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Blood

Roots to Know

leuko = white

thrombo = clot

cyto = cell

COMPOSITION OF BLOOD

Review:

The cells of the human body are organized into tissues and organs.

There must be a system to transport materials between these organs and tissues.

This function is achieved by the circulation of blood and the mechanism that moves it

The cardiovascular system.

The system of vessels that connects with the veins of the cardiovascular system is the lymphatic system.

A one-way transporting network of vessels that returns excess interstitial fluid from the tissues to the bloodstream

Blood Volume

Blood is a type of liquid connective tissue

55 % of the total volume is the fluid plasma

Plasma is a straw-color

45% consisting of the formed elements. Proteins, cells, and the like.

This fact can be easily demonstrated by placing a specimen of whole blood in a test tube with a small amount of oxalate to prevent clotting. If the sample is centrifuged or allowed to stand for a sufficient length of time, it will be found that the blood cells will settle toward the bottom of the test tube while the plasma remains on top.

The total circulating blood volume makes up about 8% of the body's weight.

a 70-kilogram (152-pound) person will have 5 to 6 liters (10.5 to 12.6 pints) of blood.

Blood is a somewhat viscous and sticky liquid.

Its viscosity is about five times that of water.

It has a characteristic odor, a salty taste'

a pH value of from approximately 7.35 to 7.45 (slightly alkaline).

The most common formed elements:

    • Erythrocytes (red blood cells)
    • Leukocytes (white blood cells)
    • Granulocytes (polymorphonuclear granular leukocytes)
    • Neutrophils
    • Eosinophils
    • Basophils
    • Agranulocytes (monomorphonuclear nongranular leukocytes)
    • Lymphocytes
    • Monocytes
    • Thrombocytes (platelets)

Plasma

The liquid portion of the blood.

A complex solution performing many of the functions of the circulatory system.

The normal volume of plasma in a 70-kilogram adult male is about 5% of the body weight (» 3.5 liters).

Color:

Transparent

Amber (straw), color.

90 - 92 % H2O

A variety of inorganic and organic substances, ions and inorganic salts.

Na+ K+ Ca++ and Mg++, and anions such as Cl -, PO44-, HC03-, and others.

Plasma proteins

albumin, globulins, fibrinogen, and lipoproteins.

And varying amounts of hormones, enzymes, pigments, and vitamins.

The composition of plasma varies with the body's activity and different physiological states.

For example:

Following a meal plasma contains an increased amount of nutrient materials.

After a period of strenuous exercise, plasma contains wastes that the blood has removed from active tissues.

Thus from one moment to the next, plasma reflects the physiological changes in the body.

PHYSIOLOGY OF THE PLASMA

The functions of the blood are closely tied to the functions of all the body's organ systems.

Transport Functions

pH balance. Is also maintained by the balance of HCO3- and H+, buffering.

Foods that have been rendered soluble by digestion are absorbed into the plasma and are transported throughout the body.

Soluble wastes are removed from the cells and carried as disolved organics in the plasma to those organs that can either eliminate them or change them into compounds that are useful for other purposes.

Hormones manufactured in glands move directly into the blood for transportation around the body.

Maintenance of [H2O] in the tissues by drawing upon H2O reserves.

Maintenance of body temperature. Enzymes work best at body temperature. High temperatures can degrade proteins, making enzymes inactive. Thus any increase in the activity of a tissue is also accompanied by an increase in the circulatory rate, and the blood passing through it is heated. This excess heat in the blood is then eliminated through the surface of the body, the lungs, or excretions.

 

Plasma Proteins

Fibrinogen: fiberous-like protein that forms a net for blood clots.

Plasma proteins (other than fibrinogen) are classified as either globulins or albumins.

A good example of an albumin that is not a constituent of blood is that in the white of an egg, while a globulin is present in the egg yolk.

Normally, the blood proteins do not pass through the capillary walls because of their relatively large size. However, since they are colloidal materials, they can give up, or take up, water-soluble substances.

