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Blood and Lymphatic System Review

Functions of Blood
  • Transport

    • Oxygen (O2) and nutrients delivery to cells.

    • Removal of metabolic wastes to lungs and kidneys for elimination.

    • Hormones transport from endocrine organs to target organs.

  • Regulation

    • Maintains body temperature by absorbing and distributing heat.

    • Maintains pH levels via buffers (normal pH 7.35-7.45).

    • Ensures adequate fluid volume in the circulatory system.

  • Protection

    • Prevents blood loss through clot formation initiated by plasma proteins and platelets.

    • Defends against infection with agents of immunity (antibodies, complement proteins, white blood cells).

Composition and Characteristics of Blood
  • Fluid Connective Tissue

    • Matrix: nonliving fluid (plasma)

    • Formed elements: living cells (erythrocytes, leukocytes, platelets).

  • Hematocrit Levels

    • Erythrocytes: ~45% of whole blood.

    • Normal values: Males 47% ±5%, Females 42% ±5%.

    • WBCs and platelets are less than 1% (Buffy coat).

    • Plasma makes up ~55%.

  • Physical Characteristics

    • Color varies with oxygen content: scarlet red (high O2), dark red (low O2).

    • Blood pH: 7.35-7.45.

    • Average volume: Males 5–6 L, Females 4–5 L.

Blood Plasma and Its Composition
  • Blood Plasma

    • Sticky, straw-colored fluid (~90% water).

    • Contains over 100 dissolved solutes (nutrients, gases, hormones, wastes).

    • Plasma Proteins

    • Most abundant solutes: produced mainly by the liver.

    • Albumin: 60% of plasma proteins, functions include carrier, blood buffer, and contributes to osmotic pressure.

Erythrocytes (Red Blood Cells)
  • Structure

    • Biconcave disc shape, lacks organelles, and is anucleate.

    • Filled with hemoglobin (Hb) for gas transport.

  • Function

    • Dedicated to respiratory gas transport.

    • Hb can bind up to four O2 molecules.

  • Production (Erythropoiesis)

    • Occurs in red bone marrow, takes about 15 days.

    • Stages include hematopoietic stem cells to proerythroblasts, then to various forms before becoming mature RBCs.

  • Regulation

    • Erythropoietin (EPO) stimulates RBC production, released by kidneys in response to low oxygen levels.

Erythrocyte Disorders
  • Anemia

    • Abnormally low O2-carrying capacity.

    • Types: hemorrhagic, iron-deficiency, pernicious anemia, aplastic anemia, renal anemia.

  • Polycythemia

    • Excess RBCs increase blood viscosity.

    • Types include polycythemia vera and secondary polycythemia due to low O2 levels.

Leukocytes (White Blood Cells)
  • Functions

    • Defense against disease.

    • Types: Granulocytes (neutrophils, eosinophils, basophils) and Agranulocytes (lymphocytes, monocytes).

  • Production

    • Stimulated by interleukins and colony-stimulating factors.

    • Myeloid stem cells and lymphoid stem cells give rise to specific types.

Hemostasis (Blood Clotting)
  • Steps in Hemostasis

    1. Vascular spasm

    2. Platelet plug formation

    3. Coagulation

  • Disorders of Hemostasis

    • Thromboembolic disorders (thrombosis, embolism).

    • Bleeding disorders (thrombocytopenia, hemophilia).

Lymphatic System
  • Functions

    • Returns fluids to blood, houses immune cells.

  • Components

    • Lymphatic vessels, lymph, lymph nodes.

  • Lymphoid Organs

    • Primary: thymus, red bone marrow.

    • Secondary: lymph nodes, spleen, MALT.

Spleen
  • Functions

    • Immune surveillance, cleanses blood, stores breakdown products (iron).

    • Composed of white pulp (immune function) and red pulp (destruction of aged blood cells).

Thymus
  • Function

    • Maturation of T cells, with the presence of thymic corpuscles for regulatory T cells development.


