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Y1 SEM 1: Medical Cell Biology and Genetics > S16) Nutrition, Diet and Body Weight > Flashcards

S16) Nutrition, Diet and Body Weight Flashcards

1
Q

What is energy?

A

Energy is the capacity to do work

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2
Q

Which five cellular processes occuring in living things require energy to occur?

A
  • Biosynthetic work – synthesis of cellular components
  • Transport work – movement of ions & nutrients across membranes
  • Mechanical work – muscle contraction
  • Electrical work – nervous conduction
  • Osmotic work – kidney
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3
Q

Illustrate the ADP-ATP cycle in terms of energy usage and energy production

A
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4
Q

What is the unit of food energy?

A

Kilojoule (kJ) is official SI unit of food energy

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5
Q

What is a Kcal and how many kJ are found in it?

A

1 Kcal = amount of energy needed to raise temperature of one kilogram of water by one degree Celsius

1 kcal = 4.2 Kilojoules

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6
Q

In terms of nutrition, identify the 7 possible nutrients obtained and the respective functions of each

A
  • Carbohydrates – mostly supplies 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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7
Q

Identify the two types of essential components of the diet

A
  • Macronutrients
  • Micronutrients
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8
Q

Identify some macronutrients

A
  • Proteins
  • Carbohydrates
  • Lipids
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9
Q

Identify some micronutrients

A
  • Vitamins
  • Minerals
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10
Q

Describe the molecular structure of carbohydrates

A

General formula (CH2O)n

  • Contain aldehyde (-C=OH) or keto (-C=O) group
  • Multiple –OH groups
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11
Q

Describe the molecular structure of the following carbohydrate units:

  • Monosaccharides
  • Disaccharides
  • Oligosaccharides
  • Polysaccharides
A
  • Monosaccharides: single sugar units (3-9 C-atoms)
  • Disaccharides: two sugar units
  • Oligosaccharides: 3-12 units e.g. dextrins
  • Polysaccharides: 10-1000’s units e.g. glycogen, starch, cellulose
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12
Q

Identify and describe the seven major dietary carbohydrate molecules

A
  • Glucose: predominant sugar in human blood
  • Maltose: glucose-glucose disaccharide
  • Fructose: fruit sugar (monosaccharide)
  • Sucrose: table sugar (glucose-fructose disaccharide)
  • Lactose: milk sugar (galactose-glucose disaccharide)
  • Starch: carbohydrate storage molecule in plants (polymer of glucose)
  • Glycogen: carbohydrate storage molecule in animals (polymer of glucose)
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13
Q

Describe the molecular structure of proteins

A

Proteins are composed of amino acids joined to form linear chains

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14
Q

20 different amino acids used for protein synthesis in body. However, 9 amino acids cannot be synthesised and must be obtained from diet.

Identify the essential amino acids

A
  • Isoleucine

- Leucine

- Threonine

- Histidine

- Lycine

- Methionine

- Phenylaline

- Tryptophan

- Valine

Mnemonic: If Learned, This Huge List Might Prove Truly Valuable

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15
Q

Arginine is a conditionally essential amino acid.

What does that mean?

A
  • Arginine can be synthesised in the body
  • A dietary supply needed only during periods of active growth e.g pregnancy
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16
Q

Tyrosine is a conditionally essential amino acid.

What does it mean?

A
  • Tyrosine can be synthesised in the body from phenylaline
  • Essential only if the diet is low in phenylaline
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17
Q

Cysteine is a conditionally essential amino acid.

What does this mean?

A
  • Cysteine can be synthesised in the body from methionine
  • Essential only if the diet is low in methionine
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18
Q

In terms of high quality and lower quality proteins, explain why the vegetarian diet must obtain protein from a wide variety of plant sources

A
  • Protein of animal origin considered “high quality” and contain all essential amino acids
  • Proteins of plant origin generally considered “lower quality” since most are deficient in one or more essential amino acids
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19
Q

Describe the molecular structure of lipids

A

Lipids are composed of triacylglycerols (3 fatty acids esterified to one glycerol

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20
Q

Provide four reasons as to why are lipids important to the diet

A
  • Greater energy yield than carbs (2x)
  • Absorption of fat soluble vitamins
  • Structural components of the cell membranes
  • Provides essential fatty acids e.g. linoleic and linolenic acids
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21
Q

Briefly explain the role of vitamins in the body

A
  • Vitamins are essential for life and required in micro- or milligram quantities
  • Deficiency diseases occur if inadequate intake
22
Q

Identify 4 fat soluble vitamins as well as their associated deficiency diseases

A
  • Vitamin A – xerophthalmia
  • Vitamin D – rickets
  • Vitamin E – neurological abnormalities
  • Vitamin K – defective blood clotting
23
Q

Identify 6 water soluble vitamins

A
  • Vitamin C (ascorbic acid) – scurvy
  • Vitamin B1 (thiamin) – beriberi
  • Vitamin B<strong>2</strong> (riboflavin) – ariboflavinosis
  • Vitamin B<strong>3</strong> (niacin) – pellagra
  • Vitamin B6 – dermatitis, anaemia
  • Vitamin B12 – anaemia
24
Q

What is the function of minerals in the body?

