Chapter 6 Composition and Function of the Blood

Chapter 6 Composition and Function of the Blood 1

Outline • • Composition and Function of Blood – Plasma – Red Blood Cells – White Blood Cells v Types of White Blood Cells Blood Clotting Capillary Exchange Blood Typing 2

The Composition and Functions of Blood • Blood is divided into two layers. – Formed Elements. v Red Blood Cells. v White Blood Cells. v Platelets. – Plasma. 3

Functions of Blood • • • Transport of oxygen, hormones, and waste. Defense against pathogens. Regulation of body temperature. 4

Plasma • • Water makes up about 92% of plasma, while the remaining 8% consists of various salts and organic molecules. Three major plasma proteins help to maintain homeostasis. – Albumins. – Globulins. – Fibrinogen. 5

Red Blood Cells • Red blood cells (erythrocytes) contain hemoglobin that allows oxygen transport. – All blood cells are formed from stem cells. – Engulfed by macrophages in the liver and spleen after about 120 days. v Releases hemoglobin. Ø Insufficient number of red blood cells or hemoglobin leads to anemia. Ø Hemolysis is rupturing of blood cells. 6

White Blood Cells • White Blood Cells (leukocytes) have a nucleus and lack hemoglobin. – Fight infection and help maintain homeostasis. – Derived from stem cells. – Found in blood, tissue fluid, and lymph. 7

Types of White Blood Cells • • Granular Leukocytes. – Neutrophils. – Eosinophils. – Basophils. Angular Leukocytes. – Monocytes. – Lymphocytes. 8

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Blood Clotting • Platelets (thrombocytes) result from fragmentation of megakaryocytes. – Platelets clump at the site of a puncture in the skin and usually seal the break. v Coagulation. Ø At least twelve factors participate in the formulation of a blood clot. 10

Blood Clotting 11

Capillary Exchange • Pumping of heart sends blood out via arteries to the capillaries where exchange takes place through capillary walls. Blood returns via veins. – Arterial blood contains more oxygen and nutrients than venous blood. – Venous blood contains more wastes, including carbon dioxide, than arterial blood. 12

Capillary Exchange 13

Blood Capillaries • Processes at work during capillary exchange. – Blood pressure. – Diffusion. – Osmotic pressure. 14

Arterial End of Capillary • When arterial blood enters tissue capillaries: – Bright red due to high oxygen levels. – Rich in dissolved nutrients. – Blood pressure is higher than osmotic pressure. v Water and nutrients exit capillary. 15

Venous End of Capillary • • Blood pressure is reduced because capillaries have a greater cross-section compared to blood vessels that enter and leave capillaries. No reduction of osmotic pressure. v Water tends to enter capillary. 16

Lymphatic Capillaries • Lymphatic vessels are one-way system that carry lymph. – Valves prevent backflow. – Lymphatic capillaries absorb excess fluid at blood capillaries. 17

Lymphatic Capillaries 18

Blood Typing • In the ABO system, the presence or absence of type A and type B antigens on red blood cells determines a person’s blood type. – Within the plasma are antibodies to the antigens that are not present on the person’s red blood cells. 19

Blood Typing 20

Blood Typing • Another important antigen is the Rh factor. – Eighty-five percent of US population have Rh antigen on red blood cells and are Rh+. v Rh individuals normally do not have antibodies to the Rh factor, but may make them when exposed. Ø Hemolytic disease may exist in newborns when mother is Rh- and father is Rh+. 21

Hemolytic Disease 22

Review • • Composition and Function of Blood – Plasma – Red Blood Cells – White Blood Cells v Types of White Blood Cells Blood Clotting Capillary Exchange Blood Typing 23

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