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2nd Yr- IBMS > Lipid digestion, absorption and transport > Flashcards

Lipid digestion, absorption and transport Flashcards

1
Q

What are lipids?

A

Lipids are fats

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2
Q

Name the different types of lipids

A

Triglycerides
Phospholipids
Steroids

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3
Q

Describe the structure of triglycerides

A

Glycerol backbone

3 fatty acids

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4
Q

What is the structure of steroids?

A

They have a ring structure that doesn’t have enough hydroxyl groups to make them water soluble

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5
Q

Give examples of steroids

A
  1. Cholesterol
  2. Cortisol
  3. Estrogen
  4. Testosterone
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6
Q

Why do lipids require a special mechanism fro digestion and absorption?

A

As they are hydrophobic and water insoluble

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7
Q

What are lipids made up of?

A

Fatty acids

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8
Q

Name the 2 difference classifications of fatty acids

A
  1. Saturated

2. Unsaturated

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9
Q

What does it mean if a fatty acid is saturated?

A

Means it has only single covalent bonds between carbons (no double bonds)

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10
Q

What does it mean if a fatty acid is unsaturated?

A

They have one or more double covalent bond between carbons

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11
Q

What can unsaturated carbons be further split into?

A
  1. Monounsaturated fatty acids

2. Poly unsaturated fatty acids

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12
Q

What does it mean if a fatty acid is Monounsaturated ?

A

It only has ONE double covalent bond between carbons

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13
Q

What does it mean if a fatty acid is poly unsaturated ?

A

Means there’s 1 or more double covalent bonds in the fattty acid chain

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14
Q

What state are saturated fatty acids found in?

A

SOLIDS

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15
Q

Give examples of saturated fatty acids

A

Any fat eg

  1. Butter
  2. Ghee
  3. Coconut oil
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16
Q

What state are unsaturated fatty acids found in?

A

Lipids

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17
Q

Give examples of unsaturated fatty acids

A

Any oils eg olive oil

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18
Q

Give some functions of lipids

A
  1. Energy source
  2. Helps body absorb important fat soluble vitamins
  3. supports key body processes such as auctioning as biosynthetic precursor
  4. Fat cushions internal organs and protects them from being damaged
  5. Fat layer below the skin insulated the body
  6. Fat play s a role in maintaining healthy skin and hair
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19
Q

When do lipids serve as a source of energy?

A

Once calories from carbohydrates are used up

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20
Q

Give examples of fat soluble vitamins

A

Vitamin A, D, E and K

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21
Q

How many calories does one gram of fat provide?

A

9

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22
Q

What are some health issues associated with lipids

A

Excessive dietary fat intake is associated with obesity, diabetes, cancer, hypertension and
atherosclerosis.

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23
Q

What is the FDAs advice regarding fats

A

No more than 35% of the total energy intake should come from fat

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24
Q

What is the FDAs advice regarding saturated fat

A

No more than 10%of the total energy intake should come from saturated fat

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25
Q

What is the recommended daily value for total fat?

A

65g per day (based on a 2000 cal diet)

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26
Q

Which fatty acid comes from fatty fish?

A

Omega 3 fatty acids

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27
Q

What does omega 3 fatty acid protect against ?

A

atherosclerosis

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28
Q

Should you take fish oil as a substitute for eating fatty fish?

A

No as they contain concentrated toxins accumulated by the fish §

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29
Q

How many fish meals are recommended per week?

A

2-3

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30
Q

Name the parts of the body involved in lipid digestion

A
  1. Oral cavity
  2. Stomach
  3. Small intestine
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31
Q

Where does digestion begin?

A

The oral cavity

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32
Q

How does digestion of lipids begin?

A

Chewing of fats increases surface area

Lingual lipase is released in the mouth which breaks down lipas

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33
Q

How are lipids digested in the stomach?

A

Lingual lipase and gastric lipase are relased

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34
Q

What do lingual and gastric lipase do?

A

They spilt triglycerides into fatty acids and diglycerides

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35
Q

What are lingual and gastric lipase also known as?

A

Acidic lipases

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36
Q

Why are lingual and gastric lipase known as acidic lipases?

A

As their activity is stimulated and increased by a acidic environment

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37
Q

Eating what can help protect you against atherosclerosis?

A

Eating foods high in omega 3 fatty acids

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38
Q

What process if very important in lipid digestion?

A

Emulsification

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39
Q

Why is emulsification important?

A

As emulsification helps fats to dissolve in water so that nutrients can be absorbed

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40
Q

Are fats soluble in water?

A

NO

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41
Q

What happens in emulsification?

A

Fat is spread out and the surface area is increased so that the fat can dissolve in water

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42
Q

What can lingual lipase do?

A

It has the capacity to emulsify fats

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43
Q

What else is present in the mouth other than lingual lipase that aids lipid digestion

A

Phospholipids

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44
Q

How do phospholipids aid lipid digestion?

