Session 1

Question 1

what is daily energy expenditure?

Answer 1

energy requirements vary between individuals (age, sex, body composition and physical activity)

• energy to support our basal metabolism: BMR
• energy for voluntary physical activities
• energy to process food we eat

a 70kg man would have a daily expenditure of 12,000 kJ

Question 2

what are the essential components of diet?

Answer 2

• Carbohydrates
• Protein
• Fats

Question 3

how do you determine the BMI of a patient?

Answer 3

BMI = weight/(height)2

Question 4

what is obesity?

Answer 4

a chronic condition caused by excess body fat

• greater proportion of fat is distributed in the upper body compared to that of the hips

Question 5

what factors are involved in the regulation of body weight?

Answer 5

1. genetics
2. drug therapy
3. endocrine disorders
4. imbalance in energy intake and energy expenditure

Question 6

what are the clinical consequences of protein and energy deficiency in humans?

Answer 6

marasmus and kwashiorkor

Question 7

what is metabolism?

Answer 7

the chemical processes that occur within living organisms in order to maintain life

• facilitates cell synthesis
• protects internal environments

Question 8

what is energy?

Answer 8

the capacity to do work

Question 9

What happens if there is excess dietary fuel in the body?

Answer 9

• Stored as fat in adipose tissue
• Stored as glycogen in the liver and muscle

Question 10

How do cells get energy?

Answer 10

• ATP - ADP cycle
• the controlled release of energy from ATP in cells is used to perform biological work such as movement

Question 11

What is BMR controlled by?

Answer 11

thyroid hormones

Question 12

How much energy do we get from different components of the diet?

Answer 12

Carbohydrates: 17kJ/g
Fat: 37kJ/g
Alcohol: 29kJ/g
Protein: 17kJ/g

Question 13

Why is fat important in our diet?

Answer 13

1. they have an energy yield 2.2 times greater than carbohydrates/proteins
2. Fat soluble vitamins: ADEK
3. structural components of cell membranes
4. precursors of important regulatory molecules and not synthesised in the body so have to be consumed by the diet

Question 14

what are the BMI ranges?

Answer 14

underweight: below 18.5
healthy weight: 18.5 - 24.9
overweight: 25 - 29.9
obese - 30 - 39.9
severely obese: 40 or above

(clinicians also use waist to hip ratios (if you’re a pair shape = healthy, an apple shape = not healthy) due to distribution of fat on the body

Question 15

what happens if we don’t eat as a method of losing weight?

Answer 15

1. initially weight loss is larger due to water loss
2. starvation associated with reduction in liver and glycogen stores that are required to provide glucose to the brain

Question 16

why is total starvation not preferred?`

Answer 16

1. protein starts to metabolise to increase BGC through gluconeogenesis
2. so lean body mass disappears
3. liver converts fatty acids to ketones used to fuel CNS that can disturb blood pH and lead to dehydration

Question 17

what is marasmus?

Answer 17

type of protein energy malnutrition commonly seen in children under the age of 5

• there are multiple nutritional deficiencies (energy, protein, vitamins and minerals, dehydration)

Question 18

why does marasmus occur?

Answer 18

insufficient energy intake: negative energy balance

• i

Question 19

why does marasmus occur?

Answer 19

1. negative energy balance means the fat stores are mobilised
2. fatty acids used so body fat is lost
3. fatty acids converted to ketone bodies —> used by CNS for energy
4. CNS and RBC cannot use fatty acids — need glucose
5. however not enough glucose from diet (carbs and glucose consumed)
6. glucose released from glycogen stores
7. once this is used up, muscle protein metabolised to release amino acids
8. amino acids undergo gluconeogenesis —> leads to loss of muscle protein

Question 20

what anatomical changes occur in marasmus?

Answer 20

1. severe body fat and muscle mass loss: looks wasted/emaciated
2. unable to replace and repair tissues
3. CV: heart muscle thins, impaired function, bradycardia, hypotension
4. brain affected

Question 21

what are some common symptoms of marasmus?

Answer 21

1. thin, dry hair
2. anaemia
3. diarrhoea

Question 22

what is kwashiorkor?

Answer 22

low protein intake, body needs essential amino acids therefore unable to synthesis some essential proteins

Question 23

what happens to liver function in those with kwashiorkor?

Answer 23

1. liver normally metabolised carbs to fats
2. liver synthesises lipoproteins that transport fat around the blood as it is hydrophobic
3. if liver is unable to produce these proteins due to lack of amino acids as low protein intake —> lipids accumulate in liver and not transported around body
4. fatty liver —> hepatic dysfunction

Question 24

what are some other reasons liver function in those with kwashiorkor is reduced?

Answer 24

• build up of fat
• protein deficiency: not enough amino acids to make albumin/serum proteins
• ingest food with malt —> releases aflatoxins —> interacts with DNA and interferes with gene expression —> liver can no longer synthesis proteins

Question 25

what is the main symptom of kwashiorkor?

