The Circulatory System

Aorta - the largest artery in the body from where oxygenated blood is pumped at high pressure from the heart to

the body through the aorta Vena cava - The superior vena cava is the large vein which returns blood to the heart from the head, neck and

both upper limbs. - The inferior vena cava returns blood to the heart from the lower part of the body

Pulmonary artery - is the only artery that carries deoxygenated blood

Pulmonary vein - is the only vein that carries oxygenated blood Pulmonary circulation - anything pulmonary should be associated with the lungs) between the heart and the

lungs and back Systemic circulation - between the heart and the rest of the body’s systems and back to the heart Oxygenated – enrich with oxygen

Deoxygenated – oxygen has been removed Arteries - carries blood away from the heart

Veins - carries blood back into the heart Capillaries – carries blood to and from the body cells Lumen- a bore of a tube

Atria- the two upper chambers of the heart Ventricles- a chamber of the heart which receives blood from a corresponding atrium and from which blood is

forced into the arteries

Septum - The wall dividing the left and right sides of the heart Tricuspid valve- The three-segmented valve of the heart that keeps blood in the right ventricle from flowing

back into the right atrium

Bicuspid (mitral) valve- One of the four valves of the heart, this valve is situated between the left atrium and

the left ventricle. It permits blood to flow one way only, from the left atrium into the left ventricle

NOTE: These two valves prevent blood flowing back into the atria from the ventricles. Semi-lunar valve - prevent expelled blood flowing back into the heart.

Heart rate (or pulse rate) – is the number of times your heart beats every minute. Stroke volume - is the amount of blood pumped out of the left ventricle per beat.

Cardiac output- is the amount of blood pumped out of the left ventricle of the heart per minute. Blood pressure-

Vasodilation- Blood is diverted to the skin where the heat can easily radiate away

Vasoconstriction- Blood is diverted away from the skin to limit heat loss. Red blood cells – as oxygen carriers; This is vital in supporting muscles during exercise.

- Also called erythrocytes. - Disc-shaped.

- Made in the bone marrow.

- Contain a red-coloured compound called haemoglobin which bonds with oxygen to form oxyhaemoglobin.

- Transport oxygen to the tissues. White cells- Act as the body’s defence system.

- Also called leucocytes.

- They are bigger than red blood cells and have large nuclei. - Some produce chemicals called antibodies that fight infection.

- Some white blood cells surround and consume harmful microbes.

Platelets- form blood clots. Formed in red bone marrow. - Produce thrombokinase – a chemical needed for blood clotting.

- Platelets help to repair tissues and close wounds both internally and externally. - When needed, they grow into irregular shapes and stick together to form a plug over the wound.

Plasma- a substance where blood cells and platelets are suspended

- Made up of glucose, inorganic salts, 90% water, antibodies, urea and other waste products, plasma

proteins. Blood doping- The process of increasing the number of circulating red blood cells

1. During exercise, extra demands are placed on the circulatory system.

a) Describe what happens to heart rate, stroke volume and cardiac output during intensive physical

activity.

- Heart rate, stroke volume and cardiac output all increase.

b) Describe how the circulatory system helps to regulate body temperature during exercise.

- Extra heat is produced during exercise. Vasodilation occurs – capillaries near the surface of the skin dilate. Blood is diverted to the skin to increase heat loss through radiation. Water is lost from the

blood through sweating, which helps to lower body temperature. 2. Blood contains several different types of cell.

a) Explain the function of red blood cells in the body.

- The main function of red blood cells is to transport oxygen from the lungs to the body’s tissues

b) Describe one way in which a performer could increase their red blood cell count.

- Altitude training – the performer lives and trains at altitude where there is less oxygen. The body

adapts by producing more red blood cells. - Blood doping – blood is removed from a performer and the red blood cells are separated and stored.

The performer produces more blood cells to replace the ones that were removed. The stored cells are later re-injected to boost the red blood cell count.