blood from the heart gets around the body through blood vessels there are 3 types of blood vessels...
TRANSCRIPT
blood from the heart gets around
the body through blood vessels
There are 3 types of blood vessels
a. ARTERY
b. VEIN
c. CAPILLARY
Thick smooth muscle
Thin smooth muscle
Elastic layer Elastic layer
The ARTERY
thick muscle and elastic fibres
Arteries carry blood away from the heart.
the elastic fibres allow the artery to stretch under pressure
the thick muscle can contract to push the blood along.
Copyright Pearson Prentice Hall
Blood Vessels
Aorta
• Transport oxygenated blood from left ventricle to rest of body
• Forms the characteristic aortic arch• Largest artery of the body
Pulmonary arteries
• Brings deoxygenated blood from right ventricle to lungs to uptake oxygen
• The ONLY arteries that transport deoxygenated blood
• 2 pulmonary arteries – one to each lung
The CAPILLARYCapillaries link Arteries with Veins
the wall of a capillaryis only one cell thick
they exchange materials between the blood and other body cells.
The exchange of materials between the blood and the body can only occur through capillaries.
Copyright Pearson Prentice Hall
Blood Vessels
artery vein
capillaries
body cell
The CAPILLARYA collection of capillaries is known as a capillary bed.
The VEINVeins carry blood towards from the heart.
thin muscle and elastic fibres
veins have valves which act to stop the blood from going in the wrong direction.
body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel.
Copyright Pearson Prentice Hall
Blood Vessels
Copyright Pearson Prentice Hall
Blood Vessels•Large veins contain valves that keep blood moving toward the heart. •Many veins are located near and between skeletal muscles.
Valve open
Valve closed
Valves closed
• Brings deoxygenated blood from head and arms to right atrium of heart
Superior Vena Cava
Inferior Vena Cava
• Brings blood from bottom part of body into right atrium of heart
Pulmonary Vein
• Transports oxygenated blood from the lungs back to the left atrium of heart
• The ONLY vein that carries oxygenated blood• 2 pulmonary veins – one from each lung
Hydrostatic & Osmotic Pressures
• The high hydrostatic pressure on the arterial side squeezes water and nutrients out of the capillaries.
• Water leaving the capillaries builds up the osmotic pressure because the blood components have become more concentrated.
• Towards the venal end, water and waste materials are sucked into capillaries by the osmotic pressure.
Veins and Venules Capillaries Arteries and Arterioles
Function is to carry blood from tissues to the heart
Function is to allow exchange of materials
between the blood and the tissues
Function is to carry blood from the heart to the
tissues
Thin walls, mainly collagen, since blood at
low pressure
Very thin, permeable walls, only one cell thick to
allow exchange of materials
Thick walls with smooth elastic layers to resist high pressure and muscle layer
to aid pumping
Function : Carry blood away from heart
Function : Carry blood towards from heart
Large lumen to reduce resistance to flow.
Very small lumen. Blood cells must distort to
pass through. Small lumen
Many valves to prevent back-flow
No valves No valves (except in
heart)
Blood at low pressure Blood pressure falls in
capillaries. Blood at high pressure
Blood usually deoxygenated
(except in pulmonary vein)
Blood changes from oxygenated to deoxygenated
(except in lungs)
Blood usually oxygenated (except in
pulmonary artery)
Veins and Venules Capillaries Arteries and Arterioles
Valves • Found in the heart and veins• Folds of the inner walls of heart and veins• Shaped like half moons, so called semilunar valves• Function: Prevent backflow of blood.
Textbook pg 130 NEXT
BACK
Unidirectional flow of blood
Vericose Veins
• When the valves in the veins near the surface of the skin fail to close properly
• Allow blood to accumulate in the veins• Causes vein to bulge (swollen appearance)
NEXT
BACK
Valves fail to close properly