digestion and absorption Flashcards
what makes up a good plate?
-1/3 rd fruit and veg
-1/3rd carb rich
-half protein
-half healthy fats
carbohydrates?
-energy source
-bread rice pasta potatoes
protein?
-repair and growth
-meat fish dairy nuts
fat?
-long term energy store
-insulation
-meat cheese cream fish avocado
vitamins?
A- vision, liver sweet potato
C- antioxidant, citrus
D - Ca absorption, oily fish
B- vegetables
minerals?
ca - bone mineralisation, milk
fe - oxygen transport, red meat
K - banana
fibre?
effective bowel movement, plants, fruit veg, nuts, cereals
what are triglycerides?
glycerol and 3 fatty acids, 90% of fat in the diet, can be saturated or unsaturated.
phospholipids?
-present in plasma membrane
-composed of 2 fatty acid chains
what is cholesterol?
present in the plasma membrane, also forms basis for synthesis of other hormones
where can we get saturated fats?
-mainly animal foods
-meat fat, butter, cream and cheese
where can we get unsaturated fats?
-mainly from plants
-olive and rape seed, nuts
where can we get cholesterol?
-plants and animals
-dairy products
-palm and coconut oil
what happens if we get too much fats?
-atherosclerosis (can lead to heart attack and stroke)
-obesity
what are the 9 essential amino acids?
body cant synthesise them
-phenylalanine
-valine
-tryptophan
-threonine
-isoleucine
-methionine
-histidine
-leucine
-lysine
what are the common carbs?
monosaccharides- glucose, fructose, galactose
disaccharides - sucrose, maltose and lactose
polysaccharides -starch
what is digestion?
process by which food is broken down into components simple enough to be absorbed in the intestine
what enzymes aid digestion?
secreted by;
-glandular cells in mouth
-chief cells in stomach
-endocrine cells of pancreas
-enzymes bound to the apical membrane of enterocytes
where is saliva produced?
parotid, submandibular and sublingual salivary glands
what is the function of saliva?
-moistens food
-starts the digestion of carbs
-starts the digestion of lipids
where is the start of protein digestion?
the stomach
how does the stomach degrade food?
parietal cells-hydrochloric acid secretion which denatures proteins and activates pepsin (conversion of pepsin to active endopeptidase)
what are zymogens?
-inactive forms of compounds
-many enzymes are synthesised as inactive precursors that are subsequently activated by cleavage of one or a few peptide bonds. the inactive precursor is called zymogen
what are the 2 functions of the pancreas?
exocrine- pancreatic juice (enzymes) and alkali secretions
endocrine- secretion of insulin and glucagon
what are released as active forms?
non proteolytic enzymes
-amylase
-lipase
-ribonuclease
-deoxyribonuclease
what are released as zymogens?
proteolytic enzyme
-trypsin
-chymotrypsin
-carboxypeptidase
-elastase
-phospholipase
what is the liver?
-production of bile
-stored in gallbladder and released into the duodenum after a meal
-emulsification of fat particles
-aids absorption of fats by forming complexes called micelles
bile salts?
synthesised from cholesterol and are transported into chalice acid and chenyeoxycholic acid which is then conjugated to amino acid (glycine or taurine)
what is the functions of bile?
-emulsification of lipid aggregates
-solubisation and transport of lipids in aqueous environment
functions of duodenum?
-mixing secretions from pancreas, liver and duodenum with food
-neutralisation of acid
-further digestion
-absorption
functions of jejunum?
-completing breakdown
-nutrient absorption
function of lleum?
nutrient absorption
what is enterokinase?
produced in the duodenum
-is a protease
-activates trypsin which activates other molecules and is a key digestive enzyme
what enzymes make up the brush border?
-integral part of the membrane (not free in lumen, tethered to plasma membrane)
-peptidase
-lactase
-sucrase
-maltase
mastication?
breaks up food and moistens it in the mouth
what happens in the mouth?
carbs - starch broken down by amylase and maltotrise maltose and limit dextrin
proteins - nothing
lipids - lingual lipase present but minor contribution
what happens in the stomach?
-highly acidic gastric juice is mixed with food and churned (chyme)
carbs - nothing
proteins - HCl denatures proteins and activates pepsin 9endopeptidase that cleaves to smaller peptides)
lipids - gastric lipase present but minor contribution
what happens in the duodenum?
chyme mixes with pancreatic juice and bile slightly alkaline
cabs- amylase further digests starch brush border disaccharides result in monosaccharides
proteins - cleaved by trypsin, chymotrypsin, elastase to produce increasingly smaller peptides, brush border peptidases produce dipeptides/amino acids
lipids - pancreatic lipase digests lipids to monoglycerides and fatty acids. phospholipase digests phospholipids to lysolecithin and fatty acids
what is passive absorption?
molecules move along conc gradient, very slow, no energy required
what is facilitated transport?
slightly faster
-involves membrane carrier
is controllable
what is active transport?
-uses energy
-fast
-uses membrane carrier
-controller
What do calcium; magnesium and phosphorous do?
Harden teeth and bones
What does iron do?
Plays a crucial pert in haemoglobin
What does potassium, sodium and chlorine do?
Helps maintain body’s pH balance and used in action potentials
What are the essential fatty acids ?
Omega 6 and 3 fatty acids
which digestive enzyme starts the digestion of carbs?
alpha-amylase
what is tyripsin?
goes onto activate all the other proteolytic zymogens that were produced from the pancreas.
what activates tyripsin?
enterokinase
what are the products of maltose?
glucose and glucose
what are the products of sucrose?
glucose and fructose
