Digestion and absorption – OPTION H

H2 – digestion.  We’ve done the basics, and because you ask good questions, we’ve gone further, so much of this you will have some idea about already.  You have the background, now we need to fill in the details.  Click here.

  • State that digestive juices are secreted into the alimentary canal by glands, including salivary glands, gastric glands in the stomach wall, the pancreas and the wall of the small intestine.
  • Explain the structural features of exocrine gland cells.
  • Compare the chemical composition of salivagastric juice and pancreatic juice.
  • Outline the control of digestive juice secretion by nerves and hormones, using the example of secretion by gastric juice.
  • Outline the role of membrane-bound enzymes on the surface of epithelial cells in the small intestine in digestion.
  • Outline the reasons for cellulose not being digested in the alimentary canal.
  • Explain why pepsin and trypsin are initially synthesized as inactive precursors and how they are subsequently activated.
  • Discuss the roles of gastric acid and Helicobacter pylori in the development of stomach ulcers and stomach cancers.
  • Explain the problem of lipid digestion in a hydrophilic medium and the role of bile in overcoming this.

B0008462 Ileum section by wellcome images on flickr

H3 – absorption of digested foods.  This is a short section, much of which we’ve covered before.  Click here. You need to be able to:-

  • Draw and label a diagram showing a transverse section of the ileum as seen under a light microscope.
  • Explain the structural features of an epithelial cell of a villus as seen in electron micrographs, including microvilli, mitochondria, pinocytotic vesicles and tight junctions.
  • Explain the mechanisms used by the ileum to absorb and transport food, including facilitated diffusion, active transport and endocytosis.
  • List the materials that are not absorbed and are egested.

Tags: , ,

Leave a Reply