18 Blood

I. Blood Overview A. Blood – is the transport mechanism for: 1. nutrients 2. signaling molecules 3. respiratory gases (oxygen and carbon dioxide) 4. waste products (Nitrogen waste compounds) B. Powered by the pumping action of the heart: 1. gases/nutrients diffuse across capillary walls to body tissues 2. transports hormones from endocrine glands 3. conveys cells of immune system 4. regulates body temperature

II. Composition of Blood A. Blood volume: depends on body size 1. males: 5–6 liters 2. females: 4–5 liters B. Blood has cellular and liquid parts (a special connective tissue) 1. blood cells - formed elements a. red blood cells (RBCs) – erythrocytes b. white blood cells (WBCs) – leucocytes c. platelets 2. plasma - liquid portion of blood

C. Centrifuge whole blood from patient D. Hematocrit 1. Is the measure of % RBC as a reflection of total blood volume a. males: 47% ± 5% b. females: 42% ± 5% c. example: 100 ml of whole blood – 45 ml erythrocytes E. Buffy coat 1. Is portion of blood composed of leukocytes and platelets a. present at junction of plasma and RBCs

Centrifuge Whole Blood Plasma 55% of whole blood Least dense component Buffy coat Leukocytes and platelets 1% of whole blood Formed elements Erythrocytes 1 Withdraw blood and place in tube. Centrifuge the blood sample. 2 45% of whole blood Most dense component 5

III. Blood Plasma A. Straw-colored, sticky fluid portion of blood B. Approximately 90% water C. Contains over 100 kinds of molecules 1. dissolved oxygen 2. ions - examples: Na+ and Cl– 3. nutrients - sugars, amino acids, lipids 4. waste compounds - carbon dioxide, urea, ammonia, creatinine

5. Three main proteins: a. Albumin i. maintains osmotic pressure of blood ii. slows water from diffusing out of blood vessels b. Globulins i. antibodies ii. blood proteins - transport lipids, iron, and copper c. Fibrinogen - involved in chemical rxns. for blood clotting

IV. Formed Elements A. Blood cells - erythrocytes, leukocytes, and platelets B. Staining of blood cells 1. acidic dye – eosin stains cells pink in color 2. basic dye - methylene blue stains blue and purple in color

Photomicrograph of a human blood smear, Wright’s stain (610) Erythrocytes Platelets Monocyte Lymphocyte Neutrophil Eosinophil Photomicrograph of a human blood smear, Wright’s stain (610) 9

IV. Erythrocytes A. Oxygen-transporting cells - 7.5 µm diameter (capillary 8–10 µm) B. Most numerous of the formed elements 1. females: 4.3–5.2 million cells/cubic millimeter 2. males: 5.2–5.8 million cells/cubic millimeter C. Are produced in red bone marrow by erythropoiesis D. Have no organelles or nuclei 1. nucleus is ejected at final stages of erythrocyte production

E. ideal measuring tool for estimating sizes of nearby structures F. Are packed with oxygen-carrying hemoglobin 1. hemoglobin consists of four distinct polypeptides 2. Each polypeptide holds one O2 bound to iron atom (Fe) 3. Fe bound to O2 molecule gives red blood cells their red color

G. Erythrocytes pick up O2 at lung capillaries H. Release O2 across other tissue capillaries to organs and tissues I. Structural characteristics contribute to respiratory function 1. biconcave shape  more surface area 2. 97% of the cell volume is hemoglobin 3. lack mitochondria - do not consume the O2 they pick up

2.5 m Side view (cut) 7.5 m Top view 13

V. Leukocytes—White Blood Cells (WBCs) A. Many fewer - 4800–11,000/cubic millimeter B. Protect the body from infectious microorganisms and cancer C. Function outside the bloodstream in loose connective tissue D. Diapedesis - circulating leukocytes can leave the capillaries E. Also originate in red bone marrow

F. Two major categories: 1. granulocytes: neutrophils, eosinophils, basophils 2. agranulocytes: lymphocytes, monocytes Proportions: most “Never Let Monkeys Eat Bananas” least

Differential WBC count (All total 4800– 10,800 cells/l) Formed elements (not drawn to scale) Platelets Neutrophils (50–70%) Leukocytes Eosinophils (2–4%) Basophils (0.5–1%) Erythrocytes Lymphocytes (25–45%) Monocytes (3–8%) 16

G. Neutrophils 1. most numerous WBC 2. granules like acidic and basic stains (neutral – “liking”) 3. nucleus - has two to six lobes 4. attracted to chemicals produced by bacteria 5. are first line of defense in inflammatory response 6. phagocytize (eat) and destroy bacteria 7. release enzymes into extracellular matrix of infected tissue

Neutrophil Multilobed nucleus, pale red and blue cytoplasmic granules 18

H. Eosinophils 1. represent 1 - 4% of all WBCs 2. granules are large and stain red (eosino = “acid”) 3. nucleus – generally has two lobes 4. granules contain enzymes active during allergic reactions and parasitic infections 5. role in ending allergic reactions by phagocytizing allergens 6. secrete enzymes that degrade histamines

Eosinophil Bilobed nucleus, red cytoplasmic granules 20

I. Basophils 1. about 0.5% of all leukocytes 2. nucleus - usually two lobes; can be difficult to distinguish 3. generally prefer stains that are basic 4. granules secrete histamines 5. function in inflammation mediation 6. similar in function to mast cells 7. direct later stages of inflammation in allergies

Basophil Bilobed nucleus, purplish-black cytoplasmic granules 22

J. Lymphocytes 1. comprise 20–45% of WBCs 2. the most important cells of the immune system 3. nucleus – large and spherical; stains dark purple 4. effective in fighting infectious organisms 5. act against a specific foreign molecule (antigen) 6. Two different types (have their own subtypes) a. B-lymphocyte (become plasma cells - antibodies) b. T-lymphocyte (killers and assistants to immune response)

Lymphocyte Large spherical nucleus, thin rim of pale blue cytoplasm 24

K. Monocytes 1. compose 4–8% of WBCs 2. the largest leukocytes 3. nucleus - kidney shaped 4. transform into macrophages (phagocytic cells)

Kidney-shaped nucleus, abundant pale blue cytoplasm Monocyte Kidney-shaped nucleus, abundant pale blue cytoplasm 26

VI. Platelets A. Cell fragments that break off from megakaryocytes B. Function in clotting of blood

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VII. Blood Cell Formation A. Hematopoiesis (“blood” “creation”) - process by which blood cells are formed in red marrow 1. 100 billion new blood cells formed each day B. Red bone marrow – site of hematopoiesis 1. site of stem cells to make blood cells (hemocytoblasts) 2. located in: a. between trabeculae of spongy bone of axial skeleton b. shoulder and pelvic girdles c. proximal epiphyses of humerus and femur