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BLOOD

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I. Functions of Blood

A. There are five functions of the blood

1. The transport of dissolved gases, nutrients, hormones, and metabolic wastes.

 2. The regulation of the pH and

electrolyte composition of interstitial fluids throughout the body.

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3. The restriction of fluid losses through damage vessels or at other injury sites/blood clotting.

 4. Defense against toxins and pathogens.

 5. The stabilization of body temperature.

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B. The composition of Blood

1. Blood contains plasma and formed elements.

 2. Plasma contains dissolved proteins. Because these proteins are in solutions, plasma is slightly denser than water.

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3. Formed elements are blood cells (red or white) and cell fragments (cell platelets) that are suspended in the plasma.

 4. Red blood cells (RBC’s) or erythrocytes transport oxygen and carbon dioxide.

 5. The less numerous white blood cells (WBC’s) or leukocytes are cells involved with body’s defense mechanisms.

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6. Platelets are pieces of cytoplasm that contain enzymes and are important to blood clotting.

 7. Together the plasma and formed elements

constitute whole blood.  

8. The volume of blood varies from 5-6 liters in the cardiovascular system of an adult man and from 4-5 liters in an adult woman.

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9. BUT, when a woman is pregnant she can have up to an extra liter of blood.

10. Whole blood components may be separated, or fractionated.

  11. Whole blood contains 55% plasma

and 45% formed elements.

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12. The plasma composition is:

Plasma proteins 7%other solutes 1%Water 92%

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13. The formed elements compositions is:

Platelets and WBC’s .1%Red blood cells 99.9%

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C. Plasma

1. Plasma contains lots of dissolved proteins.

 2. Albumins make up 60% of the proteins. Albumins contribute to osmotic concentration of plasma, transports lipids and steroid hormones.

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3. Globulins make up 35% of the proteins in plasma. Globulins transport ions, hormones, and lipids and also have immune functions.

 4. Antibodies are also called immunoglobulins

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5. Fibrinogen makes up 4% of the proteins in plasma. Fibrinogen is essential component of clotting.

 6. The fluid left after the clotting proteins are removed is known as serum.

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7. The liver makes more than 90% of the plasma proteins, including all the albumins, fibrinogen and most of the globulins.

 8. Because the liver is the primary source of plasma proteins, liver disorders can alter the composition and functional properties of the blood.

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II. Formed Elements

A. The major types of cells in blood are RBC, WBC and platelets.

 B. The production of formed elements

 1. The process of hemopoesis

produces formed elements.

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2. Embryonic blood cells appear in the bloodstream during the third week of development.

 3. These embryonic cells differentiate into stem cells.

 4. Stem cells are cells that haven’t differentiated into a particular cell. See page 358.

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C. Red Blood Cells

1. RBC’s contain the pigment hemoglobin, which binds and transports oxygen and carbon dioxide. RBC’s are the most abundant blood cells.

 2. A single drop of blood contains some 260 million RBC’s.

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3. RBC’s are specialized to transport oxygen and carbon dioxide within the bloodstream.

 4. The unusual shape of a RBC has two important reasons 1- it gives each RBC a large surface area to increase diffusion and 2- it enables RBC’s to bend, flex and squeeze through capillaries.

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5. An RBC is exposed to severe physical stresses. A single round trip of the circulatory system usually takes less than 1 minute.

 6. Because of all this stress a single RBC’s has a life of about 120 days.

 7. You are making about 3 million new RBC’s EACH second!

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8. Red blood cell formation or erythropoesis occurs in red bone marrow.

 9. Red bone marrow or myeloid tissue is located in the vertebrae, sternum, ribs, scapulae, pelvis and proximal limb bones.

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10. Other marrow areas contain a fatty tissue known as yellow bone marrow.

 11. Under extreme stimulation, such as blood loss areas of yellow marrow can convert to red marrow, increasing the rate of RBC formation.

