Unit 2 KA5 - Structure & Function of Arteries, Capillaries & Veins
Where does Blood flow through the cardiovascular system?
It circulates from the heart through the arteries to the capillaries to the veins and back to the heart
When is there a decrease in blood pressure?
When the blood moves away from the heart
The lumen (central cavity) of a blood vessel is lined with a think layer of...called the...
epithelial cells
endothelium
Arteries have an outer layer of connective tissue containing what?
Elastic fibres
Arteries have a middle layer containing what?
smooth muscle with more elastic fibres
The elastic walls of the arteries... and... accomodating the surge of blood after each contraction of the heart
Stretch and recoil
To control blood flow the smooth muscle fible surrounding arteries can contract causing
vasoconstriction
To control blood flow the smooth muscle fible surrounding arteries can relax causing
vasodilation
Capillaries allow...
Exchange of substances with tossue througj their thin walls
Veins have an...
outer layer of connective tissue containing elastic fibres
Veins have a... muscular wall compared to arteries
thinner
Veins contain valves to...
prevent the backflow of blood
What does pressure filtration cause?
Plasma to pass through the capillary walla into the tossue fluid surrounding the cells
Tissue fluid and what are similar in composition?
blood plasma with the exception of plasma proteins
Why arent plasma proteins similar?
they are too large to be filtered through the capillary walls
Tissue fluid supplies cells with
glucose, oxygen and other substances
Carbon dioxide and other metabolic wastes...
diffuse out of the cells and into the tissue fluid to be excreted
Where does most of the tissue fluid return to?
the blood
excess tissue fluid is absorbed by...
thin walled lymphatic vessels
This lymph fluid is returned to the...
circulatory system