Lecture 1 - Nutrition Flashcards
What are the essential components of a diet?
- Carbo: energy
- Protein: energy & a/a
- Fat: energy & f.a
- Minerals
- Vitamins
- Water: hydration
- Fibre: normal GI function
How does fibre maintain normal GI function?
- Fibre reduces plasmic cholesterol/reduce risks of bowel cancer
- Binds to bile salts in GI tract and removed in faeces
(Bile salts are recycled by liver, but if fibre binds to it–> make more–> more cholesterol removed)
Why isn’t cellulose digested by the body?
- Cellulose-β-1,4 sugar link X digested by body, lack enzymes
N.B Glucose is α-1,4
What are the 9 essential amino acids?
If - Isoleucine (glucogenic) Learned - Lysine (ketogenic) This - Threonine Huge - Histidine List - Leucine May - Methionine Prove - Phenylalanine Truly - Tryptophan (both) Valuable - Valine
Children and pregnant women have higher rate of protein synthesis. Which a/a do they need more of?
Arginine, Tyrosine & Cysteine
not essential a/a but CONDITIONALLY essential
What are some examples of essential fatty acids?
Linoleic & Linolenic
What is the importance and some examples of minerals?
- Establish ion gradients across membranes
- Ca & K: bone structure
- Ca: Hormone secretion, muscle contraction, exocytosis, nerve conduction
What are some nutrient requirement guidelines?
*values depend on age, gender and physical activity
- RNI (Reference Nutrient Intake): for protein,vitamins & minerals
- EAR (Estimated Average Requirement): for energy
- LRNI (Lower Reference Nutrient Intake)
How are the nutritional guidelines calculated?
- Plot frequency over nutrient requirement bell curve
- 1st decile= LRNI, mean= EAR, 3rd decile= RNI
(decile within 2 s.d of mean)
LRNI: enough for small amount of ppl who have low requirements
RNI: 97.5% needs met
What factors are involved in the regulation of body weight.
Age, Sex, Body Comp, Physical activity
What is the moderate physical activity of a 70kg adult male and a 58kg adult female a day?
- Male =12,000 kJ/day
- Female= 9,500 kJ/day
What is the basal metabolic rate (BMR) and how is it calculated?
- Energy required to maintain resting activities of body:
i) maintenance of cells
ii) function of organs
iii) maintain body temp - Calculation: weight in kg x 100
What are some factors that affect BMR?
- Body size
- Gender
- Environment temperature
- Body Temp. (12% increase per degree)
- Endocrine regulation
What is voluntary physical activity?
- Energy required by skeletal, respiratory and cardiac muscle for voluntary contraction
What are the rough values of voluntary physical activity of a sedentary person, moderate activity and very active?
- Sedentary: 30kJ/Kg/day
- Moderate: 65 kJ/Kg/day
- Active: 100kJ/Kg/day
What is obesity?
- Excessive fat accumulation in adipose tissue
- BMI (>30)
How to calculate BMI and what are its ranges?
- Weight (kg)/ Height (m)^2 (units kg/m^2)
- Range same for both sexes
1. Underweight: <18.5
2. Optimal weight: 18.5-24.9
3. Overweight: 25-29.9
4. Obese: 30-34.9
5. Severely Obese: >35
Suggest an alternative way to measure whether very muscular individuals other than BMI
- Waist:Hip
- Obese: Men >0.9, Women >0.84
What risks are increased abdominal fat associated with?
- Insulin resistance
- Hyperinsulinism
- Type 2 DM
- Hypertension
- Hyperlipidaemia
- Stroke
- Premature Death
What is marasmus? State symptoms and signs.
usually children under 5
- Protein-energy malnutrition
- Emaciated appearance
- Muscle wasting
- Loss of body fat, no oedema
- Thain and dry hair
- Diarrhoea
- Anaemia
What is kwashiorkor and its symptoms? When does it occur?
- Occurs when a young child is displaced off breastfeeding and replaced with carbo. but low protein diet (cassava)
- Symptoms:
1. Child is disinterested, lethargic and anorexic
2. Generalised/Pitting oedema
3. Abdomen is distended (hepatomegaly)
4. Serum albumin low
5. Anaemia common
Why does oedema occur in kwashiorkor?
- Low protein diet –> insufficient a.a–> decrease plasma oncotic pressure –> ⬆️net flow of fluid from capillaries to I.F–> oedema
What is refeeding syndrome and when does it occur?
- Rapid refeeding of energy rich foods in starved/malnourished patients
- Result in rapid increase in BG–> increase protein synthesis–> utilise phosphate,Mg,K (depleted)–> electrolyte abnormalities (hypophosphatemia)
What should be done to prevent refeeding syndrome and what are its risk factors?
- Re-feed 5-10kcal a day. Raise gradually to full needs.
- Risk factors:
1. BMI (<16)
2. Unintentional weight loss of >15% in 3-6 months
3. 10 days with no/little nutritional intake
What is the difference between catabolic & anabolic pathyways?
C:
- Break down large –>small
- Release large amounts of free energy
- Oxidative
- Provide reducing power (H)
A:
- Small –> large
- Use ATP frm C
- Reductive
Define cell metabolism
Process which derives energy from food–> growth, repair and activity of tissues–> sustain life
What is the function of catabolic metabolism?
- Form block materials (glucose, a.a, f.a): for cell growth/division/repair
- Form organic precursor molecules (acetyl coA)
- Produce reducing power (NADH, NADPH)
- Energy (ATP)
Why do cells need a continuous supply of energy?
- Synthesis of cellular components
- Transport work: maintenance of ion grad.
- Muscle contraction, NI conduction
- Energy intake = daily energy expenditure
What is the role of a redox reaction?
- Removal of electrons or H atoms (oxidation) followed by reduction reaction –> energy production
What is the role of H-carrier molecules and some examples of it are?
- NADP, NAD, FAD
- Act as carriers for reducing power, allow–> ATP production and biosynthesis (NADPH)
- Total conc of carriers is constant
What are the purposes of high and low-energy signals?
High: Activate anabolic pathways
- ATP
- NADH
- NADPH
- FAD2H
Low: Activate catabolic pathways
- ADP, AMP
- NAD+
- NADP+
- FAD
What is the enzyme that catalyses:
2ADP–> ATP + AMP (low energy signal)
Adenylate kinase
What is the function of creatine phosphate?
- When ATP levels are high, creatine–> c. phosphate
[ATP–>ADP] - When ATP is low creatine phosphate –> creatine [ADP–>ATP]
- Catalysed by creatine kinase
What is a marker of myocardial infarction? Why?
- Creatine Kinase
- CK is released from damaged cardiac myocytes
What is used as a marker for muscle mass or kidney function? Why?
- Creatinine (Breakdown product of creatine/c.p)
- Produced at a constant rate
- Creatinine in urine = marker for urine dilution
Explain the clinical consequences of severe protein deficiency in children.
- Lead to inadequate intake of essential a.a–> reduced protein synthesis/ nitrogen containing compounds
- Growth failure
- Impaired physical development (tiredness, weakness)
- Impaired mental development
- Negative nitrogen balance
- Oedema due to reduced serum albumin
- Increase risk of infection due to reduced immunoglobulins
- Anaemia reduced Hb
- Fatty liver due to reduced lipoprotein
Explain the biological role of ATP
- Energy currency: immediate and main source of energy for most cells
- Free energy available when fuel sources are metabolised used to make ATP
- Energy release through hydrolysis
ATP –> ADP + Pi
Explain the biological role of creatine phosphate
- Small store of free energy
- Important in first few seconds of muscle contraction
- Form ATP
