Posts Tagged ‘absorption’

Digestion and absorption – OPTION H

Friday, April 13th, 2012

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.

Demonstrating digestion and absorption

Monday, August 22nd, 2011

Here is the instruction sheet for this lab, along with the rubric.  Lab – Demonstrating Absorption You will be assessed on conclusion and evaluation only for this lab.  You need to submit the following by Thurs 1st Sept – hard copy please.  Here is the rubric for this lab: CE rubric

A copy of the lab sheet.  Your hypothesis, including justification. Your data tables. Your conclusion and evaluation.

Do you have guts?

Monday, August 15th, 2011

Plastic model by mricha15 on flickr

This unit is part of the bigger Topic 6 of the syllabus.  In this section we need to be able to:

  • Explain why digestion is necessary, and what role enzymes play in digestion.
  • Draw and label a diagram of the human digestive system.
  • Outline the functions of the main parts of the digestive system.
  • Distinguish between absorption and assimilation.
  • Relate the structure of the villus to its function.

The syllabus guide is here: Topic-6-syllabus-outline

Some excellent resources to help us through this unit.  Here, here and here.

We’ll also do a dissection of animal intestines, so look forward to that!  When else will you have the opportunity to put your hand inside a goat’s stomach or simulate peristalsis with real intestines?