CARDIOVASCULAR SYSTEM

CARDIOVASCULAR SYSTEM – BLOOD

ANATOMY AND PHYSIOLOGY SUMMER, 2002

CARDIOVASCULAR SYSTEM - heart, blood vessels and blood

I BLOOD

A. PHYSICAL CHARACTERISTICS:

1. pH 7.35 - 7.45; salinity 0.85 - 0.90%; total body weight - 8%; total volume 5-6 liter for males, 4-5 for females; viscosity 4.5 - 5.5; temperature 38C/100.4F

B. FUNCTIONS

1. Transport oxygen, carbon dioxide, nutrients, waste, hormones and enzymes

2. Prevent loss thru clotting

3. Combat foreign invaders

C. COMPONENTS

1. ELEMENTS (CELL OR CELL-LIKE)

HEMOPOIESIS - cell production 1) Pluripotent stem cell - precursor for all cellular elements

A. ERYTHROCYTES (RBC)

1) STRUCTURE

a) Biconcave discs (maximize surface area for diffusion

b) Enucleated at maturity

c) Contains HEMOGLOBIN (33% by weight)

• Globin - consists of 4 polypeptide chains

• Heme - 4 non pigmented chains; Fe in center

d) ANTIGENS( Proteins on surface) determine blood type and RH
groups

2) PRODUCTION (ERYTHROPOIESIS)

a) Initiated in bone marrow where Proerythroblast- Reticulocyte -
RBC

b) Mechanism for increasing [RBC]: Reduced [oxygen] activates
kidney cells where released enzyme RENAL ERYTHROPOIETIC
FACTOR - converts plasma protein into ERYTHROPOIETIN –

stimulates myeloid tissue to produce more RBC

3) FUNCTION

a) HEMOGLOBIN + OXYGEN = OXYHEMOGLOBIN

b) HEMOGLOBIN + CARBON DIOXIDE =
CARBAMINOHEMOGLOBIN (23% carried by blood, 70% in
blood plasma as bicarbonate)

4) LIFE SPAN (L.S.)/ NUMBER

a) L.S. - 120 days; removed by macrophages

b) Hemoglobin = Hemosiderin (converted in bone marrow to new
hemoglobin) + Bilirubin (secreted into bile) + Globin
(metabolized by liver)

c) # = 5.4MM/cubic mm of blood (for males); 4.8 for females

5) SUBSTITUTES

a) FLUOSOL-DA: high oxygen carrying capacity

6) CLINICAL INDICATORS

a) ANEMIA - low # of RBC or low [hemoglobin] - caused by lack
of iron, AA or B12 deficiency - need INTRINSIC FACTOR
(produced by mucosal cells in stomach for B12 absorption)

b) HEMATOCRIT - % of RBC in blood; for males it's 40 - 54; for
females it's 38-47; anemia <15

c) RETICULOCYTE (immature RBC) COUNT - measures rate of
Erythropoiesis

B. Leukocytes

1. STRUCTURE

a) Possesses surface proteins (HUMAN LEUKOCYTE

ASSOCIATED - HLA) antigens - unique to all; used in tissue

typing

2. TYPES FUNCTIONS:

a) GRANULAR LEUKOCYTES (GRANULOCYTES) - granules in cytoplasm and possess lobed nuclei

NEUTROPHILS –(60-70%); 10 - 12um; phagocytose bacteria

and dead matter; release enzyme (LYSOZYME); contains

DEFENSINS - AA with antibiotic, fungal and viral effects

EOSINOPHILS - (2 - 4%); 10 - 12um in dia.; release substances to combat inflammatory effects; phagocytose the anitgen-antibody complex and most parasitic worms

BASOPHILS - (0.5-1.0%); 8 - 10um in dia.; involved in allergic reactions; release substance for allergic and inflammatory responses (histamine, heparin and serotonin)

b) AGRANULAR LEUKOCYTES (AGRANULOCYTES) - no

granules in cytoplasm

LYMPHOCYTES - (20-25%); 7 - 15um in dia.;

• B cells - humoral immunity; creates antibodies specialized
proteins which inactivates antigens.

Mech: (Antigen-Antibody Response) Antigen causes lymphocytes (B cells) to change to Plasma Cells. Produces antibodies which complex with and cover antigens

• T cells- cellular immunity; defenses against foreign cells and
immune coordination. Subspecialities include cytotoxic,
regulatory, helper and suppressor

• NK cells - immune surveillance: detection and destruction of
abnormal tissue cells

MONOCYTES - (3-8%); 14 - 19um in dia.; phagocytose bacteria and dead matter; release enzyme (LYSOZYME) -bactericide: can become wandering macrophages

3) LIFE SPAN / NUMBER

a) L.S. - varies with location and overall health: few hours to
several days

b) # - 5-9M/cubic mm (ratio of 700 to 1)

4) PRODUCTION -

a) Leukocytosis - controls WBC productions; precursors are lymphoid stem cells

5) PHYSIOLOGY

a) Emigration - leave bloodstream via squeezing through
endothelium

b) Adhesion Molecules - selectively released to maintain presence
of WBC (eg. released by injured tissue)

C. PLATELETS (THROMBOCYTES)

1) STRUCTURE - round/oval disc without nucleus; 2-4um in dia.

