Question

2A4 pages on:

describe the general histological organisation if the gastro-intestinal tract.

compare and contrast the histological structure of the small and large intestine, making reference to the different functions.

Answer 1

Histologically GI tract contains 4 layers:

A) the innermost layer is the mucosa

B) underneath mucosa is the submucosa

C) next layer is the

muscularis propria  

D)the outermost layer is the adventitia .

The structure of these layers varies, in different regions of the digestive system, depending on their function.

Small intestine

A )Small intestine small intestine is about 4.5 to 7 metres in size

B) It is narrow in width about 2.5 to 3.5 in size

C) It has three parts namely duodenum, Jejunum and ileum

D) Internal surface of small intestine has circular folds, also called as 'palicae circular

E) Villi are present.

F) Peyers Patches are present. (aggregations of lymphoid tissue).

G(It forms the layer of continuous bands of muscles around it.

H) It shows small movements in the abdominal cavity

I) Epipolic apppedages is absent in small intestine.

J)Hastura Absent

K) Numerous hormones are secreted.

L) It absorb the nutrients from the digested food.

Large intestine

A) Large intestine measures around 1.5 m in size.

B) It has width of around 4 - 6 cm in diameter.

C) It has four parts, which are colon, rectum, caecum and anal canal.

D) Circular folds are absent.

E) Villi are absent.

F)Peyers patches are absent.

G) It is reduced to three types of muscles bands called as taeniae coli.

H) Hastura is Present

I) No role in digestion.

J) Epipolic appendages are present.

K) It takes part in absorption of water and electrolytes and in production of vitamins.

L) It has less mobility and is largely fixed.