1.1 Digestion

Some bacteria help to prevent infection, while others inhibit the growth of fungi.

All these bacteria exist SYMBIOTICALLY in the alimentary canal. The body pro­vides a suitable habitat and they provide the body with the above-mentioned benefits.

Problems occur when this relationship is disturbed, for instance when an ANTIBIOTIC is prescribed for a condition, for instance earache.

Remember that antibiotics are effective in the treatment of bacterial infections, but not for viral infections. One should guard against taking more antibiotics than are necessary, and should take them strictly according to the doctor’s pre­scrip­tion. It is also important to complete a prescribed course of antibiotics, because ignoring this can assist in the development of so-called “super bugs” that are impervious to all forms of antibiotics.

A simultaneous problem is that antibiotics destroy all forms of bacteria – especially broad-spectrum bacteria, which include the beneficial intestinal bacteria.

Activity: CASE STUDY

• Read the following case study and answer the questions that follow

Victoria is a seven-year-old girl who complained of abdominal pain and lost her appetite. Before these symptoms occurred, she suffered from chronic ear infection for which she had to complete four courses of antibiotics.

She was diagnosed with intestinal dysbiosis (a disturbance in the bacterial population of the alimentary canal). Her diet was adjusted to include lots of yoghurt containing live AB cultures and to cut back on sugar intake. The bacterium Lactobacillus is usually added to yoghurt. This is a bacterium that also occurs in the alimentary canal. Victoria was better within days and her ear infection has also cleared up.

1. What caused the disturbance in the alimentary canal?

2. What does “chronic ear infection” mean?

3. Why did Victoria also have to use less sugar?

4. Why did her ear infection improve when her diet was adjusted?

5. Find out what lacto- and bacillus mean as parts of the name of the bacterium. Why are they printed in italics?

Make your own live yoghurt

1. Heat a litre of fresh milk until bubbles begin to rise – do not allow the milk to come to a boil.

2. Pour it into a thermos flask.

3. Add a tablespoon of fresh yoghurt to the warm milk.

4. Screw down the top of the flask and shake it – leave to stand overnight.

5. Eat with muesli and honey for a healthy breakfast and a daily dose of beneficial bacteria!

Assessment: APPLICATION OF KNOWLEDGE:

Could you apply your knowledge to answer the questions about the case history?

LO 2.4

Assessment

Learning Outcomes 2 : Constructing Science knowledge

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

We know this when the learner:

2.4 applies knowledge.interprets information.

Memorandum

1. contractions of the involuntary muscles in the walls of the digestive tract

2. smooth muscles in the walls of the alimentary canal

3. biological catalysts that accelerate reactions

4. produced in ribosome in cells

5. transported to every cell by the circulatory system

THE HUMAN DIGESTIVE SYSTEM

1. Mucus glands – secretes mucus
2. Oesophagus – connects mouth and stomach peristalsis
3. Liver – detoxifies, stores blood, vitamins, etc.
4. Stomach – digestion
5. Gall bladder – stores bile
6. Pyloric sphincter – allows food to leave the stomach
7. Pancreas – enzymes and hormones
8. Duodenum – digestive juices added
9. Colon – reabsorbation of water and minerals

10.Small intestine – absorption of nutrients

11. Appendix – none

12. Rectum – storing food wastes

13. Anus – opening for excretion of waste matter

ANSWER THE FOLLOWING QUESTIONS: ALIMENTARY CANAL

1. The liver detoxifies by removing/absorbing preservatives, colourants, coffee and alcohol.

2. Enzyme that breaks down/catabolises starch.

3. Smallest units into which nutrients can be broken down.

4. Hydrochloric acid – oxyntic cells of the stomach wall.

5. Stomach wall protected by thick mucus membranes.

6. Weak spot in mucus membrane resulting from stress and smoking – enzymes cause the membrane to disintegrate.

7. Muscular valve at lower end of stomach.

8. Muscular spasm of wall of colon – stress.

9. Prevents constipation, stimulates peristalsis.

10. Enlarges the absorbing surface.

11. Long, twisted, villi, microvilli.

12. Labels villum:

CLASS ACTIVITY: CASE STUDY

1. Beneficial bacteria are destroyed by antibiotics.

2. Continued infection.

3. Sugar allows uncontrolled fungi to flourish.

4. Beneficial bacteria help.

5. Lacto – milk; bacillus – rod-shaped.