Digestion and Enzymes Ch.6 Flashcards
What is the tube going from the mouth to the stomach called?
Esophagus
Ingestion
Taking food into the alimentary canal
Digestion
Hydrolysis of large insoluble food molecules to small soluble food molecules
Absorption
The movement of small soluble food molecules (products of digestion) across the cell membrane of the intestine and into the blood stream by diffusion and active transport
Egestion
The removal of undigested waste products
What two methods of digestion take place in the mouth
Chemical- Enzyme amylase
Mechanical- mouth and teeth
Where is amylase found in the body and where is it secreted from
Mouth-secreted by salivary gland.
Small intestine- secreted by pancrease
What happens in the Stomach
HCL denatures enzymes, kills pathogens, and provides optimum pH for pepsin (endopeptidase). Stomach muscle walls pummel food
What two parts are there to the small intetsting and which comes first?
Duodenum comes first
Ileum second
What happens in the duodenum
Digestion continues. Pancreatic juice is secreted from the pancreas through the pancreatic duct. This contains enzymes amylase, lipase and peptidase (exopeptidase).
Where is Bile produced, stored and secreted to.
Bile is a alkaline fluid produced by the liver and stored in the gall bladder. It is secreted into the small intestine (duodenum).
What is the purpose of Bile
1) neutralise the semi-digested food coming from the stomach so enzymes from pancreas can function at optimum temperature
2) to emulsify lipids into micelles
What happens in the Ileum
Absorption occurs
How is the ileum adapted for its function
1) large surface area due to villi and micro villi
2) Thin, one cell thick walls
3) Good blood supply
Why is there membrane bound enzymes in the cell membrane of the ileum/ small intestine
To completely digest any molecules not yet hydrolyses into its monomers
What is the difference between endopeptidase, exopeptidase and dipeptidase
End- Hydrolyses molecules in the middle of the chain.
Exo- Hydrolyses molecules at the end of the chain
Di- is cell membrane bound and hydrolyses dipetides (two amino monomers)
Describe how microorganisms make carbon in starch
available to plants.
- releases enzymes;
- to hydrolysis starch to glucose
- Respire product of digestion
- Produce carbon dioxide from respiration
What happens in the large intestines?
Water is absorbed
What and where does amylase take action?
In the mouth secreted by the salivary gland. It HYDROYLSES the glycosidic bonds in starch to form disaccharide maltose.
What do lipids get digested into?
Fatty acids and glycerol
Describe the digestion of carbohydrates?
In the mouth the salivary gland secretes amylase. This hydroylses starch into disaccharide maltose. Any remaining starch is turned to maltose by pancreatic amylase in the small instestine.The enzyme Maltase is produced by membrane-bound disaccharidase and further hydroylses the disaccharide into alpha glucose monosaccharide.
How are lipids digested?
Bile produced by the liver is secreted into the small intestines and emulsifies lipid into micelles. Lipase produced and secreted from the pancrease hydrolyses the ester bonds in lipids to form fatty acids and monoglycerides.
What is a micelle?
Vesicle made of phospholipid bilayer. Digestion occurs in the micelle.
What is the purpose of emulsification?
Increases the surface area so lipid more enzymes can act an any given time.
How are the products of lipid absorbed?
Micelles fuse with epithelium cell membrane and release the fatty acid and monoglycerides into the cell. The products diffuse into the endoplasmic reticulum and recombine to form triglyceride. It is then associated with cholesterol and lipoproteins to form chylomicrons. Chylomicrons exit by exocytosis and enter lacteal in the villi. Then pass into the blood system.
What is Chylomicrons composed of?
Triglyceride, cholesterol and lipoproteins.
What is exocytosis?
Substance is transported out of the cell using the cell membrane to from a vesicle around it.
What is endocytosis?
Substance are transported into the cell by forming a vesicle around it.
How is glucose and amino acids absorbed into the blood?
Na+ ions are actively transported out of epithelial cells and into the blood using a Na/K pump. This lowers the Na+ ion conc in the cell and makes it lower than in the lumen. Na+ ions therefore diffuse into the cell carrying an amino acid/ glucose with it through a channel protein. The glucose/amino acid then diffuses into the blood.
What is an organ?
A group of tissues working to perform the same function
What is an organ system?
A group of different organs working to perform the same functions.
What is a tissue?
A collection of similar cells that perform a specific function
What is a cell
The basic unit for the building block of life.
What is a dicotyledonous plants?
A plant that has two cotyledons (embryonic leaves)
Where is dipeptidases found?
In the cell membrane of the small intestines.
What is Visking tubing?
A type of semi-permeable membrane tubing that only allows small molecules pass such as glucose but does not let large ones such as starch pass.
How would you model the absorption of starch?
Use a visking tube and put starch in it. Put in the water and then add amylase. Periodically remove some of the water solution out. Test each sample with iodine and benedicts solution. As time increases you should see a a more positive result in the benedict but never a positive result with iodine.
