The Cardiovascular System (Blood)

I. Overview

A. Components Diagram

1. Plasma
Plasma proteins
  • albumins -- produced by the liver, acts as a carrier molecule, blood buffer, and used in the regulation of osmotic pressure
  • fibrinogen -- clotting protein
  • globulins -- used as transport proteins (egs alpha and beta) and circulate as antibodies (gamma)
  • other proteins -- metabolic enzymes, antibacterial proteins, and hormones)

Water

Solutes (gases, nutrients, electrolytes, waste products)

2. Formed Elements
Erythrocytes Leukocytes Thrombocytes

B. Physical Characteristics:

C. Functions

Distribution Regulatory Protection
a. Delivery of oxygen
b. Transport of metabolic wastes
c. Transport of hormones
a. Maintenance of body temperature
b. Maintenance of pH
c. Maintenance of adequate fluid volume
a. Prevention of blood loss
b. Prevention of infection

II. Formed Elements

A. Blood Cell Formation (Hemopoiesis)

B. Erythrocytes (RBCs) Diagram

i. Characteristics

  1. Hemocytoblast
  2. Proerythroblast - Committed cell
  3. Early (basophillic) erythroblast - produce large quantities of ribosome
  4. Late (polychromatophillic) erythroblast - blue color (ribosomes) of cytoplasm turns to a pink color (hemoglobin)
  5. Normoblast - organelles are ejected
  6. Reticulosite - nucleus is ejected, contains small number of ribosomes, 1-2% are found in circulation
  7. Erythrocyte - matured reticulocutes (2 days), most if not all ribosomes degraded

NOTE: cell division takes place during the first two phases of development

ii. Regulation of Erythropoiesis via a homeostatic mechanism:

  1. Oxygen blood levels constantly monitored (e.g. chemorecetpors: carotid body? oxygen sensors in kidney?)
  2. Drop in oxygen levels as a result of:
  3. Declining oxygen levels in blood (hypoxia) signal kidney to release the hormone erythropoietin (EPO)

Note: A synthetic EPO is used by kidney dialysis patients and athletes - why?

iii. Dietary Requirements for Erythropoeisis:

iv. Destruction of RBCs

v. Life Cycle of RBCs: Diagram

vi. Issues in red blood cell production

Anemia = condition of decreased number of RBC or decreased concentration of hemoglobin

1. Insufficient number of RBCs

2. Decreased in hemoglobin content

3. Abnormal hemoglobin

C. Leukocytes (WBCs)

i. Characteristics

ii. DIFFERENTIAL WBC COUNT - measure the percentage of WBC in blood

iii. White Blood Cells 

Granulocytes Diagram

Agranulocytes Diagram

iv. Leukopoiesis

v. Leukocyte disorders

  1. Leukemias
  2. Mononucleosis

D. Platelets (thrombocytes)

II. Hemtology Results

Test Values Test Values
Hemoglobin (S)
  • Female: 12-16 g/dl
  • Male: 14-18 g/dl
Red Blood Cell Count
  • Female: 4.2-5.4 million/mm3
  • Male: 4.7-6.1 million/mm3
Hematocrit
  • Females: 37%-47%
  • Male: 42%-54%
Reticulocyte Count
  • 0.5%-2.0%
Prothrombin Time
  • 11-12.5 sec
White Blood Cell Count, Total
  • 4,000-10,000/mm3
Platelet Count
  • 150,000-400,000/mm3
White Blood Cell Count, Differential
  • Neutrophils - 55%-70%
  • Lymphocytes - 20%-40%
  • Eosinophils - 1%-4%
  • Monocytes - 2%-8%
  • Basophils - 0.5%-1%

III. Hemostasis, rapid and localized stoppage of blood flow.

i. Three phases:

A. Vascular spasms - immediate response to blood vessel injury is vasoconstriction. Factors that help to initiate the spasm response include direct injury to smooth muscle, compression of the vessel by escaping blood, chemicals released by endothelial cells and platelets, and reflexes triggered by activation of local pain receptors

B. Platelet plug formation - endothelium lining blood vessels rupture and underlying collagen fibers are exposed. Platelets change shape, forming sticky spiky processes that adhere to exposed areas. Once attached, Thromboxane A-2 is generated from lipids in the platelet membrane. Thromboxane A-2 causes degranulation. Platelet granules breakdown and release serotonin (increases vascular spasms) and ADP (attracts more platelets to the area).

C. Clotting (coagulation) - clot formation is the result of converting the soluble protein fibrinogen into relatively insoluble threads of the protein fibrin. Damage to tissue causes the production of prothrombin activator which in the presence of calcium converts prothrombin into thrombin. Thrombin, in turn, acts as an enzyme and causes fibrinogen molecules to join and form fibrin threads that stick to exposed areas/forms clot.

ii. Clot Retraction, vessel repair, and fibrinolysis:

iii. Thromboembolytic disorders

IV. Blood Plasma - clear, straw-colored, liquid portion of the blood in which the cells and platelets are suspended. Plasma is composed of water and various solutes (proteins, nonprotein nitrogenous compounds, nutrients, electrolytes, gases).

V. Blood Groups and Transfusions

A. Human Blood Groups - RBC membranes have highly specific glycoproteins (antigens). One person's RBC proteins may be recognized as foreign if transfused into another person with a different RBC type, and the transfused cells may be agglutinated (clumped) and destroyed. There are 30-100 types of RBC antigens (agglutinogens) but A,B,O and Rh cause most vigorous transfusion reactions. Preformed antibodies called agglutinins act against RBC carrying ABO antigens that are not present on a person's own red blood cells.

B. ABO Groups:

Blood Type Agglutinogen Agglutinin Blood Types Can Receive
A A Anti B A and O
B B Anti A B and O
AB A and B None A, B, AB, O
O Neither A nor B Both Anti A & Anti B O

C. Rh Blood Group - individuals may have Rh antigens on their RBC membranes and are considered Rh+. If one lacks these antigens on the membranes then they are considered Rh-. If an Rh- mother is carrying a Rh+ fetus then hemolytic disease of the newborn (HDN) may occur. Rh+ leaks through the placenta causing the mother to produce Rh antibodies. Rh antibodies may then cause hemolysis to occur. Anti-Rh gamma globulin (RhoGAM) is administered to prevent HDN in subsequent pregnancies

V. Clinical Terms