diet and digestive anatomy Flashcards
What is nutrition?
study of processes by which body receives and uses materials needed for survival, growth and repair
What are the 3 main purposes of energy from food?
- basal bodily activities
- covering expenditure of energy in simple daily activities
- work activities, energy requirements depend on occupation
With a sedentary lifestyle, what energy requirement is taken as?
BMR x 1.4
What are the essential components of diet?
- carbohydrate (CHO)
- protein
- fat (lipid)
- water
- vitamins – A, D, E, K, B complex, C
- minerals – μg g/day
What is the recommended max. adult daily intake for males and females?
- males → 2500kcal
- females → 2000kcal
Describe proteins in terms of their roles in diet, sources, chemistry and amounts required.
- role: manufacture proteins to make good this tissue loss, growth
- sources: some readily-synthesised others via animal (eggs, meat, fish, milk) and plant (i.e. grains, legumes, vegetables) proteins
- chemistry: chain of AAs
- amounts required: 1g/kg/day
Which amino acids are essential in children?
Hint - TV TILL PM!
Tryptophan, Valine, Threonine, Isoleucine, Leucine, Lysine, Phenylalanine, Methionine and Histidine
Which main disorder is caused by severe protein deficiency where protein intake deficient or main protein source is deficient (e.g. maize lacks tryptophan) and what are its symptoms?
- Kwashiorkor and Marasmus
- symptoms: mental depression, weight loss, oedema as BCOP and plasma albumin lowered, hair/skin problems
- lose N₂ after physical injuries due to increased secretion of adrenocortical hormones
- patients require high-protein, high-energy diets to restore losses
- protein balance = N₂ balance
Describe fats in terms of their roles in diet, sources, chemistry and amounts required.
- role: high-energy value, vehicle for fat-soluble vitamins (A, D, E and K) which contains essential polyunsaturated FAs which cannot be synthesised by tissues (ω-3 and ω-6 linoleic acid) and form prostaglandins
- sources: vegetables (unsaturated) than animal fats (more solid)
- chemistry: mixture of TGs which are triesters of glycerol + FAs
- amounts required: not essential if fat-soluble vitamins and essential FAs supplied
- max daily men = 97g and women = 78g
Which disease can deficiency of essential fatty acids cause and why should we eat more oily fish?
- uncommon disease but may found in patients with severe malabsorption after intestinal surgery; can result in scaling and skin lesions in worst cases
- minimum linolenic acid intake is 0.2% of total energy and ω-6 linoleic acid recommended at 1%
- ω-3 FAs and derivatives reduce TG levels and risk of fatal heart attacks
- 2-3 servings/week oily fish recommended
- interest in dietary fats as contributory factors in coronary heart disease (CHD) and as means to manipulate plasma fat profiles
Describe carbohydrates in terms of their roles in diet, sources, chemistry, amounts required.
- role: energy, protein sparer (preserves functional proteins of cells)
- sources: plant starch (polysaccharides) from vegetables, cereals, pulses and sugars (milk, fruits, table sugar)
- dietary fibre (plants) has complex carbohydrates incompletely digested (i.e. waxes, lignin and non-starch polysaccharides i.e cellulose, β glucan, guar gum and pectin)
- chemistry: C, H, O
- amounts required: enough for ketosis not to occur
What is glycaemic index and why is it important?
- rating system for foods containing carbohydrate
- shows how quicklyeach food affects BGC when its eaten alone
Describe fibre in terms of its role in diet, sources, chemistry, amounts required and deficiency.
- ‘non-starch polysaccharide’
- insoluble fibre - cellulose
- found in seeds, wholemeal flour, wheat bran, brown rice, rolled oats and maize and in pulses (peas, beans, lentils)
- soluble/viscous fibre comes from fruit, veg and pulses (pectin, guar, lignin)
- amounts required: 18g/day or 5 portions fruit/veg
What are the benefits of a diet with plentiful fibre?
• insoluble fibre:
- ‘bulks’ in intestine stimulate peristalsis by distension (dilation) decreasing transit time of faecal material through large intestine
- less water absorbed and constipation avoided
- reduces risk of bowel cancers & diverticulitis (intestine conditions)
• soluble fibre:
- evidence suggests it lowers blood cholesterol and may protect against CV disease
- helps with blood glucose control
What can deficiency of dietary fibre cause?
- may be responsible for many ‘western’ diseases
- especially intestinal malfunction and colonic carcinoma
Describe vitamins in terms of their role in diet and amounts required.
- organic compounds of low MW essential in metabolic processes
- w/o them, characteristic biochemical ‘lesions’ develop
- cannot be synthesised
- different for each vitamin, usually only small amount required
- daily requirement depends on state: increased during growth, high activity, disease, pregnancy and lactation
What are the sources, functions and deficiency diseases of:
a) vitamin A
b) vitamin D
c) vitamin E
d) vitamin K
e) vitamin B complex
f) vitamin C
a)
- sources: liver milk
- functions: β-carotene acts as antioxidant, essential for formation of light-sensitive pigments of retina, regulates osteoblast + clast activity
- diseases: night blindness, slow + faulty development of bones/teeth
b)
- sources: fish-liver oil, egg yolk, fortified milk
- functions: absorption of ca and P, works with PTH to maintain Ca levels
- diseases: rickets, osteomalacia
c)
- sources: fresh nuts, seed, seed, oils, green leafy veg
- functions: inhibits catabolism of FAs to form cell structures, promotes wound healing and CNS regulation, antioxidant
- diseases: haemolytic anemia
d)
- sources: spinach, cauliflower, cabbage, liver
- functions: co-enzyme essential for synthesis of clotting factors by liver (prothrombin),
- diseases: excessive bleeding
e)
- sources: liver, kidney, milk, eggs, cheese, meat
- functions: coenzyme essential for RBC formation, formation of methionine/choline
- diseases: pernicious anaemia, neuropsychiatric abnormalities and impaired osteoblast activity
f)
- sources: citrus fruits, tomatoes, green veg
- functions: promotes protein synthesis, antioxidant
- diseases: scurvy, anaemia, poor collagen formation
Describe minerals in terms of their role in the diet and trace minerals.
