Class: Senior Secondary School 2 (SS2 / SSS2)
Term: First Term
Week: 4
Age: 16 years
Duration: 45 minutes
Subject: Health Education
Curriculum Theme: Body Systems
Previous Lesson: Circulatory System: Blood Groups, Rhesus Factor and Diseases.
Topic: EXCRETORY SYSTEM.
Subject Matter: Meaning of excretory system (removal of metabolic wastes from the body), structure and functions of kidney, process of excretion (filtration, reabsorption), disease of excretory system and remedies, differences between circulatory and excretory system.

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define the excretory system.
Identify the major organs of the excretory system.
Explain the structure and functions of the kidney.
Describe the process of excretion (urine formation).
List common diseases of the excretory system and their remedies.
Differentiate between the circulatory and excretory systems.

Affective Domain:

Appreciate the importance of the excretory system for maintaining body health.
Value proper hygiene and healthy habits to prevent excretory system diseases.

Psychomotor Domain:

Draw and label a simple diagram of the kidney.
Identify the main parts of the excretory system on a chart.

Discuss with peers the importance of a healthy lifestyle for kidney function.

Reference Materials

The following resources were used in planning this lesson:

Senior Secondary Schools Education Curriculum
State Unified Scheme of Work
Essential Health Education for Senior Secondary Schools

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts of the excretory system
Diagrams of the kidney

Rationale for the Lesson

This lesson helps pupils understand how their bodies remove waste products, which is important for maintaining overall health. Knowing about the excretory system enables pupils to make informed choices about their lifestyle to prevent related diseases.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of human body systems and the concept of waste removal from the body.

Lesson Content/Board Summary

The Excretory System

Meaning of Excretory System

The excretory system is a biological system that removes excess, unnecessary materials and waste products from an organism’s body fluid, helping to maintain internal chemical homeostasis and prevent damage to the body.

Organs of the Excretory System

The main organs involved in excretion include:

Kidneys: Filter blood to produce urine.
Ureters: Tubes that carry urine from the kidneys to the bladder.
Urinary Bladder: Stores urine until it is expelled from the body.
Urethra: Tube through which urine leaves the body.
Skin: Excretes sweat (water, salts, urea).
Lungs: Excrete carbon dioxide and water vapour.
Liver: Processes waste products for excretion by the kidneys or in bile.

Structure and Functions of the Kidney

The kidneys are a pair of bean-shaped organs located on either side of the spine, below the rib cage. Each kidney contains millions of tiny filtering units called nephrons.

Structure of the Kidney:

Cortex: The outer region.
Medulla: The inner region, containing renal pyramids.
Renal Pelvis: A funnel-shaped structure that collects urine and passes it to the ureter.
Nephron: The functional unit of the kidney, responsible for filtering blood and forming urine. It consists of a glomerulus and renal tubule.

Functions of the Kidney:

Filters blood to remove metabolic waste products (e.g., urea, uric acid, creatinine).
Regulates fluid balance (water content) in the body.
Maintains electrolyte balance (salts like sodium, potassium).
Regulates blood pressure.
Produces hormones (e.g., erythropoietin, renin).

Process of Excretion (Urine Formation)

Urine formation occurs in the nephrons through three main steps:

Glomerular Filtration (Ultrafiltration):
- Blood enters the glomerulus under high pressure.
- Water, salts, glucose, amino acids, and urea are filtered from the blood into Bowman’s capsule, forming a filtrate. Large proteins and blood cells are retained in the blood.
Tubular Reabsorption:
- As the filtrate flows through the renal tubule, useful substances like most of the water, all glucose, and some salts are reabsorbed back into the blood capillaries surrounding the tubule.
Tubular Secretion:
- Waste products such as excess ions (H+, K+), drugs, and toxins are secreted from the blood into the renal tubule to be expelled with urine.

Diseases of the Excretory System and Remedies

The following are common diseases affecting the excretory system:

Kidney Stones: Hard deposits of minerals and salts that form inside the kidneys.
- Remedies: Drinking plenty of water, medication, lithotripsy (shock wave therapy), surgery.
Kidney Infection (Pyelonephritis): Bacterial infection of the kidneys.
- Remedies: Antibiotics, pain relievers.
Kidney Failure: When kidneys lose their ability to remove waste and balance fluids.
- Remedies: Dialysis (hemodialysis or peritoneal dialysis), kidney transplant.
Urinary Tract Infection (UTI): Infection in any part of the urinary system.
- Remedies: Antibiotics, increased fluid intake.

Prevention Habits:

Drink adequate water daily.
Maintain a healthy diet (low sodium, balanced protein).
Avoid excessive alcohol and smoking.
Exercise regularly.
Manage blood pressure and diabetes.

