The Circulatory System The bodys transport system Functions

The Circulatory System The body’s transport system:

Functions: 1. Transportation: • oxygen and nutrients etc are distributed to body cells. • carbon dioxide and wastes are taken away from the cell. 2. Maintenance of body temp & chemical balance. 3. Circulation of hormones, components of the immune system etc.

Structures: 1. Fluid which carries materials to be transported (blood) 2. Blood Vessels or tubes for the blood to move through (arteries, veins, capillaries) 3. A Pump that pushes the fluid through the blood vessels (heart)

1. Blood Vessels Artery Arteries: - carry blood away from the heart - thick and elastic walls (high pressure) - usually high O 2, low CO 2 (except pulmonary) Veins: - carry blood to the heart - thin and slightly elastic walls - contain flap-like valves to prevent backflow - usually low O 2, high CO 2 (except pulmonary) Capillaries: - tiny blood vessels one cell thick - microscopic network of blood vessels at all tissues - allows exchange of materials between cells & blood Vein

2. THE HEART

The Incredible Heart Muscle Great Strength : – Pumps 4 -5 L of blood through ~160 000 km of blood vessels. High Endurance: – Beats on average 72 beats / minute, ~ 100 000 beats / day – During a lifetime, could fill an ocean tanker full of blood TWICE Size: – Size of your fist & weighs ~ 300 grams Pace Maker: – Makes its own ‘electricity!’ – Coordinates the beating of heart cells

The Incredible Heart - Double Pump Right Side Pump: – Pumps blood that is low in oxygen to the lungs to pick up oxygen. – Deoxygenated blood from the body drains into the right atrium via the vena cava (large veins. ) – Blood goes from the right atrium to the right ventricle which pumps the blood to the lungs via the pulmonary artery.

The Incredible Heart Pump Left Side Pump: – Pumps blood that is high in oxygen to the body to give oxygen to body cells (for cell respiration) – Oxygenated blood from the lung enters the left atrium via the pulmonary veins. – Blood goes from the left atrium to the left ventricle which pumps the blood to the body via the aorta (largest artery in the body).

THE HEART

3. Blood Major blood component: • Plasma (55%): – Liquid part of blood – contains dissolved material • Red Blood Cells (RBC - 44%): – Contains haemoglobin that carries oxygen • White Blood Cells (WBC – 1%): – Immune system (WBC engulf invaders/ produce antibodies) • Platelets (< 1%): – Cell fragments needed to clot blood

Branches of the Circulatory System 1. Systemic circuit: Blood goes from the heart to the rest of the body and back to the heart. Includes: – Cardiac circuit: blood goes to the heart muscle (coronary arteries & veins) – Hepatic-Portal: transports blood from digestive tract to liver then to heart – Renal: carries blood to, and from the kidneys 2. Pulmonary circuit: Blood goes from the right side of the heart to the lungs & back to left side of the heart (pulmonary arteries & veins)

Heart Cycle: • Diastole: Heart fills with blood – The heart muscles relax – Atria collects blood & drains it into ventricles • Systole: Heart pumps – Ventricles contract – Blood is pumped out of the heart • Heart Sounds: Lubb – Dubb - Closing of the heart valves – Ventricles contract & increase in pressure causes the AV valve to close shut Lubb sound – Ventricles relax, causing blood to rush in from Atria – Decrease in pressure as blood flows in, causing semilunar valves to shut Dubb sound