1-(Circulation) Introduction blood circulation.pptx

Blood circulation in the body

1. Circulation (introduction) Dr. Mahreen Siddique Pharm.D , R.ph. , M.phil. , Ph.D Scholar (Pharmacology)

2. Circulatory Components The key components of the circulatory system are the Heart B lood vessels Blood

3. Blood Blood is composed of formed elements (cells and cell fragments) suspended in a liquid called plasma . Dissolved in the plasma are a large number of proteins, nutrients, metabolic wastes, and other molecules being transported between organ systems. The cells are the erythrocytes (red blood cells) and the leukocytes (white blood cells), and the cell fragments are the platelets.

4. More than 99% of blood cells are erythrocytes that carry oxygen to the tissues and carbon dioxide from the tissues. The leukocytes protect against infection and cancer, and T he platelets function in blood clotting. The constant motion of the blood keeps all the cells dispersed throughout the plasma.

5. hematocrit The hematocrit is defined as the percentage of blood volume that is erythrocytes. It is measured by centrifugation (spinning at high speed) of a sample of blood. The erythrocytes are forced to the bottom of the centrifuge tube, the plasma remains on top, and the leukocytes and platelets form a very thin layer between them called the buffy coat . The normal hematocrit is approximately 45% in men and 42% in women .

6. The volume of blood in a 70 kg (154 lb ) person is approximately 5.5 L. If we take the hematocrit to be 45%, then Erythrocyte volume = 0.45 X 5.5 = 2.5 L Because the volume occupied by leukocytes and platelets is usually negligible, the plasma volume equals the difference between blood volume and erythrocyte volume; therefore, in our 70 kg person Plasma volume = 5.5 – 2.5 = 3.0L

7. Plasma Plasma consists of a large number of organic and inorganic substances dissolved in water. The plasma proteins constitute most of the plasma solutes by weight. Their role in exerting an osmotic pressure that favors the absorption of extracellular fluid into capillaries.They can be classified into three broad groups: the albumins , the globulins , and fibrinogen. In addition to proteins, plasma contains nutrients, metabolic waste products, hormones, and a variety of mineral electrolytes including Na,   K,   Cl ions, and others. Serum is plasma with fibrinogen and other proteins involved in clotting removed.

8. The Blood Cells The blood cells, which are suspended in plasma, include erythrocytes, leukocytes, and platelets. Erythrocytes, which make up more than 99% of blood cells, contain hemoglobin, an oxygen-binding protein. Oxygen binds to the iron in hemoglobin. Erythrocytes are produced in the bone marrow and destroyed in the spleen and liver. Iron , folic acid , and vitamin B12 are essential for erythrocyte formation. The hormone erythropoietin , which is produced by the kidneys in response to low oxygen supply, stimulates erythrocyte differentiation and production by the bone marrow.

9. The leukocytes include neutrophils, eosinophils , basophils , monocytes , and lymphocytes . Platelets are cell fragments essential for blood clotting . Blood cells are descended from stem cells in the bone marrow. Hematopoietic growth factors control their production.

10. circulatory system circuits The circulatory system consists of two circuits: T he Pulmonary circulation —from the right ventricle to the lungs and then to the left atrium—and the systemic circulation—from the left ventricle to all peripheral organs and tissues and then to the right atrium. In the Systemic circuit , the large artery leaving the left side of the heart is the aorta, and the large veins emptying into the right side of the heart are the superior vena cava and inferior vena cava. The analogous vessels in the pulmonary circulation are the pulmonary trunk (leading to the pulmonary arteries) and the four pulmonary veins.

11. Arteries carry blood away from the heart, and veins carry blood toward the heart. The microcirculation consists of the vessels between arteries and veins: the arterioles , capillaries , and venules .

12. Reference books Vander's  Human  Physiology : The Mechanisms Of Body Function. Boston : McGraw-Hill Higher Education, 2008. Print. Widmaier , Eric P., Raff, Hershel,Strang , Kevin T.