BLOOD

FUNCTIONS OF BLOOD (12.1) Substance

DITRIBUTION/TRANSPORTATION REGULATION of substances Body PROTECTION

BLOOD FUNCTIONS: DISTRIBUTION (12.1) Blood transports:

Oxygen from the lungs and nutrients from the digestive tract

Metabolic wastes from cells to the lungs and kidneys for elimination

Hormones from endocrine glands to target organs

BLOOD FUNCTIONS: REGULATION (12.1)

Blood maintains:Appropriate body temperature by absorbing

and distributing heat to other parts of the bodyNormal pH in body tissues using buffer

systemsAdequate fluid volume in the circulatory

system

BLOOD FUNCTIONS: PROTECTION (12.1) Blood prevents blood loss by:

Initiating clot formation when a vessel is broken

Blood prevents infection by: Synthesizing and utilizing antibodiesActivating WBCs to defend the body

against foreign invaders

PHYSICAL CHARACTERISTICS OF BLOOD (12.1)

Average volume of blood:5–6 L for males; 4–5 L for females

Viscosity (thickness) - 4 - 5 (where water = 1)

Average pH of blood is 7.4 Salinity = 0.85%

Reflects the concentration of NaCl in the blood Temperature is 100F

slightly higher than “normal” body temperature

Blood accounts for approximately 8% of body weight

COMPOSITION OF BLOOD (12.2) Blood is the body’s only fluid connective

tissue Liquid = plasma (55%) Formed elements (45%)

Erythrocytes, or red blood cells (RBCs) Leukocytes, or white blood cells (WBCs) Platelets - fragments of cells

BLOOD PLASMA (12.6) Blood plasma components:

Water = 90-92%Inorganic/Organic substances = 6-8%Important for

maintain osmotic pressure of the blood, transport of lipids works as a clotting protein. transportation of nutrients such as glucose

and urea Regulation of blood pH (electrolytes)

COMPONENTS OF WHOLE BLOOD (12.2/12.3)

Withdraw blood and place in tube

1 2 Centrifuge

Plasma(55% of whole blood)

Formed elements

Buffy coat:leukocyctes and platelets(<1% of whole blood)

Erythrocytes(45% of whole blood)

• Hematocrit – the volume percentage of RBC in a

sample of whole blood. • Males: 47% ± 5%• Females: 42% ± 5%

ERYTHROCYTES (RBCS) 12.3

Biconcave disc No nucleus, no centrioles,

no organelles Filled with hemoglobin

(Hb) - 97% of cell contents Essential for carrying oxygen

Most numerous of the formed elements

Dedicated to respiratory transport.

BLOOD CELL PRODUCTION (12.4) Hemopoiesis – blood cell production

Occurs in the red bone marrowAxial skeleton and girdlesEpiphyses (end) of the humerus and femurMarrow contains immature erythrocytes

Erythropoiesis – production of RBC’s.

ERYTHROPOIESIS (12.4)

1. Hemocytoblasts – produce myeloid stem cells which develop into proerythroblasts

2. Erythroblasts – has nucleus and is synthesizing hemoglobin molecules (4 days)

3. Reticulocyte – the nucleus is shed, but other organelles are still present making more proteins. After 2-3 days, the organelles are shed and the reticulocyte enters the blood stream.

4. Erythrocyte – Once the reticulocyte has been in the blood stream for 24 hours, it is considered a mature RBC.

FATE AND DESTRUCTION OF ERYTHROCYTES (12.4)

The life span of an erythrocyte is 100–120 daysTravels about 750 miles in that time (Chicago to NYC)

Old erythrocytes become rigid and fragile, and their hemoglobin begins to degenerate

Dying erythrocytes are engulfed by macrophages

Heme and globin are separated Iron is removed from the heme and salvaged for reuse

HORMONAL CONTROL OF ERYTHROPOIESIS Erythropoietin (EPO) release by the

kidneys is triggered by:Hypoxia due to decreased RBCsDecreased oxygen availability Increased tissue demand for oxygen

Enhanced erythropoiesis increases the: RBC count in circulating bloodOxygen carrying ability of the blood

RBC/Oxygen levels EPO release RBC production

ERYTHROPOIETIN MECHANISM

Figure 17.6

Imbalance

Reduces O2 levels in blood

Erythropoietin stimulates red bone marrow

Enhanced erythropoiesis increases RBC count

Normal blood oxygen levels Stimulus: Hypoxia due to decreased RBC count, decreased availability of O2 to blood, or increased tissue demands for O2

Imbalance

Start

Kidney (and liver to a smaller extent) releases erythropoietin

Increases O2-carrying ability of blood

ERYTHROCYTE DISORDERS Polycythemia

Abnormal excess of erythrocytes Increases viscosity, decreases flow rate of blood

Anemia – blood has abnormally low oxygen-carrying capacityBlood oxygen levels cannot support normal

metabolismSigns/symptoms include fatigue, paleness,

shortness of breath, and chills

ERYTHROCYTE DISORDERS Sickle-cell anemia –

results from a defective geneCodes for an abnormal

hemoglobin called hemoglobin S (HbS)

