Lecture 28: The large intestine

Question 1

The large intestine has 5 sections, what are they?

Answer 1

Caecum 
Ascending colon
Transverse colon
Descending colon
Sigmoid colon

Question 2

What is the function of the large intestine ?

Answer 2

= is to absorb water and salts

= and to move faeces to the rectum and anal cavity for excretion

Question 3

What epithelium lines the large intestine ?

What epithelium lines the anal cavity ?

Answer 3

large intestine = simple columnar

anal cavity = stratified squamous

Question 4

What are the specialisations of the GI tract in the the large intestine?

Answer 4

The tract forms

• pouches called HAUSTRA which are formed by the inner circular layer
• bands of longitudinal muscle called TAENAE COLI

Question 5

There are two rings of muscle which form anal sphincters to control defecation, what are they?

Answer 5

INTERNAL sphincter = made of smooth muscle and is under involuntary control
EXTERNAL sphincter = made of skeletal muscle and is under voluntary control

Question 6

What does the sigmoid colon empty into?

Answer 6

The sigmoid colon empties into the rectum, which empties into the anus.

Question 7

What connects the small intestine to the large intestine ?

Answer 7

ileocaecal valve