Alimentary Canal Pt.2 Flashcards
What are the principle dietary constituents
Proteins
Carbohydrates
Fats
Vitamins
Minerals
Water
Which nutrients are macromolecules
Proteins
Fats
Carbohydrates
Why do we store nutrients as macromolecules instead of as monomers
More monomers creates a higher osmotic pressure than a single macromolecules
Controls breakdown
What are different chains of carbohydrates called and how many are in the chain
Monosaccharides - 1 molecule
Disaccharides - 2 molecules
Oligosaccharides - 3-9 molecules
Polysaccarides - 10+ molecules
What are the three main hexoses monosaccharides and are they aldoses or ketoses
Glucose - aldoses
Galactose - aldoses
Fructose - ketoses
Are simple sugars chains or cyclical in shape
Cyclical - Carbon 1 joins to carbon 5
In hexoses what does alpha or beta mean
Alpha - OH are on the same side
Beta - OH are on opposite sides
What are the different forms of glucose
Alpha-D-glucose
Alpha-L-glucose
Beta-D-glucose
Beta-L-glucose
What is the most common form of glucose
Beta-D-glucose
What are the three main disaccharides called and what are they formed from
Glucose + glucose = maltose
Glucose + galactose = lactose
Glucose + fructose = sucrose
what bonds form between monosaccharides to make a chain
Glycosidic bonds
Which enzymes break down maltose, sucrose and lactose
Maltase
Sucrase
Lactase
People with lactose intolerance don’t have which chemical in their GIT
Lactase
sugar is instead fermented by bacterial and form acids and gases causing irritation
Name 3 polysaccharides and if they are branched
Glycogen - highly branched
Starch - moderately branched
Cellulose - unbranched
Are cellulose and starch beta or alpha bonded
Cellulose - Beta
Starch - Alpha
Why cant human or any other mammals breakdown cellulose
Amylase doesn’t breakdown beta 1,4 glycosidic bonds
Cellulose is instead considered dietary fibre (bulks up faeces)
Which enzyme breaks down starch and where can it be found
Amylase
Pancreas and salivary glands
Where on the cell are the apical and basolateral membranes found on epithelial cells
Apical membranes can be found on the top (by the lumen)
Basolateral membranes can be found on the bottom of the cell
Where are tight junctions found in the intestines
Between epithelial cells
What types of transport across the membrane are there and what type of transport is it
Paracellular (between the cells) - passive diffusion
Transcellular (passes through membranes without transporter) - passive or active
Vectoral (carrier required to cross each membrane and requires nucleus in cell - active
Is a gradient requires for glucose and galactose to pass though the membrane
What makesthe gradient
Yes
ATPase
What transporter brings Na and Glucose across the apical membrane
SGLT1
What transporter moves glucose from the cell in to the blood
GLUT2
What GLUT transporters are there and where are they found
GLUT1 - blood cells and blood brain barrier
GLUT2 - liver, pancreas, intestines and kidney
GLUT3 - brain
GLUT4 - adipose tissue and skeletal muscle (insulin dependant)
GLUT5 - sperm (transports fructose)
Does SGLT1 transport aldoses or ketoses
Aldoses - glucose and galactose
Is a gradient requires for fructose to pass though the membrane
What is it called
No
Which transporter moves fructose into the cell
GLUT5
What allows fructose to leave the cell
GLUT2
Which of the 3 simple sugars can help with rehydration
Glucose and galactose
Proteins are made up of which monomer
Amino acids
What bond joins amino acids together
What is the process called
Peptide bonds
Condensation
Which enzyme breaks down proteins
Proteases
Difference between endo and exo peptidases
Endo - breaks up with in molecule
Exo - breaks up from the edges
Are aminopeptidase and carboxypeptidases exo or endo peptidases
Exopeptidases
Single amino acid transport makes up what percentage of protein transport
30%
What creates a Na gradient for amino acid transportation
