Digestive and Respiratory Systems Overview

Nov 29, 2024

Anatomy of the Digestive and Respiratory Systems

Overview of the Pharynx

  • Definition: Passage common to both respiratory and digestive systems.
  • Structure: Musculomembranous junction of respiratory and digestive tubes.
  • Parts of the Pharynx:
    • Nasopharynx: Dorsal to soft palate, primarily respiratory.
    • Oropharynx: Ventral to soft palate, primarily digestive.
    • Laryngopharynx: Both respiratory and digestive, located where air crosses to larynx and food/water cross to esophagus.
  • Landmarks:
    • Hard palate, soft palate, tongue.

Openings in the Pharynx

  • Isthmus of Phoses: Opening from oral cavity to oropharynx.
  • Caudal Nares (Chonae): Opening from nasal cavity to nasopharynx.
  • Pharyngeal Opening of Auditory Tubes: Slits in nasopharynx leading to the middle ear.
  • Laryngeal Opening (Aditus Laryngeus): Opening to larynx.
  • Esophageal Opening (Aditus Esophagi): Opening from laryngopharynx to esophagus.

Anatomy of the Esophagus

  • Function: Connects laryngopharynx to stomach.
  • Regions:
    1. Cervical
    2. Thoracic
    3. Abdominal
  • Sphincters:
    • Cranial: Cricopharyngeal muscle
    • Caudal: Cardiac sphincter of stomach
  • Positioning: Dorsal to trachea, shifts left in the neck, dorsal in thorax.

Diaphragm and Openings

  • Openings:
    • Caval Foramen: For vena cava.
    • Aortic Hiatus: For aorta.
    • Esophageal Hiatus: For esophagus.

Anatomy of the Stomach

  • Function: Stores, mixes food, adds enzymes, mucus, and hydrochloric acid.
  • Parts:
    • Greater Curvature
    • Lesser Curvature
    • Cardia
    • Fundus
    • Body
    • Pylorus
  • Internal Features:
    • Gastric folds or rugae
  • Surfaces:
    • Parietal (against diaphragm & liver)
    • Visceral (contacts abdominal organs)

Small Intestine

  • Function: Main site for digestion and absorption.
  • Divisions:
    1. Duodenum: Closely attached to body wall, contains duodenal papillae.
      • Flexures: Cranial, caudal, duodenal-jejunal.
    2. Jejunum: Longest, most movable, held by mesojejunum.
    3. Ileum: Short, firmer, muscular, terminates at cecocolic junction.

Large Intestine

  • Components:
    • Cecum
    • Ascending Colon
    • Transverse Colon
    • Descending Colon
    • Rectum
  • Functions: Dehydration of fecal contents.
  • Features:
    • Cecum: Spiral S shape, located at the right side.
    • Colon Flexures: Right colic, left colic.
  • Anal Canal: Contains internal and external sphincters.

Conclusion

  • Anatomy discussed from ingestion to defecation.
  • Next module covers digestive accessory organs: salivary glands, liver, pancreas.