Key Area 5- Structure and Function of Arteries, Capillaries and Veins Flashcards
What is the lining of the central lumen in blood vessels called?
The endothelium
Describe the structure of an artery.
. Carry blood away from the heart
. An outer layer of connective tissue containing elastic fibres
. A middle layer containing smooth muscle with more elastic fibres
. A inner layer of elastic fibres
. Lining of endothelium
. Narrow central lumen so blood is under high pressure
. Thick and strong wall structure
. The elastic walls of the arteries undergo vasoconstriction and vasodilation to control blood flow
. Divide up into smaller structures called arterioles
What is vasodilation?
The smooth muscle surrounding the arteries can relax causing vasodilation (to control blood flow). This leads to decreased resistance and increased flow through the vessel.
What is Vasoconstriction?
The smooth muscle surrounding the arteries can contract causing vasoconstriction (to control blood flow). This leads to increased resistance and decreased flow through the vessel.
Describe the structure of veins.
. They carry blood back to the heart
. They have an outer layer of connective tissue containing elastic fibers
. A much thinner muscular wall than arteries
.Wide central lumen so blood is under low pressure
.They contain valves to prevent the back-flow of blood
Describe the structure of the capillaries.
They are made of very thin walls which are only one cell thick and have a very narrow lumen
What is the function of the artery?
To carry blood away from the heart at a high pressure
What is the function of the capillaries?
. They allow for the exchange of substances with tissues through their thin walls
. It allows for the rapid diffusion of gases, glucose and wastes between the blood and tissue cells
. Blood passes through a dense network of tiny microscopic vessels that have thin walls
. They are made of a single layer of epithelium cells
What is the function of veins
To carry blood to the heart at a low pressure
What does blood consist of?
It consists of red blood cells, white blood cells, platelets and plasma
What is blood plasma?
It is a watery yellow fluid that contains all the blood cells and glucose, amino acids, carbon dioxide, plasma proteins and ions
What is pressure filtration?
When blood is forced into the narrow capillaries, undergoes pressure filtration, and much of the plasma is squeezed out through the thin capillary walls into the tissue fluid surrounding the cells.
How are tissue fluid and blood plasma different?
Tissue fluid contains little or no proteins because the protein molecules are too big to pass through whereas blood plasma does have proteins.
What is the role of lymphatic vessels?
They can absorb excess tissue fluid and return it as lymph to the circulatory stem
Where does tissue fluid return to in the blood?
The capillaries at the venule side of the capillary bed.
