Question

Q2. Describe the basic four layers of the wall of the digestive tract. Be sure to include tissue types found there and the function of the layer.

Mucosa – Absorption and secretion

• Epithelium
• Lamina Propria
• Muscularis mucosae

Submucosa – Supports mucosa

Muscularis Externa – Motility that propels food and residual through the digestive tract

• Inner circular layer
• Outer longitudinal layer

Serosa – Secretion of fluid that reduces the friction from the muscle movement

• Areolar tissue
• Mesothelium

Q3. Though that basic pattern above is followed throughout most of the digestive tract, there are a few places where we see deviations. Identify two areas with variations in this pattern and describe the differences seen.

Answer 1

Question 2-

the wall of GI tract is formed by four layers-

1. Mucus layer- innermost layer. It has three layers-

a. Epithelial lining- it is in contact with contents of GIT. It has stratified squamous epithelial cells.

b. Lamina propria- formed by connective tissue which contain fibroblast, macrophages, lymphocytes and eosinophils.

c. Muscularis mucosa - consist of thin layer of smooth Muscle fibres.

2. Submucus layer- it contains loose collagen fibres, elastic fibres, reticular fibres wnd few cells of connective tissue. Blood vessels, lymphatic vessels and nerves are present here.

3. Muscular layer- in stomach there are 3 layer- inner, middle and outer. Whereas in intestine , there are two- inner and outer. This layer help in producing Movements in GIT.

4. Serous layer -outermost layer of GIT. Formed by connective tissue and mesoepithelial cells.

Question 3-

Two deviations are-

1. Muscularis mucosa is absent in mouth and pharynx. Also submucosa layer is absent in mouth and pharynx.

2. The oesophagus lacks serosa layer.