Respiratory System I enote

Kingsley Thompson April 04, 2026

Basic Science

Class: Grade 8

Respiratory System I

1. Meaning of Respiratory System

The respiratory system is the body system that allows us to take in oxygen and remove carbon dioxide.
👉 Without it, we cannot stay alive.

2. Respiration and Its Types

Respiration is the process by which food is broken down in the body to release energy.

There are two types of respiration:

  1. Aerobic Respiration (with oxygen)
    • Uses oxygen
    • Produces much energy
    • By-products: Carbon dioxide + Water
    • Example: Normal breathing while walking
  2. Anaerobic Respiration (without oxygen)
    • No oxygen used
    • Produces little energy
    • By-products: Lactic acid (in humans) or Alcohol + Carbon dioxide (in yeast)
    • Example: Vigorous exercise leading to muscle cramps

3. Parts of the Human Respiratory System

  • Nose – Air enters here
  • Trachea (windpipe) – Passage of air
  • Bronchi – Branches that carry air to the lungs
  • Lungs – Main organs where gas exchange occurs
  • Diaphragm – Muscle that helps breathing

(Students should draw and label these parts in their notes)



Respiratory System II

1. Breathing and Its Mechanism

  • Breathing is the process of taking in oxygen (inhalation) and removing carbon dioxide (exhalation).

Steps in Breathing:

Inhalation (Breathing in):

  • Diaphragm contracts and moves downward.
  • Ribs move upward and outward.
  • Lungs expand and air enters.

Exhalation (Breathing out):

  • Diaphragm relaxes and moves upward.
  • Ribs move downward and inward.
  • Lungs contract and air goes out.

2. Artificial Respiration

  • Artificial respiration is the process of helping someone to breathe when their natural breathing has stopped.
  • It is usually done in cases of drowning, suffocation, electric shock, or poisoning.

Methods:

  1. Mouth-to-mouth resuscitation – rescuer blows air into the victim’s mouth.
  2. Mouth-to-nose resuscitation – rescuer blows air into the nose if the mouth cannot be used.

3. Problems and Diseases of the Respiratory System

Some common diseases include:

  1. Asthma – Difficulty in breathing caused by narrow airways.
  2. Tuberculosis (TB) – Lung infection caused by bacteria.
  3. Pneumonia – Inflammation of the lungs.
  4. Bronchitis – Inflammation of the air passages.

Causes:

  • Smoking
  • Dust and air pollution
  • Germs (bacteria, viruses)
  • Poor ventilation

Preventive Measures:

  • Avoid smoking.
  • Live in a clean environment.
  • Get vaccinated.
  • Practice good hygiene.
  • Avoid dusty or smoky places.

ASSIGNMENT 1

  1. What is the respiratory system?
  2. Differentiate between aerobic and anaerobic respiration.
  3. Draw and label four parts of the human respiratory system.

Assignment 2

  • Write three differences between aerobic and anaerobic respiration in your notebook.
  • Draw the human respiratory system neatly and label five parts.

Objective Questions

1. The respiratory system is responsible for:
A. Digestion of food
B. Circulation of blood
C. Breathing in oxygen and breathing out carbon dioxide
D. Movement of the body

2. What is respiration?
A. Process of eating food
B. Process of breaking down food to release energy
C. Process of drinking water
D. Process of sleeping at night

3. Which of the following uses oxygen and produces much energy?
A. Aerobic respiration
B. Anaerobic respiration
C. Internal respiration
D. External respiration

4. In humans, anaerobic respiration produces:
A. Carbon dioxide and water
B. Alcohol and carbon dioxide
C. Lactic acid and small energy
D. Oxygen and energy

5. The by-products of aerobic respiration are:
A. Alcohol and lactic acid
B. Carbon dioxide and water
C. Oxygen and nitrogen
D. Glucose and starch

6. Which part of the respiratory system is the passage of air to the lungs?
A. Bronchi
B. Nose
C. Trachea (windpipe)
D. Diaphragm

7. The organ where gas exchange takes place is the:
A. Stomach
B. Lungs
C. Heart
D. Liver

8. Which muscle helps in breathing in and out?
A. Biceps
B. Diaphragm
C. Trapezius
D. Quadriceps

9. Which of the following statements is TRUE?
A. Anaerobic respiration produces more energy than aerobic respiration.
B. Aerobic respiration requires oxygen while anaerobic respiration does not.
C. The respiratory system is not needed for life.
D. The diaphragm is a part of the digestive system.

Answers

1.      C

2.      B

3.      A

4.      C

5.      B

6.      C

7.      B

8.      B

9.      B

 


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Kingsley Thompson

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