Digestive System Overview

Study Notes

The digestive system is responsible for digesting and absorbing nutrients and eliminating waste products as stool, feces, or manure.
It is comprised of the digestive tract, digestive glands, and accessory digestive structures.

Serves as a common passage for the digestive and respiratory tracts
Made up of three main parts:
- Oropharynx: opens into the oral cavity
- Nasopharynx: opens into the nasal cavity above the oral cavity
- Laryngopharynx: opens into the larynx and esophagus ventrally

Musculo-membranous tube
Presents three segments or portions:
- Cervical segment: located adjacent to the cervical vertebrae
- Thoracic segment: located adjacent to the thoracic vertebrae
- Abdominal segment: passes through the hiatus esophagi of the diaphragm and is situated posteriorly
  - Note: The diaphragm is the main inspiratory muscle that separates the thoracic cavity above and the abdominal cavity below
Ingesta (food) passing through the esophagus is termed as bolus, which is slightly alkaline

It has four concentric layers, from inner to outer:
- Tunica mucosa
- Tunica submucosa
- Tunica muscularis
- Tunica adventitia

A hollow muscular bag
When ingesta enters the stomach and mixes with gastric juice, it is termed as chyme, which is strongly acidic
Four parts:
- Cardia
- Fundus
- Body
- Pylorus
Presents two sphincters, which are made up of smooth muscle that constrict these structures, preventing backflow of ingesta