When fibrinogen is removed, the plasma, minus its clotting proteins, is called serum.

7% of Serum

Serum albumin.

    1. More plentiful than globulin.
    2. Its principal function is to control the osmotic pressure of the blood .
    1. The result of this gradient in pressure is that food and oxygen leave the blood early in its passage through the capillary.
    2. Then waste materials pass into the blood as the capillary joins others to form a venule.
    3. Total serum albumin µ amount of fluids leaving the blood through the capillaries.

Gamma globulin.

    1. The serum globulin helps in the maintenance of osmotic pressure.
    2. Associated with the antibodies, like gamma globulin.
    3. For example, if a person has had measles, certain chemical materials in the blood will combat another attack of this disease. These materials are present in the serum globulin as definite antibodies that will neutralize the effects of a future invasion of the body by the same organism.

Table 19-2 Chart of Plasma Composition

Component

Normal Range

Description

Water

90-92%

Water acts as solvent and suspending agent for plama solids.

Plasma proteins

6-8%

 

Albumins

 

Most abundant plasma protein. Helps maintain osmotic pressure. Maintains viscosity.

Globulins

 

May help in osmotic balance. A group of important antibodies.

Fibrinogen

 

A small fraction of plasma proteins but is essential in clotting of blood.

(The remaining solutes make up 1.5%)

Inorganic salts (electrolytes)

Anions: Cl-, Poll --- I S04--, HCO3-. Cations: Na+, K+, Ca++,.Mg++. Salts help to maintain normal pH balance.

Transport of foods in solution.

Nutrients

Glucose

Amino acids

Fats (lipids)

 

 

Waste materials

Urea

Uric acid

Creatine

Creatinine

Ammonium salts

 

Breakdown products of cellular metabolism. They are carried to organs of excretion.

Respiratory gases

Oxygen

Carbon dioxide

 

A trace dissolved in plasma, primarily carried by hemoglobin.

Regulatory substances

Enzymes

Hormones

Vitamins

 

Organic catalysts for cellular metabolism.

Produced by endocrine glands for distribution.

 

Formation of Blood Cells

The erythrocytes, the leukocytes, and the thrombocytes are formed in the red marrow of many bones.

The lymphocytes and monocytes, moreover, are also formed in lymphatic tissue.

Hemopoiesis.

Because the formed elements of the blood are constantly being worn out, they must be replaced by the body at a corresponding rate.

Before birth, blood cells are formed in the yolk sac, liver, spleen, thymus gland, lymph nodes, and red bone marrow of the fetus.

At 7 years, red marrow becomes fatty and incapable of forming blood cells.

At 20 years, all hemopoiesis occurs in the red marrow.

Blood cells arise from mesenchymal stem cells.

Gives rise to the hemocytoblasts.

Eventually forms cellular elements of the blood

Erythroblasts form into erthrocytes.

Myeloblasts form into granulocytes.

Megakaryoblasts form into megakaryocytes.

Some stem cells migrate to the lymphatic tissue, where they form lymphoblasts.

Lymphoblasts form into monocytes.

Erthorocytes lose their nuclei, lymphocytes develop cytoplasmic structres.

Erythrocytes

Red corpuscles

Lack nuclei

Life span of 120 days.

Called reticulocytes before maturity.

0.8% of total erythrocytes in circulating blood.

Number of erythrocytes remains constant.

About 30 trillion in adult.

Using a hemocytometer to count the number of cells:

More in Men than in women.

5,450,000/mm3 erythrocytes for males,

4,750,000/mm3 erythrocytes for females.

Erythropoiesis:

Production of erythrocytes.

Triggered by tissues need for O2

Kidneys release erythropoietin (hormone), which activates the hematocytoblasts.

Dimensions:

Diameter: 6.5-8 m m (adverage = 7.5 m m)

2.2 m m and the edge, and 1.1 m m in the center. (Doughnut)

Area: 140 m m2

Composition:

Protein and lipids.

