lecture 9 - CVS 5: regulation of tissue blood flow Flashcards

1
Q

what happens when arterioles vasodilate?

A

resistance decreases

blood flow increases

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

what happens when arterioles vasocontrict?

A

resistance increases

blood flow decreases

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

what is resistance controlled by?

A

vascular smooth muscle surrounding arteriole

capillaries don’t have smooth muscle

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

3 major physiological mechanisms that regulate arteriole radius

A

local control

hormonal control

neural control

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

local control

A

1) autoregulation of tissue blood flow

2) metabolic control of tissue blood flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

auto regulation of tissue blood flow

A

flow stays constant with increasing pressure - high flow rates damage vessels

intrinsic activity of smooth muscle - myogenic response

safety mechanism to prevent damage to blood vessels

darcys law

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is Darcy’s law?

A

flow = MAP / resistance

1) calcium moves into smooth muscle
2) activates contractile machinery - increased myogenic activity
3) constricts harder

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

metabolic control of tissue blood flow

A
metabolism derived vasodilators 
• increased CO2 
• increased H+ - decreased pH 
• increases adenosine - breakdown of ATP 
• increased K+ 
• increased osmolarity 
• increased temp 
• decreased O2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

smooth muscle has tone, what does this mean?

A

it is never fully relaxed or contracted

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

hormonal control

A
vasodilators 
• histamine 
• kinins 
• NO
• adrenaline (beta2)

vasoconstrictors
• angiotensin II
• vasopressin
• adrenaline (alpha1)

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

role of adrenaline

A

can be a vasodilator or a vasoconstrictor depending on the receptors being expressed

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

NO and smooth muscle relaxation

A
  • NO is a potent modulator of smooth muscle
  • made in endothelial cells
  • NO synthase stimulates NO production
  • NO is short lived but has rapid diffusion across membrane to smooth muscle cells
  • causes production of cGMP
  • leads to smooth muscle reaction - increases blood flow

Ca++ has the opposite effect

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

what is angina?

A

feeling of pain/discomfort in the chest, left arm, back and jaw

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

how do you get angina?

A

symptom of chemicals being related and lack of sufficient nutrients

inability to supply efficient blood flow

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

how do you treat angina?

A

tablet under the tongue containing NO precursors

helps improve blood flow to the heart and reducing workload

only treats symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

regulation of smooth muscle function by adrenergic agonists

A

ACh binding

beta2 causes relaxation - cAMP production

alpha1 causes contraction - phospholipase C

17
Q

neural control

A

sympathetic vasoconstrictor fibres

sympathetic vasodilator fibres

parasympathetic vasodilator fibres

18
Q

sympathetic vasoconstrictor fibres

A

most widespread and most important

binding to alpha1 adrenergic receptors causes vasoconstriction - NE

blood vessels in the heart, lungs & liver don’t have many fibres but they have beta2 adrenergic receptors which cause relaxation - EP

can increase or decrease activity

19
Q

sympathetic vasodilator fibres

A

work via NO generation in endothelial cells in skeletal muscle

sympathetic cholinergic - ACh

found in arterioles of skeletal muscle, external genitalia and sweat glands

20
Q

parasympathetic vasodilator fibres

A

work via NO generation from endothelial cells

parasympathetic cholinergic

found in salivary glands

21
Q

changes in CO at rest and during exercise

A

changes to meet oxygen demand

when exercising more blood is distributed to skeletal muscles and less to the GI tract, skin, kidney and brain

22
Q

changes in BP and TPR at rest and during exercise

A

systolic pressure rises
diastolic remains constant

mean pressure doesn’t go up
• due to decrease in TPR
• modulates BP