8: Integration of cardiovascular mechanisms Flashcards
Generally, in the cardiovascular system, the heart acts as…
pump.
What is the function of the arteries?
Carries blood from the heart to the tissues
What is an important point about arterioles?
They are major resistance vessels
What occurs in the capillary beds?
Site of exchange of gas, nutrients and water between blood and tissues
Veins contain a (majority / minority) of blood volume during rest.
majority
Veins act as ___ vessels.
capacitance
Blood coming back to the heart from the veins is called the…
venous return.
What are the three constituent parts of mean arterial pressure?
Heart rate (HR)
Stroke volume (SV)
Total peripheral resistance (TPR)
MAP = SV x HR x TPR
Write an equation for pulse pressure.
Pulse pressure = Systolic BP - Diastolic BP
What is an alternative way of calculating MAP?
MAP = Diastolic BP - (1/3rd of pulse pressure)
What regulates total peripheral resistance?
Vascular smooth muscle
What is the effect of vascular smooth muscle contraction?
1) Vasoconstriction
2) Increase in TPR
3) Increase in MAP (pressure upstream)
What is the effect of vascular smooth muscle relaxation?
1) Vasodilatation
2) Decreased TPR
3) Decreased MAP
Vascular smooth muscle is controlled by ___ and ___ means.
intrinsic , extrinsic
Resistance to blood flow is mainly controlled by vascular smooth muscle through changes in the ___ of arterioles.
radius
What factor is the most important in terms of resistance to blood flow?
Radius of arterioles
Extrinsic control of vascular smooth muscle involves…
nerves and hormones.
Which division of the nervous system supplies vascular smooth muscle?
Sympathetic nervous system
What is the sympathetic neurotransmitter which acts on vascular smooth muscle to regulate blood pressure?
Noradrenaline
In vascular smooth muscle, which receptor does noradrenaline act on?
α receptors
Vascular smooth muscle is partially constricted at rest. What is this also known as?
Vasomotor tone
What generates vasomotor tone?
Tonic discharge of sympathetic nerves resulting in continous release of noradrenaline
What effect does increased sympathetic discharge have on vasomotor tone?
What effect will be seen in the vasculature?
Increases the vasomotor tone
causing vasoconstriction.
What effect does decreased sympathetic discharge have on the vasomotor tone?
What effect does this have on the vasculature?
Decreases vasomotor tone
causing vasodilatation.
Is the parasympathetic division involved in control of vascular smooth muscle?
No
Where in the body is vascular smooth muscle innervated by the parasympathetic nervous system?
Penis
Clitoris
___ is involved in nervous control of vascular smooth muscle.
___ is involved in hormonal control of vascular smooth muscle.
(adrenaline, noradrenaline)
Adrenaline - hormonal
Noradrenaline - nervous
Effects of adrenaline on vascular smooth muscle is largely ___-specific.
organ
Adrenaline is a hormone which acts on vascular smooth muscle. It has different effects depending on which organ it binds to, as each organ has different receptors. Arrange correctly:
Adrenaline acting on _ receptors causes ___.
Adrenaline acting on _ receptors causes ___.
α , β2 , vasoconstriction , vasodilatation
Adrenaline acting on α receptors causes vasoconstriction.
Adrenaline acting on β2 receptors causes vasodilatation.
Where in the body are α receptors found?
Skin, gut and kidney arterioles
Where in the body are β2 receptors found?
Skeletal and cardiac muscle arterioles
The fact that the binding of adrenaline to receptors causes differing vascular effects in different parts of the body helps with strategic redistribution of blood during ___.
exercise
Apart from adrenaline binding to α2 receptors to produce vasoconstriction, which other hormones produce this effect?
Angiotensin II
ADH
Intrinsic control of vascular smooth muscle matches blood flow to the ___ needs of cells.
metabolic