Differences Between Circulatory and Excretory Systems

The following table outlines the key differences:

Circulatory System:
- Function: Transports blood, oxygen, nutrients, hormones, and waste products throughout the body.
- Main Organ: Heart.
- Components: Heart, blood vessels (arteries, veins, capillaries), blood.
- Primary Role: Transport and distribution.
Excretory System:
- Function: Removes metabolic waste products and excess substances from the body.
- Main Organ: Kidneys.
- Components: Kidneys, ureters, urinary bladder, urethra (and skin, lungs, liver for other wastes).
- Primary Role: Filtration and waste elimination.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and asks them what happens to the waste products generated in their bodies after digestion and metabolism. The teacher also asks if they know how their body gets rid of excess water.
Pupils’ Activity: Pupils respond by mentioning excretion, urine, sweat, and other ways the body removes waste.
Learning Point: Pupils are introduced to the concept of waste removal in the body.

Step 2: Meaning of Excretory System and Organs

Time: 7 minutes
Teaching Skill: Explanation/Identification
Teacher’s Activity: The teacher explains the meaning of the excretory system and uses a chart to identify and explain the major excretory organs (kidneys, ureters, bladder, urethra, skin, lungs, liver).
Pupils’ Activity: Pupils listen attentively, observe the charts, and identify the organs as pointed out by the teacher.
Learning Point: Pupils understand what the excretory system is and can name its main organs.

Step 3: Structure and Functions of the Kidney

Time: 8 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher uses a diagram of the kidney to explain its structure (cortex, medulla, renal pelvis, nephron) and discusses the various functions of the kidney in the body.
Pupils’ Activity: Pupils observe the diagram, ask questions, and take notes on the structure and functions of the kidney.
Learning Point: Pupils understand the detailed structure and vital roles of the kidney.

Step 4: Process of Excretion (Urine Formation)

Time: 8 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher explains the three main stages of urine formation: glomerular filtration (ultrafiltration), tubular reabsorption, and tubular secretion, illustrating with simple diagrams if available.
Pupils’ Activity: Pupils listen to the explanation, ask for clarification, and try to grasp the steps involved in urine production.
Learning Point: Pupils understand how urine is formed in the nephron.

Step 5: Diseases of the Excretory System and Remedies

Time: 7 minutes
Teaching Skill: Discussion/Problem-solving
Teacher’s Activity: The teacher discusses common diseases affecting the excretory system such as kidney stones, infections, and kidney failure, along with their causes, symptoms, and possible remedies or preventive measures.
Pupils’ Activity: Pupils participate in the discussion, ask questions about specific diseases, and suggest ways to maintain kidney health.
Learning Point: Pupils learn about common excretory system diseases, their remedies, and prevention.

Step 6: Differences between Circulatory and Excretory Systems

Time: 5 minutes
Teaching Skill: Comparison/Analysis
Teacher’s Activity: The teacher guides the pupils to compare and contrast the circulatory and excretory systems, highlighting their primary functions, main organs, and roles in the body.
Pupils’ Activity: Pupils state the differences and similarities between the two systems.
Learning Point: Pupils can distinguish between the circulatory and excretory systems.

Step 7: Evaluation/Review

Time: 5 minutes
Teaching Skill: Questioning/Assessment
Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define the excretory system.
List three main organs of the excretory system.
Briefly explain the three processes involved in urine formation.
Mention two common diseases of the kidney and their remedies.
State two differences between the circulatory and excretory systems.

Pupils’ Activity: Pupils answer orally and in writing.
Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of the excretory system and the need to care for it. The teacher then gives an assignment.
Pupils’ Activity: Pupils listen to the summary and copy the assignment.
Learning Point: Pupils consolidate their understanding of the excretory system.

Lesson Keywords

Excretion – The process of removing waste products from the body.
Kidney – The primary organ of the excretory system, responsible for filtering blood.
Nephron – The functional filtering unit of the kidney.
Filtration – The first step in urine formation where blood is filtered in the glomerulus.
Reabsorption – The process where useful substances from the filtrate are returned to the blood.
Urine – The liquid waste product formed by the kidneys.
Ureter – Tubes carrying urine from the kidneys to the bladder.
Bladder – An organ that stores urine.
Urethra – The tube that carries urine from the bladder out of the body.

Differentiation

For pupils who grasp concepts quickly, the teacher can provide additional information on hormonal regulation of kidney function or more complex kidney diseases. For those who need more support, the teacher can use simplified diagrams, provide clearer notes, and offer one-on-one assistance during activities like labeling diagrams.

Note for teachers using this lesson plan

Teachers should ensure they have clear, visible charts or diagrams of the excretory system and the kidney. Encourage pupils to ask questions and relate the concepts to their own health. Emphasize practical ways to maintain a healthy excretory system.