Structure and function of arteries, capillaries and veins Flashcards Preview

Unit 2 Biology > Structure and function of arteries, capillaries and veins > Flashcards

Flashcards in Structure and function of arteries, capillaries and veins Deck (33)
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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?

The lumen


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


What does pressure filtration force?

More water out of the capillaries than re-enters by osmosis