A

Electrolytes establish ion gradients across membranes & maintain water balance

25
Identify 5 trace elements in the body
- Fe (Iron) - Zn (Zinc) - I (Iodine) - Cu (Copper) - Mn (Manganese)
26
Identify 5 major minerals in the body
- Na (Sodium) - K (Potassium) - Ca (Calcium) - Cl (Chlorine) - P (Phosphorous)
27
What is dietary fibre and why is it important?
- **Fibre** is non-digestible plant material found in cereal foods *e.g. bread, beans, fruit, veg* * -* Needed for **normal bowel function**
28
Describe the consequences of low fibre and high fibre diets respectively
- **Low fibre** intake associated with constipation and bowel cancer - **High fibre** diet shown to reduce cholesterol and risk of diabetes
29
What is the daily energy expenditure for an average male and female respectively?
- **Energy expenditure of 70 kg male** = `12 000 kJ - **Energy expenditure of 58 kg female** = `9500 kJ
30
Which factors affect the energy requirements in individuals?
- Age - Sex - Body composition - Physical activity
31
Which three measurements compose the daily energy expenditure?
- Basal metabolic rate - Diet-induced thermogenesis (energy required to process food) - Physical activity level
32
What is basal metabolic rate?
**BMR maintains the resting activities of the body:** - Maintenance of cells - Function of organs - Maintenance of body temperature
33
Which factors affect BMR?
- **Body size:** surface area - **Gender**: males higher than female - **Environmental temperature:** increases in cold - **Endocrine status:** increased in hyperthyroidism - **Body temperature:** 12% increase per degree
34
Voluntary physical activity reflects the energy demands of which muscles?
- Skeletal muscle - Heart muscle - Respiratory muscles
35
Explain how the relationship between energy intake and energy expenditure influence body weight
- **Energy intake = expenditure** → body weight stable - **Energy intake exceeds expenditure** → energy stores (fat) will increase - **Energy expenditure exceeds intake** → energy stores deplete
36
What is BMI and how is it calculated?
**BMI** is a simple way to estimate one's desirable body weight ## Footnote **BMI = weight (kg)/height (m) 2**
37
Identify the 5 categories for BMI (including ranges)
38
What is waist to hip ratio?
**Waist to hip ratio** is when the waist circumference is measured divided by the hip circumference to give a ratio
39
Why is waist to hip ratio a preferred measurement of ideal body weight?
It is increasingly used as a better measure of obesity and risk of CVD
40
What classifies as obese in waist to hip ratio measurements?
- Males \> 0.9 - Females \> 0.85
41
What is obesity?
**Obesity** is a chronic condition characterised by excess body fat and is most often defined on the basis of Body Mass Index (BMI)
42
What does body weight in most adults depend on?
The balance between energy **intake** and energy **expenditure**
43
Identify 3 other factors which contribute to weight gain
- Genetics - Drug therapy - Endocrine disorders
44
Identify 5 diseases which obese people are at increased risk of developing
- Insulin resistance - Hyperlipidaemia - Stroke - Diabetes Type II - Hypertension
45
What is marasmus?
**Marasmus** is a type of protein-energy malnutrition most commonly seen in children \< 5
46
Identify 5 signs and symptoms of marasmus
- Emaciated - Muscle wasting - Thin & dry hair - Diarrhoea - No oedema
47
What is kwashiorkor?
**Kwashiorkor** is a disease which occurs typically in a young child displaced from breastfeeding and fed with a high carbohydrate, very low protein diet
48
Identify 5 signs and symptoms of kwashiokor
- Anaemic - Lethargic - Anorexic - Generalised oedema - Low serum albumin
49
In four steps, explain why kwashiorkor leads to the development of oedema
⇒ Distended abdomen due to **hepatomegaly** and **ascites** ⇒ **Insufficient amino acids** for albumin production by the liver ⇒ Reduction in blood proteins decreases **plasma oncotic pressure** ⇒ Fluid moves from capillaries into the **interstitium**
50
What are malabsorption conditions?
- **Malabsorption conditions** are caused by the failure to digest and/or absorb ingest nutrients e.g. Coeliac disease and Crohn's disease - Under-nutrition may result from eating disorders like anorexia and bulimia nervosa or from reduced availability of food such as in developing countries

Y1 SEM 1: Medical Cell Biology and Genetics (23 decks)

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