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LS1 Metabolism > L2 - Nutrition, body weight and homeostasis > Flashcards

L2 - Nutrition, body weight and homeostasis Flashcards

1
Q

List the essential components of the diet

A 
Carbohydrates - mostly supply energy
Protein - energy and amino acids
Fat - energy and essential fatty acids
Minerals - essential
Vitamins - essential
Water - maintains hydration
Fibre - necessary for normal GI function
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2
Q

Define energy

A

The capacity to do work

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3
Q

What type of energy does the body use?

A

Chemical bond energy

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4
Q

Describe types of work the body requires energy for

A

Biosynthetic work - synthesis of cellular components
Transport work - movement of ions and nutrients across membranes
Mechanical work - muscle contraction
Electrical work - nervous conduction
Osmotic work - kidney

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5
Q

Name four main substances that the body oxidises to produce energy

A

Lipids
Carboydrates
Protein
(Alcohol)

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6
Q

What is the standard unit of food energy?

A

Kilojoule (kJ)

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7
Q

What are the major dietary carbohydrates?

A 
Starch - glucose polymer from plants
Sucrose - glucose-fructose disaccharide
Lactose - galactose-glucose disaccharide
Fructose - monosaccharide
Glucose - predominant sugar in human blood
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8
Q

How many amino acids are used for protein synthesis in the body?

A

20

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9
Q

List the 9 essential amino acids

A 
If - isoleucine
Learned - lysine
This - threonine
Huge - histidine
List - leucine
May - methionine
Prove - phenylalanine
Truly - tryptophan
Valuable - valine
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10
Q

What is meant by conditionally essential amino acids?

A

Their synthesis can be limited under special pathophysiological conditions such a pregnancy and children have a high rate of protein synthesis and also require some tyrosine and cysteine in their diet

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11
Q

Which vitamins are fat soluble - require fat for absorption from the gut?

A

K
A
D
E

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12
Q

Name two essential fatty acids?

A

Linoleic and linolenic

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13
Q

What are the functions of minerals in the body?

A
  1. Electrolytes establish ion gradients across membranes and maintain water balance
  2. Ca and K essential for structure (bone and teeth)
  3. Ca is a very important signalling molecule
  4. Enzyme co-factors (Fe, Mg, Mn, Co, Cu, Zn and Mb)
  5. Fe is an essential component of haemoglobin
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14
Q

What are the functions of vitamins in the body?

A

Essential for life. Deficiency causes diseases

E.g. Vit K deficiency - defective blood clotting

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15
Q

What type of foods is fibre found in?

A

Cereal foods - bread, beans, fruit and veg

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16
Q

Name four type of fibre

A

Cellulose
Lignin
Pectins
Gums

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17
Q

What is the function of fibre?

A

It cannot be broken down by human digestive enzymes but is essential for the normal functioning of the GI tract

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18
Q

What are the associations of a low fibre diet

A

Constipation and bowel cancer

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19
Q

What can a high fibre diet reduce?

A

Cholesterol and the risk of diabetes

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20
Q

Daily energy expenditure is the sum of which three processes?

A

Basal metabolic rate (BMR)
Diet-induced thermogenesis (DIT- energy required to process food)
Physical activity level (PAL)

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21
Q

What is the BMR?

A

Maintains resting activities of the body: maintenance of cells, functions of organs and maintaining body temperature

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22
Q

What factors affect the BMR

A

Body size
Gender
Environmental temperature
Endocrine status (increased in hyperthyroidism)
Body temperature (12% increase per degree)

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23
Q

Define voluntary physical activity

A

Energy required depends on intensity and duration of activity. Reflects energy demands of:
Skeletal muscle
Heart muscle
Respiratory muscles

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24
Q

How much energy is burnt by sedentary, moderate and very active activity per day?

A

Sedentary person - 30 kJ/Kg/day - BMR+30% of BMR
Moderate activity - 65 kJ/ Kg/ day - BMR+60-70% of BMR
Very active - 100kJ/Kg/ day - BMR+100% BMR

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25
Q

Define obesity

A

Excessive fat accumulation in adipose tissue which impairs health. Usually measured using BMI > 30.

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26
Q

Obesity is assoicated with an increased risk of developing whihc diseases?

A

Some cancers, cardiovascular disease and type 2 diabetes.

