Lecture 5 - The Carbohydrates: Sugars, Starches and Fibres Flashcards

1
Q

Why are carbs important?

A

Good (and main) source of energy, especially for our nerve cells

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2
Q

What are the 3 Carbohydrates family?

A

Monosaccharides
Disaccharides
Polysaccharides

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3
Q

What are monosaccharides ?

A

Single sugars

-Glucose, Fructose, Galactose

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4
Q

What are Disaccharides?

A

Pairs of monosaccharides

-Maltose, Sucrose and lactose

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5
Q

What are Polysaccharides?

A

Large chains of monosaccharides

-Usually glucose molecules stuck together

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6
Q

What is the body prime source of energy?

A

Glucose which is a monosaccharide

-also the most abundant sugar we consume

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7
Q

What is the difference between Glucose, Fructose and Galactose?

A

They are all formed of the same items but all differ in their molecular conformations

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8
Q

What is the sweetest monosaccharide?

A

Fructose

-what makes honey sweet

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9
Q

Where would you find galactose?

A

It is not found naturally on its own, it is bound to lactose

-usually called milk sugar

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10
Q

How does galactose split into lactose?

A

Lactase splits the bond between glucose and galactose so you are ingesting both but separately

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11
Q

Where would you find the disaccharide maltose?

A

It is not found in nature, but we do consume products that have been malted.
-it is usually a byproduct of starch digestion

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12
Q

What is the disaccharide sucrose normally referred to as?

A

Table sugar

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13
Q

What 2 monosaccharides make up the 3 disaccharides?

A

Lactose: Glucose + Galactose
Maltose: Glucose + Glucose
Sucrose: Glucose + Fructose

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14
Q

How are disaccharides formed and broken down?

A

Formed through condensation reactions

Broken down through hydrolysis reactions

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15
Q

What are the 3 main polysaccharides of carbs?

A

Glycogen
Stach
Fibre

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16
Q

Which of the 3 polysaccharides are similar?

A

Glycogen and Starch

  • glycogen is the storage form go glucose in animals
  • Starch is the storage form of glucose in plants
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17
Q

Where is glycogen stored?

A

In the liver and in muscle cells as energy reserves

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18
Q

Chemically what does glycogen look like?

A

They are highly branched chains of glucose

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19
Q

Chemically what does starch look like?

A

Long, branched (not as branched as glycogen), and unbranched chains

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20
Q

Where do we find most starches in our diet?

A

Grains, legumes and root crops

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21
Q

What is starch broken down into?

A

Glucose

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22
Q

Chemically what does fibre look like?

A

Since it is the structural component of plants, their chains of glucose are arranged in stackable rows in a complex way that our body doesn’t have the machinery to break it down

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23
Q

What are the 2 forms of fibre?

A

Soluble and Insoluble

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24
Q

What can breakdown fibre in our bodies?

A

Gut bacteria

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25
Q

What are resistant starches?

A

Starches that act as fibres in which they have a hard time being broken down

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26
Q

What is amylose?

A

A straight chain of glucose stuck together

-can be broken down into glucose

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27
Q

What is amylopectin?

A

Is a chain of glucose branched out

-can be broken down into glucose

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28
Q

Where does the digestion of carbs start?

A

In the mouth with an enzyme

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29
Q

What is dietary fibre?

A

The non digestible part of plants (the outsides of plants, nuts seeds and husks)

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30
Q

What is functional fibre?

A

Carbohydrates with known health effects, which is extracted from plants and added to foods

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31
Q

What is pectin?

A

A functional fibre that comes naturally from fruit.

It absorbed water and makes it jelly

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32
Q

What is Psyllium

A

Also a functional fibre that is soluble and turns it into jelly as well

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33
Q

What is total fibre?

A

Functional + Dietary Fibre

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34
Q

What is it meant by soluble fibres?

A

Easily digested by gut bacteria

-Fibres are dissolved in water. Water is absorbed into the fibre forming this gel around it

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35
Q

Where would we find soluble fibres?

A

Citrus fruit, berries, oats and beans

36
Q

Why is it important to have soluble fibres in your diet?

