REGULATION OF BLOOD FLOW Flashcards

1
Q

the heart pumps the of blood that the body needs is defined as?

A

cardiac output

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2
Q

cardiac output control by the?

A

autonomics

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3
Q

tissue control by?

A

local regulation

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4
Q

which of the tissues require the most blood?

A

brain and heart because of work load

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5
Q

what is the main cause for increase flow in local regulation?

A

increase metabolism or increase altitude in response to decrease local O2

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6
Q

what is the vasodilator theory?

A

increase metabolism in which the cells release chemicals to increase:

hydrogen ion concentration
histamine
adenosine
CO2
potassium 
this leads to:

relax smooth muscle to decrease resistance to increase flow

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7
Q

what is the most potent vasodilator?

A

adenosine

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8
Q

what is the intrinsic property of smooth muscle? what type of regulatory mechanism is this?

what is the effect of increase pressure?

A

when stretched it contracts

non metabolic local regulatory mechanism

increases flow and increase resistance to flow is constant

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9
Q

so if we have multiple neighboring capillary beds vasodilating, how do upstream vessels get the message?

A

EDRF

endothelial derived releasing factor aka nitric oxide which is a 6 second life span

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10
Q

what does the heart undergo due to increased metabolic demand? population this usually occurs in?

A

increased vascularity due to angiogenesis which can take days to weeks

children, damaged tissue and cancers

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11
Q

what are the signals that stimulate angiogenesis? and this is because of ____?

A

vascular endothelial growth factor (VEGF)
fibroblast growth factor (FGF)
angiogenin

increased metabolic demand

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12
Q

what is angiogenesis?

A

promotes new vessels to sprout off of the existing vessels

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13
Q

what are the important systemic vasoconstrictor humoral agents?

A

NE/EPI
Angiotensin II (constricts the arterioles and increases TPR to maintain BP)
Vasopressin
endothelin (produced by damaged vessels, limits blood loss at the wound site)

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14
Q

what are the systemic vasodilators? how do these work?

A

bradykinin
histamine

increase flow and increase capillary porosity, so area becomes flushed and edematous

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15
Q

what are the ions below affect on vascular function?

increase ECF calcium 
increase ECF magnesium
increase ECF potassium
increase ECF hydrogen ion
increase ECF PCO2
A

increase ECF calcium - vasoconstriction

rest, vasodilation and also in the brain when there is an increase in ECF PCO2

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16
Q

T/F, cardiac output is affected by autonomic regulation? if so, which ones and how

A

T

both sympathetic (positive ionotropism and chronotropism) and parasympathetic (negative chronotropism)

17
Q

what do the sympathetics not innervate in terms of the arteries? where for the ones that do?

A

capillaries, precap sphincters, metarterioles

kidney
intestine
spleen
skin

not so effective in muscle and brain

18
Q

what is the effect of arterial vasoconstriction?

A

increase resistance
increase blood pressure
decrease BF to constricted area

19
Q

in terms of venous constriction, what happens when these larger veins are affected by the sympathetics?`

A

increase venous return
increase EDV
increase cardiac output
increase arterial pressure

20
Q

what causes the sympathetics to start firing? parasympathetics?

A

vasoconstrictor area of vasomotor center in the medullary reticular formation controls the vasoconstrictor outflow

vasodilator center also in vasomotor center and controls parasympathetic outflow

21
Q

since vessels are tonically partially contracted what is this called and mediated by?

A

sympathetic vasoconstrictor tone mediated by alpha one adrenergic receptors

22
Q

what inputs affect the vasomotor center?

A

1)pons and midbrain
2)hypothalamic neurons
limbic cortex
3)baroreceptors in the carotid sinus and aortic arch

23
Q

describe vasovagal syncope?

A

increase parasympathetic outflow leads to vasodilation and decrease venous return to decrease arterial pressure and then fainting

24
Q

so when the baroreceptors in the carotid sinus work what is the effect when there is a decrease in arterial P after 10 seconds?

A

increase SV, HR, TPR so overall increase in blood pressure

25
Q

where are key baroreceptors located? what do these sense? what is the result?

A

carotid sinus and aortic arch and also located in thoracic systemic arteries and these are called pressoreceptors

increase pressure causes stretch on vessel

increase vasodilator center, decrease vasoconstrictor center, increase vagal parasympathetic center

26
Q

what is the sensitivity range for the baroreceptors? effect outside this range

A

30-180 mm Hg

less than 30, no firing
more than 30, max discharge rate

27
Q

T/F, long term BP regulation is the job of baroreceptors? if not, Than what is?

A

nope, false but they can increase sodium and water loss (decrease plasma volume)

kidneys do long term

28
Q

what is the pressure a function of?

A

blood volume via kidneys (long term) and vascular volume (baroreceptors regulate in the short term)

29
Q

T/F, there are stretch receptors in the atria and pulmonary arteries? high or low pressure receptors? the affect on cardiac output

the atrial receptors also trigger what reflex?

A

T

low pressure receptors

decrease cardiac output

volume reflex

30
Q

what is the volume reflex?

A

increase blood volume sensed, increase VR, increase atrial P leading to receptors firing which inhibit ADH released vasodilator afferent arterioles in the kidney that overall leads to urine formation decrease blood volume and the atrial reflex

31
Q

the atrial reflex triggers this reflex?

A

bainbridge reflex which decreases the atrial P