CH 24: Immune System

Innate vs. Adaptive Immunity

The immune system is divided into innate and adaptive branches, each with distinct mechanisms for defending the body against pathogens.

• Innate Immunity: The body's first line of defense, providing immediate but non-specific protection. Components include physical barriers (skin, mucous membranes), phagocytic cells (neutrophils, macrophages), natural killer (NK) cells, and soluble factors (complement, interferons).

• Adaptive Immunity: A specific, slower response involving lymphocytes (B and T cells) that recognize and remember specific antigens. Adaptive immunity includes humoral (antibody-mediated) and cell-mediated responses.

• Key Differences: Innate immunity is non-specific and present from birth; adaptive immunity is specific and develops after exposure to antigens.

Leukocytes and Their Functions

Leukocytes, or white blood cells, are essential for immune defense and are classified into several types:

• Neutrophils: Phagocytose bacteria and debris.

• Lymphocytes: Include B cells (produce antibodies) and T cells (cell-mediated immunity).

• Monocytes: Differentiate into macrophages and dendritic cells.

• Eosinophils: Combat parasites and participate in allergic responses.

• Basophils: Release histamine in allergic reactions.

Development of Immune Cells: B and T Lymphocytes

B and T lymphocytes originate from hematopoietic stem cells in the bone marrow.

• B Cells: Mature in the bone marrow; responsible for antibody production.

• T Cells: Mature in the thymus; involved in cell-mediated immunity.

• Similarities: Both undergo selection processes to ensure self-tolerance.

• Differences: B cells produce antibodies; T cells directly attack infected cells or help regulate immune responses.

Clonal Selection: The process by which lymphocytes that recognize specific antigens proliferate and differentiate.

Self-Tolerance and Hygiene Hypothesis

• Self-Tolerance: Mechanisms that prevent the immune system from attacking the body's own tissues.

• Hygiene Hypothesis: Suggests that reduced exposure to pathogens in early life may increase susceptibility to allergies and autoimmune diseases.

Activation of B and T Lymphocytes

• B Cell Activation: Occurs when B cells encounter their specific antigen and receive help from T helper cells.

• T Cell Activation: Requires antigen presentation by major histocompatibility complex (MHC) molecules on antigen-presenting cells.

Key Terms: Clonal expansion, plasma cells, memory cells, cytokines, immunodeficiencies, hypersensitivity.

CH 17: Mechanics of Breathing

Functions of the Conducting Zone

The conducting zone of the respiratory system includes the nose, pharynx, larynx, trachea, bronchi, and bronchioles. Its main functions are:

• Transporting air to the lungs

• Filtering, warming, and humidifying incoming air

• Protecting respiratory surfaces from pathogens and debris

Upper and Lower Respiratory Systems

• Upper Respiratory Tract: Nose, nasal cavity, pharynx, larynx

• Lower Respiratory Tract: Trachea, bronchi, bronchioles, alveoli

Types of Cells in the Lungs

• Type I Alveolar Cells: Form the structure of the alveolar wall; involved in gas exchange.

• Type II Alveolar Cells: Secrete surfactant to reduce surface tension.

• Pleura: Visceral pleura covers the lungs; parietal pleura lines the chest wall.

Air Exchange and Breathing Physiology

• Simple Diffusion: Oxygen and carbon dioxide move across the alveolar membrane by diffusion.

• Pulmonary Circulation: Blood flow through the lungs for gas exchange.

• Pressure Relationships: Breathing is driven by changes in thoracic volume and pressure.

Equation:

Where is the pressure difference and is resistance.

Resistance and Lung Diseases

• Bronchodilation: Decreases airway resistance.

• Bronchoconstriction: Increases airway resistance.

• Obstructive Lung Diseases: Asthma, chronic bronchitis, emphysema.

Regulation of Breathing

• Blood flow and oxygen levels are regulated by chemoreceptors and neural control centers.

• Hyperventilation and hypoventilation affect blood gas levels.

Gas Exchange and Transport

• Partial Pressure: The pressure exerted by a single gas in a mixture.

• Oxygen Transport: Most oxygen is carried by hemoglobin; a small amount is dissolved in plasma.

• Carbon Dioxide Transport: CO2 is transported dissolved in plasma, as bicarbonate, and bound to hemoglobin.

Equation:

CH 19: Kidneys

Functions of the Kidneys

The kidneys maintain homeostasis by filtering blood, removing waste, and regulating fluid and electrolyte balance.

• Excretion of metabolic waste

• Regulation of blood volume and pressure

• Regulation of electrolyte and acid-base balance

• Production of hormones (erythropoietin, renin)

Filtration and Nephron Function

• Filtration: Occurs in the glomerulus; driven by blood pressure.

• Reabsorption: Movement of substances from filtrate back into blood.

• Secretion: Active transport of substances from blood into filtrate.

• Excretion: Removal of urine from the body.

Glomerular Filtration Rate (GFR)

• Definition: The volume of filtrate produced per minute by both kidneys.

• Regulation: Influenced by blood pressure, blood flow, and hormonal control.

Equation:

Thresholds and Urine Formation

• Renal Threshold: The plasma concentration at which a substance begins to appear in urine.

• Urine Formation: Involves filtration, reabsorption, secretion, and excretion.

CH 20: Fluid and Electrolytes

Acid-Base Balance

The body maintains pH within a narrow range through buffer systems, respiratory regulation, and renal mechanisms.

• Acidosis: Blood pH below 7.35

• Alkalosis: Blood pH above 7.45

• Causes: Respiratory (CO2 retention or loss), metabolic (gain or loss of acids/bases)

Equation:

Fluid and Electrolyte Inputs and Outputs

• Inputs: Ingestion of fluids and electrolytes

• Outputs: Urine, sweat, feces, respiration

• Common Ions: Sodium, potassium, chloride, calcium

Compensation Mechanisms

• Respiratory Compensation: Adjusts CO2 exhalation to regulate pH.

• Renal Compensation: Adjusts H+ and HCO3- excretion or reabsorption.

Acid-Base Imbalances

Buffer Systems

• Bicarbonate Buffer: Main buffer in blood; involves CO2 and HCO3-.

• Phosphate and Protein Buffers: Important in intracellular and renal regulation.

Additional info: These study notes expand upon the provided questions by supplying definitions, explanations, and relevant equations for each topic, ensuring a comprehensive review for Anatomy & Physiology students.