The Heart Left Atrium Right Ventricle Right Atrium Left Ventricle Septum Atrio-Ventricular Valve Tendons Pocket Valve

Helpful Hints Homer’s Right Hand Homer’s Left Hand Right Side of Homer’s Heart Left Side of Homer’s Heart Diagrams of the heart usually show the heart as if you were looking at it in someone else’s chest The plural of atrium is… atria … because atrium is a Latin word!

…oxygenated blood. …deoxygenated blood. … muscle Vena Cava… …from body Pulmonary Artery… …to lungs Pulmonary Vein… …from lungs Aorta… …to body Walls of the heart are made of … The walls of the left ventricle are much thicker than the walls of the right ventricle because … …the left ventricle has to pump blood much further. The right side of the heart carries… The left side of the heart carries…

Filling the Heart …the body (Vena Cava) Right atrium fills with blood from… Left atrium fills with blood from… … the lungs (Pulmonary Vein) Atrio-Ventricular valves are… OPEN Blood flows from the atria into the ventricles Pocket valves are… CLOSED Blood cannot flow back from the Pulmonary Artery and Aorta into the Ventricles Heart muscle is… RELAXED

Blood flows from the Ventricles into the Pulmonary Artery and Aorta Blood from the Ventricles cannot flow back into the Atria Emptying the Heart Heart muscle is… CONTRACTING Atrio-Ventricular valves are… CLOSED Pocket valves are… OPEN To Lungs (Pulmonary Artery) To Body & Head (Aorta)

carbon dioxide… Oxygenated Blood Deoxygenated Blood Lungs Heart Head Body Pulmonary Circulation Systemic Circulation …and gains…carbon dioxide… oxygen …and gains… oxygen In the lungs, blood loses… In the tissues of the body, blood loses…

… arteries Blood is carried away from heart by… … capillaries Arteries divide to form… … veins Capillaries join to form… Veins carry blood back to the heart Blood Pressure DECREASES as it flows round system

Arteries are adapted to deal with blood under HIGH pressure Thick outer wall Thick layer of muscle and elastic fibres Narrow lumen (space through which blood flows) Veins are adapted to deal with blood under LOW pressure Wide lumen Thinner outer wall than arteries Thinner layer of muscle and elastic fibres than arteries

Veins also have valves to… …keep blood flowing in the right direction …TOWARDS heart …AWAY FROM heart Valves open to allow blood to flow… Valves close to stop blood flowing…

Carbon dioxide and other wastes diffuse from the cells to the blood Oxygen, food molecules and hormones diffuse from the blood to the cells Capillaries are adapted for ……exchange of materials. …only one cell thick …allow plasma to leak in and out (They are just large enough for a red blood cell to squeeze through) This means that blood in the capillaries moves very… SLOWLY Gaps between cells in capillary wall… Wall of capillary is very thin… The capillaries are very narrow. Cells in Body Tissues

The Blood is made up of four components… Red Blood Cells Carry oxygen White Blood Cells Fight infections Cell fragments called… …platelets Help with blood clotting A straw- coloured liquid called… …plasma Carries dissolved substances: Carbon dioxide Other wastes Food molecules Hormones

Red Blood Cells are adapted for carrying oxygen Shape: Biconcave disc … surface area for absorption of oxygen Dimple on either side of cell increases… …haemoglobin Cell is packed with … nucleus This make s more room for… haemoglobin. Mature red blood cell has no… Haemoglobin + OxygenOxyhaemoglobin In the Lungs In the BodyTissues