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The digestive system Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Which enzymes are made in the salivary glands?

A

Salivary amylase

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2
Q

What do salivary amaylse do?

A
  • They hydrolyse the 1-4 and 1-6 glycosidic bonds in starch
  • They hydrolyse starch into shorter chains
  • This increases the surface area of the molecule
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3
Q

What is found in saliva?

A

Enzymes
Buffer

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4
Q

What is a buffer?

A

It helps maintain the optimum pH

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5
Q

What pH does salivary enzymes work best at?

A

7

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6
Q

What enzymes are found in the stomach?

A

Endopeptidases

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7
Q

What does the stomach also produce apart from enzymes?

A

Hydrochloric acid

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8
Q

What do endopeptidases do?

A
  • They hydrolyse the peptide bonds within the peptide chain
  • They hydrolyse protein chains into shorter chain polypeptides
  • This increases the number of terminal ends, increasing the surface area
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9
Q

What pH do endopeptidases work best at?

A

2

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10
Q

What enzymes are found in the pancreas?

A

Endopeptidases
Exopeptidases
Pancreatic amalyse
Lipase

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11
Q

Where are the enzymes in the pancreas delivered to?

A

They are delivered by the pancreatic duct to the duodenum

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12
Q

What is the duodenum?

A

The upper part of the small intestine

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13
Q

What is bile and where is it made?

A
  • Made in the liver and stored in the gall bladder
  • Neutralises the acidic food to pH 8/9 so enzymes are at their optimum pH and not denatured
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14
Q

What do exopeptidases do?

A
  • Hydrolyse peptide bonds at the terminal ends of the shorter polypeptide chains
  • They hydrolyse shorter chains into di-peptides
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15
Q

What does pancreatic amylase do?

A

Hydrolyses shorter chain starch into maltose disacharrides

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16
Q

What do lipases do?

A
  • Hydrolyses the ester bond
  • Hydrolyses lipids into monoglyceride and 2 fatty acids
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17
Q

What enzymes do enzymes from the pancreas work at?

A

8/9

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18
Q

Which enzymes are found in the lower part of the small intestine?

A

Dipeptidase
Maltase
Sucrase
Lactase

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19
Q

What is the lower part of the small intestine known as?

A

The Ileum

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20
Q

Where are the enzymes located in the ileum?

A

They are embedded in the wall of the ileum

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21
Q

What do dipeptidases do?

A

They hydrolyse dipeptides to 2 amino acids

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22
Q

What do maltase do?

A

Hydrolyse maltase to 2 alpha glucose

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23
Q

What do sucrase do?

A

Hydrolyse sucrose to fructose and alpha glucose

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24
Q

What do lactase do?

A

Hydrolyse galactose and alpha glucose

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25
Q

What muscles do the oesphagus have?

A

It has 2 rings of muscle
- Circular
- Longitudinal
- They are separate

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26
Q

How do the 2 rings of muscle in the oesophagus ineract?

A

They are an antagonistic pair. When one contracts, the other one relaxes
They cause a wave of muscle contraction known as peristalsis

27
Q

What is chewing food known as?

A

Mastication - it increases the surface area of food and allows it to mix with the saliva

28
Q

What do the salivary glands do?

A

There are 3 pairs of salivary glands
They produce saliva (which contains enzymes and buffer and antibacterial properties)

29
Q

What is the epiglotis?

A

Every time you swallow, it closes the pathway to the trachea

30
Q

What happens if food gets stuck by the epiglotis?

A

If food gets stuck there, the trachea is closed and asphyxia (choking) takes place

31
Q

What is the oesophagus shaped like?

A

In reality, its more twisted so you cant rely on gravity to pull the food down
So, it has rings of muscle around it that help to propel the food down (peristalsis)

32
Q

How does bile act as an emulsifier?

A
  • Lipase is water soluble. Lipids are not. Bile has one part hydrophilic and one part hydrophobic
  • It keeps the lipids suspended in the place where lipase are
  • So we have also increased the surface area so the enzymes have a larger area over which to work
33
Q

What is the duodenum known as?

A

The mixing bowl where everything comes together - all the enzymes from the pancreas and also the bile

34
Q

What is on the outside of the stomach (structurally)?

A

3 layers of muscle - it helps the stomach contract (peristalsis) and digest the food

35
Q

What is the lining of the stomach like and why?