- Na, K, Ca, Mg, P, Fe, I₂ and Cl have major role in bodily function
- also, traces of minerals required as catalysts in association w/ enzymes
- trace minerals can include Cu, Zn, Mn, Co, molybdenum, selenium, Cr, Ni, Sn and F
What are the sources, functions and deficiency diseases of:
a) sodium
b) potassium
c) calcium
d) magnesium
e) phosphorus
f) iron
g) iodine
h) chloride
i) copper
j) zinc
k) manganese
l) cobalt
m) selenium
n) chromium
o) fluoride
a)
- sources: salt
- importance: formation of bones + teeth, release of NTs
b)
- sources: most foods (meats, fish, poultry, fruits, nuts)
- importance: generation + conduction of APs
c)
- sources: milk, egg yolk, leafy green vegetables
- importance: formation of bones + teeth, release of NTs
d)
- sources: whole-grain cereals, seafood, leafy green vegetables
- importance: normal functioning of muscle + nervous tissue
e)
- sources: dairy products, meat, fish, nuts
- importance: formation of bones + teeth, buffer system
f)
- sources: meat, liver, egg yolk, beans, legumes, dried fruits
- importance: component of Hb
g)
- sources: seafood
- importance: required for thyroid hormone synthesis
h)
- sources: salt
- importance: acid-base balance
i)
- sources: eggs, beans, liver, fish, spinach, asparagus
- importance: Hb synthesis
j)
- sources: meat
- importance: CO₂ metabolism
k)
- sources: spinach, pineapple
- importance: activates several enzymes
l)
- sources: liver, kidney, milk, eggs, cheese, meat
- importance: part of vit B12 → required for erythropoiesis
m)
- sources: seafood, meat, chicken, tomatoes, egg yolk
- importance: required for thyroid hormone synthesis, sperm motility
n)
- sources: wine, beer
- importance: required for normal activity of insulin
o)
- sources: seafood, tea, gelatine
- importance: improves tooth structure + inhibits tooth decay
What are the problems associated with starvation?
- 25% of BW lost without permanent damage
- rapid weight loss dangerous as it disturbs electrolyte balances (Na, K, Cl)
- these ions important for nerve and muscle function; at worst affect cardiac impulses (HF)
What is obesity?
- a BMI >30 and >20% body fat (M) and >30% (F)
- critical risk factor in development of: type 2 diabetes, hypertension, hyperlipidaemia → major risk factors for CHD
What are hunger, appetite and satiety?
- a sense of emptiness resulting from abstinence from food promoting food-seeking behaviour
- learned phenomenon which is a desire for a specific type of food
- fulfilment of requirement for food, usually from a filling meal, especially if nutritionally sufficient
Explain the regulation of food intake via the feeding centre and satiety centre.
- lateral hypothalamic area contains the feeding centre which when stimulated, causes food intake whether or not required
- ventromedial hypothalamic area contains the satiety centre which, when stimulated, causes cessation of feeding indicating hunger is satisfied
- co-operation between these two centres ensure food intake matches energy requirements
- centres influenced by higher brain areas which can result in starvation/overeating
How is feeding controlled by neural regulation?
- brain stem centres control mechanics of feeding
- hypothalamic feeding + satiety centres control quantity of food intake
- pathways which cause activation not always found within hypothalamus
- pathways activated by changes in body’s nutritional status by presence/absence of food in the body
Describe short-term control of food intake by GI regulation.
- immediate effects of feeding on GI tract
- GI distension may initiate inhibitory signals which suppress activity of feeding centre, thereby reducing
- signals may be nervous, hormonal (ghrelin, CCK) or nutritional
- important in halting feeding during a heavy meal
- mechanism ensures food enters at rate which GI tract can cope with (digestion, absorption and storage)
Describe long-term control of food intake by nutritional regulation.
- required to allow body to maintain constant stores of nutrients for activity changes (i.e. hunger vs satiety), done via:
- glucose availability to the cells (BGC)
- role of adipose tissue which secretes leptin to suppress the appetite by acting on the hypothalamus (‘ob’ gene, amount secreted correlated with body fat, and adipostat feedback system, obesity = reduced brain-sensitivity to leptin)
- thermal effects known as specific dynamic action of food due to metabolic activity as body increases secretory, absorptive processes
(feeding triggered by fall in body temp)
How does the SDA of food effect body temperature and food intake?
- increases body temp. and satiety occurs at same time
- SDA magnitude (like satiety) depends on magnitude of food intake; if well-fed, SDA is greatest and rapid satiety occurs
- food intake affected by environmental temp. (greater in cold climate), therefore closely matched to energy requirement via body temp
Describe the development of the digestive system.
- foregut gives rise to pharynx, lower respiratory system, oesophagus, stomach, duodenum, liver, pancreas and biliary apparatus
- tracheoesophageal septum separates oesophagus from laryngotracheal tube
- stomach develops from dilation of primitive gut
- rotates 90°
What is congenital pyloric stenosis?
- projectile vomiting
- more common in males than females
