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Human physiology > Lecture 12: Control of blood flow > Flashcards

Lecture 12: Control of blood flow Flashcards

1
Q

Acute control of blood flow

A

Rapid changes in local vasodilation/vasoconstriction
Occurs in seconds/minutes
Theories include vasodilator theory and oxygent lack theory

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2
Q

Long term control of blood flow

A

Increase in sizes/numbers of vessels

Occurs over days, weeks or months

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3
Q

Vasodilator theory

A

Increased metabolism causes decreased oxygen availability, which causes formation of vasodilators

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4
Q

Vasodilators include

A 
Adenosine
Carbon dioxide
Adenosine phosphate compounds
Histamine
Potassium/hydrogen ions
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5
Q

Oxygen lack theory

A

Decreased oxygen causes blood vessel relaxation causes vasodilation

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6
Q

Vasomotion is

A

Cyclical opening and closing of precapillary sphincters

Number of precapillary sphincters open at any given time is roughly proportional to nutritional requirements of tissues

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7
Q

Autoregulation

A

In any tissue, rapid increase in arterial pressure leads to increased blood flow
Within minutes, blood flow returns to normal even with elevated pressure

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8
Q

Theories to explain autoregulation

A

Metabolic theory

Myogenic theory

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9
Q

Metabolic theory

A

Increase in blood flow–>too much oxygen/nutrients–> washes out vasodilators

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10
Q

Myogenic theory

A

Stretching of vessels–> reactive vasculature constriction

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11
Q

Blood flow control mechanism in kidneys

A

Tubuloglomerular feedback- involves the macula densa/juxtaglomerular apparatus

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12
Q

Have you looked at endothelial derived mechanism for blood flow control

A

OK maybe do that

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13
Q

Humoral circulation control- Vasoconstriction

A

Norepinephrine
Epinephrine
Angiotensin II (Normally acts to increase total
Vasopressin (aka: ADH- very powerful vasoconstrictor)

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14
Q

Humoral circulation control- Vasodilation

A

Bradykinins (also increases capillary permeability)

Histamine

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15
Q

Adrenal medulla secretes

A

Epinephrine and norepinephrine

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16
Q

Sympathetic system innervates

A

All vessels except capillaries

Primarily results in vasoconstriction

17
Q

Vasoconstrictor area in brain

A

Anterolateral portions of upper medulla
Transmits continuous signals to blood vessels
Continuous firing results in sympathetic vasoconstrictor tone
Partial state of contraction of blood vessels= vasomotor tone

18
Q

Vasodilator area in brain

A

Bilateral in the anterolateral portions of lower medulla

Inhibits activity in vasoconstrictor area

19
Q

Sensory area in brain

A

Bilateral in tractus solitarius in posterolateral portion of medulla
Recieves signals via Vagus nerves (CN X) and glossopharyngeal nerves (CN IX)

20
Q

Controlled by higher nervous centers

A

Reticular substance (RAS)
Hypothalamus
Cerebral cortex

21
Q

Baroreceptors function/location

A

Inhibit vasoconstrictor center
Stimulate vasodilator center
Located in carotid and aortic sinus

22
Q

Carotid sinuses baroreceptors are stimulated by pressure

A

Greater than 60mm Hg

23
Q

Aortic sinus baroreceptors are stimulated by pressure

A

Greater than 80mm Hg

24
Q

Signals from baroreceptors do what

A

Inhibit vasoconstrictor center
Excite vasodilator center
Signals cause either increase or decrease in arterial pressure
Primary function is to reduce the minute by minute variation in arterial pressure

25
Q

Chemoreceptors location

A

Carotid bodies in bifurcation of the common carotids and in aortic bodies

26
Q

Chemoreceptors are

A

Chemosensitive cells sensitive to lack of oxygen, carbon dioxide excess and hydrogen ion excess
Signals pass through herrings nerves and vagus nerves

27
Q

Chemoreceptors play important role in

A

Respiratory control

28
Q

Increase atrial stretch results in

A 
Reflex dilation of kidney afferent arterioles
Increase in heart rate
Signals to hypothalamus to decrease ADH
Atrial natriuretic peptide to kidneys
Decreased sodium reabsorption
29
Q

Reflex dilation of kidney afferent arterioles causes

A

Increases kidney fluid loss

Decreases blood volume

30
Q

Atrial natriuretic peptide (ANP) function

A

Signals kidneys to increase GFR and decrease Sodium reabsorption

Human physiology (16 decks)

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