Digestion & Absorption Flashcards

1
Q

What are the 5 main functions of the human gut?

A
  1. Ingestion
  2. Mechanical digestion
  3. Chemical digestion
  4. Absorption & assimilation
  5. Egestion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the digestive system?

A
  • a muscular tube that extends from the mouth through the body to the anus
    -each organ has a special role to breakdown and absorb food and water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where are digestive juices produced and what do they do?

A

-produced by gland cells
-release hydrolytic enzymes and other molecules that facilitate digestion

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

What do hydrolytic enzymes do?

A

-hydrolyse large insoluble food molecules (polymers) into smaller soluble molecules (monomers) which can then be absorbed through the lining of the intestine

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

What are polypeptides & proteins hydrolysed by and into?

A

-hydrolysed into amino acids
-by proteases

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

What are carbohydrates hydrolysed by and into?

A

-into simple sugars
-by carbohydrases

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

What are fats hydrolysed by and into?

A

-hydrolysed into glycerol, fatty acids and monoglycerides
-by lipases

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

What are the 4 glands?

A

-salivary glands
-stomach
-pancreas
-ileum

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

What is the enzyme, if the gland is salivary gland?

A

-salivary amylase

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

What is the enzyme if the gland is the stomach?

A

-endopeptidases (e.g pepsin) and exopeptidases

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

What is the enzyme if the gland is the pancreas?

A

-pancreatic amylase, lipases & exopeptidases

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

What is the enzyme if the gland is ileum?

A

-membrane bound dipeptidases & disaccharides

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

What structures are involved in digestion?

A

-salivary glands
-oesophagus
-pancreas
-liver
-gallbladder
-stomach
-small intestine
-large intestine- absorption of water
-rectum

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

Describe the function of salivary glands

A

Secrete salivary amylase (the enzyme which hydrolyses starch to maltose)

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

What is the function of the stomach?

A

-food is mixed with gastric juice which is acidic
-this kills microorganisms
-this also contains endopeptidases and exopeptidases which hydrolyses polypeptides to dipeptidases

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

Describe the function of the pancreas

A

-secretes pancreatic juice containing amylase (and other carbohydrases), endopeptidases (e.g pepsin) and exopeptidases

17
Q

Describe the structure and function of the small intestine (ileum)

A

-adapted to provide a large surface area for the absorption of the products of digestion
-maltase enzymes are embedded in the epilethelium cell membrane of the small intestine, this enzyme hydrolyses maltose to glucose so s available for rapid absorption
-There are also sucrose, lactase and dipeptidases enzymes

18
Q

What is digestion?

A

-A process where large molecules are hydrolysed by enzymes into small molecules, which can be absorbed into the blood/ lymph and then be assimilated into biological molecules

19
Q

Describe how starch is broken down

A

-food enters the mouth and is broken up by teeth (mechanical digestion), then mixed with saliva
-salivary amylase starts to hydrolyse glycosidic bonds in the starch producing maltose (chemical digestion)
-in the stomach, the salivary amylase is denatured due to acidic PH
-in the small intestine, pancreatic amylase continues to hydrolyse starch into maltose
-maltose is then hydrolysed to glucose by maltase enzymes in the membrane of epilethial cells, the glucose can then be absorbed

In mammals, cellulose isn’t hydrolysed as the enzyme cellulase isn’t produced

20
Q

describe maltase/ microvilli

A

-maltase is a membrane protein (of epilethial cell lining villi) = the membrane has small folds called microvilli, increasing surface area for disaccharides (maltase, lactase, sucrose) and dipeptidases (hydrolyse dipeptidases to amino acids)

21
Q

Which 2 enzymes are involved in starch digestion

A

Amylase and maltase

22
Q

Where is amylase found?

A

Synthesised and secreted from salivary glands and pancreas

23
Q

Where is maltase found?

A

Within the membrane of epilethial cell membrane of ileum

24
Q

What is the product of a reaction catalysed by amylase?

A

Starch to maltose (hydrolyse)

25
Q

What is the product of a reaction catalysed by maltase?

A

Maltose to glucose (hydrolyse)

26
Q

Where are microvilli found?

A

Cell membrane of epilethial cell

27
Q

Explain how starch is digested/absorbed

A

-starch hydrolysed by amylase to maltose
-amylase denatured in stomach
-pancreas adds amylase into small intestine
-small intestine lining maltase hydrolyses maltose into glucose
-then absorbed and assimilated

28
Q

Describe how carbohydrates can be absorbed

A

-only monosaccharides/monomers are small enough to be transported across the epilethial cell membrane and are complimentary to the binding sites of specific carrier/ channel proteins that move specifically complimentary monomers across the epilethial cell membrane
-monosaccharides (glucose, fructose and galactose) are absorbed by facilitated diffusion and co-transport using specific carrier proteins (due to their specific shaped binding sites)

29
Q

How is glucose absorbed?

A

-to the epilethial cell (across microvilli membrane) by co-transport with Na+ ions

30
Q

describe the roles of the enzymes of the digestive system in the complete breakdown of starch (4)

A
  1. Salivary/ pancreatic amylase hydrolyses starch into maltose
  2. By hydrolysing glycosidic bonds
  3. Maltose is hydrolysed into glucose
  4. By maltase
31
Q

Describe how glucose is absorbed from the ilium into the blood (5)

A
  1. Na+ (sodium ions) are actively transported out of epilethial cell into the blood (by sodium potassium pump)
  2. This creates a concentration gradient of Na+ (between lumen of the ileum and the epilethial cell)
  3. Na+ and glucose enter by facilitated diffusion using (complimentary) cotransporter proteins
  4. Na+ diffuse into the cell down its concentration gradient
  5. Glucose moves into the cell against its concentration gradient
  6. Glucose moves into the blood by facilitated diffusion
32
Q

describe the process of absorption/ draw a diagram

33
Q

AO2 (page 6)

34
Q

Describe the process of protein digestion (6)

A
  1. Proteins are hydrolysed by proteases and this begins in the stomach
  2. endopeptidases hydrolyse the peptide bonds within the polypeptide chain (middle of chain)
  3. This produces many shorter polypeptide chains and increases surface area for the next enzyme = faster and more efficient digestion
  4. exopeptidases (ends of chains) hydrolyse peptide bonds at ends of proteins, removing amino acids one by one
  5. exopeptidases are specific, amino acids and dipeptidases are produced
  6. Dipeptidases- enzymes embedded into cell surface membrane of epilethial cells, these hydrolyse dipeptides into amino acids which can now be absorbed by facilitated diffusion, active transport and co transport
35
Q

Draw an endopeptidase

36
Q

Draw an exopeptidase