BIO 2202 Exam 2 Study Guide: Respiratory, Urinary, Fluid & Electrolyte, and Immune Systems

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Respiratory System

Overview of Respiratory Anatomy

The respiratory system is responsible for gas exchange, supplying oxygen to the body and removing carbon dioxide. It consists of a series of organs and structures that conduct air and facilitate this exchange.

Nose: Located centrally on the face, the nose is the primary entryway for air. It warms, moistens, and filters incoming air.
Paranasal Sinuses: Air-filled spaces in the skull bones surrounding the nasal cavity. They lighten the skull, produce mucus, and help warm and moisten air.
Pharynx: A muscular tube (throat) that serves as a passageway for both air and food, divided into nasopharynx, oropharynx, and laryngopharynx.

Protective Mechanisms of the Respiratory System

Mucus and cilia: Trap and move particles out of the airways.
Cough and sneeze reflexes: Expel irritants from the respiratory tract.
Immune cells: Macrophages in alveoli engulf pathogens.

Conducting vs. Respiratory Zones

Conducting Zone: Includes all respiratory passageways that carry air to the sites of gas exchange (nose, pharynx, larynx, trachea, bronchi, bronchioles).
Respiratory Zone: Site of gas exchange, consisting of respiratory bronchioles, alveolar ducts, and alveoli.

Lower Respiratory Tract Structures

Larynx: Voice box; routes air and food, houses vocal cords.
Trachea: Windpipe; a tube supported by cartilage rings, conducts air to bronchi.
Bronchi: Branch from trachea into each lung, further divide into smaller bronchioles.

Respiratory Membrane

The respiratory membrane is a thin barrier (composed of alveolar and capillary walls and their fused basement membranes) that allows efficient gas exchange between air and blood.

Respiratory Passageways (Descending Order)

Nose
Pharynx
Larynx
Trachea
Primary bronchi
Secondary and tertiary bronchi
Bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveoli

Lungs and Pleurae

Lungs: Paired organs divided into lobes (right: 3, left: 2), contain bronchial tree and alveoli.
Pleurae: Double-layered serous membranes (parietal and visceral pleura) surrounding each lung, reduce friction during breathing.

Intrapleural Pressure and Partial Vacuum

The partial vacuum in the intrapleural space keeps the lungs inflated by preventing lung collapse.

Boyle’s Law and Breathing

Boyle’s Law: (Pressure and volume are inversely related at constant temperature.)
During inspiration, lung volume increases and pressure decreases, drawing air in. During expiration, volume decreases and pressure increases, pushing air out.

Respiratory Muscles and Lung Elasticity

Diaphragm and intercostal muscles: Contract to increase thoracic volume during inspiration.
Lung elasticity: Allows lungs to recoil during expiration.

Factors Influencing Pulmonary Ventilation

Airway resistance
Lung compliance
Alveolar surface tension

Lung Volumes and Capacities

Tidal Volume (TV): Air moved in/out per breath (~500 mL).
Inspiratory Reserve Volume (IRV): Extra air inhaled after normal inspiration.
Expiratory Reserve Volume (ERV): Extra air exhaled after normal expiration.
Residual Volume (RV): Air remaining after maximal exhalation.
Vital Capacity (VC):

Dead Space

Volume of air not involved in gas exchange (e.g., in conducting airways).

Pulmonary Function Tests

Assess lung volumes, capacities, and airflow rates to diagnose respiratory diseases.

Gas Laws in Respiration

Dalton’s Law: Total pressure of a gas mixture equals the sum of partial pressures of each gas.
Henry’s Law: The amount of gas dissolved in a liquid is proportional to its partial pressure and solubility.

Atmospheric vs. Alveolar Air

Alveolar air has higher CO2 and water vapor, lower O2 than atmospheric air due to gas exchange and humidification.

Oxygen and Carbon Dioxide Transport

Oxygen: Mostly transported bound to hemoglobin; a small amount dissolved in plasma.
CO2: Transported as bicarbonate ions, bound to hemoglobin, or dissolved in plasma.

Factors Affecting Oxygen Loading/Unloading

Increased temperature, decreased pH, increased BPG, and increased PCO2 promote oxygen unloading from hemoglobin (Bohr effect).

Neural Control of Respiration

Respiratory centers in the medulla and pons regulate rate and depth of breathing.

Regulation of Breathing

Influenced by arterial pH, PO2, PCO2, lung reflexes, voluntary control, and emotions.

Exercise and High Altitude

Hyperpnea: Increased ventilation during exercise (matched to metabolic need).
Hyperventilation: Increased ventilation exceeding metabolic need, leading to decreased CO2.
Acclimatization: Physiological adjustments to high altitude, including increased ventilation and red blood cell production.

Respiratory Disorders

Chronic bronchitis: Inflammation and excess mucus in bronchi.
Emphysema: Destruction of alveolar walls, reduced surface area for gas exchange.
Asthma: Reversible airway constriction and inflammation.
Tuberculosis: Bacterial infection causing granulomas in lungs.
Lung cancer: Uncontrolled cell growth in lung tissue.

Urinary System

Gross Anatomy of the Kidney

Kidneys are bean-shaped organs located retroperitoneally, protected by a fibrous capsule, adipose tissue, and renal fascia.

Renal Blood Supply

Blood enters via the renal artery, branches into segmental, interlobar, arcuate, and cortical radiate arteries, then afferent arterioles, glomerulus, efferent arterioles, peritubular capillaries/vasa recta, and exits via veins.

Nephron Anatomy

Nephron: Functional unit of the kidney, consists of renal corpuscle (glomerulus + Bowman’s capsule) and renal tubule (proximal tubule, loop of Henle, distal tubule, collecting duct).

