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Biology 218 – Human RIDDELL

Chapter 13 Adapted form Tortora 10th ed.

LECTURE OUTLINE

A. Introduction (p. 405) 1. The cardiovascular system consists of: i. ii. iii. blood vessels (, arterioles, capillaries, venules and ) 2. Blood is a connective composed of a liquid portion called plasma (the matrix) and a cellular portion consisting of various cells and cell fragments. 3. Interstitial fluid (or tissue fluid) is the fluid that bathes body cells. 4. Blood carries oxygen and nutrients and exchanges these molecules for carbon dioxide and waste molecules released from body cells into the interstitial fluid. 5. Hematology is the study of blood, blood-forming tissues, and associated disorders.

B. Functions of Blood (p. 406) 1. Blood is a liquid that performs three major functions: i. transportation of oxygen, carbon dioxide, nutrients, heat, wastes, and hormones ii. regulation of pH, body temperature, and water content of cells iii. protection against blood loss via clotting, and against foreign microbes and toxins via the action of phagocytic white blood cells and specialized plasma proteins

C. Physical Characteristics of Blood (p. 406) 1. Blood has the following major characteristics: i. denser and more viscous than water ii. temperature of 38 degrees Celsius iii. pH that normally ranges between 7.35 and 7.45 iv. constitutes about 8% of total body weight v. average volume of 5 to 6 liters in adult males and 4 to 5 liters in adult females

D. Components of Blood (p. 406) 1. Blood consists of: i. or plasma, which has the following characteristics (see Table 13.1): a. straw-colored liquid b. accounts for about 55% of the volume of blood c. consists of about 91.5% water and 8.5% solutes d. the solutes include plasma proteins (e.g., albumins, globulins, and fibrinogen), waste molecules, nutrient molecules, enzymes, hormones, gases, and electrolytes ii. formed elements, including the following (see Tables 13.2 and 13.3): a. erythrocytes or red blood cells (RBCs) b. leukocytes or white blood cells (WBCs): - granular leukocytes () Page 1 of 4 Biology 218_Lecture Outline_13 Cardiovascular 1 Biology 218 – Human Anatomy RIDDELL

- agranular leukocytes () T cells B cells natural killer cells c. (which are cell fragments) 2. The percentage of total blood volume occupied by RBCs is called the hematocrit.

E. Formation of Blood Cells (p. 409) 1. Blood cells are formed by hemopoiesis or hematopoiesis that occurs (after birth) only in red marrow (). 2. The formation of all formed elements involves differentiation of cells in the following sequence: i. pluripotent stem cells differentiate into myeloid stem cells and lymphoid stem cells ii. myeloid stem cells differentiate into progenitor cells and precursor cells or blasts iii. progenitor cells, including colony-forming units (CFUs), and precursor cells or blasts ultimately differentiate into RBCs, platelets, neutrophils and monocytes, as well as eosinophils and basophils iv. lymphoid stem cells ultimately differentiate into B lymphocytes and T lymphocytes

3. Several hormones called hemopoietic growth factors regulate the differentiation and proliferation of specific progenitor cells; these include: i. erythropoeitin or EPO ii. thrombopoietin or TPO iii. cytokines including colony-stimulating factors (CSFs) and interleukins

F. Red Blood Cells (Erythrocytes) (p. 411) 1. Greater than 99% of the formed elements in blood are erythrocytes (red blood cells or RBCs). 2. A healthy adult male has about 5.4 million erythrocytes per microliter of blood; a healthy adult female has about 4.8 million erythrocytes per microliter. 3. Each RBC is a flexible, biconcave disc that lacks a nucleus and other organelles. 4. The cytosol of each RBC contains about 280 million dissolved hemoglobin molecules. 5. Each hemoglobin molecule consists of four globin chains and four heme groups. 6. Hemoglobin can bind reversibly to oxygen (to form oxyhemoglobin); this permits erythrocytes to transport oxygen from the to other tissues of the body. 7. Hemoglobin can also bind reversibly to carbon dioxide (to form carbaminohemoglobin); this permits erythrocytes to transport carbon dioxide from the tissues to the lungs to be expelled. 8. Hemoglobin also plays a role in regulation of blood flow and blood pressure.

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9. Erythrocytes live only approximately 120 days due to absence of organelles; the latter results in an inability to replace plasma membrane components that are damaged as RBCs squeeze through narrow capillaries. 10. starts in the red and progresses through the following successive stages of differentiation: i. ii. anucleate that enters the bloodstream iii. erythrocyte 11. Hypoxia stimulates the kidneys to release erythropoietin which in turn stimulates erythropoiesis. 12. There are two major blood group systems; each is based on the presence or absence of genetically determined cell-surface called isoantigens or agglutinogens: i. ABO blood grouping system ii. Rh blood grouping system

G. White Blood Cells (Leukocytes) (p. 413) 1. Anatomy and Types: i. Leukocytes (white blood cells or WBCs) have a nucleus and do not contain hemoglobin. ii. Granular leukocytes (granulocytes) have lobed nuclei and are classified according to the types of granules present in the cytoplasm into: a. neutrophils b. eosinophils c. basophils iii. Agranular leukocytes (agranulocytes) lack observable granules and are classified into: a. lymphocytes (including B cells, T cells and natural killer cells) b. monocytes - monocytes exit blood vessels and differentiate into , including fixed macrophages and wandering macrophages 2. WBC Functions: i. The life span of the various types of WBCs ranges from several hours to many years; however, most live for only several days. ii. The average number of WBCs ranges from 5000 to 10,000 per microliter of blood; therefore the ratio of RBCs to WBCs is about 700:1 iii. Leukocytosis is an increase in the number of WBCs while leukopenia is an abnormally low level of WBCs. iv. The general function of WBCs is to combat microbes and toxins by or immune responses; this is accomplished as follows: a. neutrophils and macrophages are active in phagocytosis b. eosinophils release enzymes that combat histamine in allergic reactions; eosinophils are also effective against certain parasitic worms c. basophils (develop into mast cells that) release substances which intensify the inflammatory reaction d. B cells destroy bacteria and inactivate their toxins e. T cells attack viruses, fungi, transplanted cells, cancer cells, and some bacteria; T cells are also responsible for transfusion reactions, allergies, and rejection of transplanted organs

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f. natural killer cells attack a wide variety of infectious microbes and certain spontaneously arising tumor cells.

H. Platelets (note that these are sometimes called thrombocytes, but the latter is a technically incorrect term in humans because technically these are not cells) (p. 416) 1. Thrombopoietin stimulates myeloid stem cells to differentiate ultimately into . 2. Platelets are produced by the shedding of 2000-3000 membrane-enclosed fragments of cytoplasm from each . 3. The average number of platelets ranges from 150,000 to 400,000 platelets per microliter of blood. 4. Each is a small disc-shaped structure whose cytoplasm lacks a nucleus. 5. Platelets help repair slightly damaged blood vessels by forming a platelet plug and promoting blood clotting. 6. Platelets have a life span that ranges from 5 to 9 days.

I. Key Medical Terms Associated with Blood (p. 420) 1. Students should familiarize themselves with the glossary of key medical terms.

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