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27
Q

Calculate the BMI of a person who weighs 60Kg and is 150cm tall

A 
BMI = (weight Kg/ (height m)^2)
BMI= 26.7
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28
Q

What is the use of BMI?

A

Used clinically to evaluate patients weight. It shows good correlation with body fat measurements. The major weakness of it is with very muscular individuals who at be wrongly classified as obese.

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29
Q

What is an alternative to BMI that can be measured?

A

Waist/ hip ratio. There is evidence that distribution of fat is clinically important.

30
Q

Greater proportion of fat in the upper body (especially abdomen), compared with that on hips is associated with an increased risk of:

A 
Insulin resistance
Hyperinsulinism
Type 2 diabetes
Hypertension
Hyperlipidaemia
Stroke
Premature death
31
Q

What three ways can malnutrition harm the body?

A
  1. Damage from low energy intake
  2. Deficiency diseases of other nutrients
  3. Oedema: low protein intake can lead to low blood protein synthesis and a decrease in plasma oncotic pressure - Kwashiorkor
32
Q

Define homeostasis

A

The control of the internal environment within set limits and is a dynamic equilibrium rather than a fixed state. Homeostasis underpins physiology and a failure in homeostasis leads to disease.

33
Q

Describe the four components to homeostatic control mechanisms

A
  1. Sensing component (monitor and responds to change)
  2. Control centre (sets range which a variable is contolled within and determines appropiate response)
  3. Effector ( brings about desired change)
  4. Negative feedback (corrects the deviation)
34
Q

What type of reaction has a greater output than input of energy?

A

exergonic

35
Q

What type of reaction has a greater input than output of energy?

A

Endergonic

36
Q

Reactions in the body require an input of energy are driven by coupling to reactions that release energy. What molecule is usually coupled to reactions to release energy?

A

ATP via the ATP-ADP cycle

37
Q

What energy usage is ATP required for?

A 
Ion transport
Muscle contraction
Biosynthesis
Thermogenesis
Detoxification
38
Q

In individuals who are not obese, how can you estimate their basal metabolic rate?

A

BMR= 100 x weight in Kg

39
Q

What is the main controller of BMR?

A

Thyroid hormones

40
Q

Why is the BMR lower in women than men?

A

Women have more adipose tissue which is less metabolically active than lean tissue.

41
Q

What increases the BMR?

A

Excessive secretion of thyroid hormones (hyperthyroidism), pregnancy and lactation.

42
Q

Why does our metabolic rate increase following the ingestion of food?

A

Because energy is required to digest, absorb, distribute and store nutrients. This energy (diet-induced thermogenesis (DIT)) is approximately 10% of the energy content of the ingested food.

43
Q

Describe a healthy diet

A

A diet which contains sufficient fat and carbohydrate to satisfy the body’s energy requirement, and which provides the minimal amount of protein, vitamins, minerals and water to prevent deficiency.

44
Q

Why is glucose not an absolute requirement in our diet, since the brain and red blood cells require a constant supply of it?

A

Because glucose can be obtained from other sources: glycerol released from the hydrolysis of triacylglycerol (fat) and gluconeogenesis from certain amino acids. It can also be synthesised from dietary sugars such as galactose and fructose.

45
Q

The body does not have an absolute requirement of fat as an energy source, therefore why are fats important in our diet?

A
  1. They have an energy yield 2.2. x greater than carbohydrates or proteins - means we can eat less
  2. Necessary for absorption of fat-soluble vitamins (K,A,D,E)
  3. Essential fatty acids (notably linoleic and linilenic acids) are structural components of cell membrane and precursors of important regulatory molecules (eiosanoids) and cannot be synthesised in the body - they must be consumed in the diet.
46
Q

Why must amino acids be obtained from the diet to remain in zero nitrogen balance?

A

Their is a continuous turnover of tissue protein. Most of the amino acids are reused to synthesise more protein but approximately 35g/day is lost by further degradation.

47
Q

What happens to the nitrogen balance during:

  1. Growing children
  2. Pregnancy
  3. Starvation/ tissue wasting diseases
A

1 and 2 require more protein for growth, therefore normally show a positive nitrogen balance.
3. In starvation and tissue wasting diseases the nitrogen balance may be negative.

48
Q

Why may a protein deficiency disease follow a vegetarian diet based solely upon cereals?