A

They are slightly more soluble than triglycerides so they help with emulsification

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45
Q

What is the activity of lipase stimulated and increased by?

A

By an acidic environment

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46
Q

What percentage of the triglycerides have been split into diglycerides and fatty acids in the stomach?

A

30%

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47
Q

Where does the main bulk of digestion take place?

A

In the small intestine

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48
Q

What is chyme?

A

Food that has been churned and partially digested in the stomach

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49
Q

Where does the chyme go after the stomach?

A

The small intestine

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50
Q

What does chyme stimulate?

A

Stimulates mucosa cells to realise the hormone choleocystokinin

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51
Q

What does the enzyme choleocystokinin do?

A

It stimulated the gall bladder and pancreas to release bile and digestive enzymes

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52
Q

What type of pH does chyme have?

A

An acidic ph

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53
Q

What does bile contain?

A

Bile salts(acid)

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54
Q

Which enzymes does the pancreases release to aid lipid digestion?

A

Pancreatic lipase and other lipase

55
Q

What does pancreatic lipase do?

A

It breaks down dyglycerides into 2- monoglycerides and fatty acids

56
Q

What do bile salts do?

A

They help emulsify fat droplets thus increasing their surface area for digestion

57
Q

Where does food that hasn’t been digested by the small intestine go?

A

To the large intestine fro excretion

58
Q

Where are bile salts secreted from/

A

The gall bladder

59
Q

What do bile salts contain?

A

Cholesterol among other substance

60
Q

What do bile salts do?

A

Emulsify lipids

61
Q

How do bile salts emulsify lipids?

A

They surround the fat droplets in the chyme and they break the fat droplet into smaller droplets and make their membrane more soluble

62
Q

Describe the structure of bile salts

A

They have a hydrophobic head and hydrophilic tail

The hydrophobic side attaches itself to the lipids and emulsifies it

63
Q

What does pancreatic lipase do to triglycerides?

A

Breaks them down into 2fatty acids and 2-mono-glycerol

64
Q

What stimulates the release of choleocystokinin?

A

The chyme moving from the stomach to the small intestine

65
Q

Where is the hormone choleocystokinin released from?

A

The mucosa cells

66
Q

What is a cholesteryl ester?

A

A cholesterol with a fatty acid attached by an ester linkage

67
Q

Name the enzyme that breaks down cholesteryl esters

A

cholesteryl ester hydrolase

68
Q

What does cholesteryl ester hydrolase do to cholesteryl esters?

A

Breaks them down into cholesterol and 1 fatty acid

69
Q

Name the enzyme that breaks does phospholipids

A

Phospholipase A2

70
Q

What does Phospholipase A2 do to phospholipids?

A

Breaks them down into lysophopholipid and fatty acid

71
Q

Name the enzyme that breaks down lysophopholipid

A

lysophopholipase

72
Q

What does lysophopholipase do to lysophopholipids

A

Breaks them down into a glycerolphosphoryl base and a fatty acid

73
Q

Name drugs used into the treatment of obesity

A

Orlistat or Xenical

74
Q

How do Orlistat and Xenical work/?

A

They work by inhibiting the action of pancreatic lipase

75
Q

What is absorption?

A

Pass through the intestinal wall to the circulatory system

76
Q

A molecule has to be what to be able to pass through the intestinal wall?

A

Has to be water soluble

77
Q

What are micelles ?

A

They are small molecules of digestive triglycerides and phospholipids that aid the absorption of lipids

78
Q

What are micelles surrounded by?

A

Bile salts/ acid

79
Q

Why are micelles important>

A

They aid in the absorption of lipids as they make lipids soluble

80
Q

What are epithelial cells called?

A

Enterocytes

81
Q

What are the 2 sides of the enterocytes

A

The apical border (brushed side) and the basolateral border (smooth side)

82
Q

How do micelles enter the endocytes?

A

Pass through the brush border via simple diffusion

83
Q

What is found outside the endocytes?

A

The lymphatic and vascular circulation

84
Q

What happens to lipids once they enter the endocyte?

A

They re assemble themselves to form triglycerides (which are insoluble)

85
Q

What do the endocytes do to the triglycerides to aid movement out of the cell?

A

The endoplasmic reticulum will package the triglycerides with apopoproteins, phospholipids, and a small amount of cholesterol to form chylomicrons (soluble)
Then this is packaged into a vesicle in the Golgi apparatus

86
Q

By what process do lipids leave the cell?

A

The triglycerides are packaged with apopoproteins, phospholipids and cholesterol to form chylomicrons with are excreted out the cell via exocytosis

87
Q

How do lipids exit the cells?

A

Chylomicrons are formed
On the basolateral side of the epithelial cells there lymph vessels called lacteals that take up chylomicrons and secrete them into the blood

88
Q

Name the substances that form chylomicrons

A

Triacylglycerol + cholesterol + phospholipid + proteins form a lipoprotein complex called a chylomicron which transports the lipids in the circulation.

