Ch. 16: Large Intestine Structure/Function

Question 1

What is the approximate length of the large intestine?

Answer 1

About 1.5 meters (5 feet), forming the terminal portion of the digestive tract.

Question 2

How does the diameter of the large intestine compare to the small intestine?

Answer 2

The large intestine has a larger diameter but is shorter in length than the small intestine.

Question 3

What is the cecum?

Answer 3

A pouch-like area where chyme enters from the ileocecal valve; chyme becomes more solid as water and salts are reabsorbed.

Question 4

Name the four sections of the colon and their locations.

Answer 4

Ascending Colon: moves upward on the right side; Transverse Colon: across the abdomen from right to left; Descending Colon: on the left side; Sigmoid Colon: S-shaped segment leading to the rectum.

Question 5

What is the function of the rectum?

Answer 5

Final section before the anal canal where fecal matter is stored before elimination.

Question 6

What is the function of the anal canal (anus)?

Answer 6

The external opening where feces is expelled during defecation.

Question 7

What type of muscle fibers are in the wall of the large intestine?

Answer 7

Smooth muscle fibers that produce churning, peristalsis, and help expel waste.

Question 8

What does the mucous membrane lining of the large intestine absorb?

Answer 8

Water, electrolytes, and some vitamins from remaining undigested food.

Question 9

What are the main functions of the large intestine?

Answer 9

Absorption of water, salts, and vitamins; bacterial action to aid nutrient release and produce vitamins like K and B-complex; protection from disease.

Question 10

Why is absorption in the large intestine less efficient than in the small intestine?

Answer 10

It lacks villi, reducing surface area, so it focuses more on water and salt reabsorption than nutrient absorption.

Question 11

How long does material normally take to pass through the large intestine?

Answer 11

About 3 to 5 days.

Question 12

What happens if the passage rate through the large intestine is too fast or too slow?

Answer 12

Too fast: diarrhea; Too slow: excessive water absorption leading to constipation.

Question 13

Name the two sphincter muscles controlling the anus and their types.

Answer 13

Inner Anal Sphincter: smooth (involuntary) muscle; Outer Anal Sphincter: striated (voluntary) muscle.

Question 14

What is the function of the anal sphincters?

Answer 14

To keep the anus closed except during defecation.