Year 9 Biology: Respiration & Respiratory System Notes

Wallace High School Year 9 Biology: Respiration & Respiratory System

Lesson 1: How We Get the Energy We Need

Learning Objectives:
  • Understand the word equation for respiration.
  • Recognize respiration as a chemical reaction.
  • Identify the three systems involved in respiration.
  • Discuss the necessity of energy.
  • Understand that plants respire too.
  • Learn how to test for carbon dioxide using limewater and bicarbonate indicator.
Defining Respiration:
  • Respiration is a process that occurs in all living cells, where glucose is oxidized to release energy.
  • Glucose (obtained from food) is our main fuel, analogous to petrol in a car.
  • Aerobic respiration occurs in the presence of oxygen:
    Glucose+Oxygen→Carbon Dioxide+Water+Energy\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon Dioxide} + \text{Water} + \text{Energy}
  • Respiration is different from breathing, which is merely the physical process of taking in air.
  • Energy is measured in joules (J).
Systems Involved in Respiration:
  1. Digestive System: Converts large food molecules into small ones for absorption into the bloodstream.
  2. Circulatory System: Transports soluble food molecules and oxygen to cells and removes carbon dioxide.
  3. Respiratory System: Facilitates the intake of oxygen and removal of carbon dioxide.

Energy Usage in Cells

Why Do We Need Energy?

Cells utilize energy for several vital processes:

  • Movement: Muscle contraction.
  • Chemical Synthesis: Creation of new chemicals.
  • Growth and Repair: Repairing damaged tissues.
  • Transport: Movement of substances, e.g., mineral absorption in plants.
  • Nervous Functions: Transmission of nerve impulses.
  • Thermoregulation: Maintaining body temperature at 37°C.
Detecting Carbon Dioxide:
  • Experiments often measure the presence of carbon dioxide, a byproduct of respiration:
    • Limewater: Turns from colorless to milky white when carbon dioxide is present.
    • Bicarbonate Indicator: Changes from red/orange to yellow in CO₂ presence and from red/orange to purple when CO₂ is removed.

Plant Respiration

  • All living organisms, including plants, respire continuously, taking in oxygen and releasing carbon dioxide.
  • During the day, high light levels lead to photosynthesis where oxygen production exceeds usage.
  • Germinating seeds respire without photosynthesis due to underground conditions.

Lesson 2: The Respiratory System and the Mechanism of Breathing

Learning Objectives:
  • Label parts of the respiratory system.
  • Explain inhalation and exhalation mechanisms.
  • Define gas exchange and ventilation.
  • Use model lungs to illustrate respiratory mechanisms.
The Respiratory System:
  • Comprises tubes that transport air to the alveoli, where gas exchange occurs.
  • The lungs are located in the thorax, protected by the rib cage and separated from the abdomen by the diaphragm.
  • Air enters through the trachea, which then branches into the bronchi leading to each lung. Smaller branches are termed bronchioles.
  • The walls of bronchi/trachea are lined with mucus and cilia to trap foreign particles.
Mechanism of Breathing:

  • Ventilation consists of inhalation (breathing in) and exhalation (breathing out).

  • Inhalation:

    • Diaphragm contracts and flattens.
    • Intercostal muscles contract.
    • Ribs move up and out.
    • Chest cavity volume increases, leading to lower air pressure and air influx.

  • Exhalation:

    • Diaphragm relaxes and domes upward.
    • Intercostal muscles relax.
    • Ribs move down and in.
    • Chest cavity volume decreases, increasing air pressure and expelling air.

The Model Lung Demonstration:

  • Model Lung Components:
    • Balloons represent the lungs.
    • Glass jar represents the chest cavity.
    • Glass tubes represent the trachea and bronchi.
    • Rubber sheet represents the diaphragm.
  • Demonstrates how volume changes affect pressure during breathing.

Lesson 3: Changes in Air Composition in the Lungs

Learning Objectives:
  • Measure and calculate lung volumes.
  • Explore changes in air during respiration.
Gas Exchange at the Lungs:
  • Gas concentrations control diffusion across the alveoli and blood.
  • Air inhaled and exhaled differs in composition (CO₂, O₂, water vapor).

Lesson 4&5: Gas Exchange at the Alveoli

Key Features of Alveoli:
  1. Large Surface Area: Enables more gas diffusion.
  2. Short Distance: Thin walls (one cell thick) allow for rapid diffusion.
  3. Diffusion Gradient: Higher concentrations of gases speed up diffusion.
  • Gases diffuse between alveoli and blood, with oxygen entering the blood and carbon dioxide leaving it.
  • The alveoli's large surface area (approximately 70m²) is critical for efficient gas exchange.
Surface Area to Volume Ratio:
  • A smaller object has a higher surface area to volume ratio, which is crucial for efficient gas exchange.
  • Alveoli maximize this surface area for mammalian respiratory efficiency.

Lesson 6: Health and the Respiratory System

Health Concerns:
  • Asthma: Caused by inflammation and narrowing of bronchial tubes.
  • Triggers: Allergies, dust, chemicals leading to wheeziness.
  • Inhalers: Two types—preventers and relievers help manage symptoms.
Smoking Dangers:
  • Nicotine: Addictive, toxic chemical impacting cardiovascular health.
  • Tar: Causes chronic diseases and stains.
  • Carbon Monoxide: Binds with red blood cells more effectively than oxygen.
  • Ammonia: Harsh chemical with cleaning fluid properties.
  • Overall Risks: Affects lung health, with a significant correlation to lung cancer and other diseases.
Research Task:
  • Create a health advice leaflet focusing on the impact of smoking and vaping, including:
    • Chemicals in cigarettes and their risks.
    • Health consequences of smoking and strategies to quit.