Blood - PC\|MAC



Blood

I. Composition

a. Components

i. Plasma

1. Non living fluid matrix

2. Straw-colored, sticky fluid

3. 90% water

4. Contains over 100 dissolved solutes

5. Plasma proteins

a. Produced by the liver

b. They are not taken up by cells to be used as fuels/nutrients

c. Albumin – acts as a carrier to shuttle certain molecules through circulation

ii. Formed elements

1. Living blood cells, suspended in the matrix (plasma)

2. Erythrocytes (Red Blood Cells, RBC’s)

a. Structure

i. Small, biconcave discs (miniature donuts)

ii. Bound with a plasma membrane

iii. No nucleus

iv. No organelles

v. Hemoglobin – the protein that helps transport oxygen

1. Carries oxygen from the lungs to the tissues

2. Returns CO2 to the lungs from the tissues

vi. Since there are no organelles, RBC’s do not consume any of the oxygen that they transport

b. Function

i. Hemoglobin – Complex protein

1. Exists in erythrocytes instead of free in plasma

a. Prevents it from breaking into fragments and leak out of the bloodstream

b. Does not contribute to the blood viscosity and osmotic pressure

2. When bonded with oxygen – oxyhemoglobin

3. Without oxygen - deoxyhemoglobin

c. Production

i. Hematopoiesis – blood cell formation

ii. Occurs in red bone marrow

iii. All formed elements come from the same stem cell – hemocytoblast

iv. Erythropoiesis – erythrocyte production

1. Delicate balance in the number of erythrocytes

a. Too few means hypoxia – lack of oxygen

b. Too many means blood is too viscous

2. Stimulated by a glycoprotein hormone – erythropoietin

3. Leukocytes – White Blood Cells

a. General characteristics

i. The only formed elements that are whole cells

ii. Account for less then 1% of total blood volume

iii. Crucial to the defense system of the body

iv. Protects from bacteria, viruses, parasites, toxins

v. Diapedesis – the movement in and out of the capillary

vi. Move in the bloodstream based on chemical concentrations

b. Granulocytes

i. Spherical, larger than erythrocytes

ii. Have granules in the cytoplasm

iii. Function as phagocytes

iv. Neutrophils

1. Most numerous WBC

2. Has a nucleus that is multilobed

3. Attracted to sites of inflammation – phagocytize bacteria

v. Eosinophils

1. Lead the counter attack on parasitic worms

vi. Basophils

1. Rarest WBC

2. Releases histamine – seen during inflammation

c. Agranulocytes

i. Lack visible granules in the cytoplasm

ii. Lymphocytes

1. Most are found in the lymphatic tissue and glands

2. T lymphocytes – act against virus-infected cells

3. B lymphocytes – give rise to plasma cells that produce antibodies

iii. Monocytes

1. largest leukocytes

2. Highly mobile macrophages with large appetites

3. Active with chronic infections - TB

4. Platelets

a. Fragments of large cells – megokaryocytes

b. Essential for blood clotting

b. Blood groups

i. RBC plasma membranes have highly specific glycoproteins (antigens)

1. There are at least 30 varieties of antigens

2. If blood is transfused and the proteins do not match, the new blood cells will be destroyed

ii. ABO

1. Based on the presence or absence of two RBC antigens

2. Type A, Type B

3. Type O has neither A or B antigens

4. Type AB has both

iii. Rh

1. Positive & negative

a. Depends on if they carry the Rh antigen or not

2. Anti-Rh antibodies are not spontaneously formed in the blood

a. The are formed after an exposure to another type of blood

II. Functions

a. Distribution

i. Delivers oxygen from the lungs to the rest of the body

ii. Delivers nutrients from the digestive tract to the body cells

iii. Transports metabolic waste products from cells to elimination sites

iv. Transports hormones from the endocrine organ to the target organ

b. Regulation

i. Maintains appropriate body temperature

1. Absorbs and distributes heat throughout the body and to the skin surface

2. Maintains normal pH, blood proteins act as buffers

3. Maintains adequate fluid volume in the circulatory system

c. Protection

i. Prevents blood loss by forming a clot with platelets and plasma proteins

ii. Prevents infection with the white blood cells

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