Answer 25

oedema

Question 26

what is albumin?

Answer 26

most abundant protein in blood - transports lipids

Question 27

what is oedema?

Answer 27

1. insufficient protein —> liver unable to synthesise albumin and other proteins 2. occurs due to reduced oncotic pressure of plasma causing fluid shifts (lowered albumin reduces osmotic pressure) 3. enlarged liver: hepatomegaly 4. ascites: accumulation of fluid in peritoneal cavity 5. Starling’s law of the capillary

Question 28

what is Starling’s law of the capillary?

Answer 28

1. insufficient amino acids from diet to make proteins such as albumin 2. decreases plasma oncotic pressure 3. increases the flow of fluid from blood capillaries into interstitium (tissue) which leads to swelling

Question 29

what is refeeding syndrome?

Answer 29

- refeeding malnourished patients gradually - rapidly refeeding energy rich foods would rapidly increase blood sugar and insulin resulting in glycogen, fat and protein synthesis - these processes will use phosphate, Mg2+ and K+ from body and lead to electrolyte abnormalities as they are being used up from an already depleted store

Question 30

what is the condition known as an electrolyte imbalance?

Answer 30

hypophosphataemia (refeeding syndrome)

Question 31

how much should you refeed a patient with kwashiorkor?

Answer 31

5-10 kcal per kg/day - gradually increasing over a week

Question 32

why is a symptom of kwashiorkor feeling lethargic?

Answer 32

- low energy intake not meeting requirements - lethargy due to anaemia: inadequate iron and folic acid - can’t make haemoglobin - weak —> muscle wasting

Question 33

why does a cell metabolise nutrients?

Answer 33

1. energy to synthesis cell components 2. building blocks needed for growth, maintenance, repair and division of cell 3. biosynthetic reducing power (NADPH) 4. organic precursor molecules used to allow interconversion of building block molecules

Question 34

what is catabolism?

Answer 34

the breakdown of larger molecules into smaller ones - OXIDATIVE: release large amounts of free energy and produce intermediary metabolites

Question 35

what is anabolism?

Answer 35

smaller molecules built up into larger ones - REDUCTION: use intermediary metabolites and energy produced by catabolism to drive synthesis of cell components

Question 36

how are reduced carrier molecules reoxidised?

Answer 36

1. cell respiration: ETC, where O2 is reduced to water - free energy releases is used to drive ATP synthesis and NAD/FAD can be reused 2. reactions in which substrate is reduced i.e anaerobic respiration where NADH —> NAD and lactic acid is produced

Question 37

what is free energy?

Answer 37

the energy released from an exergonic reaction which is able to do work ( not all the energy released is able to do work as some may appear as a decrease in entropy)

Question 38

what is Gibbs Free energy?

Answer 38

delta G = enthalpy change - temp times delta S

Question 39

where does the energy come from ATP?

Answer 39

energy is released when phosphate group is removed by hydrolysis - only limited amount of ATP so it has to be rapidly re synthesised

Question 40

where does the energy required for ATP to be resynthesised come from?

Answer 40

ATP is resynthesised from ADP using the free energy released by the catabolism of fuel molecules — ATP is not a store but a carrier of free energy

Question 41

what does high energy signal mean?

Answer 41

molecules that signal a cell has adequate energy levels for immediate needs - e.g ATP - activates anabolic pathways

Question 42

what does low energy signals mean?

Answer 42

signal the cell has inadequate energy levels - e.g NAD+, NADP+ and FAD - activates catabolic pathways

Question 43

what is the equation for creatine phosphate production?

Answer 43

creatine + ATP —> creatine phosphate +ADP - reversible reaction in muscles

Question 44

what is creatine phosphate?

Answer 44

a small store of free energy in muscle and cardiac cells that replenishes ATP - important energy source in the first few seconds of vigorous exercise

Question 45

what is creatinine?

Answer 45

- chemical product of creatine and creatine phosphate - no function in body so excreted via urine - excretion of creatinine can indicate skeletal muscle mass - increased excretion of creatinine may indicate active muscle wasting

Question 46

what are examples of trace minerals?

Answer 46

copper, zinc, iodine, selenium

Question 47

what are electrolytes?

Answer 47

sodium, potassium, chloride

Question 48

what would the routine maintenance (through IV) of electrolytes be?

Answer 48

1mmol/kg/day of electrolytes 30ml/kg/day of water

Question 49

why is dietary fibre important?

Answer 49

1. cannot be broken down as we lack enzymes to break beta 1-4 glycosidic bonds 2. reduces cholesterol and helps with digestion 3. reduces cholesterol as it binds to bile salts preventing them from being recycled, therefore stimulates the liver to use cholesterol to produce bile salts

Question 50

how is creatine kinase a good marker of muscle damage?

Answer 50

1. it is dystopia: found in cytoplasm 2. if cell is damaged, CK will be found in blood