Characteristics:

Permeable to water, urea, and salt.

Highly elastic to fit through small capalaries.

Main job to carry hemoglobin.

Some 280 million hemoglobin per erythrocyte.

Hemoglobin:

Oxygen-carrying pigments.

64,450 mwt.

It has 4 hemes, lobe-shapes, that has 1 Fe+3 per heme.

Each heme can carries 4 O2 molecules.

Affinity for O2 increases as the number of attached O2 decrease.

Oxyhemoglobin has 4 O2

Deoxyhemoglobin has no O2.

Fetal hemoglobin (Hbf) differs from Hb by being able to saturate with O2 under lower [O2]. Less O2 in mothers blood than in our lungs/air.

PHYSIOLOGY OF ERYTHROCYTES

Transport Functions

The gases involved in respiration are carried by the blood.

O2 bound to Hb in the lungs ® tissues (flushed), diffused into cell, O2 released in tissues.

CO2 bound to Hb in tissues ® lungs (HC03-) released in lungs inations.

HC03- bicarbonate buffers H+.

About 25 percent of the C02 reacts with the amino groups of hemoglobin to form carbamino compounds.

Leukocytes

White blood cells.

Less than erthrocytes.

5,000 - 9,000 per mm3 blood.

1:700 erthrocytes

Variable size and shapes.

All are nucleated.

Life span far less than erthrocytes.

Diapedesis: ameoba-like movements that allow leukocytes to move through capillary walls.

This type of movement increases when stimlated by pathogens.

Digest bacteria through various means.

Surrounds like lysosomes, engulfs, then digest bacteria. (Phogocytosis).

Two major types, based upon the number of grauales which stains well with Writght’s stain.

Granulocytes (polymorphonuclear cells)

Neutrophils

3000-6000 per mm3

Phagocytic

Eosinophils

300 per mm3

Phagocytosis of antigen-antibody complexes.

Basophils

25-100 per mm3

Agranulocytes

Lymphocytes

1500-3000 per mm3

Synthesis of antibodies

Monocytes

500 per mm3

Very motile and phagocytic.

Forms macrophages, that attack large invaders.

Thrombocytes

250,000-500,000 per mm3

Blood clotting for small punctures and cuts, (paper cuts).

Blood Platelets

Smallest elements, cells.

2-4m m

Table 19-1 The Cellular Elements of the Blood

Name

No./mm3

Diameter

(micrometers)

Characteristics and Function

Erythrocytes

 

7.2-7.7

 

Male

5,450,000

 

 

Female

4,750,000

 

 

Leukocytes

5,000-9,000

 

No nuclei, biconcave diss.

Transport 02

Granulocytes

 

 

Fine granules that stain pale lavender. Multilobed nucleus. Phagocytic.

Neutrophils

3000-6000

7-9

Large granules that stain with eosin. Bilobed nucleus.Phagocytosis of antigen antibody complexes.

Eosinophils

300

9-10

Granules stain blue with basic dye. Exact function unknown, but store histamine.

Basophils

25-100

7-9

Large single nucleus with scant cytoplasm. Synthesis of antibodies.

Agranulocytes

 

 

Large single nucleus with considerable cytoplasm. Very motile and phagocytic-form

macrophages.

Lymphocytes

1500-3000

6-8

Nonnucleated fragments of megakaryocytes, disc shaped. Contain serotonin and several clotting factors. Aid in coagulation of blood.

Monocytes

500

14-20

 

Thrombocytes

250,000-500,000

2-4

 

 

PHYSIOLOGY OF THE LEUKOCYTES

Transport Functions

Protection against disease is another important function of the blood. This is accomplished by the white blood cells in one of two ways. First, certain granulocytes, primarily neutrophils, act as phagocytes and engulf bacteria. Second, still other types of white corpuscles have the ability to manufacture chemical substances (antibodies) to destroy bacteria or to neutralize the toxins (poisons) produced by invading organisms.

