Digestion and absorbtion

• what and Where does absorbtion of food take place?

  taking in these smaller molecules into the bloodstream, primarily in the small intestine.
• Where in the body are carbohydrates digested?

  Small intestines and mouth
• What is maltase?

  An enzyme which hydrolyses maltose to form glucose.
• What is amylase?

  An enzyme produced by the salivary glands and the pancreas. It hydrolyses starch to form the disaccharide maltose, by breaking the glycosidic bonds
• What is sucrase?

  An enzyme that hydrolyses sucrose to form glucose and fructose.
• what is lactase?

  An enzyme that hydrolyses lactose to form glucose and galactose.
• Where in the body are lipids digested?

  Small intestine
• What is the role of bile salts?

  Bile salts split up lipids into smaller droplets called micelles. This process is called emulsification.
• What are lipases?

  Lipases are enzymes which break down ester bonds in lipids into fatty acids and glycerol.
• Where in the body are proteins digested?

   stomach and the small intestine.
• What is an endopeptidase?

  An endopeptidase is an enzyme which acts in the middle of a polypeptide and hydrolyses peptide bonds to produce shorter polypeptides.

  
• What is an exopeptidase?

  An exopeptidase is an enzyme which acts at the end of a polypeptide and hydrolyses peptide bonds to produce dipeptides and amino acids.
• What is a dipeptidase?

  A dipeptidase is an enzyme which hydrolyses peptide bonds to produce amino acids. 

  
• How do amino acids and monosaccharides enter an epithelial cell?

  They enter via co-transport proteins that only function when sodium ions are present. 
• The sodium ion gradient between the lumen and epithelial cell is maintained by the sodium-potassium pump.
• Amino acids and monosaccharides move from an epithelial cell into the capillaries by facilitated diffusion.
• By which process do monoglycerides and fatty acids enter epithelial cells?

  diffusion. 
• What happens to monoglycerides and fatty acids in epithelial cells?

  In epithelial cells, the endoplasmic reticulum turns them into triglycerides.

   

  Then, the Golgi apparatus packages them into lipoproteins.
• By which process do lipoproteins move out of epithelial cells?

  exocytosis
• what is the duodenum

  the first part of the small intestines
• What is the ileum?

  The last part of the small intestine.
• Amylase will hydrolyse carbohydrates to dissacharides

  and sucrase and lactase are membrane - bound enzymes that hydrolyse sucrose and lactose to form monosaccharides
• Lipid digestion:

  (physical digestion)

  Lipids are coated by bile salts, released from gall bladder

  The bile salts that coated them will cause the lipids to split into tiny droplets, forming micelles (emulsion)

  Advantage: the small droplets create a large surface area to enhable faster hydrolysis action by lipase

  Chemical digestion - physical will provide the large surface area so that the lipase can hydrolyse lipid into fatty acids and monoglycerides
• Micelles deliver fatty acids, glycerol and monoglycerides to the epithelial cells, releasing the fatty acids and glycerol to move into epitheilial cells by diffusion
• Ileum wall is covered with villi, which have thin walls surrounded by a network of capillaries and epithilal cells (villi) have even smaller microvilli. Increases surface area, decreasing diffusion distance and mantiaing concentration gradient.

  
• How does digestive food molecules get absorbed?

  Monosaccharide and amino acids are absorbed from the lumen to the gut there must be a higher concentration in the lumen compared to epithelial cells but there may be more glucose in the epithilial cells