Heart Flashcards
What are the 3 blood vessels
Arteries
Veins Cappilaries
What is the main function of the arteries
Carry blood away from the heart to the rest of the body
Why do arteries have a thick muscular layer
Contract - push blood along
Control/ maintain blood pressure
Why do arteries have an elastic tissue layer
Stretch as ventricle contracts (when under high pressure) and recoils when ventricle relaxes (under low pressure)
Reduces pressure surges / even out blood pressure and maintaining high pressue
Why do arteries have a thick wall
To withstand high pressure and prevent artery from bursting
Why do arteries have a smooth and thin endothelium
Reduce friction
Why do arteries have a narrow lumen
Increases and maintains high blood pressure
Give 3 features of arteries
Think muscle layer
Narrow lumen
Smooth endothelium
What are arterioles
Division of arteries into smaller vessels which can direct blood to different capillaries/ areas
Why can arterioles be described as organs
Made up of different tissues
Why do arterioles have a thicker muscle layer than arteries
Contracts to reduce blood flow by narrowing lumen
Dialates (relaxes) to increase blood flow by enlarging lumen
Why do arterioles have. thinner elastic tissue compared to arteries
Lowers pressure surges
Arterioles have muscle fibres
Explain how these muscle fibres reduce blood flow to capillarie
When the muscle contract, the arteriole narrows, reduces the size of the lumen and therefore reduced blood flow to capillaries
What is the role of capillaries
To allow efficient gas exchange of gases and nutrients between blood and tissue fluid
Why are the capillary walls one cell thick
Short diffusion pathway - rapid diffusion
Why is the capillary bed made of a large network of capillaries
Increases SA : V ratio
Rapid diffusion
Why do capillaries have a narrow lumen
To reduce blood flow to allow more tie fro diffusionq
Why do capillaries permeate tissue
no cell is too far away
Short diffusion pathway
Why os there pores in capillaries
Allows substances to escape
eg. WBC to deal with infections
Name 3 features of capillaries
One cell thick
Narrow lumen
Numerous
What is the role of veins
To carry blood back to the heart under low pressure
Name 2 features of veins
Wider lumen than arteries
Very little elastic and muscle tissue
What is the role of valves
Prevent back flow of blood
