1. Cardiovascular system - Blood Anatomy - Chapter20

2. The Cardiovascular system is comprised of the heart, blood vessels, & blood
The heart acts as a “pump”, creating pressure which causes blood to move through the blood vessels of the body, allowing O2 & nutrients to be distributed to, & wastes removed from, body tissues

3. Physical characteristics of blood
Fluid connective tissue
matrix – “plasma” with dissolved proteins
cells & cell fragments – “formed elements”
temperature – 38o C
5x more viscous than H2O
pH –

4. Functions of Blood Regulation Protection Transportation O2/CO2
nutrients/wastes
enzymes
hormones
Regulation
body temperature
pH & ion composition of interstitial fluid
intracellular fluid volume
Protection
defense against pathogens
restriction of fluid loss at injury sites

5. Composition of Blood 55% Plasma – liquid component of blood
45% Formed elements – cells/cellular fragments
Erythrocytes – red blood cells (RBCs)
Leukocytes – white blood cells (WBCs)
Platelets – (thrombocytes)

6. Plasma

7. Formed Elements
granular
(B & T)
agranular

8. (pluripotent stem cell)
Hemopoiesis
Megakaryoblast

9. Erythrocytes (RBCs) around 5 million RBCs per mm3 blood
Biconcave shape, flexible cells
around 5 million RBCs per mm3 blood
average “life span” of 120 days
Cells contains cytosol, no nucleus/organelles; filled with Hemoglobin (Hb)

10. Hemoglobin
Hemoglobin allows for transport of O2 & CO2

11. As RBCs get damaged/worn out, they must be removed from circulation & replaced
About 1% of the circulating RBCs are replaced each day, at at rate of about 3 million RBCs per second
Worn out RBCs are removed by phagocytic cells in the liver, spleen & bone marrow
Most of the RBC’s hemoglobin is recycled, the pigmented part (heme) gets converted to bile pigments

12. Erythropoiesis
New RBCs are made in red bone marrow (myeloid tissue) by process of erythropoiesis
stimulus for erythropoiesis is hypoxia detected by cells of kidney

13. Leukocytes (WBCs)
More like “typical” cells with single nucleus, organelles
5 types of WBCs characterized as granular or agranular
all function in defense
average WBCs/mm3 of blood
variable “life” span depending on type of WBC- days (neutrophils) to decades (lymphocytes); in sick person, some WBCs live minutes to hours

14. Differential Count & Functions of WBCs
“WBC differential count” – normal range (in percentage) of WBCs in the peripheral circulation
differential count will vary during specific types of disorders, depending on which type of WBC responds
WBC response based on functions of specific type

15. Differential Count & Functions of WBCs
Neutrophils %
Lymphocytes – 20-30%
Monocytes – 4-8%
Eosinophils – 2-4%
Basophils - <1%
function in acute bacterial infections; phagocytic
function in chronic bacterial infections; migrate into tissues to become “wandering macrophages”
active against parasites & elevated in allergic reactions; destroy antibody-coated antigens by phagocytosis
release chemicals (histamine, heparin) during tissue inflammation

16. Differential Count & Functions of WBCs
Lymphocytes – 20-30%
Function in “immunity” – specific resistance to disease
T cells- involved in “cell-mediated (aka cellular) immunity”; defense against abnormal cells & intracellular pathogens
B cells- involved in “antibody-mediated (aka humoral) immunity”; defense against pathogens (Ag’s) in body fluids (blood/lymph)

17. Platelets (Thrombocytes)
Cellular fragments (cell membrane “packet” filled with cytoplasm) from large Megakaryocytes found within bone marrow
around 350,000 platelets/mm3
platelets circulate for 9-12 days before being removed from circulation
platelets function in hemostasis– the processes that stop bleeding from damaged blood vessels – including “platelet plug formation” and “coagulation”