TRANSPORT IN MAMMALS
I. Circulation- The circulatory system is a system of blood vessels with a pump and valves to ensure one-way flow of blood.
Circulation in Different Animals:
- Fish have a two-chambered heart and a single circulation. This means that for every
one circuit of the body, the blood passes through the heart once.
- Mammals have a four-chambered heart and a double circulation. This means that for
everyone circuit of the body, the blood passes through the heart twice.
- The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs (the pulmonary circulation).
- The left side of the heart receives oxygenated blood from the lungs and pumps it to the body (the systemic circulation).
- Heart Structure:
- The ventricles ( lower-chambers of the heart) have thicker muscle walls than the atria as they are pumping blood out of the heart and so need to generate a higher pressure The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body, whereas the right ventricle is pumping blood at lower pressure to the lungs
- The septum separates the two sides of the heart and so prevents mixing of oxygenated and deoxygenated blood
- The heart is labelled as if it was in the chest so what is your left on a diagram is actually the right hand side and vice versa
The right side of the heart receives - The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs
- The left side of the heart receives oxygenated blood from the lungs and pumps it to the body
- Blood is pumped towards the heart in veins and away from the heart in arteries. The two sides of the heart are separated by a muscle wall called the septum. The heart is made of muscle tissue which are supplied with blood by the coronary arteries
III. Blood Vessels
Arteries, Veins & Capillaries
- Arteries
- Carry blood at high pressure away from the heart
- Carry oxygenated blood (other than the pulmonary artery)
- Have thick muscular walls containing elastic fibres
- Have a narrow lumen
- Speed of flow is fast
- Carry blood at low pressure towards the heart
- Carry deoxygenated blood (other than the pulmonary vein)
- Have thin walls
- Have a large lumen
- Contain valves
- Speed of flow is slow
- Coordinated Science-Biology notes
- Capillaries
- Carry blood at low pressure within tissues
- Carry both oxygenated and deoxygenated blood
- Have walls that are one cell thick
- Have ‘leaky’ walls
- Speed of flow is slow
- Blood is carried away from the heart and towards organs in arteries
- These narrow to arterioles and then capillaries as they pass through the organ
- The capillaries widen to venules and finally veins as they move away from the organs
- Veins carry blood back towards the heart
- Components of Blood
Blood consists of red blood cells, white blood cells, platelets and plasma
- Functions of the Parts of the Blood
- Plasma is important for the transport of carbon dioxide, digested food (nutrients), urea, mineral ions, hormones and heat energy mineral ions, hormones and heat energy.
- Red blood cells transport oxygen around the body from the lungs to cells which require it for aerobic respiration. They carry the oxygen in the form of oxyhaemoglobin require it for aerobic respiration. They carry the oxygen in the form of oxyhaemoglobin
- White blood cells defend the body against infection by pathogens by carrying out phagocytosis and antibody production phagocytosis and antibody production
- Platelets are involved in helping the blood to clot
0 Nhận xét: