Red Blood Cells

Formation and structure

Regulation of RBC Production

Decrease in oxygen in blood Hemorrhage Excessive RBC destruction Decreased oxygen availability

• Hypoxia Higher altitudes decreased oxygen

availability

Platelets Also called thrombocytes.

Smallest of formed elements. Important in blood clotting:

Constitute most of the mass of the clot. Release serotonin to reduce blood flow to

area and ADP to cause pseudopodia to grow.

Secrete growth factors Maintain the integrity of blood vessel wall.

RED BLOOD CELL ABNORMALITIES

Anemia

Polycythemia

Sickle Cell Anemia

General definition – reduced O2 carrying capacityCauses:

• Low number of erythrocytes• Hemorrhage – blood loss• Hemolytic – ruptured RBC’s• Aplastic – inability of bone marrow to synthesize RBC

Decreased hemoglobin• Iron-deficiency• Athletes anemia – expanded blood volume• Pernicious anemia – B12 deficiency or lack factor for B12

absorption

Anemia

Polycythemia

Over production of RBCs Hematocrit = 80% (normal = 45%) Cause: bone marrow cancer Symptoms: headache, dizziness, blood clots

Secondary causes Adaptation to high altitude Blood doping Supplemental Erythropoeitin

Sickle Cell Anemia Shape of erythrocyte is altered

1 amino acid (out of 267) is different in hemoglobin

Blood cells have a crescent shape Decreased organ blood flow

White blood cells (Leukocytes)

How do they differ from erythrocytes?1. Contain nuclei and other cell organelles2. Almost invisible under a microscope3. Lifespan: 12 hours300 days

Types of Leukocytes:• Neutrophils, lymphocytes, monocytes,

eosinophils, basophils

Bacterial or viral infection: increased WBC production

WBC disorders

Leukopenia – low WBC count (nutrition/ radiation)

Leukemia – cancer of WBC Large number of immature, non-functioning

WBCs• Anemia• Hemorrhage• Massive infections

Blood types

RBC plasma membranes have specific antigens which are unique

• A,B,AB (universal recipient), O (universal donor)• Rh negative or Rh positive (85% of population)

Red Blood Cell Antigens ABO system: Major group of antigens of RBCs.

Type A:• Only A antigens present.

Type B:• Only B antigens present.

Type AB:• Both A and B antigens present.

Type O:• Neither A or B antigens present.

RBC Antigens

Type B: May have inherited B gene from each parent. May have inherited B gene from 1 parent and O

gene from the other parent.

Type AB: Inherited the A gene from one parent and the B

gene from the other parent.

Type O: Inherited O gene from each parent.

Transfusion Reactions

If blood types do not match, the recipient’s antibodies attach to donor’s RBCs and agglutinate.

Type O: Universal donor. Recipient’s antibodies cannot agglutinate the

donor’s RBCs. Type AB universal recipient:

Lack the anti-A and anti-B antibodies. Cannot agglutinate donor’s RBCs.

Rh Factor

Another group of antigens found on RBCs. Rh positive:

Have these antigens. Rh negative:

Do not have these antigens. Significant when Rh negative mother give

birth to Rh positive baby. At birth, mother may become exposed to Rh

positive blood of fetus. Mother at subsequent pregnancies may produce

antibodies against the Rh factor.

Fig. 4.12

Reading thus far:

Pages 366-375: Circulatory system, WBC, RBC, hematopoiesis, hemostasis, blood types

Pages 378-383: Heart anatomy, structure, cardiac circulation

Page 354: Cardiac muscle fibers