Module 7.10 Large Intestine

Question 1

The large intestine can be divided into the

• ____,
• ____,
• ____ (____, ____, ____, and ____) and
• ____

Answer 1

The large intestine can be divided into the

• cecum,
• appendix,
• colon: (ascending, transverse, descending, and sigmoid) and
• rectum

Question 2

The large intestine extends from the ____ ____\_where the entrance is sealed by the ____\_ ____\_and ____\_ to the ____\_where the exit is sealed by an ____\_ and ____\______\__ ____\_

Answer 2

The large intestine extends from the small intestine where the entrance is sealed by the ileocecal sphincter and valve to the anus where the exit is sealed by an internal and external anal sphincter

Question 3

Three longitudinal bands of smooth muscle called _______ ___\_extend the length of the large intestine

Answer 3

Three longitudinal bands of smooth muscle called teniae coli extend the length of the large intestine

Question 4

The large intestine is involved in all four of the digestive processes:

Answer 4

The large intestine is involved in all four of the digestive processes:

1. motility,
2. secretion,
3. digestion,
4. absorption

Question 5

The large intestine functions primarily in:

1. the _____\_of the remaining _____\_, which serves to _____\_ wastes into feces,
2. the _____\_of _____\_ until defecation.

Answer 5

The large intestine functions primarily in:

1. the absorption of the remaining water, which serves to concentrate wastes into feces,
2. the storage of feces until defecation.

Question 6

What are the two forms of motility of the large intestine?

Answer 6

1. haustral contractions
2. mass movements.

Question 7

What are Haustra?

Answer 7

Haustra are bulges of the large intestine that are formed when the teniae coli contract

Question 8

Haustral contractions are responsible for the ___\_, ___\_-___\_____\__ of the ___\_ contents

Answer 8

Haustral contractions are responsible for the slow, segmentation-like mixing of the intestinal contents

Question 9

What are mass movements responsible for?

Answer 9

Mass movements are large, peristaltic-like contractions that function to propel the feces toward the rectum

Question 10

What 3 factors regulate Mass Movements?

Answer 10

Mass movements are regulated by

1. gastrocolic reflex,
2. gastrin, and
3. autonomic nervous system (ANS) activity.

Question 11

The exit of feces from the large intestine is mediated by the _____\_ reflex

Answer 11

The exit of feces from the large intestine is mediated by the defecation reflex

Question 12

The defecation reflex is initiated by ____\_of the ____\_, which stimulates ____\_receptors, resulting in ____\_ of the ____\______\__ ____\_and in increased ____\_ of the ____\_ colon

Answer 12

The defecation reflex is initiated by distension of the rectum, which stimulates stretch receptors, resulting in relaxation of the internal anal sphincter and in increased contraction of the sigmoid colon

Question 13

_____\_relaxation of the ______ ______ _____\_ then allows for defecation to occur.

Answer 13

Voluntary relaxation of the external anal sphincter then allows for defecation to occur.

Question 14

What does the Large Intestine secrete?

Answer 14

An alkaline, mucous fluid

Question 15

What is the function of the alkaline, mucuous fluid secreted by large intestine secretion?

Answer 15

functions to lubricate the large intestine and to neutralize acids produced by colonic bacteria

Question 16

What regulates the secretion of the large intestine?

Answer 16

Secretions of the large intestine are regulated by short reflexes and parasympathetic nervous system activity

Question 17

Although no digestive enzymes are present in the large intestine, the _____ ______ digest some of the material, such as _____, that passes through the large intestine.

Answer 17

Although no digestive enzymes are present in the large intestine, the colonic bacteria digest some of the material, such as cellulose, that passes through the large intestine.

Question 18

Does the large intestine absorb nutrients?

Answer 18

The large intestine lacks most of the transport proteins found in the small intestine and does not participate in the absorption of nutrients

Question 19

Which (3) ions are absorbed in the large intestine?

How are they each absorbed?

Answer 19

• Na+ is actively absorbed through transport proteins
• Cl- is passively transported down the electrochemical gradient produced from the absorption of Na+
• H2O is passively transported down the electrochemical gradient produced from the absorption of Na+