Major Renal Processes

Glomerular filtration: Movement of water and solutes from blood into Bowman’s capsule.
Tubular reabsorption: Return of useful substances from filtrate to blood.
Tubular secretion: Addition of unwanted substances from blood to filtrate.

Forces Affecting Glomerular Filtration

Promoted by glomerular hydrostatic pressure; opposed by capsular hydrostatic and blood colloid osmotic pressures.

Control of Glomerular Filtration Rate (GFR)

Intrinsic controls: Renal autoregulation (myogenic and tubuloglomerular feedback).
Extrinsic controls: Neural (sympathetic) and hormonal (renin-angiotensin) mechanisms.

Water and Solute Reabsorption

Most reabsorption occurs in the proximal tubule via active and passive transport; water follows solutes osmotically.

Regulation in Distal Tubule and Collecting Duct

Aldosterone: Increases Na+ reabsorption.
ADH: Increases water reabsorption by making collecting ducts more permeable.

Tubular Secretion

Removes drugs, wastes, excess K+, and regulates blood pH by secreting H+ or HCO3-.

Medullary Osmotic Gradient

Established by countercurrent mechanisms in loop of Henle and vasa recta, allows concentration of urine.

Formation of Dilute and Concentrated Urine

Depends on ADH presence; without ADH, urine is dilute; with ADH, water is reabsorbed, concentrating urine.

Ureters, Bladder, and Urethra

Ureters: Muscular tubes transporting urine from kidneys to bladder.
Urinary bladder: Muscular sac for urine storage.
Urethra: Tube for urine excretion; longer in males (also carries semen), shorter in females.

Micturition (Urination)

Reflex involving stretch receptors in bladder, parasympathetic stimulation, and voluntary control via external urethral sphincter.

Fluid, Electrolyte, and Acid-Base Balance

Body Water Content and Fluid Compartments

Body water content depends on age, sex, body mass, and fat content.
Major compartments: intracellular fluid (ICF) and extracellular fluid (ECF, includes plasma and interstitial fluid).

Fluid Volumes and Solute Composition

Compartment	Volume (%)	Main Cations	Main Anions
ICF	~66%	K+, Mg2+	HPO42-, proteins
ECF	~33%	Na+	Cl-, HCO3-

Electrolytes vs. Nonelectrolytes

Electrolytes: Dissociate into ions, have greater osmotic power.
Nonelectrolytes: Do not dissociate, less effect on osmotic balance.

Water Balance

Water intake: drinking, food, metabolism.
Water output: urine, sweat, feces, respiration.
Regulated by thirst mechanism and hormones (ADH, aldosterone).

Obligatory Water Losses

Minimum urine output required to excrete wastes, insensible losses via skin and lungs.

Dehydration and Hypotonic Hydration

Dehydration: Water loss exceeds intake; leads to thirst, dry mucosa, low urine output.
Hypotonic hydration: Excess water intake dilutes ECF, can cause cellular swelling (water intoxication).

Sodium and Potassium Balance

Sodium: Main ECF cation, regulates fluid volume and blood pressure; controlled by aldosterone, ANP, and ADH.
Potassium: Main ICF cation, affects membrane potential; regulated by aldosterone and renal secretion.

Acid-Base Balance

Acids produced by metabolism (CO2, lactic acid, ketones).
Three major buffer systems: bicarbonate, phosphate, protein buffers.
Respiratory system regulates CO2 (acid), kidneys regulate H+ and HCO3-.
Acidosis: Blood pH below 7.35; Alkalosis: pH above 7.45.
Respiratory and renal compensations help restore pH balance.

Immune System

Innate (Nonspecific) Defenses

Surface barriers: Skin and mucous membranes provide physical and chemical protection.
Phagocytosis: Neutrophils and macrophages engulf pathogens.
Natural killer (NK) cells: Destroy infected or abnormal cells.
Fever: Inhibits pathogen growth, enhances immune response.
Inflammation: Local response to injury; chemicals (histamine, prostaglandins) increase blood flow and attract immune cells.
Antimicrobial substances: Interferons, complement proteins attack pathogens.

Adaptive (Specific) Defenses

Antigen: Substance that triggers an immune response.
Complete antigen: Has immunogenicity and reactivity; hapten: Small molecule, immunogenic only when attached to carrier.
Antigenic determinant: Specific region of antigen recognized by immune cells.
B lymphocytes (B cells): Mature in bone marrow, produce antibodies (humoral immunity).
T lymphocytes (T cells): Mature in thymus, mediate cellular immunity.
Immunocompetence: Ability to recognize specific antigens; self-tolerance: Unresponsiveness to self-antigens.
Antigen-presenting cells (APCs): Dendritic cells, macrophages, B cells; present antigens to T cells.

Humoral Immunity

Clonal selection: B cell binds antigen, proliferates into plasma cells (secrete antibodies) and memory cells.
Active immunity: Acquired by infection or vaccination; passive immunity: Antibodies from another source (e.g., maternal, injection).
Antibodies: Y-shaped proteins; five classes: IgG, IgM, IgA, IgD, IgE; neutralize, agglutinate, and precipitate antigens.

Cellular Immunity

T cell activation: Requires antigen presentation and co-stimulation.
Types of T cells: Helper T (CD4+), cytotoxic T (CD8+), regulatory T cells.
Functions: Helper T cells activate B and other T cells; cytotoxic T cells kill infected cells; regulatory T cells moderate immune response.

Immunity Types and Disorders

Innate vs. adaptive immunity: Innate is immediate and nonspecific; adaptive is slower, specific, and has memory.
Autoimmune disorders: Immune system attacks self (e.g., lupus, rheumatoid arthritis).