Digestion and absorption Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is digestion?

A

Secretion of enzymes that hydrolyse large, insoluble molecules to smaller, soluble molecules for absorption and transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the stomach?

A

A muscular sac that secretes enzymes from the inner layer (specifically protease)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the ileum?

A

A long muscular tube that further digests food molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the large intestine do?

A

Absorbs water, most of which is from the secretions of many digestive glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is egestion?

A

The removal of faeces from the anus after being stored in the rectum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What enzyme(s) do salivary glands secrete?

A

Amylase, which hydrolyses starch into maltose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the pancreas?

A

A large gland situated below the stomach, that produces pancreatic juices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What enzymes are within pancreatic juices?

A

Protease, lipase and amylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the two stages of digestion?

A

Physical and chemical digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is physical digestion?

A

Breaking of large food, by structures such as teeth, which provide large surface area for chemical digestion, the churning in the stomach is also physical digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is chemical digestion?

A

Hydrolysis of large insoluble molecules into smaller soluble ones, carried out by enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does amylase do?

A

Hydrolyses the alternate glycosidic bonds of the starch molecule to produce the disaccharide maltose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is maltose hydrolysed?

A

By the disaccharidase maltase, into alpha glucose molecules, in the ileum lining

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do mineral salts in saliva do?

A

Maintain the pH at around neutral, which is optimum for amylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does pancreatic amylase maintain a neutral pH?

A

Alkaline salts are produced by both the pancreas and the intestinal wall, so amylase can function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where are lipases produced and what do they do?

A

The pancreas, they hydrolyse the ester bond found in triglycerides to form fatty acids and monoglycerides

17
Q

What is emulsification?

A

The production of micelles (droplets of fats and oils) by bile salts

18
Q

What are three different proteases?

A

Endopeptidase, exopeptidase and dipeptidase

19
Q

What does endopeptidase do?

A

Hydrolyse the peptide bonds between amino acids in the central region of a polypeptide chain, forming a series of peptide molecules

20
Q

What does exopeptidase do?

A

Hydrolyse the peptide bonds on the terminal amino acids of of the peptide molecules formed by endopeptidases, they progressively release dipeptides and single amino acids

21
Q

What does dipeptidase do?

A

Hydrolyse the bond between the two amino acids of a dipeptide

22
Q

Where are dipeptidases found?

A

They are membrane-bound, being part of the cell-surface membrane of epithelial cell lining the ileum

23
Q

How is the ileum adapted for its function?

A

1mm long villi and a rich network of blood capillaries

24
Q

How do the villi increase absorption?

A

Increase surface area, thin walled, contain muscles which mix contents of ileum and maintain concentration gradient, rich blood supply and microvilli

25
Q

How are amino acids and monosaccharides absorbed?

A

Diffusion and co-transport

26
Q

What’s the average diameter of micelles?

A

4-7nm

27
Q

How are micelles broken down?

A

The come into contact with epithelial cells lining the ileum

28
Q

How do monoglycerides and fatty acids enter epithelial cells?

A

As they are non-polar molecules, they easily diffuse across the cell-surface membrane

29
Q

What happens once monogylcerides and fatty acids enter the epithelial cells?

A

They are transported to the endoplasmic reticulum, where they are recombined to form triglycerides

30
Q

What happens after triglycerides are formed by the endoplasmic reticulum?

A

Continue to the Golgi apparatus, where they associate with cholesterol and lipoproteins to form chylomicrons

31
Q

What are chylomicrons?

A

Special particles adapted for the transport of lipids

32
Q

How do chylomicrons move out of the epithelial cells and where do they go?

A

Exocytosis, they enter lymphatic capillaries called lacteals

33
Q

Where are lacteals found?

A

At the centre of each villus

34
Q

How do the chylomicrons move into blood vessels and how are they hydrolysed?

A

They pass via the lymphatic vessels into the blood system, they are hydrolysed by an enzyme in the endothelial cells of blood capillaries, from where they diffuse into cells