Blood and Hematocrit

Normal adult female hematocrit

37% - 47%

Normal adult male hematocrit

42% - 52%

Normal newborn range

49% - 61%

Why do newborns have a higher hematocrit than males/females and why do females have lower hematocrit?

Newborns are coming out from the womb which is low oxygen, so they need more erythrocytes to raise oxygen levels. Males have higher testosterone and will produce more EPO. Females have a menstrual cycle leading to blood loss.

How is hematocrit obtained

Centrifugation and measure erythrocytes, buffy coat, and plasma (cm) and divide by total

Leukocytosis

High white blood cell count, buffy coat is greater than 1%, caused by infection and some types of leukemia

Anemia

Erythrocyte count is too low, hematocrit value is below average, decreased oxygen carrying capacity of blood

Aplastic anemia

Red bone marrow doesn’t produce enough erythrocytes

Iron-deficiency anemia

Erythrocytes are smaller, not healthy to efficiently carry oxygen

Hemolytic anemia

Erythrocytes are destroyed too quickly

Sickle cell anemia

Sickle-shaped erythrocytes

Hemorrhagic anemia

Caused by blood loss, NOT detected by hematocrit

Individuals living in high altitudes tend to have

Higher hematocrit due to the lower oxygen level in the air, more erythrocytes formed to increase blood oxygen levels

Dehydration

Plasma percentage decreases, loss of water = less plasma

Polycythemia

increase in RBCs, may be due to bone marrow cancer

Leukopenia

white blood cell count below 4000/mm³, due to exposure to chemicals, toxins, or anticancer agents

Leukemia

Cancer of lymphoid tissues, uncontrolled proliferation of abnormal WBCs, reduction in RBCs and platelets. Can be detected by total WBC count and differential WBC count

Differential WBC count

100 WBCs counted and classified to type. Off percentages may indicate a source of pathology.

Can someone be anemic with normal RBC count?

Yes. Oxygen carrying capacity can be determined by hemoglobin content. More hemoglobin in RBCs = increased oxygen carrying capacity

Oxygen binds reversibly to

Heme (iron-containing portion)

What is the normal amount of hemoglobin

12-18g of hemoglobin per 100mL of blood

Men: 13-18g (higher)

Women: 12-16g

Hemostasis

Mechanism to stop bleeding (when a blood vessel breaks)

The three steps of hemostasis

1. Vascular Spasm

2. Platelet plug formation

3. Coagulation

What is contained in plasma

Over 90% water, electrolytes, plasma proteins, clotting factors (procoagulants).

What are the plasma proteins

Albumin, fibrinogen, globulins

Albumin function

Osmotic balance

Fibrinogen

Blood clotting

Globulins

Defense as antibodies, lipid transport

Non-living fluid matrix of blood

Plasma

Formed elements

Erythrocytes, leukocytes, platelets

Fibers

Fibrin threads, only when clotting occurs

Composition of blood

45%,, <1%, 55%

What do platelets and injured tissues release that trigger the clotting cascade?

Tissue factoor (TF), phosphatidylserine

TF and phosphatidylserine (platelet factor 3) interact with other clotting factors and Ca²+ in plasma to form

Prothrombin activator → prothrombin → thrombin

Thrombin combines soluble fibrinogen proteins into

Insoluble fibrin

Fibrin function

Creates meshwork that traps RBCs and forms basis of clot

How long until blood removed from body clots?

2-6 minutes

How does the platelet plug form

Injury to lining of vessel exposed collagen fibers; platelets adhere, platelets then release chemicals that make other platelets sticks