Blood = Transport Medium Components of the Circulatory System Heart = Pump Blood = Transport Medium Blood vessel = Passageways

Blood vessel White blood cell Red blood cell platelet Plasma

Separation of Components Plasma = Less Dense Platelets / WBC’s Hematocrit “Packed Cells” More Dense

Components of Plasma Blood plasma Consists of: Other components: Water 90% Plasma Proteins 6-8 % Electrolytes (Na+ & Cl-) 1% Other components: Nutrients (e.g. Glucose and amino acids) Hormones (e.g. Cortisol, thyroxine) Wastes (e.g. Urea) Blood gases (e.g. CO2, O2)

Plasma Proteins Plasma Proteins: (albumins, globulins, fibrinogen) 1. Maintaining colloid osmotic balance (albumins) 2. Buffering pH changes 3. Transport of materials through blood (such as water insoluble hormones) 4. Antibodies (e.g. gamma globulins, immunoglobulins) 5. Clotting factors (e.g. fibrinogen)

3 Cellular Elements of Blood 1. Red Blood Cells 2. White Blood Cells 3. Platelets

1. RBC’S (Erythrocytes) Shape - a biconcave disc with large surface area Can change shape No Nucleus / organelles Contains hemoglobin Primary Function = Transport oxygen from the lungs to the cells of the body & assist with CO2 removal

Mechanism of Transport HEMOGLOBIN * 4 Heme Molecules = * 4 Oxygen Molecules *Oxygenated Hemoglobin Bright Red (systemic) *Deoxygenated Hemoglobin Blue (venous circulation) Minutia- Every erythrocyte has more than 250 million hemoglobin molecules- which means each RBC can carry more than a billion oxygen molecules!!!!

RBC’S (Erythrocytes) cont… Lack intracellular organelles necessary for cellular repair, growth, division Short Life Span (~120 days) Aged RBC Fragile - prone to rupture Ruptured RBC’s are destroyed in spleen Phagocytic WBC’s “clear the debris”

Formation of New RBC’s Ruptured cells must be replaced by new cells by a process called……… ..Erythropoiesis Secretion of the hormone erythropoietin New RBC’s (and platelets & leukocytes) are produced in the Bone Marrow We each have 25-30 trillion RBCs going through our vessels. Every second, we replace 2-3 million RBCs!

WBC’ s RBC’s

2. White Blood Cells (Leukocytes) Mobile units of body’s defense system: “Seek and Destroy” Functions: Destroy invading microorganisms Destroy abnormal cells (ie: cancer ) Clean up cellular debris (phagocytosis) 3. Assist in injury repair

5 - Types of WBC’s Each WBC has a specific function Granulocytes Agranulocytes Each WBC has a specific function

Blood Cell Origin and Production Bone Marrow All leukocytes ultimately originate from the same undifferentiated multipotent stem cells in the red bone marrow that also give rise to erythrocytes and platelets All new WBCs except for lymphocytes are produced in the bone marrow. Most new lymphocytes are produced by colonies of cells in lymphoid tissues, such as lymph nodes and tonsils. Circulation Figure 11-8

plasma (55%) red blood cells (5-6-million /ml) white blood cells Blood cells – magnification 400x plasma (55%) red blood cells (5-6-million /ml) white blood cells (5000/ml) platelets

Plasma liquid part of blood plasma transports:- soluble food molecules waste products hormones antibodies

Red blood cells (RBCs) transport oxygen specialised to do this Also carry some CO2

White blood cells the bodies “defense” part of the immune system much larger than RBCs far fewer have a nucleus 4000-13000 per mm3 2 types phagocytes and lymphocytes

Platelets if you get cut:- platelets produce tiny fibrin threads these form a web-like mesh that traps blood cells. these harden forming a clot, or "scab." 150,000 to 400,000 per mm3

Types of WBC’s Granulocytes Neutrophils Eosinophils Basophils

1. NEUTROPHILS * 50-70% of all leukocytes (most abundant of WBC’s) * Important in inflammatory responses * Phagocytes that engulf bacteria and debris

Neutrophils – small, multi-lobed nuclei

2. EOSINOPHILS * 1-4% of the WBC's * Attack parasitic worms * Important in allergic reactions

Eosinophils – bi-lobed nuclei

3. BASOPHILS * 0.5% of the WBC's * Release histamine and heparin * Important in Allergic Reactions * Heparin helps clear fat from blood

Basophils – least common of WBCs - Large cytoplasmic granules

Agranulocytes 4. Monocytes 5. Lymphocytes (B and T cells) Types of WBC’s Agranulocytes 4. Monocytes 5. Lymphocytes (B and T cells)

Monocytes

4. MONOCYTES * 2-6 % of the WBC's * Exit blood (diapedesis) to become macrophages * Phagocytic = defend against viruses and bacteria

Monocytes are the largest white blood cells They are distinguished with U-shaped nuclei.

LYMPHOCYTES These are the most numerous white blood cell in young children and the second most numerous in older children and adults. Their numbers increase in response to viral infections.

Lymphocyte

5. LYMPHOCYTES * 25-33 % of the WBC's * B-lymphocytes: Produce antibodies * T-lymphocytes: Directly destroy virus- invaded cells and cancer cells B cells responsible for antibody-mediated (or humoral) immunity. – An Ab binds with and marks for destruction (by phagocytosis) the specific foreign matter that induced production of the Ab. T cells directly destroy their specific target cells by releasing chemicals that punch holes in the cell (process is called cell-mediated immunity)

3. Platelets (Thrombocytes) Platelets are produced by the bone marrow. They are not whole cells, but are fragments of extraordinarily large bone marrow-bound megakaryocytes. The hormone THROMBOPOIETIN (produced by liver) increases the # of megakaryocytes in the bone marrow, stimulating them to produce more platelets * Cell fragments bound to megakaryocytes * “bud off” and are released into the blood

Blood clotting mechanism http://health.howstuffworks.com/adam-200077.htm