Large Intestine Structure and Function Flashcards Preview

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Flashcards in Large Intestine Structure and Function Deck (36):
1

What muscular layer of the large intestine is complete?

The circular muscle layer

2

What muscle layer of the large intestine is incomplete and how does it appear on the large intestine?

The longitudinal muscle layer - 3 strips of longitudinal muscle run along the entire length of the outside of the colon

3

What are the 3 strips of longitudinal muscle running along the outside of the large intestine known as?

Teniae coli

4

The contractions of the teniae coli cause

the haustra - puckered appearance of the colon

5

What epithelium is the mucosa of the large intestine composed of?

Simple columnar epithelium

6

What cells provide the lubrication needed in the large intestine for the movement of faeces?

Goblet cells

7

What nerve is the main innervation from the parasympathetic system to the GI tract?

Vagus nerve

8

What nerve is the main innervation from the sympathetic system to the GI tract?

Splanchnic nerve

9

What effect do the parasympathetic and sympathetic systems have on the GI tract, respectively?

Parasympathetic - stimulatory
Sympathetic - inhibitory

10

What functions does the pancreas have?

Exocrine and endocrine

11

What are the functions of the large intestine?

It actively transports sodium from the lumen into the blood causing the osmotic absorption of water and dehydration of the chyme to produce solid faeces

12

What are the main components of the large intestine?

Caecum
Ascending colon
Transvers colon
Descending colon
Sigmoid colon

13

What is the ileocaecal valve?

Where the ileum and the large intestine join

14

What essential vitamin is obtained from the bacterial fermentation of undigested carbohydrates in the intestines?

Vitamin K

15

Why is vitamin K essential?

It is essential for the clotting of blood

16

What can be obtained from the bacterial flora in the intestines that acts as an energy source?

Short chain fatty acids

17

The bacterial flora in the colon protects against

pathogenic bacteria in the colon

18

What is the rectum?

Straight, muscular tube between the end of the sigmoid colon and the anal canal

19

What is the epithelium type of the mucosa of the rectum?

Simple columnar epithelium

20

How does the muscularis externa of the rectum compare to elsewhere in the alimental canal?

It is thicker in the rectum

21

Is the muscularis externa of the anal canal thicker or thinner than that of the rectum?

Thicker

22

What muscle type is the external anal sphincter formed from?

Skeletal muscle

23

How does the epithelium of the anal canal change as you move down the canal?

Epithelium changes from simple columnar to stratified squamous

24

Normally the anus is closed by the

internal anal sphincter

25

What muscle type is the internal anal sphincter formed from?

Smooth muscle

26

Which anal sphincter is under autonomic control and which is under voluntary control?

Autonomic - internal
Voluntary - external

27

The rectal wall distends as a result of

the mass movement of faecal material into the rectum

28

The distension of the rectal wall triggers the

mechanoreceptors responsible for the defaecation reflex which stimulates the urge to defaecate

29

Is the defaecation reflex under sympathetic or parasympathetic control?

Parasympathetic via the pelvic splanchnic nerves

30

What is caused by the defaecation reflex?

Contraction of rectum
Relaxation of internal anal sphincter
Contraction of external anal sphincter

31

What is the defaecation reflex?

Increased peristaltic activity in the colon increasing the pressure on the external anal sphincter which relaxes under voluntary control and allows the expulsion of faeces

32

What is diarrhoea?

The too-frequent passage of faeces which are too liquid

33

What are the common causes of diarrhoea?

Pathogenic bacteria
Protozoans
Viruses
Toxins
Food

34

Enterotoxigenic bacteria produce protein enterotoxins which

maximally turn on intestinal chloride secretion from the crypt cells, causing increased water secretion

35

Increased water secretion swamps the

absorptive capacity of the villi

36

What solutions can be given to drive water reabsorption and cause rehydration?

Sodium or glucose solutions