This defect causes RBCs to become sickle-shaped in low oxygen situations

LEUKOCYTES (WBCS) 12.5 Leukocytes – complete cells with

nucleus and organelles4-8,000/mm3

Number increases in response to bacterial/viral invasion (over 11,000/mm3)

Protect the body from infectious microorganisms

TWO MAJOR TYPES OF WBCS 12.5 Granulocytes include Neutrophils,

Eosinophils, Basophils (ben)Are 2x larger than RBC and

only live for 12 hoursHave lobed nucleiAre all phagocytic cells

Agranulocytes include Monocytes, LymphyocytesLive for months to yearsNormal shaped nucleiLack granules

GRANULOCYTES (12.5) Neutrophils account for 65-75% of WBC

Our body’s bacteria slayers Eosinophils account for 1–4% of WBC

Lead the body’s attack against parasitic infections

Lessen the severity of allergies by phagocytizing immune complexes (ending allergic reactions)

Basophils account for 0.5-1% of all WBC Releases histamine – inflammatory

chemical that acts as a vasodilator and attracts other WBCs

AGRANULOCYTES (12.5) Lymphocytes Account for 20-25% of

WBCThe most important cells of the immune

system T cells - attack foreign cells directly B cells - give rise to cells that produce

antibodies Monocytes account for 3–7% of WBC

They are the largest leukocytesThey leave the circulation, enter tissue, and

differentiate into macrophages

LEUKOCYTE DISORDERS Leukocytosis

WBC count is abnormally high at 11,000 cells per millimeter cubed. This is common during sickness

Leukopenia decrease in WBC count - below 4,800 mm3

Leukemiacancer of WBCBone marrow begins to make abnormal

WBC’s that grow faster, and larger than normal cells.

PLATELETS “THROMBOCYTE” Platelets are small cell fragments

Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels

BLOOD TYPING KEY TERMS

ANTIGEN: Proteins on the surface of red blood cells that determine blood type and stimulate B cells to produce antibodies.

ANTIBODY: Proteins that B cells of the immune system produced in response to non-self antigens (antibodies react with antigens)

AGGLUTINATION: Clumping of blood cells in response to a reaction between an antibody and antigen.

HUMAN BLOOD GROUPS (12.9) RBC membranes have antigens on their external surfaces

These antigens are:Unique to the individual Recognized as foreign if

transfused into another individual

Promoters of agglutination Presence or absence of

these antigens is used to classify blood groups

BLOOD GROUPS (12.9)

Humans have 30 varieties of naturally occurring RBC antigens

The antigens of the ABO and Rh blood groups cause vigorous transfusion reactions when they are improperly transfused

ABO BLOOD GROUPS (12.9)

The ABO blood groups consists of:Two antigens (A and B) on the surface of the

RBCs Two antibodies in the plasma (anti-A and

anti-B)

ABO BLOOD GROUPS

RH BLOOD GROUPS (12.9)

85% of the population have the presence of the Rh antigen on RBCs = Rh+

15% - Lack of antigen indicated as Rh–

Anti-Rh are not spontaneously formed only in Rh– individualsOnly after the Rh– individual receives Rh+

blood will the anti-Rh antibodies form.A second exposure to Rh+ blood will result in

a negative transfusion reaction with agglutination.

TRANSFUSION REACTIONS (12.9) Transfusion reactions occur when

mismatched blood is infused Donor’s cells are attacked by the

recipient’s plasma antibodies causing:Diminished oxygen-carrying capacityClumped cells (agglutination) that impede

blood flowRuptured RBCs that release free

hemoglobin into the bloodstream Circulating hemoglobin precipitates in

the kidneys and causes renal failure

FETAL AND MATERNAL BLOOD TYPES (12.10)

FETAL AND MATERNAL BLOOD TYPES (12.10) Rh- mom pregnant with an Rh+ fetus Rh– mother becomes sensitized when Rh+ blood

(from Rh+ baby or a Rh+ transfusion) causes her body to synthesis Rh+ antibodies

In a second pregnancy, Rh+ antibodies of a sensitized Rh– mother cross the placenta and attack and destroy the RBCs of an Rh+ baby

DETERMINE THE BLOOD TYPE.. Has A antigens Universal donor A antibodies Universal recipient AB antigens Both Antibodies Rh factor is present NO antibodies

Type A

Type O

Type B

Type AB

Type AB

Type O

+

Type AB

BLOOD TYPE TESTING (12.9) When serum containing anti-A or anti-B

antibodies is added to blood, agglutination (clumping) will occur.

Positive reactions indicate (clumping)Signifying the correct blood type

*antibodies serum

BLOOD TYPE:

AB-

BLOOD TYPING (12.9)

Blood type being tested

RBC antigen Serum Reaction

Anti-A Anti-B

AB A and B + +

B B – +

A A + –

O None – –