IV. Circulatory System
A. Blood, vessels, heart
B. General functions
C. Amount of blood (5-6 liters males; 4-5 l females)8% body weight
D. Formed elements 45% of blood
1. Erythrocytes(4-5 million/mm3) one drop of blood has about 250 million blood cells
2. Function-Carries 4 oxygen molecules per hemoglobin, 250 million hemoglobins/RBC, 1 billion oxygens/RBC!!
3. Color– Bright red when oxygenated, dull red-blue when deoxygenated
b. Production in red bone marrow (2 million/sec)– Over 1000 lbs in a lifetime!!
Blood production/RBC production. Occurs in bone marrow, takes about a week.
2. Life span
120 days, then destroyed and iron recycled from liver & spleen
A hormone that stimulates erythropoiesis. Can increase erythropoiesis up to 20 million/second!!
a. Kidneys are source of EP
b. Genetic engineered
c. Stays in vessels
d. ABO System
3. A, B, AB, O blood types
e. Rh Factor & Erythroblastosis fetalis when Rh negative mother is carrying an Rh positive fetus
a. Granulocytes, Agranulocytes
1-Neutrophils – Most common WBC, pale granules and segmented nucleus, function in phagocytosis
2-Eosinophils – Not very common WBC, red granules and segmented nucleus, help in phagocytosis and excellent in fighting parasites
3-Basophil – Rarest of all WBC, dark purple granules, segmented nucleus, contain histamine that promotes inflammation and heparin that inhibits clotting of blood
1-Lymphocytes – Second most common WBC, large round nucleus, Function in immunity with T lymphocytes developing in the thymus and B lymphocytes developing in bone marrow. Immunity allows a large and quick response to disease-causing invader.
2-Monocytes – Third most common WBC, bean shaped nucleus, foamy cytoplasm and large cells. These exit the bloodstream in chronic infections and become excellent phagocytes called macrophages.
b. Life span & Formation
1. Phagocytosis; Migration out of bloodstream
-Lytic enzymes are abundant in phagocytic WBCs
-Macrophages – large actively phagocytic monocytes
-Plasma cells Differentiated B lymphocytes make antibodies
Based on memory response allowing a bigger and quicker response to antigen
3. T cells
Lymphocytes from Thymus
3. Thrombocytes (platelets)100,000-300,000/mm3
a. Life span & Production (stays in vessels)
200 billion/day in bone marrow
b. Hemostasis– Arresting bleeding
c. Vascular constriction– Spasms of smooth muscle in wall of blood vessels is first step in hemostasis.
d. Platelet Plug (chemicals such as ADP promote the formation of the plug)This step is inhibited by aspirin.
e. Coagulation– Conversion to a fibrin clot
1. Clotting factor
4. Liver makes clotting factors
5. Vitamin K necessary for synthesis of some clotting factors such as prothrombin
6. Extrinsic mechanism [15-20 sec]
7. Intrinsic mechanism [1-2 min]
-Hemophilia – Most common form is lack of factor VIII
f. Clotting retraction
30 to 60 minutes later, clot pulls together and serum is squeezed out. Serum is plasma minus the clotting factors.
g. Clot control
Heparin is an anticoagulant released by mast cells, basophils, endothelium is very smooth which inhibits platelet adherence.
h. Clot dissolution=Fibrinolysis –Plasmin promotes fibrinolysis
i. Intravascular clotting
Intravascular clot e.g. in the coronary artery leading to a myocardial infarction
2. Embolism (embolus)
Thrombus floating in the blood stream, could lodge in the brain – stroke
1. Water (91 1/2%)
Maintains blood osmotic pressure
Principle antibody fraction
Inactive clotting factor
3. Interstitial fluid
Fluid bathing tissues, very similar to plasma in content.