Biology 322 Human Anatomy I Digestive System

Functions:

Organs Two functional groups: 1. Alimentary Canal or Gastrointestinal tract Organs which ingest, propel, digest, absorb, & eliminate Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anus 2. Accessory Digestive Organs Assist with digestion Teeth, tongue, salivary glands, liver, gall bladder, pancreas

Organs:

Oral Cavity: Includes: Opens Which

Three Pairs of Salivary Glands:

From esophagus to anus: Alimentary Canal:

Esophagus: Propels food from pharynx to stomach Posterior to trachea & heart : Nonkeratinized stratified squamous epithelium Many mucous-secreting cells Thin lamina propria Thin muscularis mucosa : Thick layer of dense irregular CT : Upper third = skeletal muscle Middle third = mixed Lower third = smooth muscle Thin layer of connective tisssue

Esophagus: Passes from thorax to abdomen through diaphragm, enters stomach (left of midline).

Stomach: Storage: Highly distensible Delivers

Stomach

Stomach: Regions

Stomach:

Small Intestine:Total length: 6 to 7 meters Diameter: 2.5 to 3 centimeters

Small Intestine: Three parts

Small Intestine: Mucosa Epithelium Lamina propria Muscularis mucosa Submucosa Muscularis Externa Serosa or Adventitia

Small Intestine: Mucosa specialized three ways to increase surface area for absorption 1. All layers of mucosa thrown into folds called

Small Intestine: Mucosa specialized three ways to increase surface area for absorption 2.Epithelium and lamina propria form finger-like

Small Intestine: Mucosa specialized three ways to increase surface area for absorption 3. Plasma membranes of epithelial cells form finger-like

Small Intestine: Nutrients, ions, etc. are absorbed through these plasma membranes & passed through the cell to the deeper lamina propria, where they are absorbed into capillaries & lymphatic vessels.

Large Intestine (colon): From ileocecal junction to anus ~ 2 meters long ~ 5 to 8 cm diameter

Abdominal Accessory Organs: Liver, Gall bladder, Pancreas, & associated ducts

Four lobes Blood supply: Liver Most superior organ in abdomen Immediately inferior to diaphragm Partially protected by ribs Develops from embryonic intestine Mass ~ 1.5 kg

Liver: Enter / exit together on inferior surface

Pancreas: Inferior & posterior to stomach Fits into concavity of duodenum

The abdominal cavity is lined

More terminology:

Intraperitoneal Retroperitoneal