digestion n absorbtion Flashcards
What is the primary function of the digestive system?
The digestive system breaks down food and absorbs nutrients and water.
What do gland cells in the digestive system produce?
Digestive juices containing hydrolytic enzymes and other molecules.
What is the role of hydrolytic enzymes in digestion?
They hydrolyse large insoluble food molecules into smaller soluble molecules.
What are polypeptides and proteins hydrolysed into?
Amino acids by proteases.
What do carbohydrases hydrolyse carbohydrates into?
Simple sugars.
What are fats hydrolysed into by lipases?
Glycerol, fatty acids, and monoglycerides.
What enzyme is secreted by the salivary glands?
Salivary Amylase.
Which enzymes are found in the stomach?
Endopeptidases (e.g. Pepsin) and Exopeptidases.
What does the pancreas secrete?
Pancreatic Amylase, Lipases, and Exopeptidases.
What is the function of maltase in the small intestine?
It hydrolyses maltose to glucose.
What happens to salivary amylase in the stomach?
It is denatured due to acidic pH.
What is the complete breakdown process of starch?
Starch is broken down by salivary amylase into maltose, then by pancreatic amylase in the small intestine, and finally maltose is hydrolysed to glucose by maltase.
True or False: Cellulose is hydrolysed in mammals.
False.
What type of transport do monosaccharides use to cross the epithelial cell membrane?
Facilitated diffusion and co-transport.
How is glucose absorbed from the ilium into the blood?
Na+ ions are actively transported out, creating a gradient; glucose enters via cotransporter proteins.
What role do cotransporter proteins play in glucose absorption?
They have binding sites for both Na+ and glucose, allowing their transport into the cell.
What happens if sodium ions are not actively transported out of the cell?
Facilitated diffusion from the lumen will stop, preventing glucose absorption.
What enzymes hydrolyse proteins in the stomach?
Endopeptidases and exopeptidases.
What do endopeptidases do?
They hydrolyse peptide bonds within the polypeptide chain.
What do exopeptidases produce?
Amino acids and dipeptides by hydrolysing at the terminal ends.
Where are dipeptidases located and what do they do?
Embedded in the cell surface membrane of epithelial cells; they hydrolyse dipeptides into amino acids.
How are amino acids absorbed?
By facilitated diffusion and co-transport using specific carrier proteins.
Describe the role of bile salts in lipid digestion.
They emulsify fat droplets, increasing the surface area for lipase action.
What do lipases hydrolyse lipids into?
Glycerol, fatty acids, and monoglycerides.