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Blood and Lymphatic System Review

Functions of Blood

  • Transport

    • Oxygen (O2) and nutrients delivery to cells.
    • Removal of metabolic wastes to lungs and kidneys for elimination.
    • Hormones transport from endocrine organs to target organs.
  • Regulation

    • Maintains body temperature by absorbing and distributing heat.
    • Maintains pH levels via buffers (normal pH 7.35-7.45).
    • Ensures adequate fluid volume in the circulatory system.
  • Protection

    • Prevents blood loss through clot formation initiated by plasma proteins and platelets.
    • Defends against infection with agents of immunity (antibodies, complement proteins, white blood cells).

Composition and Characteristics of Blood

  • Fluid Connective Tissue

    • Matrix: nonliving fluid (plasma)
    • Formed elements: living cells (erythrocytes, leukocytes, platelets).
  • Hematocrit Levels

    • Erythrocytes: ~45% of whole blood.
    • Normal values: Males 47% ±5%, Females 42% ±5%.
    • WBCs and platelets are less than 1% (Buffy coat).
    • Plasma makes up ~55%.
  • Physical Characteristics

    • Color varies with oxygen content: scarlet red (high O2), dark red (low O2).
    • Blood pH: 7.35-7.45.
    • Average volume: Males 5–6 L, Females 4–5 L.

Blood Plasma and Its Composition

  • Blood Plasma
    • Sticky, straw-colored fluid (~90% water).
    • Contains over 100 dissolved solutes (nutrients, gases, hormones, wastes).
    • Plasma Proteins
    • Most abundant solutes: produced mainly by the liver.
    • Albumin: 60% of plasma proteins, functions include carrier, blood buffer, and contributes to osmotic pressure.

Erythrocytes (Red Blood Cells)

  • Structure

    • Biconcave disc shape, lacks organelles, and is anucleate.
    • Filled with hemoglobin (Hb) for gas transport.
  • Function

    • Dedicated to respiratory gas transport.
    • Hb can bind up to four O2 molecules.
  • Production (Erythropoiesis)

    • Occurs in red bone marrow, takes about 15 days.
    • Stages include hematopoietic stem cells to proerythroblasts, then to various forms before becoming mature RBCs.
  • Regulation

    • Erythropoietin (EPO) stimulates RBC production, released by kidneys in response to low oxygen levels.

Erythrocyte Disorders

  • Anemia

    • Abnormally low O2-carrying capacity.
    • Types: hemorrhagic, iron-deficiency, pernicious anemia, aplastic anemia, renal anemia.
  • Polycythemia

    • Excess RBCs increase blood viscosity.
    • Types include polycythemia vera and secondary polycythemia due to low O2 levels.

Leukocytes (White Blood Cells)

  • Functions

    • Defense against disease.
    • Types: Granulocytes (neutrophils, eosinophils, basophils) and Agranulocytes (lymphocytes, monocytes).
  • Production

    • Stimulated by interleukins and colony-stimulating factors.
    • Myeloid stem cells and lymphoid stem cells give rise to specific types.

Hemostasis (Blood Clotting)

  • Steps in Hemostasis

    1. Vascular spasm
    2. Platelet plug formation
    3. Coagulation
  • Disorders of Hemostasis

    • Thromboembolic disorders (thrombosis, embolism).
    • Bleeding disorders (thrombocytopenia, hemophilia).

Lymphatic System

  • Functions
    • Returns fluids to blood, houses immune cells.
  • Components
    • Lymphatic vessels, lymph, lymph nodes.
  • Lymphoid Organs
    • Primary: thymus, red bone marrow.
    • Secondary: lymph nodes, spleen, MALT.

Spleen

  • Functions
    • Immune surveillance, cleanses blood, stores breakdown products (iron).
    • Composed of white pulp (immune function) and red pulp (destruction of aged blood cells).

Thymus

  • Function
    • Maturation of T cells, with the presence of thymic corpuscles for regulatory T cells development.