Flashcards in Structure and function of arteries, capillaries and veins Deck (33)
What are the blood vessels which blood circulate from the heart called?
Arteries, arterioles, capillaries, venules and finally veins, before returning to the heart
What are blood vessels?
Tubes with walls composed of different tissues dependent on the function of the vessel
What is the central space or cavity of the blood vessels called?
What is lumen lined with?
A layer of cells called endothelium
What is the endothelium lining the central lumen of blood vessels surrounded by?
Layers of tissue that differ between arteries, capillaries and veins
What does arteries do?
Carry blood away from the heart
What pressure is the blood pumped through the arteries?
At a high pressure
What does arteries have?
An outer layer containing smooth muscle with more elastic fibres
What do the thick elastic walls of the arteries do?
Stretch and recoil to accommodate the surge of blood after each contraction of the heart
What can the smooth muscle in the walls of the arterioles do?
Contract or relax causing vasoconstriction and vasodilation to control blood flow
What does the ability of the arterioles to vasoconstrict or vasodilate allow?
The changing demand of the body's tissue to be met
What happens to the arterioles supplying the muscle vasodilate during exercise?
Increases the blood flow
What happens to the arterioles supplying the abdominal organs during exercise?
Reduces the blood flow to them
What do arteries branch into?
smaller blood vessels called arterioles
From the arterioles where is the blood transported?
To the venules by passing through a dense network or bed of capillaries
Describe the walls of capillaries?
They're only one cell thick, which allows quick and efficient exchange of materials
What do capillaries allow to exchange?
substances with tissues
What happens when capillaries merge into one another
produce wider blood vessels called venules, which finally form veins
What do veins do?
Carry blood towards the heart
What is the structure of a vein?
Outer layer of connective tissue containing elastic fibres but a much thinner muscular wall than arteries
What is the difference between a lumen of a vein and of an artery?
The lumen of a vein is relatively wider than of an artery
Why are valves present in veins?
To prevent the backflow of blood
Why are valves needed?
As the blood is flowing back to the heart at low pressure and generally against the force of gravity
Comparison of blood in arterioles than capillaries
Arterioles is at a higher pressure than the blood in the capillaries
What is the result of higher blood pressure at the arteriole end of the capillary bed?
It results in pressure filtration, forcing the plasma, with small soluble molecules, out of the capillaries into the tissues
What is tissue fluid similar to?
Blood plasma but does not contain plasma proteins
What does tissue fluid contain?
Glucose, oxygen and dissolved substances, which supply the tissues with all their requirements
What happens to the useful and waste substances?
Useful molecules such as glucose and oxygen diffuse into cells and carbon dioxide and waste substances diffuse out of the cells and into the tissue fluid to be excreted
How does the tissue fluid re-enter?
Through capillaries at the venule end of the capillary bed by osmosis