2) FUNCTION - prevents fluid loss by initiating reactions for blood
clotting

3) LIFE SPAN/NUMBER

a) L.S.: 5 - 9 days

b) #: 250 - 400M/ cubic mm

4) PRODUCTION

a) Myeloid stem cell - Megakaryoblast - Megakaryocytes (large cells which shed cytoplasmic fragments). Each fragments enclosed by piece of cell membrane developed into Platelets

PLASMA - straw colored liquid

a. COMPONENTS

1) Water - 91 % (90% absorbed from GI tract, 10 % for cell respiration); acts as solvent; absorbs heat; suspends solid components

2) Proteins

ALBUMINS - produced by liver; regulates blood viscosity; maintains water balance between blood and tissue (blood volume)

GLOBULINS - form antibodies (ie. Gamma globulins)

FIBRINOGEN - produced by liver, essential for blood clotting

4) Non-proteins: Nitrogen Substances (NPN) - breakdown product of protein metabolism

4) Food Substances - products from digestive processes

5) Regulatory Substances - enzymes and hormones

6) Respiratory Gases - carbon dioxide and oxygen

7) Electrolytes - inorganic salts: Cations - Na, K, Ca, Mg;
Anions - Cl, phosphate, sulfate and bicarbonate

D. HEMOSTASIS - stoppage of bleeding

1. MECHANISMS:

a. VASCULAR SPASM - contractions of smooth muscle in blood vessel wall
upon damage; operates up to 30 minutes

b. PLATELET PLUG FORMATION - activated by platelet encountering
damage to a blood vessel; effective for small blood vessels: reinforced by
fibrin during coagulation

1. Mech:

a) Platelets enlarge and become irregular and sticky

b) Increase in # which then stick to original platelets - form platelet plug

c. COAGULATION

1) TERMINOLOGY:

SERUM - plasma minus clotting proteins

CLOT - network of insoluble fibers trapping cellular

components of blood

COAGULATION FACTORS (CF)- chemicals needed for

clotting: source is plasma or platelets

2) MECHANISM:

a) Formation of PROTHROMBIN activator -

2 pathways: EXTRINSIC – from surrounding tissue

INTRINSIC- from within blood itself

b) Conversion of PROTHROMBIN (plasma protein) into
THROMBIN

c) Conversion of FIBRINOGEN into insoluble FIBRIN by thrombin

3) CLOT RETRACTION/SYNERESIS

a) Consolidation/tightening of fibrin clot - fibrin threads attach to damaged surface and contract pulling tissue layers together

4) FIBRINOLYSIS - dissolution of clot

a) Plasminogen (inactive plasma enzyme) is incorporated into
formed clot.

b) Plasmin (active plasma enzyme) contained in body tissue and
blood

t-PA (tissue plasminogen activator) - genetically engineered enzyme - helps dissolve clots

5) CLOT PREVENTION

a) THROMBOSIS - clot in unbroken blood vessel; EMBOLUS -
free moving thrombosis

b) ANTICOAGULANT - any substance which prevents clotting
(ie Heparin)

CLOTTING TIME- simulate clot on slide; shows

breakdown of platelets

BLEEDING TIME - inflate pressure cuff and pierce

forearm; shows breakdown of platelets and constriction of

blood vessels

PROTHROMBIN TIME - tests amount of prothrombin in

blood

d.     TYPING (GROUPING )- antigens found on RBC surface
(AGGLUTINOGENS AND ISOANTIGENS)
1)     MAJOR TYPES: ABO: has 2 agglutinogens (A & B)
TYPE                  WHITE     OF COLOR (2001)

A 40% 27%

B 11% 20%

AB 4% 4%

O 45% 49% Can change B to O with alpha

galactosidase (enzyme found in green coffee beans)

a) Have genetically determined antibodies (agglutinins and

isoantibodies) - possess agglutinins against agglutinogens you don't synthesize - otherwise cause agglutination (clumping)

2) RH system - antigens on RBC surface WHITE OF COLOR

RH positive - has RH agglutinogens 85% 95%

RH negative - doesn't have RH agglutinogens 15% 5%

a) Erythroblastosis fetalis - if fetus is RH negative, no problem, if RH positive - agglutination

II INTERSTITIAL FLUID (INTERCELLULAR FLUID)

A. COMPOSITION - MODIFIED PLASMA: less proteins, variable # of leucocytes and various organic material (from GI tract)