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III. RBC’s and blood Types

A. Antigens are substances that can trigger an immune response, a defense mechanism that protects you from infection.

 1. Cell membranes contain surface antigens, substances that the body’s immune defenses recognize as “normal.”

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2. A person’s blood type is determined by the presence or absence of specific antigens in the blood.

3. The surface antigens of RBC’s are often called agglutinogens.

 4. Three particular important antigens are A, B and Rh.

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Blood types Antigens Antibodies

 A A BB B AAB A B ---O - --- A, B RH+ + ----RH- ------ +

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5. See chart page 352 to view break down of blood types.

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Antibodies and cross-reactions

1. Blood type is checked before an individual gives or receives blood. If someone is given the wrong blood type he/she will die.

2. Plasma contains antibodies, or agglutinins that will attack the surface antigens on foreign cells.

 

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3. When an antibody meets its specific antigen, a cross reaction occurs. Initially the RBC’s clump together this is called agglutination. They may also break up or hemolyze.

 4. Clumps and fragments of RBC’s under attack form drifting masses that can plug small vessels in the kidneys, lungs, heart, or brain.

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 5.   To avoid this the donor and the recipient must be compatible in blood type and Rh factor.

  6. Rh- has no antigens BUT it has

antibodies against Rh+

Rh+ has + antigens BUT NO antibodies.

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  6. IF a women was Rh- and her unborn child was Rh+ there is a possibilities that her body will attack the unborn child because the child is + and destroy the child. This usually does not happen with the first child.

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C. White Blood Cells

1. White blood cells, also known as leukocytes can be distinguished from RBC’s because each has a nucleus and does not have hemoglobin.

 2. WBC’s help defend the body from pathogens and remove toxins, wastes and abnormal or damaged cells.

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3. WBC’s are divided into two groups on the basis of their appearance after staining 1- granulocytes (lots of granules) 2-agranulocytes (not many if any granules)

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D. WBC circulation and movement

1. WBC’s do not circulate for extended periods.

2. WBC’s are sensitive to chemicals, radiation.

 3. Circulating WBC’s have four characteristics:

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a. Have amoeboid movement.

B b. Migrate out of the bloodstream.

c. Attracted to specific chemical stimuli, they are called positive chemotaxis.

d. Neutrophils, eosinophils and monocytes are capable of phagocytosis.

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E. General Functions

1. Neutrophils, eosinophils, basophiles and monocytes contribute to the body’s nonspecific defenses of the immune system.

 2. Lymphocytes are the cells responsible for specific immunity.

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  3. 50-70% of the circulating WBC’s are Neutrophils. They are usually the first of the WBC’s to arrive at an injury site. They are very active phagocytes, and specialize in attacking and destroying bacteria. They have a short life span of only 10 hours

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4. 2-4% of WBC’s are eosinophils and are similar to Neutrophils. But they generally ignore bacteria and cellular debris. They are attracted instead to foreign compounds that have reacted with circulating antibodies. They increase during an allergic reaction or a parasitic worm infection.

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5. Less than 1% of WBC’s are basophiles. They migrate to sites of injury and cross the capillary wall to accumulate within the damaged tissue. They prevent blood clotting.

 6. 2-8% of WBC’s are monocytes and they are about 2 the size of a RBC. They stay in the circulatory system for about 24 hours before entering the peripheral tissue.

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7. 20-30% of WBC’s are lymphocytes and they are about the same size of a RBC. They continuously migrate from the bloodstream to the peripheral tissue and back. They protect the body and its tissues. They attack both foreign cells and abnormal cells of the body and secrete antibodies into the circulation.

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F. The differential count and changes in WBC profiles

1. The normal range for each cell is on page 357.

 2. Certain disorders or diseases will be discovered examining the blood.

 3. Leukopenia indicates inadequate numbers of WBC’s.

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4. Leukocytosis refers to excess numbers of WBC’s.

 5. Leukemia is cancer of blood forming tissues.