Respiratory System

Upper Respiratory Tract

The upper respiratory tract is responsible for the initial passage of air into the body and its filtration, warming, and humidification.

• External nose: The visible part of the nose that serves as the main entrance for air.

• Nasal cavity: Contains conchae (bony projections that increase surface area) and meatuses (air passages beneath each concha).

• Oral cavity: Includes the hard palate, soft palate, tongue, lingual tonsil, and uvula.

• Pharynx: Divided into:

  • Nasopharynx: Contains the pharyngeal tonsil.

  • Oropharynx: Contains the palatine tonsil and isthmus of fauces.

  • Laryngopharynx

• Paranasal sinuses: Air-filled spaces that lighten the skull and help warm and moisten air.

Lower Respiratory Tract

The lower respiratory tract is involved in the conduction of air to the lungs and gas exchange.

• Larynx: Contains the thyroid cartilage, cricoid cartilage, vocal folds, and glottis.

• Trachea: A tube supported by cartilaginous rings, conducting air to the lungs.

• Respiratory tree:

  1. Primary bronchi

  2. Secondary (lobar) bronchi

  3. Segmental (tertiary) bronchi

  4. Terminal bronchioles

  5. Respiratory bronchioles

  6. Alveolar duct

  7. Alveolar sac

  8. Alveoli (site of gas exchange)

• Lungs:

  • Right lung: superior, middle, and inferior lobes

  • Left lung: superior and inferior lobes

Histology of the Respiratory System

Histological examination reveals the tissue types lining the respiratory tract, such as pseudostratified ciliated columnar epithelium in the trachea and alveolar epithelium in the lungs.

Respiratory Volumes and Capacities

Respiratory volumes and capacities are measurements used to assess lung function.

• Tidal volume (TV): Volume of air inhaled or exhaled in a normal breath.

• Inspiratory reserve volume (IRV): Maximum volume of air that can be inhaled after a normal inhalation.

• Expiratory reserve volume (ERV): Maximum volume of air that can be exhaled after a normal exhalation.

• Residual volume (RV): Volume of air remaining in the lungs after maximal exhalation.

• Total lung capacity (TLC): Total volume of the lungs ().

• Vital capacity (VC): Maximum amount of air that can be exhaled after a maximal inhalation ().

• Inspiratory capacity (IC): Maximum amount of air that can be inspired ().

• Functional residual capacity (FRC): Volume of air remaining in the lungs after a normal exhalation ().

Pressure Relationships in Breathing

Breathing is driven by pressure differences between the atmosphere and the lungs.

• Positive pressure: Pressure greater than atmospheric pressure.

• Negative pressure: Pressure less than atmospheric pressure.

• CO2 and pH: Increased CO2 lowers blood pH, stimulating increased breathing rate.

Digestive System

Layers of the Alimentary Canal

The alimentary canal consists of four main layers that facilitate digestion and absorption.

• Mucosa: Innermost layer, contains epithelium, lamina propria, and muscularis mucosae.

• Submucosa: Connective tissue containing blood vessels, nerves, and glands.

• Muscularis externa: Smooth muscle responsible for peristalsis.

• Serosa: Outermost layer, also called the visceral peritoneum.

Anatomical Identification

• Mouth/oral cavity: Includes hard palate, soft palate, tongue, lingual tonsil, uvula, lingual frenulum, and palatine tonsil.

• Pharynx: Same divisions as in the respiratory system.

• Esophagus: Contains the gastroesophageal (cardiac) sphincter.

• Stomach: Regions include fundus, cardiac, lesser curvature, greater curvature, rugae, pylorus, and pyloric sphincter.

Small Intestine

The small intestine is the primary site for digestion and absorption.

• Duodenum, jejunum, ileum: Three regions of the small intestine.

• Microvilli: Increase surface area for absorption.

Large Intestine

• Cecum

• Ileocecal valve

• Ascending, transverse, descending, and sigmoid colon

• Rectum, anal canal, anus

• Appendix

• Haustra: Pouches that segment the colon.

• Tenia coli: Longitudinal muscle bands.

Liver and Gallbladder

• Common hepatic duct

• Cystic duct

• Common bile duct

• Hepatocytes: Liver cells responsible for metabolism, detoxification, and bile production.

• Functions:

  • Liver: Metabolism, detoxification, bile production.

  • Gallbladder: Stores and concentrates bile.

Digestive Physiology

Enzymes and other substances facilitate the breakdown of food.

• Enzyme: Biological catalyst that speeds up chemical reactions.

• Substrate: Substance acted upon by an enzyme.

• Major digestive enzymes:

  • Amylase: Found in saliva; digests starch.

  • Pepsin: Found in the stomach; digests proteins.

  • Trypsin: Found in the small intestine; digests proteins.

  • Lipase: Found in the pancreas; digests fats.

• Bile: Emulsifies fats; produced by the liver and stored in the gallbladder.

Urinary System

Anatomical Identification

The urinary system removes waste products from the blood and regulates water and electrolyte balance.

• Kidney: Contains renal hilum, renal cortex, renal medulla, renal pelvis, major and minor calyces, renal pyramid, renal column.

• Blood vessels:

  • Renal artery and vein

  • Cortical radiate artery and vein

  • Afferent and efferent arterioles

  • Arcuate vein

  • Interlobar vein

• Nephron: Functional unit of the kidney; includes proximal convoluted tubule (PCT), nephron loop, distal convoluted tubule (DCT), and collecting duct.

• Ureters: Transport urine from kidneys to bladder.

• Urinary bladder: Stores urine.

• Internal and external urethral sphincters: Control urine flow.

• Adrenal glands: Sit atop kidneys; produce hormones.

Physiology: Urinalysis

Urinalysis is used to detect substances in urine that indicate health or disease.

• Glucose: Positive indicates possible diabetes mellitus.

• Proteins: Positive indicates possible kidney disease.

• Ketones: Positive indicates fat metabolism, often seen in diabetes or starvation.

• Hemoglobin: Positive indicates possible hemolysis or bleeding.

• Bile: Positive indicates possible liver dysfunction.

• Erythrocytes: Positive indicates bleeding in the urinary tract.

• Leukocytes: Positive indicates infection.

Summary Table: Respiratory Volumes and Capacities

Example: Digestive Enzymes

• Amylase: Found in saliva; breaks down starch into maltose.

• Pepsin: Found in the stomach; breaks down proteins into peptides.

• Trypsin: Found in the small intestine; further digests peptides into amino acids.

• Lipase: Found in the pancreas; breaks down fats into fatty acids and glycerol.

Additional info: These notes expand on the outline provided in the images, adding definitions, examples, and formulas for clarity and completeness.