1. The Circulatory System Lesson 2: Composition and Function of Blood27
The Circulatory System
Lesson 2:
Composition and Function of Blood

2. Lesson Objectives
Upon completion of this lesson, students should be able to …
Define and spell the terms to learn for this chapter.
List and describe the components of blood.
Discuss the importance of blood typing and cite which blood types are compatible.
State the difference between Rh-positive blood and Rh-negative blood.

3. Blood Average adult has about 5 liters of blood
Circulates through body within vessels of cardiovascular system
Is a mixture of plasma with cells
The cells are called formed elements:
Erythrocytes
Leukocytes
Platelets 3

4. Functions of Blood
Transportation
Defense
Regulation 4

5. Plasma is about 55% of the total blood components.

6. The remaining part of blood is composed of formed elements.6

7. Formed Elements of Blood7

8. Erythrocytes (Red Blood Cells)
Enucleated–no nucleus
Hemoglobin gives red color
5 million per cubic millimeter of blood
Adult has 35 trillion
Life span of 120 days
Then spleen removes worn out ones, iron can be reused, bilirubin is disposed of by liver 8

9. Leukocytes White blood cells Provide protection against pathogens
Bacteria
Viruses
Foreign material
Spherical shape with nucleus
8,000 per cubic millimeter of blood 9

10. Leukocyte Classification
Granulocytes
Basophils – Release histamine and heparin to damaged tissue
Eosinophils – Destroy parasites and increase during allergic reaction
Neutrophils – Important for phagocytosis
Agranulocytes
Monocytes – Important for phagocytosis
Lymphocytes – Provide protection through immunity 10

11. Neutrophils The most common leukocyte Categorized as granulocytes
Have many lobes
Known as polymorphonucleated leukocytes (PMN) or poly
Develop in the red marrow
Live a few days or even a few hours if they are actively destroying bacteria 11

12. Neutrophils
A neutrophil has cytoplasm that contains granules that do not readily stain with either a red or blue dye. It has a nucleus with three or more lobes. 12

13. Eosinophils One of the least common leukocytes
Categorized as granulocytes; also known as eosinophils
Develop in the red marrow
Engulf and destroy foreign cells (pollen, animal dander, and so forth)
Release toxic chemicals that kill parasites that invade the body 13

14. Eosinophils
An eosinophil has cytoplasm that contains granules that stain bright pink to red. It has a nucleus with two lobes. 14

15. Basophils One of the least common leukocytes
Categorized as granulocytes
Nucleus of a basophil has 2 lobes
Develop in the red marrow
Release histamine at the site of tissue damage
Release heparin, an anticoagulant 15

16. Basophils
A basophil has cytoplasm that contains granules that stain dark blue to purple. It has a nucleus with more than one lobe. 16

17. Lymphocytes Second most common leukocyte
Categorized as agranulocytes because the granules in their cytoplasm are nearly invisible
Some lymphocytes live for just a few days, while others live for many years
Begin their development in the red marrow
Present in the blood and in the lymph nodes, lymphoid tissues, and organs of the lymphatic system 17

18. Lymphocytes
A lymphocyte has little cytoplasm with nearly invisible granules and a round nucleus. 18

19. Monocytes One of the least common leukocytes
Categorized as agranulocytes because the granules in their cytoplasm are nearly invisible
Have a large amount of cytoplasm, and the nucleus is shaped like a kidney bean
Develop in the red marrow
Are phagocytes that engulf and destroy all types of invading microorganisms, cancerous cells, dead leukocytes, and cellular debris
Found in the blood and in the lymph nodes of the lymphatic system 19

20. Monocytes
A monocyte has cytoplasm with nearly invisible granules and a kidney bean-shaped nucleus. 20

21. Thrombocytes (Platelets)
Different from other blood cells because they are only cell fragments
Active in the blood clotting process
Begin in the red marrow as stem cells that then become megakaryoblasts
The cytoplasm of the megakaryocyte constantly breaks away at the edge to form the cell fragments that are released into the blood 21

22. Thrombocytes (Platelets)
Smallest of all blood elements
Not whole cells
200, ,000 per cubic millimeter
Critical in clotting or hemostasis
Agglutinate into small clusters
Leads to formation of thrombin, which converts fibrinogen to fibrin 22

23. Blood Typing
Each person’s blood is different from others’ due to the presence of marker proteins on the surface of his/her erythrocytes
Before a person receives a blood transfusion it is important to do a blood typing
This is a laboratory test to determine if the donated blood is compatible with the recipient’s blood
There are many different subgroups of blood markers, but the two most important ones are the ABO system and Rh factor 23

24. ABO System There are two possible RBC markers, A and B
A person with an A marker is said to have type A blood.
Type A blood produces anti-B antibodies
The presence of a B marker gives type B blood and anti-A antibodies 24

25. ABO System
Absence of either an A or a B marker results in type O blood, which contains both anti-A and anti-B antibodies
If both markers are present, the blood is type AB and does not result in any antibodies 25

26. Blood Types
Antigens
Type A
Type B
Four blood types A B AB O 26

27. Universal Donor
Because type O blood does not have either marker A or B, it will not react with anti-A or anti-B antibodies
For this reason a person with type O blood is referred to as a universal donor
In an emergency, type O blood may be given to a person with any of the other blood types
A person with type AB blood has no antibodies against the other blood types and therefore, in an emergency, can receive any type of blood. They are universal recipients. 27

28. Rh Factor
A person with the Rh factor on his/her red blood cells is said to be Rh-positive (Rh+)
Since this person has the factor, he/she will not make anti-Rh antibodies
A person without the Rh factor is Rh-negative (Rh-) and will produce anti-Rh antibodies
Therefore, an Rh+ person may receive both an Rh+ and an Rh- transfusion, but an Rh- person can receive only Rh- blood 28

29. Questions? 29