Ileum (3) by GreenFlames09 on flickr
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 saliva, gastric 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.
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.
Categories: G12 HL Biology Tags: absoption, digestion, egestion, enzymes, gastric juice, glands, Helicobacter pylori, ileum, option H, pancreatic juice, pepsin, saliva, trypsin
REMINDER
Block B will have their test on Topics 6.1 Digestion and 6.2 Transport System on THURSDAY 17th SEPTEMBER. Block F will have theirs on WEDNESDAY 16th SEPTEMBER. Usual format – part multiple choice, part short answers – all from past IB papers.
COME TO TUTORIALS if you need help with anything.
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 Tues 15th Sept – either soft or hard copy.
A copy of the lab sheet. Your hypothesis, including justification. Your data tables. Your conclusion and evaluation.
Describe the route taken by a ham, cheese and lettuce sandwich through the human digestive system, explaining what happens to each part of the sandwich as it passes through each region of the digestive tract. [20 marks]
Complete and correct route given [4]
Digestion of bread [4]
Digestion of ham [4]
Digestion of cheese [4]
Digestion of lettuce [2]
Bibliography in MLA format [2]
You will have class time on Tuesday 1st September for this, and must submit it no later than Thursday 3rd September. Here is a link you might find useful.
Here is the link to that powerpoint we used in class today. If you like his work, I’m sure Mr. Taylor would appreciate you letting him know. Get ready for dissection tomorrow!
Human parts by Mundoo on flickr
Our next topic will be a loooooong one – Human Physiology will last the rest of the semester. We’ll start with the core material, which is Topic 6. You can download the syllabus guide here: Topic 6 – syllabus outline.
The first section is on the digestive system. You can get a head start by reading your textbook – Chapter 19. We’ll cover the theory first, and end the week by dissecting a complete digestive system. When will you have the chance to stick your hand inside a goat’s stomach again, or simulate peristalsis on some real intestines?
You are in the process of writing up a lab report on demonstrating absorption and digestion. Block B students have already had a lesson on this and are due to submit their final version to me, either electronically or on paper, by THURSDAY 27th AUGUST. Block F students have until FRIDAY 28th AUGUST (We will spend next Tuesday on this so don’t panic!). Please make sure you see me during tutorials if you need help. Our next unit will be on the transport system (the heart, blood and blood vessels), so read your textbook if you want to get a head start on this.
ham and cheese by Diego Lorenzo F. Jose on flickr
Here is a link to a resource with some good information that might help with the digestion homework you are currently working on. Click on the various links about digestion of different macromolecules.
REMINDER – DUE ON THURSDAY 20th AUGUST 
Here is a link to a fantastic presentation on Topic 6.1 (Digestion). Well worth a look
Describe the route taken by a ham, cheese and lettuce sandwich through the human digestive system, explaining what happens to each part of the sandwich as it passes through each region of the digestive tract. [20 marks]
Complete and correct route given [4]
Digestion of bread [4]
Digestion of ham [4]
Digestion of cheese [4]
Digestion of lettuce [2]
Bibliography in MLA format [2]
This assignment is due on THURSDAY 20th AUGUST for both B block and F block students. NOTE: F block students don’t have class on this day, but Friday is a holiday. You may submit either a hard copy to me, or soft copy via email.
Mrs Dickinson