Anatomy and Physiology

Components of Blood

  • Components of Blood:

    • Blood consists of various components which can be categorized into plasma and formed elements.

Blood Production

  • Organs Producing Blood:

    • Before Birth: Blood is produced in the yolk sac, liver, and spleen.

    • After Birth: Primarily produced in the bone marrow.

  • Origin of Blood Cells:

    • All blood cells originate from hematopoietic stem cells in the bone marrow.

  • Process of Blood Cell Production:

    • Hematopoiesis.

Functions of Blood

  • Primary Function of Blood:

    • To transport oxygen and nutrients to cells and remove waste products.

  • Protective Functions of Blood:

    • Defending against pathogens (white blood cells) and containing proteins for clotting (platelets).

  • Transportation Functions of Blood:

    • Carries gases (oxygen and carbon dioxide), nutrients, hormones, and metabolic waste.

  • Regulatory Functions of Blood:

    • Maintains homeostasis of temperature, pH, and fluid balance in the body.

Blood Characteristics

  • Normal pH Range of Blood:

    • Approximately 7.35 to 7.45.

  • Normal Color & Density of Blood:

    • Oxygenated blood is bright red; deoxygenated blood is dark red. Density is about 1.065 to 1.075 g/mL.

  • Amounts/Percentages of Each Component:

    • Plasma: ~55%, Red Blood Cells: ~45%, White Blood Cells and Platelets: <1%.

Blood Plasma Components

  • Components of Blood Plasma:

    • Water, electrolytes, nutrients, waste products, gases, hormones, and proteins.

  • Most Common Component of Plasma:

    • Water (about 90-92% of plasma volume).

Blood Plasma Proteins

  • Types & Functions of Blood Plasma Proteins:

    • Albumin: Maintains osmotic pressure; most abundant plasma protein.

    • Globulins: Immune functions (antibodies) and transport proteins.

    • Fibrinogen: Clotting factor.

  • How Common is Each Type:

    • Albumin: 60% of plasma proteins; Globulins: 35%; Fibrinogen: 4%.

  • What is Serum?

    • The liquid that remains after blood has clotted, containing water, electrolytes, and proteins but lacks clotting factors.

Erythrocytes (Red Blood Cells)

  • What is an Erythrocyte?

    • A biconcave, disc-shaped cell without a nucleus, responsible for oxygen transportation.

  • Function of RBCs:

    • Carry oxygen via hemoglobin and transport carbon dioxide back to the lungs.

  • How & Where Are RBCs Made?

    • Produced in the bone marrow through erythropoiesis stimulated by erythropoietin from the kidneys.

  • Anatomy of RBC:

    • Composed of a plasma membrane enclosing cytoplasm and hemoglobin, lacking organelles.

  • End of RBC Life:

    • Typically live for about 120 days; aged RBCs are phagocytized by macrophages in the spleen and liver.

  • Importance of Hemoglobin:

    • Essential for oxygen transport; binds to oxygen in the lungs and releases it in tissues.

  • Difference Between Oxyhemoglobin & Deoxyhemoglobin:

    • Oxyhemoglobin: Hemoglobin bound to oxygen; Deoxyhemoglobin: Hemoglobin without oxygen.

Nutritional Requirements for RBC Production

  • Essential Nutrients/Vitamins:

    • Iron, Vitamin B12, and Folate are critical for erythropoiesis.

Hematocrit

  • What is Hematocrit?

    • A measurement of the proportion of blood volume occupied by red blood cells; expressed as a percentage.

Blood Disorders

  • Anemia:

    • A condition characterized by a deficiency of red blood cells or hemoglobin, resulting in reduced oxygen transport.

  • Polycythemia:

    • A condition with an excess of red blood cells, increasing blood viscosity and risk of clotting.

  • Sickle Cell Disease:

    • A genetic disorder leading to the formation of abnormal hemoglobin, causing sickle-shaped red blood cells that can obstruct blood flow.

Leukocytes (White Blood Cells)

  • What is a Leukocyte?

    • A component of blood that plays a crucial role in the immune system, defending against infections.

  • Function of Each Type of Leukocyte:

    • Neutrophils: Phagocytize bacteria; first responders to infection.

    • Lymphocytes: B cells (antibody production) and T cells (cell-mediated immunity).

    • Monocytes: Differentiate into macrophages and dendritic cells, also important in phagocytosis.

    • Eosinophils: Combat parasitic infections and are involved in allergic reactions.

    • Basophils: Release histamine during inflammatory reactions.

  • Commonality of Each Type of Lymphocyte:

    • Neutrophils (55-70% of WBC), Lymphocytes (20-40%), Monocytes (2-8%), Eosinophils (1-4%), Basophils (<1%).

  • Granular vs. Agranular Leukocytes:

    • Granular: Neutrophils, Eosinophils, Basophils; Agranular: Lymphocytes, Monocytes.

  • Leukocytosis:

    • An increase in the number of white blood cells, often indicating infection or inflammation.

  • Leukopenia:

    • A decrease in white blood cell count, which can increase infection risk.

  • Phagocytic Blood Cells:

    • Neutrophils and Monocytes are phagocytic.

  • Longest Life Span Blood Cell:

    • Lymphocytes can live for years in the body.

Thrombocytes (Platelets)

  • What is a Thrombocyte?

    • Small cell fragments involved in the clotting process, derived from megakaryocytes in the bone marrow.

  • Function of a Thrombocyte:

    • Crucial for hemostasis; they aggregate at sites of blood vessel injury to form a plug and release clotting factors.

Hemostasis Phases

  • Three Phases of Hemostasis:

    1. Vascular spasm: Blood vessels constrict to minimize blood loss.

    2. Platelet plug formation: Platelets adhere to the site of injury and form a temporary plug.

    3. Coagulation: Cascade of events leading to the formation of fibrin strands, solidifying the platelet plug into a stable clot.

Blood Typing

  • Understanding Blood Typing:

    • Involves the recognition of specific antigens (agglutinogens) on the surface of red blood cells and the corresponding antibodies (agglutinins) in plasma.

  • Antigen/Antibody Characteristics:

    • Type A: A antigens, anti-B antibodies

    • Type B: B antigens, anti-A antibodies

    • Type AB: A and B antigens, no antibodies (universal acceptor)

    • Type O: No antigens, both anti-A and anti-B antibodies (universal donor).

  • Rh Factor (Antigens):

    • Rh+ has the Rh antigen; Rh- does not. This factor is critical in blood transfusions.

Blood Transfusions

  • Safe Transfusions:

    • Type O can be transfused into A, B, AB, or O.

    • Type A can be given to A and AB.

    • Type B can be given to B and AB.

    • Type AB can only receive AB.

  • Universal Donor:

    • Type O negative (Rh-).

  • Universal Acceptor:

    • Type AB positive (Rh+).

Hemolytic Disease of the Newborn

  • Situations Causing Hemolytic Disease of the Newborn:

    • Occurs when an Rh- mother carries an Rh+ fetus, leading to the mother’s immune system attacking fetal red blood cells.

  • Another Name for This Condition:

    • Rh incompatibility.

  • Father’s Blood Type Requirement:

    • The father must be Rh- to prevent this condition.

  • Prevention of This Condition:

    • Administering anti-Rh immunoglobulin (RhIg) to the mother during and after pregnancy to prevent the formation of antibodies against Rh factor.