structure and function of blood vessels

What do arteries carry

Oxygenated blood away from heat

What are the properties of arteries

• thick muscular walls - withstand pressure

• Thick elastic layer (stretch and recoil)

• Smooth muscles help blood flow

• No valves

Why are there no valves and what is exception

No need for high pressure for blood

Semi lunar valves (aortic and pulmonary valves)

Stop blood flowing back into ventricles - located at beginning of aorta and pulmonary artery

What is the smooth muscle wal lined with

Endothelium

Reduces friction and create less restriction for blood flow

What happpens in arteries to enable blood to move at high pressure and fast

CONSTRICTION

Are arterioles bigger or smaller than arteries and in what way?

Smaller in diameter than arteries

Smaller lumen and thin muscle walls

What do arterioles carry blood to and from

From arteries to capillaries

What are the features of arterioles

Thick. Muscle layer - movement of blood into capillaries is controlled

Elastic layer is thinner - blood pressure is reduced

What is the importance of what arterioles do with the blood

It reduces the pressure so capillaries dont rupture

What is the importance of vasodilation of arterioles and what is it

Vasodilation is - relaxation of smooth muscle walls

There is vasodilation of lumen to allow blood to be controlled when flow into capillaries

What happens at. The capillaries?

Site of metabolic exchange

Exchange substances between the blood and body tissues

What are the properties of capillaries (4)

• extremely narrow - decreases diffusion distance between RBC and cells that need oxygen - increases diffusion

• Many capillaries throughout body and highly branched - large surface area for exchange + diffusion pathway is short allowing cells to be surrounded by it

• One cell thick (single layer of endothelial cells). - rapid diffusion

• Small spaces between endothelial cells and capillary - allow space for WBCto leave capillaries and destroy infections in tissues

Where does the blood go after capillaries

VENULES

What is the properties of venules

Larger than capillaries but smaller than veins

Blood goes capillaries - venues back into veins to go heart

Thinner walls than arterioles

What does veins transport

Deoxygenated blood from body back to heart

What are the properties of veins

Muscle and elastic layer is thin - constriction isn’t needed (blood is low pressure - veins wont burst

Valves - blood p = low - ensures no backflow

Wide lumen (to increase volume of blood)

Porous - (blood and fluid move through)