Lesson Notes By Weeks and Term - Senior Secondary 1

The digestive system

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  4. The digestive system

Term: 1st Term

Week: 11

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes

Date:       

Subject:      Food and nutrition

Topic:-       The digestive system

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Define digestion
  2. Discuss the process of digestion

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S ACTIVITY

STEP 1

INTRODUCTION

The teacher reviews the previous lesson on dietary deficiencies

Students pay attention

STEP 2

EXPLANATION

She defines digestion

Students pay attention and participates

STEP 3

DEMONSTRATION

She discusses the process of digestion

Students pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a summarized note on the board

The students copy the note in their books

 

NOTE

THE DIGESTIVE SYSTEM

Digestion is the process by which food molecules are broken down into various small substances that can be absorbed into the blood stream and assimilated into the cells for utilization. Digestion is mainly a chemical process brought about by the action of many enzymes.

The whole process of digestion takes place in the ALIMENTARY CANAL, which takes place in four major sections that is, the mouth, stomach, duodenum and small intestine.

  1. The mouth: In the mouth, the food is mixed and softened with the saliva secreted by many enzymes and masticated and crushed into smaller particles by the teeth. Saliva contains mucin which lubricates the food and makes swallowing easier, it also provides an alkaline medium necessary for the action of ptyalin, an enzyme.
  2. The stomach contains gastric juice which is acidic due to the presence of hydrochloric acid [HCL].

The hydrochloric acid performs three major functions viz:

a. Stops the action of ptyalin from the mouth.

b. provides the acidic medium necessary for the action of rennin and pepsin in the stomach.

c. Destroys any bacteria that might have accompanied the food from the mouth.

 

From the stomach, the products of digestion are passed into the duodenum.

  1. The duodenum

The pancreatic juice from the pancreas is secreted into the duodenum and the  bile from the liver are emptied into the duodenum through the bile duct. The bile does not contain any enzyme rather it emulsifies the fats or oils present in the chime.

The pancreatic juice on the other hand contains carbohydrate, protein, and fat splitting enzymes.

Amylase– converts starch to maltose

Trypsin– converts protein to peptides and peptones.

Lipase–converts fats to fatty acid glycerol.

 

EVALUATION:    1. Define digestion

  1. Discuss the process of digestion

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively