blood press

8/11/2019 Blood Press

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The Functions of Blood

Cardiovascular System Overview Provides a system for rapid

transport within the body

Nutrients

Hormones

Waste products

Respiratory gases

Cells

Heat


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The Functions of Blood

Blood functions include: Transport of cells and compounds

Regulate pH and electrolytes of

interstitial fluids

Limit blood loss through damaged

vessels

Defend against pathogens, toxins

Absorb, distribute heat as part of

temperature regulation

Copyright 2007 Pearson Education, Inc., publishing as Benjamin Cummings


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The Composition of Blood

Blood Collection and Analysis Whole blood can be fractionated into:

Plasma (liquid component)

Formed elements(cellular components)

Red blood cells (RBCs)

White blood cells (WBCs)

Platelets



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The Composition of Blood

The Compositionof Whole Blood

Figure 11-1(a)


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Plasma

Plasma Basics Makes up about 55% of whole blood

Watermakes up about 92% of plasma

Has more protein and oxygen thaninterstitial fluid

Plasma proteins fall in three classes

Albumins

Globulins

Fibrinogen



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Plasma

Key NoteApproximately half the volume

of whole blood consists of cells

and cell products (the formedelements). Plasma resembles

interstitial fluid but contains a

unique mixture of proteins notfound in other extracellular

fluids.



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Plasma

The Composition of

Whole Blood

Figure 11-1(b)


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Formed Elements

Hemopoiesis

The cellular pathwaysby which the formed elements are

produced.

Stem cells (hemocytoblasts)Cells

that divide and mature to produce all

three classes of formed elements.



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Formed Elements

Red Blood Cells

Also called, erythrocytesor RBCs

Make up about 45% of whole blood

volume

Make up 99.9% of the formed

elements



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Formed Elements

HematocritPercentage of whole

blood volume taken up by formed

elements (mostly RBCs). In

clinical shorthand, its called, the

crit.



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Formed Elements

The Composition of Whole Blood

Figure 11-1(c)


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FormedElements

Properties of RBCs Transport oxygen and carbon

dioxide in blood stream

Have large surface to volume ratio

Speeds up gas loading/unloading Lack most organelles

Makes more room for hemoglobin

Degenerate after about 120 days



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FormedElements

The Anatomy of Red Blood Cells

Figure 11-2


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FormedElements

Red Blood Cell Composition

Hemoglobinmakes up 95% of RBC protein

Globular protein composed of four subunits

Each subunit contains:

A globinprotein chain

A molecule of heme

An atom of iron

A binding site for one oxygen molecule

Phagocytesrecycle hemoglobin from

damaged or dead RBCs



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FormedElements

X ErythropoiesisProcess for formation

of red blood cells

Occurs mainly in the bone marrow

Stimulated by erythropoietin(EPO)

EPO increases when oxygen levels are low

Development stages include:

Erythroblasts

Reticulocytes(after nucleus is expelled)



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FormedElements

The Origins and

Differentiation ofRBCs, Platelets,

and WBCs

Origins and

Differentiation of

Formed Elements

Figure 11-5

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Figure 11-6

1 of 7Copyright 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Bone marrow

Stemcells

Erythroblasts

Reticulocytes

Increased

mitotic rate

Acceleratedmaturation

Release oferythropoietin

(EPO)

Tissueoxygenlevels

decline

Tissueoxygenlevelsrise

Improvedoxygencontentof blood

Increased numbers

of circulating RBCs


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Figure 11-6


Tissueoxygenlevels

decline


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Figure 11-6



(EPO)

Tissueoxygenlevels

decline


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Figure 11-6


Bone marrow

Stemcells

Erythroblasts

Increased

mitotic rate


(EPO)

Tissueoxygenlevels

decline


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Figure 11-6


Bone marrow

Stemcells

Erythroblasts

Reticulocytes

Increased

mitotic rate



(EPO)

Tissueoxygenlevels

decline


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Figure 11-6


Bone marrow

Stemcells

Erythroblasts

Reticulocytes

Increased

mitotic rate



(EPO)

Tissueoxygenlevels

decline

Increased numbers

of circulating RBCs


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Figure 11-6


Bone marrow

Stemcells

Erythroblasts

Reticulocytes

Increased

mitotic rate



(EPO)

Tissueoxygenlevels

decline

Tissueoxygenlevelsrise

Improvedoxygencontentof blood

Increased numbers

of circulating RBCs

F d El t


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FormedElements

Key Note

Red blood cells (RBCs) are the most

numerous cells in the body. They

circulate for about four months before

being recycled; millions are produced

each second. The hemoglobin inside

transports oxygen from the lungs to

peripheral tissues and carbon dioxide

from the tissues to the lungs.


F d El t


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Formed Elements

Blood Type

Determined by presence or absence of

specific antigens(agglutinogens) on

outside surfaceof RBC

Antigens are calledA, B, and Rh

Antibodies(agglutinins) in plasma react

with foreignantigens on RBCs

RBCs clump and break open

Anti-Rh antibody made after exposure to

Rh-positive blood cells



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Figure 11-7(b)1 of 5Copyright 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Surfaceantigens

Opposingantibodies+

+

Agglutination (clumping) and hemolysis


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Surfaceantigens


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Surfaceantigens

Opposingantibodies+

+


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Surfaceantigens

Opposingantibodies+

+

Agglutination (clumping)


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Surfaceantigens

Opposingantibodies+

+

Agglutination (clumping) and hemolysis

Formed Elements


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FormedElements

White Blood Cells (WBCs) Also called, leukocytes

Defend the body against:

Pathogens Toxins

Abnormal cells

Damaged cells


Formed Elements


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Formed Elements

WBC Properties

Perform diapedesisPush between

cells to cross blood vessel walls and

enter the tissues

Exhibit chemotaxisMove toward

specific chemicals released by

bacteria or injured cells

Consist of two groups: Granulocytes(cytoplasmic granules)

Agranulocytes (no granules)


Formed Elements


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Formed Elements

Three Types of Granulocytes Neutrophils

5070% of circulating WBCs

Phagocytic

Eosinophils Less common

Phagocytic

Attracted to foreign proteins

Basophils Release histamine

Promote inflammation


Formed Elements


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Formed Elements

Two Types ofAgranulocytes Lymphocytes

Found mostly in lymphatic system

Provide specificdefenses

Attack foreign cells Produce antibodies

Destroy abnormal (cancer) cells

Monocytes

Migrate into tissues Become macrophages

Live asphagocytic amoeba


Formed Elements


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Formed Elements

White Blood

Cells

Figure 11-8(a)


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Formed Elements


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Formed Elements

White Blood

Cells

Figure 11-8(c)

Formed Elements


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Formed Elements

White Blood

Cells

Figure 11-8(d)

Formed Elements


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Formed Elements

White Blood

Cells

Figure 11-8(e)

Formed Elements


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FormedElements

X Production of WBCs in Bone Marrow

Myeloid stem cells produce:

Granulocytes (three types)

Monocytes (future macrophages)

Lymphoid stem cellsproduce lymphocytes

Process called, lymphopoiesis

Lymphocytes enter blood

Migrate to lymphoid tissues


Formed Elements


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FormedElements

X Regulation of WBC Maturation Colony-stimulating factors (CSFs)

Hormones which regulate certain WBC

populations

Four CSFs are known

CSFs target stem cell lines

Several CSFs used with cancer patients

with bone marrow suppression


Formed Elements


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FormedElements

X Regulation of WBC Maturation Regulation of lymphocyte maturation is

poorly understood

Thymosins (hormones in thymusgland)

triggerTcellsto develop


Formed Elements


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FormedElements

Key Note

RBCs outnumber WBCs by a 1000 to 1.

WBCs defend the body against infection,

foreign cells, or toxins, and assist in the

repair of damaged tissues. Most

numerous are neutrophils, which engulf

bacteria, and lymphocytes, which are

responsible for the specific immune

defenses.


Platelets


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Platelets

Platelets are

Produced in the bone marrow

Released from megakaryocytes

as cytoplasmic fragments into

the blood

Essential to clotting process


Hemostasis


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Hemostasis

HemostasisProcesses that stopthe loss of blood from a damaged

vessel. Largely dependent on

platelets and soluble proteins(clotting factors).


Hemostasis


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Hemostasis

Three phases in Hemostasis: Vascular phase

Local contraction of injured vessel

Platelet phase Platelets stick to damaged vessel wall

Coagulation phase

Clotting factorsin plasma form blood clot


Hemostasis


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Hemostasis

X The Clotting Process

Coagulationpathways require an externaltrigger

Extrinsic pathway

Triggered by factors released by injuredendothelial cells or peripheral tissues

Intrinsic pathway

Triggered by factors released by

platelets stuck to vessel wall Both pathways lead to common pathway

Thrombinconverts soluble fibrinogensubunits to an insoluble polymer, fibrin



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Hemostasis


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Hemostasis

Figure 11-10

Events in the Coagulation Phase of Hemostasis


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Hemostasis


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Hemostasis

Key Note

Platelets coordinate hemostasis (bloodclotting). If they are activated byabnormal changes in their surroundings,

platelets release clotting factors andother chemicals. Hemostasis is acomplex cascade that produces a fibrouspatch that is subsequently remodeledand then removed as repair proceeds.

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