3.3.3 Digestion And Absorption Flashcards
Stage of digestions
Ingestion：food is taken into the body through the mouth
Digestion : breakdown of large insoluble, molecules into food into small, simple molecule by mechanical or chemical means
Absorption : the small molecules can be absorbed through the lining of the small intestine (ileum) into the blood
Egestion: any food that can’t be digest, is eliminate from the body
Structure of digestive system
Ws / lesson 60
Mouth
Salivary glands
Oesophagus
Liver
Gall bladder
Stomach
Pancreas
Large intestine (colon)
Small intestine ( Duodenum, Jejunum, ileum)
Rectum
Anus
How do you break down large insoluble molecules?
Physical mechanical breakdown
Large food is broken down into small pieces by chewing with teeth in the mouth by mastication and churning of the stomach muscle
Chemical, digestion
Digestive enzymes, hydrolyse, large insoluble molecules into smaller soluble ones which can then be absorbed and used in the body
Three. Digestive enzyme and their uses.
Carbohydrases (amylase [mouth] , membrane bounded disaccharidases [duodenum,ileum])
Hydrolyse of carbohydrates (polysaccharides) into disaccharide , and then into monosaccharides
Lipases (bile [liver, emulsification], lipase [pancreatic juice ~ duodenum])
Hydrolyses of fat and oils (lipid triglycerides) into micelles (tiny droplet) ,then into fatty acids and glycerol, monoglyceride
Proteases/ peptidases (endopeptidases [stomach, pancreatic juice], exopeptidases [pancreatic juice ~ duodenum ], membrane bounded dipeptidases [ileum]
Hydrolyse of protein(polypeptides) , shorter, polypeptide chain , dipeptide into amino acid
Different types of proteases, help in digestion of protein
Endopeptidases
Hydrolyse peptide bond in the middle of the peptide to produce shorter polypeptide
Exopeptidase
Hydrolyse peptide bond at the end of the polypeptide to produce dipeptides or single amino acid
Dipeptidase
hydrolyse any remaining dipeptides into single amino acid
Function of different part of the digestive system
Mouth: food is ingested, teeth physically digest the food
Salivary glands : produce amylase, starting a chemical digestion of starch
Oesophagus : tube, connecting mouth to the stomach, through contract and relax of war (circular longitudinal, muscle )to move the food bolus (Peristalsis )
Stomach : Muscular bag that turns food by mechanical and physical digestion, adding hydrochloric acid, and pepsin to start protein digestion (mucus protect the wall)
Liver : produce bile for emulsification of fats that are stored in the gallbladder into fat droplet (micelles)
Pancrease : produce many (all 3) digestive enzyme which are released into the duodenum
Ileum : long tube with villi, site of final stage of digestion (dipeptidase/ disaccharidases sit on the apical membrane of microvilli）
Large intestine : where water and ions are absorbed
Rectum : storage of faeces before being expelled through egestion from the anus
How does bile help in digestion of lipid?
Hydrophobic and hydrophilic (outside)
There’s around at the separated droplet (micelles)
To prevent them joining together again
Definition of digestion
Large, biological molecules are hydrolysed into smaller molecules that can be absorbed across cell membrane
Adaptation of ileum
Large surface area
Villi and microvilli
Shorts, diffusion distance
Oneself thick, lining, villi (epithelial cell)
Rich Blood supply
Steep concentration, gradient for diffusion
Villi could move
Mixed up the food with enzyme
Maintain concentration gradient, so the products of digestion can keep moving into blood
How monosaccharides and amino acid absorb?
Sodium potassium pump (3 sodium, two potassium) against a concentration gradient use of ADP
Set up concentration gradient with low sodium concentration in epithelial and high in lumen
Low glucose concentration gradient, and amino acids gradient in lumen
Co transport Sodium ions diffuse from high to low concentration, gradient, release energy
Allowed glucose and amino acid enter against a concentration gradient
Glucose and amino exit, facilitated diffusion from epithelial cell to blood through carrier protein
Fatty acid/ glycerol/ monoglycerides absorption
Diffuse into epithelial cell in ileum (lipid soluble)
Transport to smooth, endoplasmic reticulum
Recombined into triglyceride
Triglyceride transport to Golgi apparatus
Add cholesterol, lipoprotein to form chylomicrons
(Exam ans : modify/process, triglyceride. Combine triglycerides with protein.)
Chylomicrons exit the epithelial cell via basal membrane through exocytosis
Enter lacteal : large pore between cell is easier for large chylomicron to get in
Then into the bloodstream, the circulatory system to the heart
If need : enzyme in epithelial cell of the Oregon hydrolyse, triglyceride back into fatty acids and glycerol than the views through blood capillaries to cell, which need
Definition of Clylomicrons
Structure able to transport protein to wherever in the body that need
Use of micelles
Move monoglyceride and fatty acid toward the epithelium
Constantly breakdown and reform
Carries fatty acid and glycerol through membrane to cell
Describe the role play by rough endoplasmic reticulum in the formation of chylomicrons
Protein synthesis in rough, endoplasmic reticulum
With the help of ribosome
Where are protein is transported
Vesicle is formed
Under what condition we can’t make conclusion about their relationship of something
No information provided
Cannot compare
No statistic information /t-test
