Heart
Heart structure
Compose of entirely muscle
The wall of the heart:
two thin layers of epithelial called myocardium
Myocardium contraction pump the blood through
circulatory system.
Adult heart contract ~72 times a minute
Heart
4 chambers
A wall called septum separate the right and the left
Septum prevent oxygen-rich blood and oxygen-poor blood
from mixing.
The upper chamber called atrium : receive blood from the
body
The lower chamber called ventricles : pump blood out of
heart
Blood flow through the heart
Blood from body enter the heart through right
atrium.
Blood from lung enter the heart through left
atrium.
Valves connect between atria and ventricles
Valves keep the blood moving through heart in
one direction.
Heart’s blood supply
Heart muscle need a constant supply of nutrient
and oxygen.
Pair of blood vessels called coronary arteries,
supply blood to heart muscle.
If they are blocked, heart muscle cells running out
of oxygen and could begin die.
Heart attack!!!!!!!
Blood vessels
Arteries : Large vessel carry blood from heart to
tissue of body.
Super highway of blood with thick elastic walls help
them withstand the powerful pressure
Three layers : connective tissues, smooth muscles and
endothelium
Capillaries : smallest blood vessels with extremely
thin wall allow oxygen and nutrient diffuse from
blood to tissue and carbon dioxide and waste
move from tissue to blood
Blood vessels
Veins : return blood from capillaries to
heart
Flow against gravity
When we move contracting muscle squeezing
the vein push the blood toward the heart
Many veins contain valves to direct the blood
flow in one direction