Blood and blood vessels Flashcards
(25 cards)
What is the tunica interna?
inner lining of squamous epithelium or endothelium.
What is tunica media?
middle layer of smooth muscle and elastic tissue.
What is externa?
outer layer of fibrous tissue.
Muscular activity depends
on the size and function.
Why do large arteries consist of more tunica media?
to absorb pressure waves from the heartbeat.
Arterioles consist of…
virtually all smooth muscle.
Veins distend and hold approx…
2/3 of blood.
Veins are…
blood vessels that return blood flow to the heart under low pressure.
The walls are thinner due to
less muscle elastic tissue.
Pulmonary arteries carry…
deoxygenated blood to the lungs.
Pulmonary veins carry…
oxygenated blood to the heart.
Where do arteries carry the blood?
away from the heart and are oxygenated.
Where do veins carry blood to?
the heart and are deoxygenated.
What are capillaries?
a single layer of endothelial cells sitting on a thin basement membrane.
What does the autonomic nervous system do?
it changed diameter and controls the volume of blood contained.
What does sympathetic stimulation do?
determines diameter of lumen.
What is sympathetic stimulation decreased activity?
relaxes stimulation to smooth muscle and vasodilation occurs.
What is sympathetic stimulation increased activity?
causes vasoconstriction and thickening of tunica media.
What are the 3 factors of resistance of flow?
diameter/ length and viscosity.
What happens when cardio-accelerator centre is stimulated?
nerve impulses travel along sympathetic fibres to SA/AV nodes.
What happens when the cardio-inhibitory centre is stimulated?
nerve impulses travel along parasympathetic fibres to SA/ AV nodes.
What happens when the vasomotor centre is stimulated?
nerve impulses travel along sympathetic fibres to blood vessels.
What does a drop in blood pressure lead to?
increased sympathetic tone from the vasomotor centre.
What does the vasomotor centre change?
vascular smooth muscle tone.
