Digestive System General Info

Headgut

• Parts: Mouth, pharynx 

• Mechanical: Chewing

• Chemical: 

  • Amylase: Breaks down sugars 

Foregut

• Parts: Esophagus, Esophageal sphincter, stomach, pyloric sphincter

• Mechanical: Mixing, beginning of digestion 

• Chemical:

  • Gastrin: HCl secretion (lowers pH)

    • Food in stomach → vagus nerve stimulated →  Gastrin Secreted

    • Stimulates stomach motility (gut movement)

  • Pepsinogen (inactive): Activated in low pH and turns into pepsin (active) to digest proteins 

    • Inhibits further gastrin 

Midgut

Parts: Small intestine (Duodenum), Live, Gallbladder, pancreas

• Mechanical: mixing

• Chemical: 

  • More Amylase

  • Trypsin: more protein digestion!

  • Gastrin Inhibitory Peptide (GIP)

    • Tells pancreas to secrete insulin

    • Preps for cellular sugar absorption

  • The small intestine is a major area of enzymatic digestion (duodenum) and absorption.

  • Cholecystokinin (CCK) & Secretin

    • Tells gallbladder to drip some bile which will be used in fat digestion and absorption 

HIndgut

• Large Intestine

  • Mechanical: 

    • Electrolyte absorption

    • Water absorption 

    • Fermentation and vitamin K synthesis

    • Forming and storing waste 

Fermentation

• Digesting carbohydrates (cellulose) with the help of bacteria and bacterial enzymes!

• Different animals ferment in different places, cows in the foregut, fish in the midgut and rabbits in the hindgut

• Midgut - Fish

  • Microbes in my small intestine help digest aglae and then I absorb it right there!

• Foregut - Cows, sheep, camels, goats

  • Omasum - Water Absorption 

  • Abomasum - Acidic environment 

  • Reticulum - Filters big chunks 

  • Rumen - Microbe spa

• Hindgut: Rhino, horse, koala, bunny

  • Takes place in the large intestine, but specifically the cecum 

  • Microbial breakdown 

  • Is very slow