center

  • adjacent to…
  • function
  • what are the centers?
A 
adjacent to part of the vasomotor center
adjusts rate and force of heart contraction to meet needs of the body
centers
-cardioaccelerator
-cardioinhibitory
23
Q

cardiovascular center

  • combo of what centers?
  • how do these work together
A

cardiac center + vasomotor center
stimulation of vasomotor center under normal conditions also stimulates cardiac centers
-therefore, control heart heart function and vascular function simultaneously
–get increased vasoconstriction with increased HR
-get vasodilation with decreased HR

24
Q

rapid control of arterial pressure by nervous system - BP regulation
-how fast?

A

nervous system control of BP most rapid of responses
can increase BP within seconds
2-fold increase within 5-10 seconds
decrease to 1/2 normal can occur in 10-40 seconds

25
increase in arterial pressure - simultaneous stimulation of... - reciprocal inhibition of... - results
simultaneous stimulation of vasoconstrictor and cardioaccelerator reciprocal inhibition of PSNS vagal signals to the heart results -must arterioles constrict -veins and other large vessels constrict -SNS stimulation of heart
26
mechanisms to maintain normal arterial pressure
baroreceptors
27
baroreceptors - what are they - how do they work
neural receptors in the carotid sinuses, aortic arch, and walls of nearly every large artery in the neck and thorax pressure sensitive: respond to stretch or lack of stretch in vessel walls stretch sends rapid impulses to the vasomotor center and cardiac center decline in MAP initiates reflex vasoconstriction and increases CO - BP rises
28
sequence of events concerning baroreceptors when blood pressure rises
- baroreceptors in carotid sinuses and aortic arch stimulated - inhibit vasomotor center - sympathetic impulses to heart decline (decreased HR) - decreased CO and R - rate of vasomotor impulses declines, allows vasodilation
29
baroreceptor functions
protect circulation against acute changes in BP: "pressure buffer system" -carotid sinus reflex -aortic reflex variation in BP minimized ineffective with prolonged pressure changes - adapt
30
baroreceptor example with hypertension
baroreceptors will "reset" at higher set point with prolonged pressure change, which limits their long term response to perceived higher pressure
31
chemoreceptor control of arterial BP - respond to... - location - function - important at...
respond to changes in O2, CO2, and H+ chemoreceptors located in carotid bodies and aortic bodies stimulate nerve fibers traveling to the vasomotor center important at low arterial pressures (<80 mmHg)
32
chemoreceptor MOA
in contact with arterial blood senses low O2 or high levels of CO2 or H+ that results with a drop in arterial pressure initiates reflexive vaso/venoconstriction
33
atrial reflexes - location - types or receptors
within walls of atria: respond to change in pressure types -low-pressure receptors (stretch receptors) --minimize arterial pressure changes -bainbridge reflex
34
bainbridge reflex
with increased arterial pressure, will get an increase in HR and strength of contraction to prevent blood from "backing up" into system
35
what can reduce the effective response of the atria to pressure changes
damage to atria
36
CNS ischemic response
occurs when blood flow to vasomotor center severely decreased - compromises nutritional accesss = cerebral ischemia get strong reaction of vasoconstrictor and cardioaccelerator centers large rise in systemic arterial pressure
37
CNS ischemic response - can raise ____ to _____ for _____ - how strong is it?
can raise the MAP to 250 mmHg for up to 10 minutes | most powerful activator of SNS vasoconstrictor system
38
Cerebral ischemic response flowchart
- massive decrease in BP - decreased cerebral blood flow - increased PCO2, increased H+ - activation of VMC - increased smypathetic - increased HR, increased TPR - restores BP

S2 MAP II (17 decks)

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