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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Long term control of blood flow

A

Increase in sizes/numbers of vessels

Occurs over days, weeks or months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Vasodilator theory

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Vasodilators include

A
Adenosine
Carbon dioxide
Adenosine phosphate compounds
Histamine
Potassium/hydrogen ions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Oxygen lack theory

A

Decreased oxygen causes blood vessel relaxation causes vasodilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Theories to explain autoregulation

A

Metabolic theory

Myogenic theory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Metabolic theory

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Myogenic theory

A

Stretching of vessels–> reactive vasculature constriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Blood flow control mechanism in kidneys

A

Tubuloglomerular feedback- involves the macula densa/juxtaglomerular apparatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Have you looked at endothelial derived mechanism for blood flow control

A

OK maybe do that

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Humoral circulation control- Vasoconstriction

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Humoral circulation control- Vasodilation

A

Bradykinins (also increases capillary permeability)

Histamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Adrenal medulla secretes

A

Epinephrine and norepinephrine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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
Chemoreceptors location
Carotid bodies in bifurcation of the common carotids and in aortic bodies
26
Chemoreceptors are
Chemosensitive cells sensitive to lack of oxygen, carbon dioxide excess and hydrogen ion excess Signals pass through herrings nerves and vagus nerves
27
Chemoreceptors play important role in
Respiratory control
28
Increase atrial stretch results in
``` 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
Reflex dilation of kidney afferent arterioles causes
Increases kidney fluid loss | Decreases blood volume
30
Atrial natriuretic peptide (ANP) function
Signals kidneys to increase GFR and decrease Sodium reabsorption