Structure and function of arteries, veins and capillaries

Comparison of blood vessels:

artery

vein

capillary

diameter

narrower

wider

microscopic

wall thickness

thick

thin

one cell thickness

lumen

narrow

wide

RBCs can pass

elasticity

elastic

inelastic

no elastic fibres

valves

absent

present

absent

direction of blood flow

away from heart

towards the heart

from an artery end to a vein end/material exchange

within tissues

composition

more oxygen

less carbon dioxide

except pulmonary artery

less oxygen

more carbon dioxide

except pulmonary vein

more oxygen in artery

less oxygen in vein

pressure

high

low

Steadily decreases from an artery towards vein.
wall layers

three:

tunica adventitia

tunica media

tunica intima

three:

tunica adventitia

tunica media

tunica intima

one: tunica intima

pulse to be found

present and can be felt when near the surface

absent

none

position in the body

usually deep in the body

close to the surface

everywhere

if cut

blood spurts out

blood trickles out

blood trickles out

How can we identify blood vessels under microscope?

    • Walls of arteries are thicker as they are made up of three distinct layers.
    • Veins are thinner but have wider lumen.
    • Capillaries are so small that are not visible under light microscope.

Main blood vessels of the human body:

Main Arteries of the body:

Heart:  

    • The aortic arch from left ventricle

Lungs:

    • The pulmonary arteries from right ventricle

Liver:

    • the hepatic artery to the liver.

Kidneys:

    • the renal arteries, one to each kidney.

Main Veins of the body:

Heart:  

    • The anterior/superior vena cava returns blood from head, neck and arms to right atrium
    • The posterior/inferior vena cava returns blood from lower body to right atrium

Lungs:

    • The pulmonary vein brings blood from lungs to left atrium

Liver:

    • the hepatic vein bring blood from  the liver.

Kidneys:

    • the renal veins bring blood from kidneys.

Subscribe to our Newsletter