9. THE HEART
The heart
Structure and functions
Overview
Structure and location
• A muscular pear or cone-shaped organ
• Size of a clenched fist of the same person
• Located behind and to the left of the sternum or
breast bone in the chest area between the lungs
• Pointed end – apex downward, forwards pointing
towards the left
• Contained within a sack called pericardium on top of
the diaphragmatic muscle surrounded by rib cage for
protection
Structure …
• Divided into separate right and left sections by the
interventricular septum
• Right and left sections divided into upper and lower
compartments – atria and ventricles
• Four main chambers: 2 small – atria and 2 bigger
ventricles - Right Atrium; Right Ventricle; Left
Atrium, Right Ventricle
The left ventricle is the largest and strongest chamber and
needs more muscle
• The heart muscle is the myocardium
Pumping blood
• Deoxygenated blood pumps through the right atrium
from the Superior and Inferior Vena Cava and leaves
the right ventricle by Pulmonary Artery to take blood
to the lungs
• Oxygenated blood pumps through the left atrium
from the Pulmonary Veins and leaves the left
ventricle by the Ascending Aorta to take blood to
the body
Blood flow
• Blood flows in the correct direction through 4 valves
• Tricuspid valve
• Pulmonary valve
• Mitral or bicuspid valve
• Aortic valve
• Coordination of blood flow and rhythmical
contraction are maintained by electrical activity
Functions
Right-Hand side
Receives deoxygenated blood from body tissues into the right
atrium passing through the right tricuspid valve into the right
ventricle- the blood is pumped under high pressure to the
lungs
Left- Hand side
Receives oxygenated blood from the lungs into the left atrium
passing through the bicuspid valve into left ventricle then
pumped to the aorta under great pressure ensuring the
oxygenated blood is delivered to other parts of the body via
blood vessels http://www.ivy-rose.co.uk