Digestion Flashcards
What is digestión?
The hydrolysis of large insoluble macromolecules to smaller soluble micromolecules
Breakdown and absorption and assimilation
What is the exchange surface in digestion?
Ileum
State the stages of digestión
Ingestion Digestión Absorption Assimilation Egestion
Define assimilation
When nutrients are incorporated and used within a cell (make proteins)
Name the organs involved in digestion
Salivary Glands Oesophagus Stomach Ileum pancreas Liver Colon Rectum anus
What is the role of the salivary Glands?
Produce saliva (salivary amylase and mineral salts)
Hydrolyse starch to maltose
Maintain pH 7 for optimum function of amylase
How does saliva get to the mouth?
Through a duct
What and how is the esophagus adapted for?
Transportation
Thick muscular walls
What is the function of the stomach and how is it adapted?
Store and digest and breakdown food
Endopeptidases
Hcl= acid =optimum for peptidase
Strong muscular walls= pummel food
What is the function of the stomach and how is it adapted?
Store and digest and breakdown food
Endopeptidases
Hcl= acid =optimum for peptidase
Strong muscular walls= pummel food
Why does the stomach produce mucus?
Protect linig cells from protease and acid
What is the function of the pancreas and how does it achieve this?
Secrete enzymes for digestion
Secretes/empties pancreatic juices into ileum
Contains peptidase, lipase and amylase (pancreatic)
What is the function of the liver?
Produce bile salts to lower pH the 7 optimum enzyme function and emulsify fats
What and how is the ileum adapted for?
Absorption of soluble molecules
Villi and microvilli
What is the function of the Colon?
Reabsorb water e.g from secretions
What is the function of the Rectum?
Store feceas before egestion
What are the two types of digestión?
Physical breakdown
Chemical digestion
What does physical breakdown involve? Why does it happen?
Teeth and stomach to breakdown food into smaller pieces.
Allow ingestion
Increase sa for enzyme action
What is chemical digestión and why does it occur?
Hydrolysis of bonds using enzymes
Allow substances to be absorbed
What is hydrolysis?
Breaking of a bond by adding a water molecule to it
Outline the steps of carbohydrate digestion
Starch to maltose in mouth due to salivary amylase
Digestión stopped in stomach due to acid
(de nature)
Further digestión to maltose in ileum due to pancreatic amylase
Digestión to alpha glucose due to membrane bound maltase
Absorption of glucose via co transport with sodium ions
Transport of glucose via bloodstream
Assimilation of glucose in cells
What components aid with strach digestion and why?
Salivary amylase: Hydrolyse alternage glycosidic bonds
Mineral salts: maintain neutral PH for optimum function of enzymes
Why do we chew our food?
To physically break down the food into smaller pieces
Increase sa for enzyme action
Allow food to be throughly mixed with saliva so enzyme and substrates come into contact, more es complexes
How do the pancreatic juices aid starch digestión in the ileum?
Juices secreted into ileum
Contain pancreatic amylase to Hydrolyse alternate glycosidic bonds
Contain alkaline salts to maintain neutral PH (neutralise stomach acid) for optimum function of amylase
Why is it important for the ileum to have strong muscular walls?
To move the contents along
For egestion
Allow substrates to come into contact with membrane bound enzymes
What are sucrase and lactase
Membrane bound dissacharidases
Hydrolyse glycosidic bonds in dissacharides sucrose or lactose
Outline the stages of protein digestion
Endopeptidases in stomach Hydrolyse specific peptide bonds in the middle of polypeptide chain
Exopeptidases and Endopeptidases in pancreatic juices Hydrolyse further (peptide bonds towards ends=exo) in ileum
Membrane bound dipeptidases Hydrolyse glycosidic bonds between specific dipeptides
Amino acid absorption via co transport with sodium ions
Travel in blood stream
Assimilation in cells
Where are endo peptidase found?
Ileum(Pancreatic juices)
Stomach
What is the function of Endopeptidases?
Hydrolyse peptide bonds between specific Amino acids in the middle of the polypeptide chain.
Prdoduce more ends for faster rate of protein digestion in ileum by Exopeptidases
Where are exo peptidase found?
Ileum (Pancreatic juices)
What is the function of Exopeptidases?
Hydrolyse peptide bonds between specific Amino acids at the end of the polypeptide chain
Compare the products of exo, endo and do peptidase reactions
Endo= small polypeptide chain
Exo= dipeptides, Amino acids, shorter polypeptide chain
Di= Amino acids
Outline the steps of lipid digestion
Bile salts emulsify lipid droplets into micelles
Pancreatic lipase Hydrolyse ester bonds (monoglycerides and fatty acids) and package them into smaller micelles
Micelles breakdown to release monoglycerides and fatty acids near epitheilal cells
Monoglycerides and fatty acids absorbed via simple diffusion into epithelial cell
Transported to ER where they are made into triglycerides
Transported to golgi apparatus where lipoproteins and cholesterol are added to form chylomicrons
Chylomicrons are removed via exocytosis into lacteal (lymphatic capillary)
Pass into blood
Lipases in endothelial cells Hydrolyse ester bonds to release monoglycerides and fatty acids which diffuse into cell
What are micelles? Why do they form?
Small droplets of lipids
Adapted to transport poorly soluble monoglycerides and fatty acids to epithelial cells
Why must the micelles break down before the lipids can diffuse into the cells?
Micelles are to big to diffuse across the plasma membrane
Monoglycerides and fatty acids are non-polar and lipid soluble
What are chylomicrons and why do they do?
Lipoprotein made of cholesterol, monoglycerides and fatty acids
Adapted to transport lipids
Water soluble
Why are bile salts produced (by what organ)?
Liver
Emulsify lipid droplets
Increase sa
Increase rate of reaction
How is the ileum adapted for absorption?
Villi and microvilli increase sa
Villi= one cell thick surface layer = short diffusion pathway
Muscular walls and contract and good blood supply= maintain conc gradient
Membrane bound enzymes= short diffusion pathway
Function of lipid droplets
Allow more sa for enzyme action
Contrast lipid droplet and Michelle function
Lipid droplet= increase sa
Micelle=transport fatty acids and monoglycerides to epithelial cells