89
Q

Name the classes of lipoproteins

A 
chylomicrons 
Very Low Density Lipoprotein (VLDL)
Intermedial Density Lipoprotein (IDL) 
Low Density Lipoprotein (LDL)
High Density Lipoprotein (HDL)
90
Q

What are lipoproteins?

A

They are a mixture of lipids and proteins

91
Q

Are chylomicrons made up of predominantly lipids or proteins

A

99% Lipids

1% Protein

92
Q

If a molecule has a high Density Lipoprotein does it have more lipids or proteins?

A

The higher the density the more proteins the molecule has

93
Q

Are VLDLs made up of predominantly lipids or proteins

A

92% lipids

8% protein

94
Q

Are IDLs made up of predominantly lipids or proteins

A

85% lipids

15% protein

95
Q

Are LDLs made up of predominantly lipids or proteins

A

80% Lipids

20% protein

96
Q

Are HDLs made up of predominantly lipids or proteins

A

50% lipids

50% protein

97
Q

Where are Chylomicrons assembled?

A

In the intestinal mucosal cells

98
Q

How do Chylomicrons enter the lymphatic system?

A

Via the thoracic duct

99
Q

Which tissues in the body take up triglycerides, proteins etc?

A

Fat tissue like adipose

100
Q

What are Chylomicrons contain mostly?

A

TAG

101
Q

What is the main function of Chylomicrons?

A

They transport dietary TAG to the adipose tissues where it can be stored as fat or to muscles

102
Q

Where are VLDLs synthesised?

A

By the liver

103
Q

What are VLDLs a product of?

A

The Chylomicrons when they lose a lot of triglycerides

104
Q

What is the purpose of VLDLs?

A

They deliver triglycerides, cholesteryl esters, and cholesterol to peripheral tissues

105
Q

What do VLDLs give rise to and why?

A

Gives rise to IDLs as their triglyceride content is largely depleted at target tissues

106
Q

What are LDLs derived from?

A

Derived from VLDLs and IDLs in the plasma

107
Q

What do LDLs contain ?

A

A large amount of cholesterol and and cholesteryl esters.

108
Q

What is the main role of LDLs?

A

To deliver cholesterol and cholesteryl esters to peripheral tissues

109
Q

What proportion of cholesterol and its ester found in the plasma associated with LDLs?

A

2/3

110
Q

Are VLDLs good for the body?

A

bad

111
Q

What is the general rule of thumb regarding lipoproteins and health?

A

The lower the protein density the higher the risk

so the higher the lipid density the higher the risk

112
Q

Which of the classes of lipoproteins is the smallest?

A

The HDLs

113
Q

What do HDLs play a primary role in in?

A

The removal of excess cholesterol from cells and returning them to the liver

114
Q

What happens to excess cholesterol cells in the liver?

A

They are metabolised to bile acids and salts

115
Q

What do LDLs and HDLS play a major role in?

A

Maintain the cholesterol balance in the body

116
Q

What is a high ratio of HDL to cholesterol associated with/

A

Correlates well with a lower incidence of disease in humans

117
Q

What do blood cholesterol have a high correlation with?

A

atherosclerosis

118
Q

What is known as the bad cholesterol?

A

LDLs

119
Q

What happens if theres a high concentration of LDLs in the body?

A

The LDLs can form fatty deposits in your arteries and damage their lining

120
Q

What can having fatty deposits in your arteries increase your risk of getting?

A

Coronary heart diseases and stroke

121
Q

What is known as the good cholesterol?

A

HDLs

122
Q

Why are HDLs known as the good cholesterol?

A

As they remove other forms of cholesterol from the body

123
Q

What are higher levels of HDLs associated with?

A

A lower risk of heart disease

124
Q

Name some HDLs that are highly recommend to lower the risk of cardiovascular disease?

A

Omega 3 and fish oils

125
Q

Which molecules play a major role in balancing the bodies cholesterol levels?

A

HDLs and LDLs

126
Q

How is Hyperlipidaemia treated?

A

By statins

127
Q

People with type 2 diabetes prescribed

A

statins

128
Q

What is cholesterol synthesised by?

A

synthesised in the liver by a HMG-CoA reductase enzyme.

129
Q

Why are diabetes prescribes with statins?

A

To reduce their risk of getting atherosclerosis and lower the risk of heart attack and cardiovascular diseases

130
Q

How fo stratins work?

A

They are a competitive inhibitor of HMG-CoA reductase as they mimic the natural cholestero and compete for binding to the HMGCoA-R enzyme.

131
Q

What does HMG-CoA reductase do?

A

Synthesises cholesterol

132
Q

What is the natural way or treating high blood cholesterol?

A

By lowering your dietary intake of dietary lipids and fats

And by eating more fibre

133
Q

Why is increasing your fibre content a good way to reduce blood cholesterol ]?

A

As fibres stick to the fats and they are not easily digested

2nd Yr- IBMS (9 decks)

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