food and nutrition 100-end is digestion and absorption Flashcards
what are some of the reasons why we need to eat
growth, repair, replace, reproduce, optimal function including brain, muscle and immunity
what are the 5 components of the eat well plate
fruit and veg
carbohydrates - bread, rice, potatoes, pasta
dairy - milk, cheese, yoghurt
high fat and sugar - cake, crisps, coke, chocolate
protein - meat, fish, beans, eggs
what is a approximate energy value (cals/g) of carbohydrates
4cals/g
what is a approximate energy value (cals/g) of protein
4cals/g
what is a approximate energy value (cals/g) of fat
9cals/g
what is a approximate energy value (cals/g) of alcohol
7cals/g
what are macromolecules
big molecules - carbohydrates, lipids, proteins, nucleic acids
macromolecules are polymers, what are the subunits called
monomers
what reaction connects monomers together
dehydration reaction - water produced as a by product
what reaction disassembles polymers
hydrolysis
what are carbohydrates
sugars and polymers of sugars
what are the simplest carbohydrates
monosaccharides - monomers - they are on single unit
what are disaccharides
double sugars - consist of two monosaccharide sugars joined together by a covalent bond - 2 monomers
what are polysaccharides
carbohydrate macromolecules, composed of many monomers - they have more than 8 sugar monomers
what are oligosaccharides
carbohydrates composed of 3-8 sugar monomers
which type of carbohydrate is a major nutrients for cells
monosaccharides e.g. cellular respiration
what joins 2 monosaccharide subunits together
glycosidic linkage - a covalent bond
which sugars are digestible by humans
starch:
amylose
amylopectin
monosaccharides: glucose fructose mannose ribose deoxyribose
disaccharides: sucrose lactose maltose trehalose
which sugars aren’t digestible by humans
oligosaccharides: raffinose stachyose verbascose fructans
sugar alcohols: sorbitol mannitol dulcitol inositol
cellulose
there are 2 classes of sugars: intrinsic and extrinsic. How do they differ
Intrinsic sugars are naturally occurring sugars whereas extrinsic sugars are added to foods
when is glucose released from glycogen stores
when the body is in a fasted state
what type of carbohydrate can’t be digested by brush border enzymes
fructo-oligosaccharides (pre biotics)
where are fructo-oligosaccharides fermented
in the colon
is dietary fibre digestible in the small intestine
no
where is dietary fibre digested
fermented by bacteria in the large intestine
what is the role of dietary fats in the body
store of energy
provide essential fatty acids
help carry fat soluble vitamins
what are the roles of lipids in the body
store of energy
structural role in cell membranes
metabolic functions
what types of molecules do lipids form
fats
phospholipids
steroids
are fats polymers
no, they are just large molecules assembled from smaller molecules - glycerol and fatty acids
what functional group do fatty acids have
carbonyl at one end of the hydrocarbon chain
what structural factors affect fatty acids
number of carbon atoms in the hydrocarbon chain presence of double bonds -saturated and unsaturated fatty acids -cis and trans isomer -position of double bond
what dies monosaturated mean
the molecule has one double bond
what does polyunsaturated mean
the molecule has multiple double bonds
what is a cis isomer of a fatty acid
when the H atoms are on the same side of the double bond
what is a trans isomer of a fatty acid
when the H atoms are on opposite sides of the double bond
what are the main characteristics of essential nutrients
they cannot be synthesised in the body
must be included in the diet or a deficiency disease occurs
are essential for the body
when glycerol and fatty acids join together what bond is formed
an ester link
what are the roles of essential fatty acids
formation of cell membranes
growth
development
biologically active compounds
until which carbon is the body unable to synthesise double bonds
9th carbon
How do we get all of the essential amino acids
by consuming a large variety of proteins so that they can be broken down into amino acids
what are vitamins
Essential organic substances that occur in food in small amounts and are necessary for the normal functions of the body
can vitamins be synthesised by human cells
no
which vitamins are water soluble
B and C but they are not stored in the body
which vitamins are fat soluble
A,D,E and K - they are stored in fat
name 7 types of vitamin B
thiamine riboflavin niacin folate biotin pantothenic acid B6
what coenzymes are made of riboflavin
FAD and FMN
what are the dietary sources of riboflavin
dairy products, meats, enriched grains and veg
what are the symptoms of riboflavin deficiency
skin lesions
what are the major functions of thiamine
it forms a coenzyme that removes carbon dioxide from organic compounds
it is also involved in the production of ribose
what are the main dietary sources of thiamine
pork, legumes, meat, wholegrains
what are the symptoms of deficiency of thiamine
beriberi (tingling, poor coordination, reduced heart function)
what are the main dietary sources of niacin
nuts, meat, grains
what are the major functions of niacin
component of NAD and NADP - therefore essential for metabolism
what are the symptoms of niacin deficiency
pellagra (skin and gastrointestinal lesions, delusions and confusion)
what are the main dietary sources of pantothenic acid
meat, dairy, wholegrains, fruit and veg
what are the main functions of pantothenic acid
is a component of coenzyme A
what are the symptoms of deficiency of pantothenic acid
fatigue, numbness, tingling very rare deficiency
what is the main food source of vitamin B6 (pyridoxine)
meat, veg, wholegrains - synthesised by colonic bacteria
what are the main functions of vitamin B6
it is a component of a coenzyme used in amino acid metabolism
what are the symptoms of deficiency of vitamin B6
irritability, convulsions, muscular twitching, anaemia
what are the main dietary sources of biotin
legumes, other veg and meats
what are the main functions of biotin
part of the coenzyme in the synthesis of fat (lipogenesis) , glycerol (gluconeogenesis) and amino acids
