The Blood Discuss the composition of blood including the functions of the various components Explain the anatomy and functions of the red blood cells, including a description of blood typing Discuss the types of white blood cells found in the blood and give the functions of each Give a brief accounting of the platelets Review hemopoiesis, including RBC and leukocyte formation

what’s in red blood cells white blood cells platelets plasma carbon dioxide digested food waste (urea) hormones oxygen

The Blood plasma red blood cell white blood cell platelets

Functions of Blood Distribution - nutrients, wastes, hormones, gases, etc. Self-sealing – hemostasis Disease/ infection fighting

Blood = connective tissue extracellular matrix: Plasma specialized cells: (= Formed elements) RBCs WBCs Platelets color ? volume ?

Plasma Composition Water 92% Plasma proteins 7% Other solutes 1% Transports organic and inorganic molecules, formed elements, and heat

Plasma Proteins There are some proteins that are essential which swims in the blood: There are some proteins that are essential which swims in the blood: example Fibrinogen (4%) Essential component of clotting system (conversion to insoluble fibrin) Fibrinogen

Plasma A straw- coloured liquid that carries the cells and the platelets which help blood clot. carbon dioxide glucose amino acids proteins minerals vitamins hormones waste materials like urea. It also contains useful things like;

BLOOD CELLS Red and White Blood Cells Platelets WBCs RBCs.1% 99.9%

. white Why white blood cells

RBCs = Erythrocytes Measured by hematocrit or PCV Most abundant blood cell: 1000 RBCs/1 WBC Contain hemoglobin, carry O2 Very regular shape - biconcave discsshape NO Nucleus: Lifespan ~ 120 days replacement rate ~ 3 mio RBCs / sec

Red Blood Cells contain haemoglobin, a molecule specially designed to hold oxygen and carry it to cells that need it. can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries. a biconcave disc that is round and flat without a nucleus

Structure of Hemoglobin (Hb) Fe ion in heme group reversibly binds O 2 How many oxygen molecules can 1 Hb molecule carry?  

Acclimatization People living at high altitudes usually have large number of RBCs. Compensate for low oxygen concentration at high altitudes

Clinical Brief Anemia: Reduced oxygen carrying ability of blood. Causes One cause of anemia is iron deficiency anemia as iron is essential to make hemoglobin which is needed to transport oxygen

WBCs = Leukocytes Quantity and type determined by differential WBC count Circulating WBCs are only a small fraction of total WBCs. Most are located in BETWEEN CELLS There are many types of WBC

White Blood Cells there are many different types and all contain a big nucleus. the two main ones are the lymphocytes and the PHAGOCYTES. some lymphocytes fight disease by making antibodies to destroy invaders by dissolving them. other lymphocytes make antitoxins to break down poisons. PHOGOCYTES engulf and digest micro-organisms.

Phagocytic cell

Other phagocytes

Lymphocytes ~ 20% - 30% of circulating WBCs Relatively small (slightly larger than RBCs) Large round nucleus

Antibodies Pathogens contain antigens (chemicals) on their sufaces These antigens stimulate lymphocytes to produce specific antibodies Antibodies can: »kill bacteria »neutralize toxins »Cause bacteria to clump together (agglutination)

Specificity Antibodies specific for bacteria A (eg. measles) will not attack bacteria B (eg. chicken pox)

Immunity After an illness (e.g. chicken pox), antibodies against chicken pox persist and remain in the blood Thus, the person is said to be immune to chickenpox

Memory cells Special type of lymphocytes (WBCs) Formed after an infection / illness Remain in the blood stream for life Able to be activated very quickly if person encounters the same antigen again Person is said to be immune to that infection/ illness

Vaccines Dead or harmless form of the pathogen (BCG vaccine against tuberculosis) Toxoid – the inactivated toxin from the pathogen (tetanus vaccines)

Organ transplant and tissue rejection Replacement of diseased organ with healthy one BUT new organ must not be rejected by body (Body detects new organ as foreign particle  Defence system kicks in)

Prevention of tissue rejection Donor and recipient must be close relatives Suppress immune system »Use of drugs called immuno-supressive drugs »X-ray of bone marrow to reduce blood production

Platelets = Thrombocytes Cell fragments of Megakaryocytes (~ 4,000 thrombocytes per Megakaryocyte)  ~ 160  m Lifespan ~ 12 days involved in blood clotting

Platelets Platelets are bits of cell broken off larger cells. Platelets produce tiny fibrinogen fibres to form a net. This net traps other blood cells to form a blood clot.

Blood clotting Clotting of blood seals the wound Prevents excessive blood loss Prevents foreign particles from entering blood

Blood Clotting Injury/ Ruptured blood vessel Thrombokinase (enzyme) Prothrombin (inactive) Thrombin (active) Fibrinogen (soluble) Fibrin (insoluble) Blood Clot Activates platelets to release catalyses (Ca 2+, Vit K) catalyses Forms meshwork

Why doesn’t blood clot in undamaged blood vessels? Anticlotting substance called heparin Produced in liver Thrombokinase able to neutralize the action of heparin

Abnormal Blood Cell Counts Leukopenia < 2,500/  L (normal 6000 – 9000) Leukocytosis > 30,000/  L Thrombocytopenia: < 80,000/  L (normal ~ 350,000) Thrombocytosis: > 1,000,000/  L Also Lymphopenia vs. _____________ _________vs. Neutrophilia

Hemopoiesis = Blood Cell Formation Hemocytoblasts: One type of stem cell for all blood cells In red bone marrow... then differentiation into 4 types of progenitor stem cells: Erythroblast Myeloblast Monoblast Lymphoblast Fig 20.8