(CVS)
, INTRODUCTION
• The CVS otherwise called the CIRCULATORY SYSTEM consists of a
muscular pump (THE HEART) and the network of several BLOOD VESSELS
through which blood is conveyed to all parts of the body and via which blood
from the tissues is returned to the heart.
• Major functions of the CVS include the following:
1) Transport of O2 from the lungs to the tissues
2) Transport of CO2 from the tissues to the lungs where the CO2 is excreted
3) Transport of nutrients from the Gastrointestinal tract (GIT) to all parts of the
body
4) Transport of hormones from the body from the endocrine glands to the target
tissues.
5) transport of waste products of cellular metabolism from the tissues to the
kidneys and other excretory organs such as lungs, gut and skin.
6) Transport of heat between the body’s core and its surfaces thereby aiding
temperature regulation.
7) Transport of blood cells (mainly leucocytes) and chemical factors (immune
substances) that defend the body against foreign substances, infective agents (e.g.
bacteria, viruses and fungi) and abnormal cells, including cancer cells.
, Functional divisions of the
circulation
• The heart consists of two (2) pumps- RIGHT and LEFT pumps:
RIGHT PUMP
• The RIGHT PUMP is a low pressure pump and consists of Right atrium (RA) and
Right Ventricle (RV).
• The RA receives deoxygenated blood from the superior and inferior venae cavae
which is then passed to the RV.
• The wall of the RV is about 3-4mm thick and it pumps out its blood through the
pulmonary arteries (PAs) into the lungs.
• Backflow of blood from the pulmonary trunk (PT) into the RV is prevented by the
presence of pulmonary valves (PVs).
• The right pump, the pulmonary trunk, the pulmonary arteries, the pulmonary
capillaries and pulmonary veins that bring the Oxygenated blood from the lungs to
the left atrium of the heart constitutes the PULMONARY CIRCULATION.