Composition of Blood

What percentage of total body weight does blood represent?

Approximately 8% of total body weight

What are the three types of cellular elements in blood?

Erythrocytes (red blood cells), leukocytes, and platelets

What is another name for platelets?

Thrombocytes

What liquid suspends all blood cells?

Plasma

Which blood cell type makes up 99% of all blood cells?

Erythrocytes (red blood cells)

Define hematocrit (packed cell volume).

Percentage of total blood volume occupied by erythrocytes

What is the average hematocrit value in adult women?

Approximately 42%

What is the average hematocrit value in adult men?

Approximately 45%

What percentage of blood volume is plasma in women?

Approximately 58%

What percentage of blood volume is plasma in men?

Approximately 55%

What is the buffy coat?

A thin, cream-colored layer containing leukocytes and platelets after centrifugation

What percentage of total blood volume does the buffy coat represent?

Less than 1%

Why do blood cells remain evenly distributed during circulation?

Constant movement of blood prevents settling of cellular elements

What happens when whole blood with anticoagulant is left standing?

Heavier cells settle at the bottom and plasma rises to the top

What process accelerates separation of blood components?

Centrifugation

What is plasma primarily composed of?

90% water

What is the main transport function of plasma?

Transportation of nutrients, wastes, hormones, and gases

How does plasma contribute to temperature regulation?

Absorbs and distributes metabolic heat and facilitates heat loss at skin surface

What percentage of plasma weight is inorganic constituents?

Approximately 1%

List major inorganic ions found in plasma.

Sodium, chloride, bicarbonate, potassium, and calcium

What are the main functions of plasma inorganic ions?

Osmotic balance, membrane excitability, and pH buffering

What percentage of plasma weight is plasma proteins?

Approximately 6–8%

List major organic constituents of plasma.

Plasma proteins, nutrients, waste products, dissolved gases, and hormones

List major plasma nutrients.

Glucose, amino acids, lipids, and vitamins

List major plasma waste products.

Creatinine, bilirubin, and urea

Which gases are dissolved in plasma?

Oxygen and carbon dioxide

In what physical state do plasma proteins exist?

Colloidal dispersion (not dissolved)

Why do plasma proteins remain in blood vessels?

They are too large to pass through capillary pores

What pressure is generated by plasma proteins?

Colloid osmotic (oncotic) pressure

What is the function of oncotic pressure?

Prevents excessive plasma loss into interstitial fluid and maintains plasma volume

How do plasma proteins help regulate pH?

By binding or releasing hydrogen ions

Which two pressures regulate water movement across capillaries?

Hydrostatic pressure and colloid osmotic pressure

What is capillary hydrostatic pressure?

Pressure exerted by blood against capillary walls pushing fluid outward

What is oncotic pressure?

Osmotic pressure generated by plasma proteins pulling fluid into capillaries

What solutes can cross capillary walls easily?

Most small solutes

What cannot cross capillary walls easily?

Large plasma proteins

What are the three major groups of plasma proteins?

Albumins, globulins, and fibrinogen

Which plasma protein is most abundant?

Albumin

What substances does albumin bind?

Bilirubin, bile salts, and some drugs (e.g., penicillin)

Why does albumin strongly contribute to oncotic pressure?

Because of its high concentration

What are the three types of globulins?

Alpha, beta, and gamma globulins

What substances do alpha and beta globulins transport?

Thyroid hormones, cholesterol, and iron

Which globulins include clotting factors?

Alpha and beta globulins

Which globulin serves as angiotensinogen precursor?

Alpha globulin

What is the function of gamma globulins?

They are immunoglobulins (antibodies)

What is fibrinogen?

Inactive precursor of fibrin

What is fibrinogen’s main function?

Blood clot formation

Where are most plasma proteins synthesized?

Liver

Which plasma proteins are not synthesized by the liver?

Gamma globulins

Which cells synthesize gamma globulins?

Lymphocytes

What is the normal total leukocyte count range?

5,000–10,000 cells per microliter

Define leukocytosis.

WBC count greater than 11,000 cells per microliter

What does leukocytosis usually indicate?

Normal homeostatic response to infection

What is chemotaxis?

Movement of leukocytes toward chemical signals released by damaged tissue

What happens to WBC production during infection?

It can double and appear in blood within hours

What are the two main categories of leukocytes?

Granulocytes and agranulocytes

Which leukocytes are granulocytes?

Neutrophils, eosinophils, and basophils

Why are granulocytes called polymorphonuclear?

They have multilobed nuclei

Which leukocyte has neutral dye affinity?

Neutrophil

Which leukocyte stains with eosin (red dye)?

Eosinophil

Which leukocyte stains with basic blue dye?

Basophil

List leukocytes from most to least abundant.

Neutrophils > lymphocytes > monocytes > eosinophils > basophils

Mnemonic for leukocyte abundance.

Never Let Monkeys Eat Bananas

What is hemopoiesis?

Blood cell production

Where does hemopoiesis occur?

Bone marrow

What is the origin of all blood cells?

Pluripotent hematopoietic stem cells

What is the primary function of neutrophils?

Phagocytosis and defense against bacteria

Which condition is associated with neutrophilia?

Acute bacterial infection

Why is neutrophilia clinically useful?

It helps distinguish bacterial from viral infections

What therapy is indicated when neutrophilia is confirmed?

Antibiotic therapy

What conditions are associated with eosinophilia?

Allergic diseases and parasitic infections

How do eosinophils kill parasites?

Attach and release toxic enzymes from granules

Which leukocytes resemble mast cells?

Basophils

What substances are released by basophils and mast cells?

Histamine and heparin

What is the function of histamine?

Allergic and inflammatory responses

What is the function of heparin?

Anticoagulation and lipid clearance after meals

How long do basophils circulate in blood?

Less than 1 day

How long do basophils survive in tissues?

3–4 days

What is the function of monocytes?

Phagocytosis

What do monocytes differentiate into in tissues?

Macrophages

How long do macrophages live?

Months to years

Why do macrophages eventually die?

Overload from phagocytosis

What are the two types of lymphocytes?

B lymphocytes and T lymphocytes

What is the function of B lymphocytes?

Produce antibodies

What is the function of T lymphocytes?

Directly destroy infected or tumor cells

What is the lifespan of lymphocytes?

100–300 days

What is leukopenia?

Abnormally low WBC count

What causes leukopenia?

Radiation, benzene, or anticancer drugs

What is the most dangerous consequence of leukopenia?

Reduced phagocytes and weakened immunity

Which cells provide defense when bone marrow fails?

Lymphocytes from lymphoid organs

What virus causes infectious mononucleosis?

Epstein–Barr virus

What blood cell change occurs in infectious mononucleosis?

Increased atypical lymphocytes

What are classic symptoms of infectious mononucleosis?

Fever, sore throat, fatigue

How is infectious mononucleosis transmitted?

Saliva

What is leukemia?

Uncontrolled cancerous proliferation of white blood cells

How high can WBC count reach in leukemia?

Up to 500,000 cells per mm³

Why are leukemic WBCs ineffective?

They are immature blast cells

Why does leukemia cause anemia?

Suppressed erythropoiesis

Why does leukemia cause bleeding?

Reduced platelet production

Most common causes of death in leukemia?

Infections and hemorrhage