TOPIC 1.CLASSIFICATION KINGDOM FUNGI
Double circulation in human being
In other less complex
organisms like the fish, blood goes through the heart only once; this is known
as single circulation.
Pulmonary circulation
- During pulmonary circulation, deoxygenated blood is brought to the heart through the vena cava. This blood is emptied into the right auricle. The right auricle pumps blood to the right ventricle. When the right ventricle contracts, it pumps blood to the lungs through the pulmonary artery.
- In the lungs, the blood is oxygenated. It then flows back to the heart through the pulmonary vein. The movement of blood between the heart and the lungs is called the pulmonary cycle.
Systemic circulation
- In systemic circulation, the pulmonary vein transports blood to the left auricle. The left auricle then pumps the blood into the left ventricle. The left ventricle has strong muscles that pump blood to all parts of the body through the aorta.
- After the tissues have derived their requirements from the blood, it flows back to the heart through the vena cava. This movement of blood between the heart and the various parts of the body is called the systemic cycle.
Formation of tissue fluid
The aorta is the largest artery in
the body. It braches into smaller arteries, which in turn branch into even
smaller vessels called arterioles. Arterioles branch into capillaries which are
in contact with the tissue of the body. The capillaries have tiny pores that
allow some components of blood to filter into the tissues.
At the arterial end of the
capillary, there is high blood pressure. This forces fluid out through the any
pores in the capillaries
The fluid is composed of water,
oxygen, hormones and nutrients. This fluid bathes the cells. It is called
tissue fluid or interstitial fluid.
The substances in this fluid diffuse into the
cells through the cell membrane. In addition, the waste products from the cells
diffuse into the tissue fluid. These wastes include carbon dioxide, minerals,
heat and nitrogenous wastes.
