The mammalian circulatory system

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The mammalian circulatory system
3 main parts
Heart

• works as pump

Blood

• dissolves and carries materials

Blood vessels

• Tubes for blood to flow along

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Blood vessels
Types of blood vessels
arteries
veins
capillaries

• return blood to heart

• carry blood away from heart

• connect arteries to veins
• exchange materials with body tissues

Venule
Arteriole
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How is blood driven along the blood vessels ?
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How is blood driven along the artery?
Heart
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External Structure of heart
Heart consists of 4 chambers
2 auricles
2 ventricles

• smaller
• on the upper part

• larger
• below auricles

right auricle
left auricle
left ventricle
right ventricle
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Internal Structure of heart
Heart consists of 4 chambers
2 auricles
2 ventricles

• smaller
• on the upper part

• larger
• below auricles

right auricle
left auricle
left ventricle
right ventricle
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auricles and ventricles are separated by valves
to prevent backflow of blood
semi-lunar valves
tricuspid valve
bicuspid valve
valve tendon holds valves in position and avoids
them to turn inside-out
Septum prevents mixing of blood in both sides of
the heart
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Blood flow and blood vessels
pulmonary artery
aorta
to lung
from body
to body
from lung
superior vena cava
pulmonary veins
inferior vena cava
from body
deoxygenated blood
oxygenated blood
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External Structure of heart
pulmonary vein
aorta
pulmonary artery
coronary artery
superior vena cava
coronary vein
inferior vena cava
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How is blood driven along the vein ?
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Blood flow in veins
muscles beside vein contract
action of valves
blood flows towards heart
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Differences between Artery Vein

• thick
• elastic wall
• samll lumen
• no valves

• thin wall
• large lumen
• valves are
• present

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Double circulation in mammals
Blood vessels
Circulatory system
Heart
Blood
pulmonary circulation
As blood passes through heart twice, this also
known as double circulation
systemic circulation
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The pulmonary circulation

• The blood becomes oxygenated

• Deoxygenated blood in right ventricle

• The blood is pumped through pulmonary artery into
  lungs for gas exchange

• The blood flows through pulmonary veins to left
  auricle

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The systemic circulation

• O2 and nutrients diffuse into cells while CO2 and
  wastes diffuse out

• Oxygenated blood in left ventricle

• The blood is pumped through aorta to all parts of
  the body except lungs

• The blood flows through inferior/ superior vena
  cava to right auricle

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Capillaries

• allow exchange of materials between the blood and
  the body tissues

arterioles
capillaries
venules

• the wall is thin permeable to O2, CO2, glucose,
  water ... etc.

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Exchange of materials between the blood and the
body cells
white blood cells
water
O2
nutrients
plasma
waste products
CO2
tissue fluid
Diffuse across the capillary wall
Diffuse across the capillary wall
Squeeze through the wall
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Formation of the tissue fluid
At arterial end
some materials are forced out of the capillaries
high pressure
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Formation of the tissue fluid
similar to blood plasma but NO plasma proteins
and red blood cells
Tissue fluid is mainly water with some mineral
salts, fats, sugars and hormones
too large to be forced through capillary wall
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Formation of the tissue fluid
At venous end
some tissue fluid return to capillaries
, others are drained into lymph
vessels