Download Biology 218 – Human Anatomy - RIDDELL

Biology 218 – Human Anatomy
RIDDELL
Chapter 13 Adapted form Tortora 10th ed.
LECTURE OUTLINE
A. Introduction (p. 405)
1. The cardiovascular system consists of:
i. blood
ii. heart
iii. blood vessels (arteries, arterioles, capillaries, venules and veins)
2. Blood is a connective tissue 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 connective tissue 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. blood plasma 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 (granulocytes)
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neutrophils
eosinophils
basophils
- agranular leukocytes (agranulocytes)
lymphocytes
T cells
B cells
natural killer cells
monocytes
c. platelets (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 bone marrow (myeloid tissue).
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 lungs 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. Erythropoiesis starts in the red bone marrow and progresses through the
following successive stages of differentiation:
i. proerythroblast
ii. anucleate reticulocyte 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 antigens 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
macrophages, 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
phagocytosis 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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RIDDELL
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
megakaryocytes.
2. Platelets are produced by the shedding of 2000-3000 membrane-enclosed
fragments of cytoplasm from each megakaryocyte.
3. The average number of platelets ranges from 150,000 to 400,000 platelets per
microliter of blood.
4. Each platelet 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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