Blood Components

1. Blood Components

2. Overview • There are 4 main components within blood that we are concerned with: • Red Blood Cells • White Blood Cells • Blood Plasma • Platelets

4. Blood • Blood =a collection ofspecialized cells that perform specific functions for an organism • Even though it appears liquid, blood is considered a tissue • like skin, muscle, bone, etc • Consists of two distinct elements: • Fluid plasma portion • Solid or “formed” portion

5. Blood • About 55% of blood is plasma, • Water • Dissolved gases • Proteins, sugars, vitamins, minerals, and waste products. • The remaining 45% of the blood is composed of cells • White Blood Cells • Red Blood Cells

6. Red Blood Cells (RBCs) • Also called erythrocytes • Make up 44% of the total volume of your blood. • The average male has 5.5 million RBCs/mLof blood • the average female has 4.5 millionRBCs/mL of blood • The shape of a RBC is described as a biconcave disk

8. RBCs • The red blood cell is specialized for oxygen transport • Only 2% of the oxygen that enters the blood stream is transported by the fluid portion of the blood. • The remainder is transported by RBCs • these cells vastly increase the oxygen carrying capacity of the blood. • A mature red blood cell has no nucleus but is packed with 280 million molecules of hemoglobin • an iron-containing molecule • Has several binding sites for oxygen

9. Hemoglobin • Hemoglobin is a pigment molecule, which gives blood its red color (when bound to oxygen) in humans

10. RBCs • Hemoglobin is specially designed to perform two opposite functions: • Pick updissolved oxygen from the lungs andcarry it to the cells of the body. • Release this oxygen, but only in the presence of the cells that requireit. • This ability is dependent on the structure of hemoglobin

12. RBCs • A hemoglobin molecule contains four iron (Fe)atoms • Each represents a separate binding site(heme group) • When the concentration of oxygen is high,eachheme group may form a loose bond with oxygen • e.g. In the capillaries of the lungs • When the concentration of O2 is low, this loose bond is broken • e.g. in the cells of working muscles • Theoretically, four molecules of oxygen can become attached to one molecule of hemoglobin. • In reality, not all of the possible heme positions will be occupied by oxygen.

13. Capillaries in the Lungs Oxygen binds to Hb Working muscle cells in the body Oxygen is released from Hb

14. White Blood Cells (WBCs) • also called leucocytes • make uponly1% of your total blood volume. • may increase to more than double normal levels, however, when your body is fighting an infection. • Have a number of different roles that help protect the body from disease-causing agents, or pathogens. • In contrast to red blood cells, all white blood cells have nuclei and appear colourless.

17. WBCs • There are several types of WBCs • Macrophages • can pass through the walls of the capillaries to engulf and digest pathogens (phagocytosis = “cell eating”) • part of the body’s innate immune response • which is the body’s generalized, automatic response to infection.

19. WBCs • Lymphocytes • are non-phagocytic cells • involved in the body’s acquired immune response • the body’s abilityto recognize and fend off specific pathogens. • There are two main types of lymphocytes: • T cells & B cells • Each contributea specific part of the response that allows the body to become immune to certain toxins.

22. WBCs • In addition to their role in fighting disease, lymphocytes can (under particular conditions) undergo changes to become a variety of cell types. • Converted into red blood cells the bone marrow • Help construct different kinds of connective tissue fibres throughout the body.

23. Platelets • Also called thrombocytes • They areonly fragments of cells that were created when larger cells in the bone marrow break apart. • Do not contain a nucleus • Break down quickly in the blood • each platelet lasts only about a week to 10 days • Platelets play an important role in clotting bloodand preventing excessive blood loss after an injury

24. Blood Clotting • Process is not completely understood • Clotting is first triggered by the injury. • Does not occur until a blood vessel is broken • Platelets are attracted to the site of the damaged vessels and combine with other clotting agents in the plasma • producesthe enzyme thromboplastin • Thromboplastin reactswithprothrombinto produce thrombin. • Thrombin is an enzyme that reacts witha plasma protein to produce fibrin. • Insoluble, forms a mesh of strandsthat traps escaping blood and forms the clot

26. Blood Plasma • The fluid portion of the blood in which the blood cells are suspended. • Also contains substances that play an important role in maintaining the body’s well-being. • Fibrinogen (blood clotting) • Serum albumin: maintaining the blood volume and blood pressure. • Serum globulin: protein antibodies to defend against disease. • Plasma also plays a role in the transport of carbon dioxide in the blood. • carried in the plasma from tissues to the lungs for gas exchange.

28. Plasma • Serum= The straw-coloured liquid that remains when the clotting agents are removed • contains cellular nutrients, hormones, electrolytes, enzymes, hormones, antibodies, and waste materials. • Serum from an animal or a person immune to a particular disease can be injected into a patient to provide temporary immunity from that disease.

31. Summary • Using a full page, copy table 9.2 into your notebook • For each component of blood you are responsible for knowing: • the relative amounts (% or cells per mL blood) • sizes compared to each other • lifespan • important function(s)