ATPase
Which molecule transports Na and a single amino acid across the apical membrane
SAAT1
What pulls Na into the cell while expelling H ions and creating a H ion gradient
NHE3
Which transporter bring H ions and dipeptides into the cell
PepT1
Dipeptide transport makes up what percentage of protein transport
70%
What can cross the apical membrane via PepT1
Dipeptides
antibiotics
penicillin
What form are most fats in
triacylglycerol
Draw the structure of glycerol and triacylglycerols
Check google for the answers
which enzyme breaks down fats
Lipase
Are fats hydrophobic or hydrophilic
hydrophobic
Is lipase hydrophobic or hydrophilic
Hydrophilic
Is fat degradation fast or slow
Why
Slow
Fats are hydrophobic and lipase is hydrophilic so they don’t mix
Without emulsifiers degradation can only take place on the surface of the droplet
Where does fat digestion take place
Small intestines
Where is lipase produced
Pancreas
Triacylglycerol + lipase –>
Monoglyceride + 2 fatty acids
Where is bile synthesised
Liver - hepatocytes
What are biles salts function
Emulsifier/surfactant - amphipathic molecule
How do emulsifiers benefit lipase
Increases surface area for the lipase to act on
What factors are required for emulsifaction
Mechanical disruption
Emulsifying agent
What are tiny emulsions droplets also know as
Micelles
What is in a micelle drop
Bile salts
Monoglycerides
Fatty acids
Phospholipids
Once broken down to fatty acids and monoglyceride (hydrophobic) where do the molecules go
Can diffuse through the cell membrane
In the epithelium cell where do fatty acids and monoglycerides move to
Why
Smooth endoplasmic reticulum
To make triacylglycerol
If a molecule is transported out of the cell by a vesicle is it exocytosis or endocytosis
Exocytosis
If a molecule is transported into othe cell is it exocytosis or endocytosis
Endocytosis
In the cell where does the triacylglycerol go before being transported out of the cell
Golgi apparatus
Once triacylglycerol leaves the cell what is it called
Chylomicron
Where do chylomicrons get absorbed
Lacteal
Where do lacteals take the chylomicrons
Lymphatic system
What do chylomicrons contain
Triacylglycerol
Phospholipids
Cholesterol
Vitamins
What are the two classes of vitamins
Water soluble
Fat soluble
Name the fat soluble vitamins and how the enter the body
A D E K
Through lacteals in chylomicrons
Name water soluble vitamins and how they enter the body
B C Folic acid
Passive diffusion or carrier mediated transport
What is produced in the stomach and binds to B12
What is produced
Intrinsic factors
Complex
Vit B12 complex is absorbed where in the GIT
Distal ileum
What does Vit B12 deficiency cause
Pernicious anemia
How long can symptoms of pernicious anaemia take to show
Why
3 years
Lots of Vit B12 stored
What is pernicious anaemia/symptoms of pernicious anaemia
Failure of red blood cell maturation
Effect on neurons
Is vit B12 hydrophobic or hydrophilic
Hydrophilic (highly charged)
Where is Vit B12 stored
Liver and other tissues
How do we administer Vit B12 in cases of deficiency
Intramuscular injection
Unable to absorb Vit B12 through the gut
How much of ingested iron we consume do we absorb into our body
10%
Where is iron absorbed
Intestines - brush border - into duodenal enterocytes
Which transporter carries iron into the body
DMT1
Iron ions are incorporated into ferritin
What is ferritin
Protein iron complex - intracellular iron store
What iron crosses into the blood
Unbound iron
In blood where does iron bind to
transferrritin
What is hyperaemia and how does the body fix it
Increased iron in blood
More iron binds to enterocytes
What is anaemia and how does the body fix it
Decreased iron in the blood
More iron released into the blood
Is ferric divalent (+2) or trivalent (+3)
Trivalent
How is ferric (+3) reduced to ferrous
DCytb
Why must iron be reduced to ferrous (+2)
DMT1 transporter only carries divalent molecules
