L1 Overview of the Alimentary Tract Structure and Function

Question 1

Appreciate the overall layout of the gastrointestinal tract from headgut, through to foregut to midgut, to hindgut. Including the associated glands, with an understanding of the major functions along the GIT.

Answer 1

Headgut
Prehension and mastication with the lips, tongue and teeth.

Salivary glands: the mandibular gland, the sublingual gland, the parotid gland and the zygomatic gland found in carnivores.

Foregut
Oesophagus contains stratified squamous epithelium with extra keratin for ruminants.

Stomach contains simple columnar epithelium with a highly folded epithelium which can expand. Lots of mucous. Invaginations form gastric pits.

Midgut
Small intestine duodenum lining secretes mucous and fluids, bile duct and pancreatic duct. The jejunum and illeum secretes fluids, digestive and absorptive.

The cranial duodenum vili massively increase the surface area so more absorption per space of time.

Brunner glands in the cranial duodenum secrete protective mucous.

Midgut/Hindgut large intestine 
Caecum M
Ascending colon M
Transverse colon M/H
Descending colon H
Rectum H

Absorb water and ions, compaction of undigested materials. Digestion of cellulose by microflora by cellulase.

Question 2

Describe the cellular arrangement of GIT highlighting the common patterns and variations along its length, explaining how these relate to regional function.

Answer 2

Mixed serous and mucous salivary gland; serous demi lunes. Cluster of cells for mucous arranged in a acinus. Drain into interlobular striated ducts.

The stomach has 3 layers of thick lamina muscularis with outside and inner layer circular and longitudinal layer.