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Biology AS > Digestion and Absorption 3.3 > Flashcards

Digestion and Absorption 3.3 Flashcards

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1
Q

What is the function of the mouth and tongue?

A

They break down large pieces of food into smaller pieces for easy ingestion.

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2
Q

What is the function of the salivary glands?

A

To secrete amylase.

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3
Q

What is the function of the oesophagus?

A

It carries food from the mouth to the stomach.W

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4
Q

What is the function of the Liver?

A

It processes nutrients absorbed in the small intestine. It also secretes bile into the small intestine.

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5
Q

What is the function of the gallbladder?

A

It stores and concentrates bie.

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6
Q

What is the function of the rectum?

A

It stores faeces.

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7
Q

What is the function of the anus?

A

It egests faeces.

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8
Q

What is the function of the stomach?

A

It is a muscle sac which stores and digests food. The walls nd glands produce digestive enzymes.

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9
Q

What is the function of the pancreas?

A

It is a large gland which produces pancreatic juice which contains hydrolytic enzymes.

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10
Q

What is the function of the large intestine?

A

It absorbs water.

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11
Q

What is the function of the small intestine?

A

It absorbs soluble food molecules.

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12
Q

What enzymes are found in the mouth?

A

Amylase.

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13
Q

What enzymes/chemicals are found in the stomach?

A

HCl and protease.

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14
Q

What enzymes are found in the pancreas?

A

Amylase, protease and lipase.

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15
Q

What enzymes are found in the large and small intestines?

A

Bile, amylase, protease and lipase.

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16
Q

How is the small intestine adapted for the absorption of nutrients?

A

It has thin epithelial walls and has a large surface area from the villi and microvilli. It also has lots of capillaries around the villi as well as muscular mixing which helps to maintain the concentration gradient.

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17
Q

What are carbohydrates broken down into during hydrolysis?

A

Disaccharides and then monosaccharides.

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18
Q

What is the role of amylase?

A

It hydrolyses starch into maltose.

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19
Q

What are the three disaccharide enzymes?

A

Maltase, sucrase and lactase.

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20
Q

Sucrase is a membrane bounddisaccharide. Where in the body would you find sucrase?

A

On the cell membranes of epithelial cells lining the epithelium.

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21
Q

Explain the role of sucrase in the body.

A

Sucrase catalyses the hydrolysis of ucrose into glucose and fructose. This allows for these smaller molecues to be asorbed across the ileum epithelium into the blood stream.

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22
Q

What are proteins broken down by?

A

Peptidases.

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23
Q

What are peptidases?

A

Enzymes which catalyse the conversion of proteins into amino acids by hyrdolysing the bonds between amino acids.

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24
Q

What do endopeptidases do?

A

Break bonds in the middle of polypeptides to produce shorter polypeptides.

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25
Q

What do exopeptidases do?

A

They break bonds at the ends of polypeptides to produce dipeptides or individual amino acids.

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26
Q

What do dipeptidases do?

A

They seperate to amino acids which make up a dipeptide by hydrolysing the peptide bond between them.

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27
Q

What does lipase do?

A

It catalyses the breakdown of lipids into monoglycerides and fatty acids, it involves the hydrolysis of ester bonds in lipids.

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28
Q

Where are bile salts produced?

A

In the liver.

29
Q

Where are bile salts stored?

A

In the gallbladder.

30
Q

Where does the gallbladder release the bile salts into?

A

The small intestine.

31
Q

What do bile salts do?

A

Help to break down large fat globules.

32
Q

How do bile salts break down large fat globules?

A

They emulsify them into smaller droplets.

33
Q

What does the bile salts breaking down large fat globules help?

A

It helps to speed up the action of lipases by increasing the surface area of lipids that can be exposed to the enzyme.

34
Q

What is the ileum?

A

The finl section of the intestine.

35
Q

What is the function of th ileum?

A

It is where the nutrients are absorbed into the blood stream.

36
Q

How does the villi help to maximise the movement of substaces in the small intestine into the blood stream?

A

It gives the small intestine a larger surface area and they have a thin epithilium which helps to keep th diffusion pathway short.

37
Q

What is the beneift of villi in the small intestine having lots of capilaries?

A

It helps to maintain the concentration gradient by allowing for the constant transportation of absorbed nutrients.

38
Q

What does the lipsae enzyme catlayse?

A

The breakdown of lipids into monoglycerides and fatty acids, this involves the hydrolysis of ester bonds in lipids.

39
Q

What is the product of complete
hydrolysis of proteins?

A

Amino acids.

40
Q

What is the role of protease
enzymes?

A

To hydrolyse proteins into amino acids so they can be absorbed into the blood stream

41
Q

What are lipids broken down into
during hydrolysis?

A

Monoglycerides and fatty acids.

42
Q

What is the role of lipase?

A

To hydrolyse ester bonds between fatty acid chains and glycerol to break down lipids.

43
Q

Where are lipase enzymes made and where do they act?

A

Made in pancreas, act in the small intestine.

