Unit 5 Physiological Structure and Life Processes

Unit 5: Physiological structure and life processes Blood Circulatory System Introduction - a system that helps in the transportation of nutrients and oxygen to the body cells through blood and collects waste products for their removal. - helps regulate body temperature and carry substances that protect the body from various diseases. Functions of the blood circulatory system 1. Transportation- to transport all the nutrients and oxygen to all cells and waste products from cells to the excretory organ. 2. Protection: WBC produces antibodies which increase the immune power to fight against pathogens, viruses and bacteria, etc. 3. Regulation: regulates the amount of water and temperature -The blood circulatory system in humans consists of three major parts: a) Blood b) Blood vessels c) Heart a) Blood  a fluid connective tissue flowing in its closed path called blood vessels.  red due to the presence of iron-rich pigment called haemoglobin in RBC.  Red coloured, viscous fluid connective tissue  consists of 55% plasma and 45% blood cells  average human body consists of 5.5 litres of blood  circulates in the arteries and veins to supply nutrients and oxygen to different tissues of the body and carry back wastes Fig: Composition of blood Composition of blood Blood is composed of 55% blood plasma and 45% blood cells. Blood Plasma -transparent yellowish liquid -contains about 90% water, 2% different types of proteins and 2% clotting factors - blood cells are suspended in the plasma. Functions  Transports digested food to different parts of the body  Transports various waste materials to the excretory organs  Maintains the amount of water in the body, regulates the body temperature, and helps in blood clotting Blood Cells/ Blood corpuscles  Blood cells are found suspended in the plasma  Occupy 45% of the total volume of blood a) Red blood Cells           also called erythrocytes Circular, biconcave and disc-shaped cells have no nuclei One cubic mm of blood contains about 4.5 million to 6 million RBCs Formed in the bone marrow and destroyed in the liver or spleen Life span is about 120 days They contain haemoglobin, which is an iron-pigmented substance, due to which blood is red. function of RBC is to transport oxygen and carbon dioxide between the lungs and all parts of the body. Deficiency of RBC in the blood leads to the disease called anaemia are also called oxygen carriers. RBC is more than average, which causes polycythemia. Symptoms of anaemia: Loss in weight and appetite a. Slow and retarded growth b. Pale and dull colour of Skin, etc c. Weakness and tiredness even after a short walk. b) White blood cells       They are also called leukocytes Irregular in shape, contains a nucleus but lacks haemoglobin One cubic mm of blood contains about 4000 to 11000 WBCs Formed in the bone marrow lymph nodes, and destroyed in the spleen/ liver Life span is about 12 to 14 days They are the cells of the immune    system involved in defending the body against both pathogens and foreign materials Excess amount of WBCs in the blood leads to the disease called Leukaemia ( blood cancer) Less WBCs in blood leads to leukopenia [ baldness] caused due to fall in neutrophil cells. Leucocytes are of 2 types: i) Granulocytes- having granules in their cytoplasm and a lobed nucleus [neutrophils, eosinophils and basophils] ii) Agranulocytes- without granules in their cytoplasm and unilobed nucleus [ monocytes and lymphocytes] c) Platelets  also called thrombocytes  Smallest blood cells, oval and no nucleus  Formed in the bone marrow and destroyed in the spleen  One cubic mm of blood contains about 1.5 lakhs to 4.5 lakhs platelets  Life span 5 to 10 days, formed in the bone marrow, destroyed in the spleen  They contain a pigment called fibrinogen, which helps in blood clotting and thus prevents the excess loss of blood  Fewer platelets cause thrombopenia – excessive bleeding can occur (Haemophilia)  Excess platelets cause thrombocytosis, obstructing blood vessels Functions of blood a) Transport oxygen from the lungs and all parts of the body b) carries waste products from different tissues to the excretory organs c) carries hormones produced by endocrine glands to the target cells d) helps to destroy various microorganisms and pathogens e) helps to regulate body temperature f) helps in blood clotting and minimises the excess loss of blood Differences between RBC and WBC RBC WBC 1. They are oval, biconcave and without a 1. They are irregular and nucleated nucleus 2. They are small in size 2. They are large 3. They are red due to the presence of 3. They are colourless haemoglobin 4. They help in respiration 4. They help in the defence of the body Differences between Blood and plasma Blood Plasma