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Human Anatomy, First EditionMcKinley & O'Loughlin

Chapter 21:

Blood

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Blood Considered a connective tissue: contains

Cells

a liquid ground substance (called plasma) dissolved protein fibers.

About four times more viscous (or thicker)than water.

Temperature of blood is about 1C higherthan measured body temperature.

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Blood Whole blood can be separated:

Liquid component

cellular components machine called a centrifuge.

blood is withdrawn from a vein and collected in acentrifuge tube

tube is placed into the centrifuge, which thenspins it in a circular motion for several minutes

rotational movement separates the blood into

liquid and cellular components

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Components of Blood Erythrocytes (or red blood cells)

form the lower layer of the centrifuged blood

typically make up about 44% of a blood sample Buffy coat

makes up the middle layer

thin, slightly gray-white layer composed of cells calledleukocytes (or white blood cells) and cell fragments calledplatelets

forms less than 1% of a blood sample

Plasma straw-colored liquid that rises to the top

generally makes up about 55% of blood

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Components of Blood Erythrocytes and the components of the buffy coat

are called the formed elements.

notcells, merely fragments broken off from a larger cell

Formed elements and the liquid plasma composewhole blood.

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Functions of Blood

Transportation Transports numerous elements and compounds

throughout the body.

erythrocytes carry oxygen from the lungs to body cells andthen transport carbon dioxide from the cells back to thelungs for expulsion from the body

blood plasma

transports nutrients that have been absorbed from the GI tract

hormones secreted by the endocrine organs to their target cells

plasma

carries waste products from the cells to organs such as thekidneys, where these waste products are removed

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Functions of Blood

Regulation of Body Temp. Regulates body temperature.

plasma absorbs and distributes heat throughout

the body for cooling the blood vessels in the dermis dilate

and dissipate the excess heat through theintegument

when the body needs to conserve heat, thedermal blood vessels constrict, and the warmblood is shunted to deeper blood vessels in thebody

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Functions of Blood

Regulation of pH Levels pH is a measure of how alkaline or acidic a fluid is.

Neutral pH is measured at exactly 7.

Acidic fluids (e.g., orange juice) are between 0 and 7.

Alkaline fluids (e.g., milk) are between 7 and 14.

Blood plasma contains compounds and ions that maybe distributed to the fluid among tissues (interstitialfluid) to help maintain normal tissue pH.

Blood plasma pH is continuously regulated at a valueof7.4 the pH level required for normal cellularfunctioning.

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Functions of Blood

Maintenance of Fluid Levels Maintains normal fluid levels in the cardiovascular

system.

Prevents fluid loss. Constant exchange of fluid between the blood plasma

and the interstitial fluid.

Iftoo much fluid is absorbed in the blood, high blood

pressure results. Iftoo much fluid escapes the bloodstream and enters

the tissues, blood pressure drops to unhealthy lowlevels, and the tissues swell with excess fluid.

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Functions of Blood

Maintenance of Fluid Levels To maintain balance of fluid exchange between the

blood and the interstitial fluid, blood containscompounds (such as salts and some proteins) to

prevent excess fluid loss in the plasma.

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Functions of Blood

Protection Leukocytes (white blood cells) help guard against

infection by mounting an immune response if apathogen or an antigen is found.

Plasma transports antibodies, which are moleculesthat can immobilize antigens until a leukocyte cancompletely kill or remove the antigen.

Platelets and blood proteins protect the body againstblood loss by forming blood clots on damaged

vessels.

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Components of Plasma Complex mixture of water, proteins, and other

solutes.

When the proteins are moved from plasma, theremaining fluid is termed serum.

Watermakes up about 92% of plasmas totalvolume.

water facilitates the transport of materials in the plasma

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Plasma Proteins The next most abundant materials in plasma

are the plasma proteins.

Make up about 7% of the plasma.

6 and 8 grams of protein in a volume of100milliliters of blood (referred to as g/dl)

The plasma proteins include:

albumins globulins

fibrinogen

regulatory proteins

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Plasma Proteins Albumins Smallest and most abundant of the plasma proteins.

make up approximately 58% of total plasma proteins

Regulate water movement between the blood andinterstitial fluid.

Albumins act as transport proteins that carry ions,hormones, and some lipids in the blood.

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Plasma Proteins Globulins Second largest group of plasma proteins, forming

about 37% of all plasma proteins.

