6. Digestion Flashcards Preview

Biology: Y12 EOY > 6. Digestion > Flashcards

Flashcards in 6. Digestion Deck (21)
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1
Q

Name all the structures (e.g. stomach) involved in digestion and their role.

A
  1. mouth - ingestion and chewing
  2. esophagus - swallowing
  3. stomach - killing pathogens and protein digestion
  4. gall bladder - stores bile
  5. liver - secretes bile
  6. pancreas - secretes digestive enzymes
  7. small intestine - digestion and absorption
  8. large intestine - absorption of water
  9. anus - egestion of faeces
2
Q

Draw and label the cross sectional structure of the small intestines.

A

outside to in:

  • circular muscle layer
  • longitudinal muscle layer
  • submucosa
  • mucosa
  • villi
3
Q

How does food move through the small intestine?

A
  • waves of muscle contraction, called peristalsis, pass along the intestine
4
Q

Explain how circular muscle contraction and longitudinal muscle contraction moves food through the small intestine.

What additional effect do these contractions have?

A
  • contraction of circular muscle behind the food constricts the gut to prevent food from being pushed back towards the mouth
  • contraction of longitudinal muscle where the food is located moves it on along the gut
  • mixes food with enzymes in the small intestine
5
Q

What is the role of enzymes in digestion?

A

enzymes digest most macromolecules in food into monomers in the small intestine

6
Q

Give examples of some macromolecules that enzymes digest in the small intestine.

A

proteins, starch, glycogen, lipids, and nucleic acids

7
Q

Give an example of a macromolecule that enzymes in the small intestine cannot digest.

A

cellulose

8
Q

Name three types of enzyme the pancreas secretes to digest macromolecules.

A
  • lipase
  • endopeptidase
  • amylase
9
Q

Where does the pancreas secrete its enzymes?

A

into the lumen, the top part of the small intestine

10
Q

What is lipase? What does it break down? What are the products of this reaction?

A
  • an enzyme
  • lipids
  • fatty acids + glycerol
11
Q

What is endopeptidase? What does it break down? What are the products of this reaction?

A
  • an enzyme
  • polypeptides
  • shorter peptides
12
Q

What is amylase? What does it break down? What are the products of this reaction?

A
  • an enzyme
  • starch
  • maltose
13
Q

State the two types of molecule in starch.

A
  • amylose

- amylopectin

14
Q

Compare amylose and amylopectin.

A
  • molecules of starch
  • polymers of a-glucose
  • linked by 1,4 bonds
15
Q

Contrast amylose and amylopectin.

A
  • amylose: 1,4 bonds therefore chains are unbranched

- amylopectin: 1,4 bonds and has some 1,6 bonds that make the molecule branched

16
Q

How does amylase break 1,4 bonds? Comment on the significance of this?

A
  • in chains of four or more glucose monomers

- it can digest amylose into maltose but not glucose

17
Q

What does the specificity of the active site of amylase mean?

A

amylase can break 1,4 bonds, but cannot break 1,6 bonds in amylopectin

18
Q

What are dextrins?

A

fragments of the amylopectin molecule containing a 1,6 bond that amylase cannot digest

19
Q

What is digestion of starch completed by?

A

enzymes in the membranes of microvilli on villus epithelium cells. The enzymes are maltase and dextrinase that digest maltose and dextrins into glucose

20
Q

What else, apart from the enzymes maltase and dextrinase, are in the membranes of microvilli in the small intestine?

A

protein pumps that cause the absorption of the glucose produced by digesting starch

21
Q

Outline the path glucose takes on its way to being stored, once it is in the blood.

A
  • blood carrying glucose and other products of digestion flows through villus capillaries to venules in the submucosa of the wall of the small intestine
  • blood in these venules is carried via the hepatic portal vein to the liver, where excess glucose can be absorbed by liver cells and concerted to glycogen for storage