A

Wheat for example, is low in lysine (an essential amino acid).

49
Q

How is water lost from the body?

A

Mainly urine, but also in expired air, through the skin and in faeces.

50
Q

How does water enter the body?

A

Drinking and partly from production in cellular metabolism.

51
Q

What is the average water loss from the body?

A

Approximately 2.5L/day

52
Q

Which minerals have important anti-oxidant properties in the body?

A

Vitamin C
Vitamin E
Selenium

53
Q

If you were underweight what would your BMI look like?

A
54
Q

If you were in the desirable range, what would your BMI look like?

A

18.5-24.9

55
Q

If you were overweight what would your BMI look like?

A

25-29.9

56
Q

If you were obese what would your BMI look like?

A

30-34.9

57
Q

If you were severely obese what would your BMI look like?

A

> 35

58
Q

How does WHO defined abdominal obesity based on the hip to waist ratio?

A

Males > 0.9

Females > 0.85

59
Q

What diseases are excess body fat associated with?

A 
Increased risk of:
Hypertension
Heart disease
Stroke
Type 2 diabetes
Certain cancers
Gall bladder disease
Osteoarthiritis
60
Q

Why when dieting is a large initial weight loss seen, which then slows down to a steady rate?

A

Initially starvation is met by a reduction in liver glycogen stores that are required to provide glucose for the brain. The glycogen stores contain more water than fat, and this water loss creates a rapid weight reduction. As these glycogen stores are lost, the weight loss slows to the theoretical maximum as fat is mobilised.

61
Q

Why is starvation not a preferred method of weight loss?

A

Protein loss occurs due to protein metabolism for gluconeogenesis, so after a relatively short time lean body mass begins to disappear.
Also, the liver begins to convert fatty acids into ketone bodies for use as a fuel by the CNS, but they can disturb blood pH and lead to dehydration.

62
Q

Who does The Eatwell Plate not apply to?

A

Everyone but children under two, some people with special dietary needs and those that are malnourished with specific dietary needs.

63
Q

What is used in the University Hospitals of Leicester NHS Trust to screen for malnutrition?

A

Malnutrition Universal Screening Tool (MUST), which is the only recognised evidence-based tool.

64
Q

Screening for malnutrition should be carried out by health care professionals with appropriate skills and training and should take place for which groups of people?

A

All people on registration at GP surgeries
All people in care homes on admission
All hospital inpatients on admission
All outpatients at their first appointment

65
Q

Define malnutrition

A

Any in-balance between what an individual eats and what that individual requires to maintain health. This can be over-nutrition and under-nutrition and may also be caused by an imbalance in nutrients.

66
Q

What are causes of under-nutrition?

A
  1. Eating disorders: anorexia nervosa and bulimia nervosa
  2. More commonly from reduced availability of food.
    Reduced availability of food in many developing countries produces the condition known as protein-energy malnutrition.
67
Q

What are two types of protein-energy malnutrition?

A

Marasmus and Kwashiorkor.

68
Q

What are the signs and symptoms of Marasmus?

A

Most commonly seen in children under 5.
Emaciation, obvious signs of muscle wastage, loss of body fat, NO OEDEMA, thin dry hair, diarrhoea is common and anaemia may be present.

69
Q

What are the signs and symptoms of Kwashiorkor?

A

Typically occurs in a young child displaced from breastfeeding and fed a diet with some carbohydrate but very low proteins, such as cassava.
Apathy, lethargy, anorexic (loss of apetite), generalised oedema, distended abdomen due to hepatomegaly and/or ascites. Serum albumin is always low and anaemia is common.

70
Q

A man with a BMI of 19kg/m2 is underweight, desirable weight, overweight, obese or severely obese?

A

Under 18.5kg/m2 is underweight
Over 25kg/m2 is overweight
Therefore he is of desirable weight

71
Q

A man with a BMI of 40kg/m2 is underweight, desirable weight, overweight, obese or severely obese?

A

18.5-24.9kg/m2 is desirable weight
25-29.9kg/m2 is overweight
30-34.9kg/m2 is obese
He is over 35kg/m2 and therefore is severely obese

72
Q

A woman has a body mass index of 26. Which classification for weight does she fall under?

A

Desired range 18.5-24.9kg/m2
Overweight 25-29.9kg/m2
Therefore she is overweight

LS1 Metabolism (18 decks)

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