Circulatory System
a. Introduction/Definitions
Circulatory system is defined as the combination of organs coming together to perform the task of
moving blood, nutrients,andd waste round the body.
b.Classification of circulatory system
1.Open circulation:This occurs when blood flows freely without being confined to blood vessels
as in invertebrates e.g insects.
2.Closed circulation:This mechanism of circulation deals with movement of blood within the
blood vessels.
3.Pulmonary circulation:This deals with movement of de-oxygenated blood to the lungs.
4.Systemic circulation: This encompasses movement blood round the body through the process
systole i.e contraction and diastole i.e relaxation of the heart.
c.Associated Organs of the Circulatory System
Heart, arteries,veins, capillaries,arterioles and venules
d.Functions of the Circulatory System and associated structures
1.Movement of nutrients and waste products(arteries and capillaries)
2.Immunity from disease(white blood cells)
3.Transportation of oxygen (red blood cells)
4. Transportation of blood (heart)
5.Draining of de-oxygenated blood back to the heart(veins).
6.Movement of blood round the body (arteries).
7.Regulation of osmotic pressure (heart).
