Circulatory system

What are we going to learn ? Heart Blood circulation Blood vessels Blood Blood groups

Heart Acts like a pump of the circulatory system supplying blood to the whole body Located between the lungs a little to the left; size roughly equal to a fist Made up of muscle with a dual protective layer Two internal sections unconnected to each other Left section contains Oxygen-rich blood received from the lungs Right section contains Oxygen-poor blood to be sent to lungs Each section has two chambers Upper chamber called Atrium; Lower chamber called as Ventricle Atrium and ventricle connected to each other by a one-way valve

Heart Internal structure Pulmonary artery valve Aorta valve Aorta (carries blood to body) Superior vena cava (carries blood to heart) Left pulmonary arteries (carry blood to lung) Right pulmonary veins (carry blood from lungs) Left atrium Pulmonary artery valve Aorta valve Right atrium Mitral valve Tricuspid valve Left ventricle Right ventricle Pericardium Inferior vena cava (carries blood to heart)

How does the heart function? Both valves close so that blood cannot go back to atria. Ventricles contract and blood goes out to lungs through pulmonary arteries and to the rest of the body through the aorta. Atria then expand and the cycle starts again. 3 Atria contract, both valves open and blood enters ventricles 2 Oxygen-poor blood from all over the body Oxygen-rich blood from the lungs Both atria expand and the blood enters right atrium through vena cava and left atrium through pulmonary veins 1

Heart beats Heart beats occur due to the rhythmic expansion-contraction of the heart muscles. Normally they range between 60 to 80 per minute. In other words the heart expands and contracts almost one hundred thousand times day !

Blood circulation Lungs This is the process of supply of blood to all the limbs of the body and its return to the heart. Two types Pulmonary circulation: Oxygen-poor blood travels from the heart to the lungs and Oxygen-rich blood travels back Systemic circulation: Oxygen-rich blood travels from the heart to the all the limbs of the body and Oxygen-poor blood travels back Cells in the body

Blood circulation video

Blood vessels Blood circulates through blood vessels Three types Network of vessels spread throughout the body Circulation only in one direction Three types Arteries Veins Capillaries

Arteries Carry blood from the heart to various limbs No valves Blood flows under pressure (100mm of Hg) Other than pulmonary arteries all arteries carry Oxygen-rich blood Walls of arteries are made of three layers of muscle. These thick walls contract and push blood forward

Veins Except for pulmonary veins all other veins carry Oxygen-poor blood from various limbs to the heart Walls are thin Valves stop blood from flowing in reverse direction Blood flows under low pressure (2 mm of Hg) Valves permit flow only in one direction

Capillaries Consist of a network of microscopic vessels joining arteries with veins Extremely thin walls Capillaries permit exchange of nutrients, gases etc. in the blood with the cells Capillary network Artery Veins Cells

Constituents of blood - 1 Red blood cells Platelets Plasma Carbon dioxide Nutrients (Glucose, Amino acids) Unwanted items Ammonia, Urea Hormones Blood Oxygen White blood cells

Constituents of blood - 2 Plasma Light yellow colour Alkaline 90% water, 7% proteins, 3% non-organic matter Blood cells Red blood cells White blood cells Platelets Plasma 54.3% White blood cells and platelets 0.7% Red blood cells 45% White blood cells Red blood cells Platelets Plasma

Red blood cells Circular shape, No nucleus, concave on both sides Function: Supply Oxygen to body cells Hemoglobin in the red blood cells acts as the transport of Oxygen 1 cubic mm contains 500 to 600 thousand red blood cells

White blood cells Colourless, amoeba-like cells with nucleus Function: Protect body from bacteria 1 cubic mm contains 5000 to 10000 white blood cells

Platelets Small, irregular shape Function: Help in coagulation of blood After a wound platelets create a network of fibrin strings Red blood cells are trapped in the network and form a scab on the wound 1 cubic mm = 150 to 400 thousand platelets

Blood groups Blood is grouped into 4 categories based on proteins in it A, B, O, AB Sub-groups Rh+ and Rh- in each group Before donating blood the blood groups have to be matched as under Blood group of a person Blood can be donated to Blood can be received from A A, AB A, O B B, AB B, O AB A, B, AB, O O

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