A

It has a thick cell lining to protect the stomach tissue from HCl

36
Q

What cells are found in the lining of the stomach and that of they do?

A
  • Goblet cells
  • These produce mucus
  • These are barriers to protect the lining of the stomach
37
Q

What glands are on the lining of the stomach?

A

Peptic glands which produce peptic juice

38
Q

What does peptic juice contain and why is this useful?

A
  • It contains enzymes and HCl
  • It moves into the stomach and mixes with the food
39
Q

What does HCl acid do in the stomach?

A

It kills pathogens in food and ensures optimum pH for enzymes in the stomach

40
Q

What cells line the ileum?

A

Epithelial cells

41
Q

What is the lining of the ileum like?

A

It is a single cell lining - one cell thick for short diffusion pathway

42
Q

What is found on the walls of the ileum?

A

Enzymes
Goblet cells - produce mucus as don’t want food to be dried out

43
Q

What are on the individual cells on the ileum?

A

Microvilli - increases the surface area at which absorption happens so increases the rate of absorption

44
Q

What are on the cell - surface membrane of epithelial cells?

A

Protein channels

45
Q

What do epithelial cells contain a lot of?

A

Mitochondria - high production of ATP from respiration for active transport

46
Q

Why is it useful that enzymes are embedded on the wall of the ileum?

A
  1. So they are not lost as once the ‘food’ leaves the ileum, the remnants are egested
  2. Allows the final hydrolysis of disomers to occur next to the ileum wall so the efficiency of absorption increases and less are lost
47
Q

What is the hepatic portal vein?

A

Blood from the small intestine(ileum) is carried to the liver to remove excess monosaccharides, vitamins, minerals, lipids etc

48
Q

What muscles surround the ileum?

A

Circular and longitudinal muscles - will allow peristalsis so we can propel everything along

49
Q

What do capillaries that surround the ileum do?

A

Carry absorbed substances away

50
Q

How are capillaries adapted for efficient exchange?

A
  • One cell thick meaning there is a short diffusion pathway
  • Large network so they have a large surface area so increases rate of diffusion
  • Constant flow of blood which maintains concentration gradient
51
Q

What are lacteal?

A

Responsible for carrying lipids (monoglycerides + fatty acids) which are reconstructed

52
Q

What is the lymphatic system and what does it do?

A
  • Absorbs lipids
  • Used for removal of lymphatic fluids
  • Carries leukocytes(WBC) - part of our immune system
  • Used to make milk (more in women)
53
Q

What passes into the large intestine from the ileum?

A

Undigested material (e.g. cellulose(fibre)) + water (+ any minerals or dissolved vitamins in water)

54
Q

What happens in the colon?

A
  • Water is absorbed via osmosis
  • Water potential inside colon is higher than outside so water moved into blood via osmosis
55
Q

What is stored in the rectum?

A

Faeces

56
Q

What happens in people who are lactose intolerant?

A
  • They don’t produce sufficient lactase so the lactose is not digested in the ileum
  • This passes into the large intestine but it is too large so it is uncomfortable
  • Millions of bacteria in the large intestine so produces gas
  • Lactose lowers water potential of colon so less water moves out by osmosis and results in diarrhoea
57
Q

What are smaller lipid droplets known as?

A

Bile salts

58
Q

What is a micelle?

A
  • It is what we call the fat droplets after hydrolysis has occurred
  • It consists of a mono glyceride, fatty acids and bile salts
59
Q

How do micelles enter epithelial cells?

A

They fuse with the membrane and pass through via diffusion (they can pass through the bilayer as they are lipid soluble)
This is known as endocytose

60
Q

What happens to micelles when they enter the epithelial cells?

A

These will diffuse into the smooth endoplasmic reticulum where they will be rebuilt

61
Q

What happens to the reconstructed lipids after they leave the smooth endoplasmic reticulum?

A
  • They are passed though the Golgi
  • They have proteins attached to them and form structures called chylomicrons
62
Q

What happens to the chylomicrons after they leave the Golgi?

A

They are in transported in vesicles to the basal membrane where they are exocytosed
They diffuse into the lacteal

63
Q

What happens to chylomicrons in the lacteal?

A

The lymph in the lacteal transports them away from the intestine

64
Q

What is also absorbed from the micelles by the intestinal cells?

A

Fatty acids, fat soluble vitamins and sterols

Biology (13 decks)

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