Hemostosis

In the event of an injury involving blood loss, a number of events take place to arrest the blood flow.

    1. small vessels constrict immediately.
    1. The smooth muscles in their walls go into spasm.
    2. As a result of the initial spasm, the endothelial cells lining the vessel stick together, as if "glued together".
    1. Platelets adhere to the rough surface of a broken vessel.
    1. Possibly bonding to the collagen which became exposed.
    2. These clumped platelets attract others until an aggregate, or plug, of platelets is formed.
      1. The platelets release two powerful vasoconstrictors called serotonin and epinephrine.
      2. These chemicals prolong the constriction of the injured vessels.
    1. Blood clotting.
    1. Coagulation of blood is the most effective and complex of the hemostatic mechanisms.
    2. Blood loses its fluid properties and becomes a semisolid mass similar in consistency to gelatin.
    3. Fibrinogen Soluble ® Fibrin insoluble, by the enzyme thrombin.
    4. Fibrin threads form a meshwork that traps blood cells and plasma.
    5. The clotting mechanism that leads to the formation of fibrin involves a complex series, or "cascade," of reactions that involve at least twelve factors. (In summary, 3 stages)
      1. Thromboplastin is released when platelets disintegrate (intrinsic) at the site of vascular injury. Additional thromboplastin is released by the injured tissues themselves (extrinsic), especially vascular walls, in the presence of Ca +2.
      2. Prothrombin is converted to thrombin by both intrinsic and extrinsic thromboplastin and several plasma coagulating factors. Again, calcium ions are necessary, along with vitamin K.
      3. Thromboplastin

        + C+2 + Vitamin K

        Prothrombin ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ ® thrombin

      4. In this stage fibrinogen, which is soluble, is converted to fibrin, which is insoluble, by the thrombin formed in stage 2. Additional plasma coagulation factors are also involved.

thrombin

Fibrinogen soluble ¾ ¾ ¾ ¾ ® Fibrin insoluble

Fibrin forms a meshwork of fine protein threads. The platelets, having contractile properties, pull the fibrin fibrils together and squeeze out the remaining fluid-the serum. Once hemorrhaging is stopped, tissue repair can begin.

Physical Factors of Coagulation

  1. Water hastens the process. If you prevent water from the area, the process occurs slower.
  2. There appears to be a rapid destruction of the blood platelets when they contact a rough surface. The process can be hastened by placing a piece of gauze or other cloth with a relatively rough surface over a wound. This further stimulates the formation of a clot.
  3. Temperature also affects the rate of clotting. Blood clotting ­ with To.
  4. Naturally occurring anticoagulants prevents premature clotting.
    1. Heparin interferes with thrombin’s ability to catalyze the reaction fibrinogen ® fibrin. Normally, heparin occurs in insufficient quantities in the blood to be detectable as an anticoagulant.

 

Blood Types

The most successful method of combating excessive loss of blood is transfusing whole blood into the circulatory system of the victim. Usually, whole blood is superior to any blood substitute or component part of blood.

To transfuse blood from one individual to another, the blood types of both must be known to able to mix safely, that is, to be compatible. The mixing of unsafe, or incompatible, blood may lead to very serious or possibly fatal transfusion reactions. The problem occurs when the protein outer layer of the red corpuscles of the donor becomes "sticky" when introduced into an antagonistic plasma of the recipient. The "sticky" red blood cells clump together and block the vessels of the patient. This clumping of blood cells is called Agglutination. The plasma proteins concerned in agglutination are antibodies called agglutinins, while the proteins in the walls of the corpuscles are antigens, called agglutinogens.

ABO groups.

The blood group of each person is designated as A, B, AB, or 0, depending on the kind of agglutinogen (antigen) present in the red blood corpuscles.