what are the symptoms of biotin deficiency
scaly skin inflammation, neuromuscular disorders - very rare deficiency
what are the main food sources of folate
green veg, oranges, nuts legumes, wholegrains
what are the main functions of folate
coenzyme in nucleic acid and amino acid metabolism
what are the symptoms of folate deficiency
anaemia, birth defects
what are the main dietary sources of vitamin c (ascorbic acid)
citrus fruits, broccoli, tomatoes
what are the main functions of vitamin c
used in collagen synthesis; it is an antioxidant
what are the symptoms of vitamin C deficiency
scurvy(degeneration of skin and teeth), delayed wound healing
what are the main dietary sources of vitamin A (retinol)
dark green and orange veg and fruits, dairy products
what is the main function of vitamin A
component of visual pigments - formation of visual purple; maintenance of epithelial tissues; promotion of bone remodelling
what are the symptoms of vitamin A deficiency
blindness, skin disorders, impaired immunity
what are the symptoms of vitamin A overdose
anorexia, irritability, tender bones, enlarged liver and bones, double vision
what does vitamin A being teratogenic mean
high doses can harm the foetus
what is the main food source of vitamin E
veg oil, nuts, seeds
what are the main functions of vitamin E (tocopherol)
antioxidant; helps prevent damage to cell membranes
what are the symptoms of vitamin E deficiency
nervous system degeneration
what are the main food sources of vitamin K
green veg, tea - its also made by colon bacteria
what are the main functions of vitamin K
Important in blood clotting; catalyses synthesis of prothrombin in liver factors
what are the symptoms of vitamin K deficiency
defective blood clotting
or can be found in infants born with a sterile gut
what are the main food sources of vitamin D
dairy, egg yolk
what are the main functions of vitamin D
aids in absorption and use of calcium and phosphorus
what are the symptoms of vitamin D deficiency
rickets (bone deformities) in children, bone softening in adults
lack of enamel calcification
what are the symptoms of vitamin D overdose
deposits of bone in soft tissue
what are dietary minerals
inorganic nutrients such as iron and sulphur, usually required in small amounts
what are the main dietary sources of calcium
dairy, dark green veg, legumes
what are the main functions of calcium
bone and tooth formation, blood clotting, nerve and muscle function
what are the symptoms of calcium deficiency
impaired growth; loss of bone mass; increased risk of osteoporosis
when calcium is absorbed what vitamin must bind to it first.
vitamin D
which hormone increases calcium incorporation into bone
oestrogens
lactose and citric acid increase the absorption of which mineral
calcium
fat decreases the absorption of which mineral
calcium
what are the main dietary sources of iron
meat, eggs, wholegrains, green leafy veg, legumes
what are the main functions of iron
component of haemoglobin, haem protein, myoglobin, iron containing enzymes and electron carriers; enzyme cofactor
what are the symptoms of iron deficiency
iron deficiency anaemia, weakness, impaired immunity
which vitamin increases iron uptake
vitamin c
iron uptake is inhibited by which mineral
calcium
what are the most likely causes of iron deficiency
blood loss
weaning in babies
veganism
menstrual loss
which mineral has low bioavailability
iron - only 10-30% is absorbed
what are the main functions of salivary secretions
maintain healthy oral tissues start digestion of carbohydrates contribute to digestion of fats provides mucous keeps mouth moist
what is the pH of amylase
6.9
what bonds can salivary amylase break
1,4 glycosidic bonds
salivary lipase is able to work without what
bile
as well as salivary lipase where else is lipase found
the stomach
what does lipase break down
triglycerides into fatty acids
salivary lipase may act as a signal to begin what
fat digestion
what are stomach ulcers caused by
helicobacter pylori
what do the pyloric glands of the stomach release
mucous, small amount of pepsinogen and gastrin
Gastroferrin enzyme facilitates absorption of what
iron
what is the exocrine function of the pancreas
pancreatic juice and alkali secretions
what is the endocrine function of the pancreas
secretion of insulin and glucagon
what stimulates pancreatic juice
CCK (Cholecystokinin) and secretin from small intestine
does pancreatic juice contain bicarbonate
yes
which solution buffers the acidic secretions of the stomach
pancreatic juice
where does the pancreatic juice enter the alimentary tract
the duodenum
name 5 pancreatic enzymes secreted by acinar cells
phospholipase trypsin chymotrypsin carboxypeptidase elastase
name 4 non proteolytic pancreatic enzymes
amylase
lipase
ribonuclease
deoxyribonuclease
at what part of the villus does most absorption occur
the tip
where is bile released to after a meal
duodenum
what is the main function of the jejunum
completing breakdown
nutrient absorption
what is the main function of the ileum
nutrient absorption
what is the main function of the duodenum
mixing secretions from pancreas, liver and its own with food
neutralisation of acid
further digestion
absorption
what types of cells are in the mucosa of the small intestine
absorptive
globlet
granular
endocrine
run through the process of protein digestion
starts in stomach with pepsin
continues in small intestine with trypsin, chymotrypsin and carboxypeptidase
continues at brush border by peptidases
amino acids absorbed
what are micelles
bile acids with fatty acids
where are fatty acids absorbed
brush border
if fatty acids are more than 12 carbons long instead of going straight to the portal blood what happens
triglyceride reformed and coated in protein to make chylomicron which is secreted into the lymphatic system via lacteals
are there villi in the mucosa of the large intestine
no
what happens if carbohydrates and protein are not digested in the small intestine
they are fermented by the colonic microflora to short chain fatty acids and gases
where are fats digested
small intestine
where are proteins digested
stomach
duodenum
where are carbohydrates digested
mouth
small intestine
