BSC 2086 - ANATOMY AND PHYSIOLOGY

Lecture Notes:
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I. Functions of Blood

Blood is a water-based solution that transports dissolved solutes and a suspension that carries cells.

A. Transport gases (O2 and CO2), nutrients (glucose, amino acids, fatty acids), water, hormones, urea, electrolytes, other ions

B. Regulates pH, temperature, water

C. Protects against blood loss, disease
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Relate blood functions with those of other systems.

II. Components of blood (5-6 liters of blood in body) A. Formed elements (~ 50% volume of blood)

All cells formed by hemopoesis starting with hemocytoblasts in red bone marrow
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1. RBC (erythrocytes) a. 4-6 million per microliter (uL) always in vessels -cannot move by themselves.

b. Biconcave, anucleate discs that are small, 7-8 micrometer (um) that can't undergo mitosis so they live only about 3 months and die.

c. 1/3 of cell contents is hemoglobin (iron containing protein) that is responsible for transporting metabolic gaess (O2 and CO2) from lungs to body cells and back.

1) Hemoglobin structures
4 heme (iron-containing) groups in 4 globin polypeptides

If globin defective then changes shape of cell (sickle cell anemia) reduce O2 carrying capacity.

2) Hemoglobin binds with O2 then becomes oxyhemoglobin, the major way of transporting O2

3 ) Hemoglobin binds with CO2 then becomes carboaminohemoglobin, a minor way of transporting CO2

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d. Regulation of erythropoiesis ( negative feedback by hormonal control)
balance of cell production and destruction ~ 2 x 106 cells/second

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1) Low blood oxygen level (hypoxia) stimulates production of Erythropoietin (EPO) by kidney endocrine cells.

2) Increased Erythropoetin stimulates RBC production in target cells (hemocytoblasts in red bone marrow)

3) Action of hormone is to increase red blood cell count in blood.

4) Response is the increased ability of blood, with increased RBC's) to carry 02, thus increasing blood oxygen level.
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e. Destruction of RBCs 1) RBCs (anucleate) cannot live more than about 3 months because damaged and can't repair because because of no protein synthesis

2) Damaged RBCs attacked by by phagocytic cells (macrophages) mostly in spleen and digested.

3) Hemoglobin breakdown
Heme degrades to bilirubin (goes into bile) + iron
Globin degrades into amino acids

2. WBC = leucocytes (all perform a different type of disease resistance in response to foreign cell or protein=antigen)
all nucleated with cytoplasmic granules (some conspicuous and some not)
Total WBC count 10,000 per uL
WBC's are chemotaxic (follow chemical trails) and can move outside CV vessels (= diapedisis or emigration)

a. Basophils <1% of all WBC
blue/black staining granules
slightly larger than RBC

act to resist disease by producing chemicals that:
stimulate migration of other white blood cells to injury );
increase blood flow to injury (inflammation) thereby by production of histamine (vasodilator) and heparin (blood thinner). This increase in blood flow increases other disease resistance mechanisms

b. Eosinophils <5% of all WBC
red/orange staining granules
slightly larger than RBC

act to resist disease by producing chemicals that:
phagocytizes antibody/antigen complexes
reduce inflammation by production of antihistamines
inhibit parasitic worm production

c. Neutrophils <70% most numerous of all WBC
small dark staining (hard to see) granules w/many-lobed nucleus

phagocytic
produce hydrogen peroxide that destroys neutophil and antigen
produce antimicrobial substances -defensin

d. Monocytes <10% of all WBC
no granules, large = twice RBC size, C- shape indented nucleus

act to resist disease by turning into mobile or fixed macrophages =large active phagocytes
also initiates immune response by presenting antigen (usually foreign protein or cell) to lymphocytes.

e. Lymphocytes <25% Second most abundant
no granules, small and large (> RBC), dark stained cell, with small crescent of cleaqr cytoplasm
found in lymph tissue (B cells) and blood (T cells)

Lymphocytes provide specific disease resistance =immunity
B lymphocytes produce antibodies into blood in response to foreign chemicals (antigens) or cells.
antibodies bind with cells (antigens) to cause agglutinating, neutralizing or immobilizing them
binds with non-cellular antigens to form a precipate (dead mass of stuff) known as an antibody-antigen complex
All of these forms (agglutinate clumps, etc) cano be more easily phagocytized

T lymphocytes actually bind with foreign or viral infected cells
Then secrete perforin a chemical that causes cytolysis.
produce lymphotoxin to poison viral infected cells
Also secrete interferons in response to viral attacks, stopping viral replacement in infected cells.

Note: Leukopoesis - WBC count >11,000 per uL controlling factors vary, levels of leukocytes vary in response to infection to provide homeostasis (called leukocytosis)
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3. Platelets (megakaryocyte fragments)
fragments of cells, very small (1/10 to 1/50 th of size of RBC)
number = 250,000 – 500,000 per uL
short life span ~ 1 week

act to repair tears in blood vessels
reduce blood loss by making plug

Compare and contrast structural and functional differences between the seven cell types. Compare functional differences betwee B and T lymphocyte cells.

B. Plasma (50% of blood volume) mostly very thick liquid contains dissolved proteins (viscosity 4-6 x water)
90% H2O, 8% proteins (made by liver), and 2% others (ions mostly).

Plasma proteins
In general, proteins reduce blood loss by increasing viscosity, increases blood osmotic pressure

1. Albumin most abundant protein - transports steroid hormones and fatty acids. Most abundant protein so major promoter of blood osmotic presure. Increases blood viscosity.

2. Globulins -antibody proteins which stick cells together (agglutinate) or clump debris to allow easier phagocytosis. Also can immobolize swimming microbes.

3. Fibrinogen - provides fibers for clotting and production of platelet plug
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Compare and contrast plasm protein functions.

III. Physiology of reducing blood loss (stopping blood flow) (Hemostasis)
A. Vascular spasm - smooth muscle in arteries and veins contact to squeeze vessel closed

B. Platelet Plug
accumulation of large numbers of platelets eventually fills hole in
vessel
stick to each other in presence of collagen from broken walls of vessel

C. Blood clotting (coagulation)

involves two pathways both requiring adequate blood levels of Ca++ to convert fribinogen (soluble) fibrin(insoluble)

pathways are positive feedback and all work at same time

Describe the mechanisms for preventing blood loss.

A. ABO blood groups (dual gene system) 1. Agglutinogens on cell surface

gene produces A agglutigen \ then A blood
1 gene produces B agglutigen \ then B blood
no genes produce A or B agglutigen \ then O blood
both genes produce A and B agglutigen \ then AB blood

2. Antibodies (agglutinins)

person with A antigens in blood makes anti-B antibodies, vice versa person with AB blood produces no antibodies

person with O blood produces both A and B antibodies

B. Rh(esus) monkey group 1. Rh– no agglutinogen on cell surface
Rh+ antigens (dominant)

2. No antibodies spontaneously produced in Rh– 3. Problem arises when mother (Rh --) and child( Rh+) are different.

Mother can produce anti-Rh antibodies to destroy babies' RBCs which are Rh+.

Describe the function of blood cell antigens, blood plasma antibodies. Understand which situation results in danger to fetus.

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Professor Thomas M. Lancraft

Human Anatomy and Physiology Courses
at St. Petersburg College
St. Petersburg/Gibbs Campus

5/2008

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