Respiratory System Overview

Respiratory System Overview

• Air pathway: Nares → vestibule → nasal cavity → nasopharynx → oropharynx → laryngopharynx → larynx → trachea → primary bronchi → secondary bronchi → tertiary bronchi → bronchioles → terminal bronchioles → alveolar ducts → alveolar sacs (containing alveoli). CO2 follows the same path in reverse.

Nose and Nasal Cavity

• Nares (nostrils): external openings for air entry.
• Nasal bones and cartilage: form the nose's bridge.
• Vestibule: area inside the nostrils.
• Nasal conchae (superior, middle, inferior): increase air cleaning efficiency.

Paranasal Sinuses

• Air spaces in bones (named after the bones they reside in).
• Lighten skull weight.

Pharynx (Throat)

• Nasopharynx: lies behind nasal cavity, above soft palate; contains pharyngeal tonsils (adenoids).
• Oropharynx: bordered by soft palate and hyoid bone; contains palatine tonsils and lingual tonsils.
• Laryngopharynx: below hyoid bone, above esophagus.

Larynx (Voice Box)

• Epiglottis: spoon-shaped cartilage, covers the glottis during swallowing.
• Functions: air passage, prevents food entry, voice production, and in cough/sneeze reflexes.
• Thyroid cartilage: largest, superior, Adam's apple (more prominent in males).
• Cricoid cartilage: inferior, smaller cartilage.
• Vocal folds: produce sound by vibrating with air passing through the rima glottis (opening between vocal folds).
• Pitch: determined by vocal fold tension; longer folds mean greater range.
• Loudness: determined by air volume through vocal folds.

Trachea (Windpipe)

• Anterior to esophagus, inferior to larynx, supported by C-shaped cartilaginous rings.
• Flexible protection for the esophagus behind it..

Bronchial Tree

• Trachea divides into bronchi, subdividing into smaller bronchioles.
• Bronchioles: lack cartilage, contain smooth muscle.
• Bronchi 1, 2, 3: have cartilage.
• Terminal bronchioles: lead to alveolar ducts.

Respiratory Portion

• Alveolar ducts: lead to alveolar sacs.
• Alveolar sacs: clusters of alveoli.
• Alveoli: small saccular outpocketings; site of gas exchange with pulmonary capillaries.

Alveoli

• Type I cells: simple squamous epithelium; form boundary for rapid gas diffusion.
• Type II cells: cuboidal, produce surfactant, reducing surface tension (preventing collapse).
• Pulmonary surfactant: reduces surface tension in alveoli, critical for infant health.

Respiratory Membrane

• Thin barrier between alveolus and gas exchange.

Pulmonary Ventilation

• External respiration: gas exchange between atmosphere and blood.
• Internal respiration: gas exchange between blood and body cells.
• Inhalation: thoracic cavity expands, decreasing intrapulmonary pressure, pulling air into lungs.
• Exhalation: thoracic cavity contracts, increasing intrapulmonary pressure, forcing air out of lungs.
• Ribs and diaphragm mechanics are essential for expansion/contraction.

Skeletal Muscles of Breathing

• Quiet breathing (eupnea): inhalation and exhalation.
• Forced breathing: use additional muscles for increased thoracic expansion (inhalation) or contraction (exhalation).
• Diaphragmatic breathing (more common in infants): involving abdominal movement.

Respiratory System Disorders

• Smoking: significant detrimental effects on the respiratory system, reduces life expectancy.
• Respiratory infections (common cold, pneumonia, bronchitis): involve viral or bacterial infection of the upper or lower tracts.
  • Pneumonia: fluid build-up in alveoli, potentially serious.
  • Bronchitis: inflammation of bronchi, mucous discharge, and coughing. Acute (bacterial) or chronic (smoking).
  • Asthma: inflammation and narrowing of airways, causing wheezing.
  • Emphysema: alveoli rupture and lose elasticity.
  • Pulmonary fibrosis: caused by inhaled particles, scar tissue forms, lessening lung elasticity.
• Common Cold: upper respiratory tract infection.
• Jaundice: yellowing due to bilirubin buildup (liver problem).

Lungs-Structure and Function

• Visceral and parietal pleurae: membranes surrounding lungs.
• Pleural cavity: space between pleurae; contains fluid to reduce friction.
• Lungs: sections each lobe supplied by own arteries and bronchi. Left lung is smaller with oblique fissure. Right lung has oblique & horizontal fissures into 3 lobes.
• Lung capacities:
  • Tidal volume: volume exchanged in resting breaths.
  • Vital capacity: maximum airflow.
  • Reserve volumes: supplemental inhale/exhale.
  • Residual volume: air remaining after maximum exhale.
  • Total lung capacity: total space.

GI Tract Overview

• Four tunic layers (deepest to superficial): mucosa, submucosa, muscularis, serosa.
• Structures: oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anal canal.
• Accessory digestive organs: teeth, tongue, salivary glands, liver, gallbladder, pancreas.

Accessory Digestive Organs

• Liver: key digestive function; filters blood, produces bile (emulsifier).
• Liver vasculature: hepatic portal vein (nutrient-rich), hepatic artery (oxygenated), hepatic veins (drainage).
• Gallbladder: stores and concentrates bile.
• Pancreas: endocrine (insulin/glucagon) and exocrine (pancreatic juices) functions.

GI Tract Pathway

• Precise pathway from mouth to anus.

Oral Cavity

• Palate: hard (bony) and soft (muscular)
• Uvula: prevents food from entering nasal cavity.
• Tongue: important function in mixing food and speech.
• Salivary glands: produce saliva (moistens, cleanses, and digests food). Extrinsic salivary glands include parotid, submandibular, and sublingual.
  • Teeth: enamel (protective outer layer); dentin (major tooth structure); pulp cavity (nerves and vessels). Teeth types include incisors, canines, premolars, molars.

Pharynx

• Oropharynx and laryngopharynx are shared by respiratory and digestive systems.

Esophagus

• Transports ingested food from pharynx to stomach via peristalsis.
• Sphincters (upper and lower esophageal) control food movement, preventing reflux.

Stomach

• Mechanical digestion: churning.
• Chemical digestion: gastric acid production.
• Chyme: mixture of food and gastric acid.
• Rugae: folds in the stomach lining.
• Greater and lesser curvatures, stomach regions (cardia, fundus, body, pylorus), the pyloric sphincter controls chyme entry.

Small Intestine

• Duodenum, jejunum, ileum: regions specialized for chemical digestion and absorption.

Large Intestine

• Absorbs water and electrolytes; forms and stores feces for elimination.

Clinical Applications

• Appendicitis, diarrhea, constipation, diverticulosis/diverticulitis, jaundice (various types).
• Diseases impacting liver function or digestion pathway.

This quiz covers the anatomy of the respiratory system, detailing the pathways of air through various structures including the nasal cavity, pharynx, and larynx. It also explores the purpose of each component and the function of the paranasal sinuses. Test your understanding of these essential systems in human physiology.