44
Q

Describe how bile enters the small intestine.

A

Bile salts are produced by the liver and stored in the gall bladder which releases them into the small intestine.

45
Q

What is the ileum?

A

The final section of the small intestine where nutrients are absorbed into the blood stream. Enzymes are secreted by glands in its walls. Inner walls are folded into villi which gives them a large surface area.

46
Q

How does having villi help the small intestine?

A

Internal walls are folded into projections called villi (~1mm in
length) which give a large surface area.

47
Q

How does villi having thing epithelium help the small intestine?

A

Villi have thin epithelium (one cell thick) to help keep the diffusion
pathway short.

48
Q

Why do the villi in the small intestine have lots of capillaries?

A

Villi have lots of capillaries to help maintain the concentration gradient by constantly transporting absorbed nutrients away.

49
Q

Why do villi in the small intestine contain muscles?

A

Villi contain muscles and can move which helps them to mix the
contents of the ileum so that villi always have new material next
to them to absorb nutrients. This also helps to maintain the
concentration gradient.

50
Q

What is the first step of the absorption of monosaccharides?

A

Sodium ions are actively transported out of the epithelial cells in the ileum, into the blood, by the sodium-potassium pump, creating a concentration gradient.

51
Q

What is the second step of the absorption of monosaccharides?

A

There is a higher concentration of sodium ions in the lumen than in the cell, causing sodium ions to diffuse from the lumen of the ileum into the epithelial cell, down the concentration gradient.

52
Q

What is the third step of the absorption of monosaccharides?

A

The sodium acts as a co trasnporter and carries the glucose into the cell with it, causing the concentration of glucose inside the cell to increase.

53
Q

What is the first step of the absorption of monosaccharides?

A

The glucose then leaves the cell down its concentration gradient through protein channels by facilitated diffusion.

54
Q

How do amino acids get absorbed?

A

The same way as monosaccharides.

55
Q

What is the first step of the absorption of triglycerides?

A

Micelles hit epithelial cells and breakdown allowing monoglycerides and fatty acids to diffuse across phospholipid membrane because they are
lipid-soluble and non-polar.

56
Q

What is the second step of the absorption of triglycerides?

A

Monoglycerides and fatty acids are transported to the Endoplasmic Reticulum where they recombine to form triglycerides again.

57
Q

What is the third step of the absorption of triglycerides?

A

Inside the golgi they bind with cholesterol and proteins make packages of lipoproteins called chylomicrons.

58
Q

What is the fourth step of the absorption of triglycerides?

A

Chylomicrons travel in a vesicle to the cell membrane and leave the
epithelial cell through exocytosis.

59
Q

What is the fifth step of the absorption of triglycerides?

A

Chylomicrons enter lymphatic capillaries called lacteals which transport them away from the small intestine to adipose, cardiac, and skeletal muscle tissue, where the triglycerides can be hydrolysed and fatty acids used by the tissues.

60
Q

How are ileum epithelial cells adapted for absorption of carbohydrates?

A

Microvilli (folded membrane) which increase the surface area for diffusion further. Many mitochondria to provide energy and carrier proteins for active transport of glucose and galactose. Many channel proteins for facilitated diffusion of fructose.

61
Q

The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how.

A
  • Microvilli provide a large surface area.
  • Many mitochondria produce ATP
  • Carrier proteins for active trasnport.
  • Channel / Carrier proteins for facilitated diffusion.
  • Cotransport of sodium ions and glucose.
  • Membrane-bound enzymes digest disaccharides.
62
Q

What is the role of endopeptidases?

A

Hydrolyse peptide bonds within a large protein (polypeptide) to create smaller polypeptide chains.
Endopeptidases create more terminal ends for exopeptidases to then work on. (increase surface area)

63
Q

Describe the action of
exopeptidases.

A

Hydrolyse terminal peptide bonds (between amino acids on the ends of a polypeptide chain) to remove individual amino acids and create smaller polypeptide chains.

64
Q

How are Na+ involved in the
absorption of amino acids?

A

Needed for co-transport. Sodium ions are actively transported out of the ileum cells so that they diffuse back in down their concentration gradient with amino acids.

65
Q

How do bile salts help the digestion of lipids?

A

Bile salts help to break down large fat globules by emulsifying them into smaller droplets. This helps to speed up the action of lipases by increasing the surface area of lipids that can be exposed to the enzyme.

66
Q

How are the products of lipid digestion absorbed?

A

Micelles hit epithelial cells, monoglycerides and fatty acids diffuse across the cell membrane where they are transported to the ER and reform into triglycerides. In the golgi they bind with cholesterol and proteins and are packaged to form chylomicrons which travel in a vesicle to the cell membrane and are exocytosed from epithelial cell. Chylomicrons enter lacteals which transport them away from the small intestine to cells to
be used.

67
Q

What is digestion?

A

Digestion is the hydrolysis of large biological molecules into smaller molecules which can be absorbed across cell membranes.

68
Q
A

Biology AS (12 decks)

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