Smaller alpha-globulins and the larger beta-globulinsprimarily bind, support, and protect certain water-insoluble or hydrophobic molecules, hormones, andions.

Gamma-globulins: Also called immunoglobulins orantibodies.

Produced by some of our defense cells to protect the

body against pathogens that may cause disease.

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Plasma Proteins Fibrinogen Makes up about 4% of all plasma proteins.

Responsible for blood clot formation.

Following trauma to the walls of blood vessels,fibrinogen is converted into long, insoluble strands offibrin, which is the essence of a blood clot.

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Plasma Proteins Regulatory

Proteins Form a very minor class of plasma proteins.

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Solutes Plasma is an extracellular fluid (ECF).

it includes all body fluids that are not found insidecells

Plasma is somewhat like interstitial fluid, in that

both have similar concentrations of nutrients,waste products, and electrolytes

Concentration ofdissolved oxygen is higher in plasma

than in interstitial fluid, because the cells take up anduse the oxygen from the interstitial fluid duringenergy production.

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Solutes Difference in concentration ensures that

oxygen will continue to diffuse from the

blood into the tissues. Difference in concentration ensures that

carbon dioxide will readily diffuse from

the interstitial fluid into the blood,where it will be carried to the lungs anddischarged from the body.

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Formed Elements in the Blood Erythrocytes

make up more than 99% of formed elements

primary function is to transport respiratory gases in the

blood

Leukocytes

make up less than .01% of formed elements

contribute to defending the body against pathogens

Platelets make up less than 1% of formed elements and

help with blood clotting

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Hematocrit Percentage of erythrocytes in the blood.

Values vary slightly and are dependent on age and sex.

Adult males range between 42% and 56% .

Females range from 38% to 46%.

Childrenshematocrit ranges also vary and differ from adultvalues.

Altitude can affect the hematocrit.

body compensates by making more erythrocytes more erythrocytes in the blood can carry more oxygen to

the tissues

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Erythrocytes Mature erythrocytes lack nuclei. Transport oxygen and carbon dioxide to and from the

tissues and the lungs.

Lack of nuclei enables them to carry respiratory

gases more efficiently.

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Hemoglobin in Erythrocytes Every erythrocyte is filled with approximately 280

million molecules of a red-pigmented protein calledhemoglobin.

Transports oxygen and carbon dioxide, and isresponsible for the characteristic bright red color ofarterial blood.

Hemoglobin that contains no oxygen has a deep red

color that is perceived as blue because the bloodwithin these veins is observed through the layers ofthe skin and the subcutaneous tissue.

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Hemoglobin in Erythrocytes Each hemoglobin molecule consists offour protein building

blocks, called globins. Alpha (a) chains

Beta (b) chains.

All globin chains contain a nonprotein (or heme) group: ring shaped

an iron (Fe) ion in its center.

Oxygen binds to these iron ions for transport in the blood.

Each hemoglobin molecule: four iron ions

is capable of binding four molecules of oxygen.

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Hemoglobin in Erythrocytes Oxygen binding is fairly weak

ensures rapid attachment and detachment of oxygen withhemoglobin.

Oxygen binds to the hemoglobin

when the erythrocytes pass through the blood vessels of the lungs.

It leaves the hemoglobin

when the erythrocytes pass through the blood vessels of bodytissues.

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Erythrocyte Life Cycle No organelles, therefore can not sustain itself.

Finite life span of about 120 days.

Daily: About 1% of oldest RBCs are removed

Are phagocytized by liver and spleen.

By macrophages

Some components saved, some discarded

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Erythrocyte Life Cycle Some components saved, some discarded

Heme group:

Converted to biliverdin (green pigment)

Then converted to bilirubin In bile, produced by liver

Bile enters the digestive tract

Helps emulsify fat

Bilirubin modified and removed via urine and feces

Iron: Transported by transferrin to liver

Transferred to ferritin for storage

Ferritin can be transported to red bone marrow

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Blood Types Determined by membrane proteins in the RBC cell

membrane.

Called surface antigens (agglutinogens).

Most common group: ABO blood group

Two antigens: A and B

ABO blood types:

Type A: have the A surface antigen

Type B: have the B surface antigen

Type AB: have both the A and the B surface antigens

Type O: have neither the A or the B surface antigen.