A

Reduces risk for type 2 diabetes, cardiovascular disease

Lowers blood cholesterol and glucose levels

37
Q

What happens when soluble fibres are fermented?

A

They can produce short chain fatty acids

38
Q

What are insoluble fibres?

A

Still absorb water, but do not form the gel around it

39
Q

Where would we find insoluble fibres in our diet?

A

Whole grains, husk of grains and many veggies

40
Q

Why is having insoluble fibres in our body good?

A

They are able to pull water into the digestive tract in order to soften faces

41
Q

How much energy does fibre give us?

A

Not a lot of energy but it is extremely important for our gut health

42
Q

What is something you have to be cautious about when consuming fibre?

A

You must stay hydrated because it is pulling water out of your body

43
Q

Why do we need carbs?

A
fuel daily activity, exercise
Helps preserve (spare) protein for other uses
44
Q

What substance in our body relies solely on carbs as its energy source?

A

Red blood cells rely only on glucose for their energy supply

45
Q

How much energy to you get from carbohydrates?

A

4kcal/ 1 gram

46
Q

What activity requires carbs at more than 2/3 as its source of energy?

A

Intesene exercise, carbs will supply 2/3 or more of the total energy needed

47
Q

Why do we need a sufficient intake of carbohydrates?

A

To prevent the production of ketones and an alternative energy source

48
Q

Why are ketone bodies bad?

A

Excessive ketones can result in high blood acidity and ketoacidosis

  • low pH damages tissue
  • makes you feel sick and not want to eat
49
Q

What does higher fibre foods do to the rate of digestion?

A

High fibre carbs slow down digestion and make you feel full longer
-carbs alone wont keep you full

50
Q

How may fibre decrease blood cholesterol levels?

A

The liver makes bile using cholesterol. Bile is stored in the gallbladder. Bile is secreted into the intestine to air in the digestion of fat.

  • in high fibre diets, the fibre (with gel) binds to bile and is excreted in feces. Results in less cholesterol being reabsorbed from the remaining bile
  • in low fibre diets, less fibre is present to get rid of the bile. More cholesterol is remains which can be reabsorbed into the blood
51
Q

Why is a high fibre diet important in terms of bowls?

A

Not enough fibre= more solid bowls which puts pressure on large intestinal walls which can cause pockets (diverticulosis).

High fibre draws in more water, making feces softer, decreasing pressure on the intestinal walls.

52
Q

What is diverticulitis?

A

When the pockets caused by increased pressure in the large intestinal wall get inflamed
-get inflamed when feces is trapped in the pockets

53
Q

How does digestion of carbohydrates start?

A

Mechanically in the mouth by chewing of food

Chemically in the mouth by the enzyme salivary amylase

54
Q

Is there digestion of carbohydrates in the stomach?

A

No, there are no gastric enzymes to work on digesting the carbs
-too acidic for carb enzymes

55
Q

How are carbs digested in the intestines?

A

In the duodenum,, the pancreas releases pancreatic amylase enzymes to break down carbs
-enzymes keep breaking down carbs into smaller carbs

56
Q

Where are monosaccharides and disaccharides digested in the small intestine?

A

Enzymes secreted by the mucosal cells that line the small intestine
-maltase, sucrase, lactase

57
Q

What is the fate of monosaccharides after they have been absorbed by the small intestinal cells?

A

Monosaccharides are absorbed and then enter the blood stream, to the liver to be converted into glucose to provide immediate energy

58
Q

Where is excess glucose stored?

A

glucose is converted to glycogen and stored in the liver and muscles

59
Q

What adds bulk to stool?

A

When excess fibre passes thought the small intestine undigested and enters the colon, which adds bulk to stools and is extreeted

60
Q

What is lactose intolerance?

A

When you can not absorb the lactose disaccharide.

-Need help to digest and absorb the lactose

61
Q

What is primary lactose intolerance?

A

When you stop making the enzyme that breaks down lactose

  • this is linked to a gene
  • as you get older your body stops making lactase (enzyme)
62
Q

What is secondary lactose intolerance

A

Celiac Disease

  • The lining of the intestines gets destroyed
  • The lining is where the lactase enzyme is made
63
Q

What are symptoms of lactose intolerance?

