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ESA 3 - Gastrointestinal System > Intestines > Flashcards

Flashcards in Intestines Deck (278)
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1

Into where does the stomach empty chyme?

The duodenum

2

What happens to chyme in the duodenum? 

It is conditioned 

3

What features of chyme are modified in conditioning? 

  • Acidic
  • Hypertonic
  • Partly digested

4

How is the acidity of chyme modified in conditioning? 

It is corrected by HCO3-

5

Where does the HCO3- used to correct the acidic nature of chyme in conditioning come from? 

Secreted from the pancreas, liver, and duodenal mucosa 

6

When is the HCO3- used to correct the acidity of chyme in conditioning produced? 

During the production of gastric acid 

7

How is hypertonicity of chyme modified in conditioning? 

Corrected by the osmotic movement of water into the duodenum across its wall 

8

How is the partly digested nature of chyme modified in conditioning? 

Digestion is completed by enzymes

9

Where do the enzymes used to finish digestion of chyme in conditioning come from? 

The pancreas and duodenal mucosa 

10

Other than enzymes, what is required from the completion of digestion of chyme in conditioning? 

Bile acids from the liver

11

What conditions does absorption require? 

A large surface area, to which the luminal contents of the small intestine needs to be exposed to through gentle agitation for hours 

12

How is the surface area of the small intestine maximised? 

  • Very long
  • Increased by millions of villi projecting into the lumen

13

How do epithelial cells (enterocytes) arise? 

By rapid division in the crypts between the villi, and migration towards the tips

14

What happens to enterocytes at the tips of the villi? 

They are shed 

15

What happens to newly formed enterocytes as they migrate to the tip? 

They mature 

16

What covers the luminal surface of the enterocytes? 

Microvilli 

17

What is the purpose of the microvilli present on the enterocytes? 

  • Further increase surface area 
  • Form the brush border

18

What does the brush border form? 

An 'unstirred layer'

19

What happens at the unstirred layer? 

Nutrients meet and react with enzymes secreted by the enterocytes, completing digestion prior to absorption

20

Label this diagram

  • A - Muscle layers 
  • B - Villi 
  • C - Hepatic portal vein 
  • D - Lumen 
  • E - Capillary bed 
  • F - Lacteal 
  • G - Microvilli
  • H - Villi 

21

What is the function of the large intestines? 

Absorb water from the indigestible residues of chyme

22

What do the large intestines do to the indigestible residues of chyme? 

Convert them into semi-solid stool or faeces 

23

What happens to the faeces formed by the large intestines? 

It is stored temporarily and allowed to accumulate until defecation occurs 

24

What are teniae coli? 

The thickened bands of smooth muscle of the large intestines 

25

What do the teniae coli constitute? 

Most of the longitudinal coat of the large intestines 

26

Where do the teniae coli run? 

The length of the large intestine

27

What is the effect of the teniae coli on the part of the wall they are associated with? 

They shorten it 

28

Why do the teniae coli shorten the part of the wall they are associated with? 

Because of their tonic contraction

29

What does the shortening of the wall due to teniae coli form? 

Haustra

30

What are haustra? 

Where the colon becomes sacculated, or 'baggy', between the teniae