Circulatory system 1 What are we going to

Circulatory system 1

What are we going to learn ? Heart n Blood circulation n Blood vessels n Blood groups n 2

Heart n n 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 n n n 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 n n Upper chamber called Atrium; Lower chamber called as Ventricle Atrium and ventricle connected to each other by a one-way valve 3

Heart Internal structure Superior vena cava (carries blood to heart) Right pulmonary veins (carry blood from lungs) Pulmonary artery valve Right atrium Tricuspid valve Aorta (carries blood to body) Left pulmonary arteries (carry blood to lung) Left atrium Aorta valve Mitral valve Left ventricle Right ventricle Inferior vena cava Pericardium (carries blood to heart) 4

How does the heart function? Oxygen-poor blood from all over the body Oxygen-rich blood from the lungs Both atria expand the blood enters right atrium through vena cava and left atrium through pulmonary veins 1 Atria contract, both valves open and blood enters ventricles 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 the cycle starts again. 2 3 5

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 ! 6

Blood circulation n n This is the process of supply of blood to all the limbs of the body and its return to the heart. Two types n n Lungs Pulmonary circulation: Oxygenpoor 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 7

Blood circulation video 8

Blood vessels n Blood circulates through blood vessels n n n Network of vessels spread throughout the body Circulation only in one direction Three types n n n Arteries Veins Capillaries 9

Arteries n n Carry blood from the heart to various limbs No valves Blood flows under pressure (100 mm 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 10

Veins n n 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 11

Capillaries n n n 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 12

Constituents of blood - 1 Plasma Red blood cells Oxygen White blood cells Blood Platelets Unwanted items Ammonia, Urea Nutrients Hormones (Glucose, Amino acids) Carbon dioxide 13

Constituents of blood - 2 n Plasma n n Blood cells n n n Red blood cells Platelets Light yellow colour Alkaline 90% water, 7% proteins, 3% nonorganic matter Red blood cells White blood cells Platelets Plasma 54. 3% White blood cells and platelets 0. 7% White blood cells Plasma Red blood cells 45% 14

Red blood cells n n Circular shape, No nucleus, concave on both sides Function: Supply Oxygen to body cells n n Hemoglobin in the red blood cells acts as the transport of Oxygen 1 cubic mm contains 500 to 600 thousand red blood cells 15

White blood cells n n n Colourless, amoeba-like cells with nucleus Function: Protect body from bacteria 1 cubic mm contains 5000 to 10000 white blood cells 16

Platelets n n Small, irregular shape Function: Help in coagulation of blood n n n 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 17

Blood groups Blood is grouped into 4 categories based on proteins in it n n n A, B, O, AB Sub-groups Rh+ and Rh- in each group Before donating blood the blood groups have to be matched as under n Blood group of Blood can be donated to Blood can be received a person from A A, AB A, O B B, AB B, O AB AB A, B, AB, O O 18

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