A

Bloating
Abdominal discomfort
Diarrhea

64
Q

What are some of the causes of lactose intolerance?

A
Some foods 
Medication can cause the destruction of the lining 
Disease affected intestinal villi
Prolonged diarrhea 
Malnutrition
Genetics
65
Q

What happens when we don’t frequently consume milk as adults?

A

We stop making lots of the lactase enzyme

-usually when you stop consuming dairy, you will stop making the enzyme

66
Q

How do you treat lactose intolerance?

A

Lactose free products
Yogurts with bacteria
Hard cheese treated with bacteria

67
Q

What happens when sell don’t need carbs (energy)?

A

If cells don’t need glucose, it is turned into glycogen and stored in the liver and muscles

68
Q

How would you get glucose stored in the liver out?

A

Glycogen stores in the liver would have to be broken down into glucose via hydrolysis in order for glucose to be released into the blood.

69
Q

How would you get glucose stored in muscle out?

A

Protein likes to keep their glucose for itself. Glycogen is broken down in the muscle via hydrolysis so that the glucose can be used by the muscle only.

70
Q

How do you make glucose form protein?

A

Amino acids have to be deaminated. The backbone is used to produce glucose
-this would be classifies as gluconeogenesis

71
Q

How are ketone bodies made from fat?

A

Fat can be a source of fuel when fat fragments join to form ketone bodies. Which is another energy source for the body, but not its favourite
-Ketone bodies cant be an energy source for brain and blood cells

72
Q

What is insulin?

A

Hormones secreted into the blood by the pancreas to help regulate blood glucose levels
-stimulates liver to take up glucose and convert it into glycogen

73
Q

What is glucagon?

A

Hormone secreted by the pancreas to signal the breakdown of glycogen to glucose for cells to take up
-also stimulates gluconeogenesis

74
Q

What is the role of epinephrin and norepinephrine in blood glucose regulation?

A

Secreted by adrenal glands and nerve endings when blood glucose is low

  • this increases glycogen breakdown by liver
  • increases gluconeogenesis
75
Q

What is the role of cortisol and growth hormone in blood glucose regulation?

A

Both secreted by the adrenal gland to act on liver, muscles and adipose tissue

  • cortisol increases gluconeogenesis and decreases use of glucose by other organs
  • growth hormone decreases glucose uptake by muscles and increases mobilization and use of fatty acids, increases livers output of glucose
76
Q

How do we maintain constance blood glucose levels?

A

Having balanced meals at regular intervals and to have proper levels of hormones within the body

77
Q

What is hypoglycaemia?

A

When blood sugar levels are too low

78
Q

What is hyperglycaemia?

A

When blood sugar levels are too high

-results in type 1 and 2 diabetes

79
Q

What is the difference between type 1 and type 2 diabetes?

A

T1: Autoimmune disease in younger people. Insulin is not produced

T2: chronic and developed over time. Usually poor diet choices and not enough exercise

80
Q

What are the symptoms of Type 1 diabetes?

A
Frequent urination
Unusual thirst
Extreme hunger
Unusual weightless
extreme fatigue
Irritability
81
Q

What are the symptoms of Type 2 diabetes?

A
Any of type 1 +
Frequent infection
Blurred vision
Cuts/bruises slow to heal
Numbness in hands and feet
82
Q

Which type of diabetes accounts for about 10% of all cases?

A

Type 1

-% decreasing because of the number of people getting type 2 now

83
Q

What is the glycemic index?

A

Food classification based on glycemic response

-only looking at carbs

84
Q

What is the glycemic response?

A

The speed of glucose absorption, blood glucose levels increasing and speed of return to normal levels

85
Q

What can cause a lower glycemic index?

A

When you consume carbs with something else which causes a slower rise in blood sugar

Different processing of foods

86
Q

What is a low glycemic diet good for?

A

Better for people with type 2
Higher in fibre
may reduce risk of heart disease, colon and prostate cancer