    1. Antigen A is present in group A.
    2. Atigen B is present in group B.
    3. Both antgens A and B are present in group AB.
    4. Neither antigen is present in group 0 individuals.
    5. This blood trait 's inherited, with A and B being dominant, while 0 is recessive.

Transfusion reactions. The terms universal donor and universal recipient are frequently applied to members of groups 0 and AB, respectively.

    1. Group 0 blood can be transfused into most people without ill effects.
      1. Although the plasma of this type of blood contains both a and b agglutinins, it does not cause agglutination. When transfused these antibodies become so dilute in the recipient's plasma that they are ineffective. It is the destruction of the transfused cells that produces the transfusion reaction. Since group 0 corpuscles lack agglutinogens, they will not clump in the presence of either a or b agglutinins.
    1. In like manner, a person with group AB is a universal recipient because the blood lacks any agglutinins that affect the corpuscles of the donor.
    2. In crossmatching the donor's and recipient's bloods are mixed together. If the bloods are compatible, no agglutination will occur.

Rh factor. There are several other proteins in the blood that may bring about agglutination under certain conditions. The most important of these is the Rh factor, which, like the blood type, is an inherited characteristic. The letters "Rh" are used since this factor was first studied in the rhesus monkey.

    1. A number of different kinds of Rh antigens have been discovered.
    2. The most important is antigen D.
    1. In the United States, approximately 85 percent of the people have the Rh factor
      1. They are said to be Rh positive (Rh+).
      2. This means that these individuals have antigen D on the surfaces of their red blood cells.
    1. The 15 percent or so of the population who do not have antigen D on their erythrocytes are said to be Rh negative (Rh).
      1. These individuals will produce antibodies against that antigen if given a transfusion of blood which is Rh+.
    1. A later transfusion of Rh' blood results in a severe reaction.
    2. Testing for the presence of antigen D is done in much the same manner as for the general blood type, as described earlier.
    3. Hemolysis.
    1. Damage to an infant's blood occurs before birth as the result of the presence or absence of the Rh factor.
    2. If the mother is RH, and the child is Rh+, the mother's first pregnancy has no complications.
    3. However, the mother has now developed antibodies against the Rh factor.
    4. Another pregnancy, where she carries an Rh-positive child, her antibodies can cross the placenta into the fetus, whose erythrocytes they attack, causing hemolysis, which is the breakdown of erythrocytes and the release of hemoglobin into the plasma. The released hemoglobin may damage many organs, including the brain. This serious effect on the child is called erythroblastosis fetalis, a condition characterized by severe anemia and jaundice. If the child is alive at birth, the condition is treated by means of numerous transfusions by which the child's blood is replaced with Rh- blood. The antibodies are thus removed.

  Table 19-3

Blood Groups and Corresponding Antigens and Antibodies

Blood Group

Antigens of Red Cells

Antibody in Plasma or Serum

A

A

Anti-B

B

B

Anti-A

AB

AB

None

O

NONE

Anti-A and Anti-B

 

 

Table 19-4

Blood Grouping

Type

Percentage of Population

Red Cell Antigens or Agglutinogens

Plasma Antibodies or Agglutinins

ABO

 

 

A

41%

A

Anti-B

B

10%

B

Anti-A

AB

4%

A,B

 

0

45%

 

Anti-A, Anti-B

Rh(D)

 

 

 

Positive

85%

Rh

 

Negative

15%

 

 

SUMMARY

Blood is considered a type of connective tissue composed of approximately 55 percent intercellular fluid (the plasma) and 45 percent formed elements. The contents of the blood maintain the water content of the body, protect against disease, and maintain an acid-base equilibrium in the internal environment.

Special features of blood include hemostosis (blood clotting), the control of osmotic balance by plasma proteins, the capacity of the blood to buffer acids or bases, and the ability for blood from different individuals of the some blood type to be mixed.

Disorders of the blood include different forms of anemia, clotting within vessels (thrombus) hemophilia, and hemorrhaging.