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Blood TypesAntibodies (agglutinins) to the surface

antigens are in the plasma

ABO group has anti-A antibodies andanti-B antibodies Type A: have anti-B

Type B: have anti-A

Type AB: has neither anti-A or anti-B

Type O: has both anti-A and anti- B

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Antibodies An antibody interacts with a specific antigen.

The ABO blood group has both anti-Aand anti-Bantibodies that react with the surface antigen A andthe surface antigen B, respectively.

The antibodies in your blood plasma do not recognize

the surface antigens on your erythrocytes.

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Blood Types Rh blood type

Based on another surface antigen

Called either Rh or D

Rh positive (Rh+): has the antigen

Rh negative (Rh-): does not have the

antigen

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Blood Types Rh blood type

Antibody only present with exposure to Rh+

blood (the antigen) Only people with Rh- blood can have the

antibody

Erthryroblastosis fetalis: Rh+ antibodies in

plasma of an Rh-

mother can cross theplacenta RhoGAM: prevent antibody development

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Leukocytes

Leukocytes help initiate an immune response anddefend the body against invading pathogens.

Leukocytes are true cells in that they contain anucleus and cellular organelles.

Leukocytes also differ from erythrocytes in that theyare about 1.5 to 3 times larger, and they do notcontain hemoglobin.

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Leukocytes The five types of leukocytes are divided into two

distinguishable classesgranulocytes andagranulocytesbased upon the presence or absence

of visible organelles termed specific granules.

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Leukocytes Granulocytes Neutrophil

6070% of the total number of leukocytes

Eosinophils have reddish, or pink-orange granules in theircytoplasm. constitute about 24% of the total number of leukocytes

nucleus usually has two lobes, which are connected by a thinstrand

Basophils are 1.5 times larger than erythrocytes

least numerous of the granulocytes constitute about 0.51% of the total number of leukocytes

always exhibit a bilobed nucleus and abundant blue-violet granulesin the cytoplasm

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Leukocytes Agranulocytes Agranulocytes are leukocytes that have such small

granules in their cytoplasm that they are frequentlyoverlooked upon casual observationhence the

name agranulocyte. Agranulocytes include both lymphocytes and

monocytes.

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Leukocytes Agranulocytes -

Lymphocytes T-lymphocytes (T-cells)

manage and direct an immune response

some directly attack foreign cells and virus-infected cells

B-lymphocytes (B-cells)

stimulated to become plasma cells and produce

antibodies Natural killer cells (NK cells)

attack abnormal and infected tissue cells

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Leukocytes Agranulocytes -

Monocytes Up to three times the diameter of an erythrocyte.

Constitute about 38% of all leukocytes.

Nucleus is kidney-shaped or U-shaped.

Macrophages phagocytize bacteria, cell fragments,dead cells, and debris.

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Platelets Irregular, membrane-enclosed cellular

fragments about 2 micrometers in diameter (less than one-

fourth the size of an erythrocyte). In stained preparations, they exhibit a dark

central region.

Sometimes called thrombocytes.

Continually produced in the red bonemarrow by cells called megakaryocytes.

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Platelets Severe trauma to a blood vessel causes

the blood to coagulate, or clot.

Components in the plasma produce aweb offibrin that traps erythrocytesand platelets in the web to halt blood

flow.

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HemopoiesisAlso called hematopoiesis

Production of the formed elements of

blood

Occurs in red bone marrow

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Hemopoiesis Begins with hemopoietc stem cells

Called Hemocytoblast

Pluripotent cells

Produce two cell lines

Myloid line

Everything but lymphocytes Lymphoid line

lymphocytes

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Hemopoiesis

Influenced by a number of hormones andgrowth factors

Colony-stimulating factors: Multi-CSF: RBCs,granulocytes,monocytes, platelets

From myloid stem cell

GM-CSF: granulocytes, monocytes

From progenitor cell G-CSF: granulocytes

From myeloblast cells

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Hemopoiesis

Colony-stimulating factors: contined

M-CSF: monocytes

From monoblasts

Thrombopoietin: megakaryocytes andplatelets

Erythropoietin: hormone from the kidney,RBCs

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Hemopoiesis

Erythropoiesis: from progenitor cell

Reticulocyte: loses all organelles

Thrombopoiesis Leukopoiesis

Granulocyte maturation: from myeloblast

Monocyte maturation: from monoblast

Lymphocyte maturation: from lymphoid stem cell

B-lymphoblast

T-lymphoblast

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