nutrient digestion and absorption Flashcards
What is sucrose normally found in and what is it made of
Fruits
made of glucose and galactose
What is maltose normally found in and what is it made of
Seeds and cereal
made of Glucose and glucose
What is lactose normally found in
Milk
Made of glucose and fructose
How do we digest disaccharides in the body
They - lactose sucrose and maltose - are broken down into monosaccharides such as glucose galactose and fructose
What bods do amylase break
Alpha-1,4 glycosidic bonds
What bonds do cellulase break
Alpha-1,4 glycosidic bonds
What breaks down glycogen
Cellulase since it breaks down the alpha-1,4 glycosidic bonds
What breaks down starch
Amylase - breaks down the alpha-1,4 glycosidic bond
What happens in lactose intolerant patients compased to normal
In the large intestine:
Lactose is broken down by lactase into glucose and galactose in normal patient
In lactose intolerant patients, they have no lactase so bacteria ferments the lactose which converts it into acids and gases which causes irritation
What does the basolateral membrane face
Blood vessels
What does the apical membrane face
The lumen
Describe glucose transport between blood from the small intestine
NA/K/ATPase pump at the basolateral membrane which pumps 3 NA+ out and 2 K+ into the cell which polarises the cell
Na/glucose transporter 1 transports 2 Na and 1 glucose at a time - the electrochemical gradient of sodium is what causes this pump to work and is found at the apical membrane
Glucose transporter 2 - facilitated transport to the blood - found on basolateral membrane
Describe function of glucose transporter 1
NA/Glucose transporter 1 – transports 2 sodium and one glucose at the same time – the electrochemical gradient of sodium pushes this pump to work – mainly found at apical membrane
Sodium attaches to the transporter which opens the outer gate - once glucose enters the gate, it opens the inner gate and closes the outer gate which results in the particles entering the cell
Describe glucose transporter 2
Glucose transporter 2 – facilitated transporter which transports glucose to the blood – mainly found in the basolateral membrane of the small intestine
How are proteins digested
Enzymes such as pepsin which hydrolyse the peptide bond and adding a OH to the bond which causes the formation of an amino acid
What are proteases or peptidases
Enzymes which hydrolyse peptide bonds and reduce proteins or peptides to amino acids
How are fats stored in the body
Triglycerides
Where are fats stored in the body
Mainly in white adipose tissue
What is lipolysis
Breakdown of fats by lipase
What causes lipolysis
Starvation , stress and exercise
Where is fat digestion done in the body
It is done by pancreatic lipase
What happens when the lipid droplets are too large for lipase to work on them
Surfactant or emulsifiers are added which disperse the oil in water as small droplets so the lipase can break it down easier
What is an example of natural emulsifiers in the body and where are they produced
Bile salts - produced in the liver - have lipophilic and hydrophilic sides
What is a phospholipid
Trigyclerol with 3 fatty acids attached including a phosphate
Phosphate - hydrophilic head
Fatty acid tail - lipophilic tail
Describe the structur of an emulsified fat droplet
hydrophilic on the outside and lipophilic on the inside - overall hydrophilic
What does bile consist of
bile salts and phospholipids
Why is lipase break down of emulsified fats slow
Lipase if hydrophilic and the emulsified products are slightly hydrophilic but very hydrophilic on the inside
How is absorption of fats enhanced further then emulsification
Formation of micelles which are even smaller - hydrophilic outside and hydrophobic inside
What PH is the microvilli of the small intestine
Acidic
What is the breakdown product of micelles
Small amount of free fatty acids and monoglycerides
Describe what happens to the fat breakdown product once it is absorbed into the cell
Cytosol is mainly made of water so the free fatty acids go to the smooth endoplasmic reticulum which reforms the triacylglycerol - triaglycerol emulsifies and coats proteins in the cell
Vesicle formed at the smooth endoplasmic reticulum which coats the triacylglycerol which then goes to the Golgi apparatus which packages and sends off the vesicles out the cell.
These exocytosed vesicles of the triacylglycerol are called chylomicrons. Chylomicrons travel in the lymphatic system.
What are the fat soluble vitamins
A,D,E,K
What are the water soluble vitamins
B, C and folic acid
how is vitamin b absorbed
Binds to intrinsic factor to form a complex which is absorbed in the distal ileum
Where is Vit B12 intrinsic factor produced
parietal cells in the stomach
What is pernicious anaemia
B12 deficiency - takes 3 years to develop due to the large stores of B12 which the body has
What is hyperaemia
Increased ferritin levels - leads to iron bound in enterocytes to fix it
What is anaemia
Decreased ferritin levels - iron stored in ferritin - leads to iron being released in blood to try fix it
What is the storage unit of iron in the body and why
Ferritin as iron is corrosive in its free state - ferrous state iron 2+
What transports iron
Transferrin - carries ferric iron +3 charge
