The circulatory system: the transport of blood around the body

Aims of the session To recap on the previous session: the structure and function of the heart. To introduce the body ’ s method of transporting blood around the body. To explain blood pressure and what effects a persons blood pressure. Introduce types of blood vessels and blood cells.

The Heart Right side – deoxygenated Left side – oxygenated Separated by a thick walled septum Right atrium and ventricle connected by tricuspid valve Left atrium and ventricle connected by bicuspid (mitral) valve Cuspid valves held shut by Chordae Tendinae Left ventricle is thicker than the right

Vessels of the Heart Pulmonary artery* Pulmonary vein Superior and Inferior Vena cava Aorta* *Semi-lunar valves

Control of the Heart Sinoventricular node (SV node) Sends waves of excitation along Purkinje Fibres which collectively make up the Bundle of Hiss. Along septum, radiate upwards Ventricles contract Both atria and both ventricles contract at the same time Systole-contraction of heart Diastole-Relaxation/filling of the heart

Blood pressure Systolic blood pressure. When the heart contracts pushing the blood out through the arteries.

Blood pressure Diastolic blood pressure, when the heart is relaxed and allows blood to enter.

Factors affecting blood pressure Age Blood pressure tends to increase with age. Gender Blood pressure in generally higher in males. Exercise Blood pressure increases in short-term exercise but decreases in long-term. Stress Stress increases blood pressure through adrenalin and other hormones.

Effects of high blood pressure Angina Sharp pains in the chest, mainly caused by the heart not getting enough oxygen. Heart Attacks The heart stops beating due to lack of oxygen. Strokes Damage to the brain due to oxygen starvation.

Blood vessels There are three types of blood vessels you need to know: Arteries Veins Capillaries

Arteries Carry oxygenated blood away from the heart (the pulmonary artery brings blood to the heart!!) They have thick strong elastic walls. Small arteries are called arterioles.

Veins Carry deoxygenated blood back to the heart (the pulmonary vein carries blood away from the heart!!). The veins have thinner walls as the blood pressure is lower. Veins have valves that keep blood flowing in the right direction. Small veins are called venules.

Capillaries Carry digested foods and oxygen directly to the tissue. Take away waste products of the body. Very small and vary in size.

How it works!! Heart Arteries Arterioles Capillaries Gas exchange Venules Veins Heart

Blood Blood is made up of: Cells Platelets Plasma

Blood cells Red Blood cells carry oxygen around the body in haemoglobin. They have no nucleus (brain) thus leaving more space for oxygen

White blood cells Fight against disease. Destroys bacteria by using antibodies. Fights toxins by using antitoxins. Kills foreign microbes by consuming them.

Plasma Includes everything. Blood cells. Digested foods (glucose). Waste. Hormones.

Platelets Platelets re tine fragments in the body that help blood clot at wounds.

Warm-up questions How many circuits are there in the circulatory system? What type of blood is carried back to the heart? Which type of blood vessel carries blood away from the heart? Which type of blood cell carries oxygen? Which type of blood cell fights diseases?

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