Internal Transport in Mammals L2 Biology

Circulatory Systems Mammals have a closed system, with; a double pump 3 types of tubes a liquid moving one way

Functions of the Circulatory System Transports oxygen and nutrients from where it enters blood to all body cells Transports carbon dioxide and other wastes from body to where they are removed Transports hormones and antibodies around body Prevents blood loss by clotting Kills germs Controls the amount of fluid in tissues Helps control body temperature

The Heart A double pump to move blood through blood vessels Left side stronger than right Made from Cardiac Muscle 4 chambers: 2 atriums ( auricles) above and 2 ventricles below 4 valves, to stop backflow Cardiac muscles contract due to electric impulses that pressurize the blood.

Blood flow in summary Left ventricle – aortic valve - aorta – body – vena cava – right atrium (auricle) – tricuspid valve – right ventricle – mitral (bicuspid) valve - pulmonary artery – lungs – pulmonary vein – left atrium (auricle) – pulmonary valve - left ventricle … and so on…

Heart beat (pulse rate) control The heart beat and pulse rate is controlled by an electrical signal from the sinus node, located in the upper right atrium. From the sinus node, the electrical signal spreads across the 2 atria, causing them to contract, and to push their load of blood into the ventricles. The signal then causes the 2 ventricles to contract and push the blood out of the heart towards the lungs and body tissue. This signal controls the number and sequence of heart contractions and assures the heart works as efficiently as possible.

Blood vessels 3 main types: Arteries: carry blood away from the heart, thick walled, under high pressure (arterioles link to capillaries). Veins: carry blood back to the heart, thinner walls than arteries, larger internal diameter, valves stop back flow (venules link to capillaries). Capillaries: smallest vessels, fluid leaks out of capillary walls to bathe the surrounding tissue cells to exchange gases, nutrients, wastes and kill germs

Blood

Blood Components Red Blood Cells (RBC) – full of haemoglobin (an iron based molecule) which carries oxygen, disc shaped cells with no nucleus so cannot self-repair, made in bone marrow. White Blood Cells (WBC) – protects body against disease, cells with a nucleus, no haemoglobin, can move through capillary walls into tissues, made in bone marrow. Plasma – 90% water, part of blood that RBC, WBC, platelets, nutrients and wastes travel in, carbon dioxide dissolves in as bicarbonate. Platelets – involved in blood clotting, also made in bone marrow