Human Respiratory System

Factors Affecting Breathing Rate

Physical Exercise

  • • Increases respiration rate
  • • More CO₂ produced
  • • Higher demand for O₂

Excitement and Sudden Fear

  • • Adrenaline release
  • • Increases breathing rate

CO₂ Levels in Blood

  • • Elevated CO₂: Stimulates medulla oblongata, increases respiration
  • • Lower CO₂: Reduces breathing rate

Experiment: Measuring Breathing Rate

Aim

To measure and compare the breathing rate before and after physical activity.

Materials

  • • Stopwatch or timer
  • • Chair or seat
  • • A quiet area for resting
  • • A space for running in place

Procedure Steps

  1. Sit calmly for 5 minutes
  2. Measure resting breathing rate (1 minute)
  3. Run in place for 5 minutes
  4. Rest for 1 minute
  5. Measure post-exercise breathing rate
  6. Compare and analyze results

Expected Results

The breathing rate will be higher after exercise, demonstrating the body's response to increased oxygen demand.

Breathing Control & Gaseous Exchange

Factors Controlling Breathing

  • • Brain and nervous system
  • • Physical activity
  • • Excitement and sudden fear

Role of Medulla Oblongata

  • • Regulates basic breathing rhythm
  • • Controls diaphragm and intercostal muscles

Gaseous Exchange in Lungs

  • • Occurs in alveoli by diffusion
  • • O₂ diffuses from air into blood
  • • CO₂ diffuses from blood to lungs
  • • Haemoglobin plays crucial role

Gaseous Exchange in Tissues

  • • O₂ diffuses from capillaries to tissue fluid
  • • CO₂ diffuses from tissue fluid to blood
  • • CO₂ carried as H₂CO₃

Respiratory System Adaptations

General Adaptations

Wide Moist Surface

Facilitates easy dissolution and diffusion

Dense Blood Capillary Network

Transports O₂ and CO₂ efficiently

Haemoglobin

High O₂ affinity, found in RBCs

Ventilation System

Inhales and exhales air

Lung Adaptations

  • • Numerous alveoli for gas exchange
  • • Thin epithelium for faster exchange
  • • Mucous membrane warms and moistens air
  • • Epiglottis prevents food entry
  • • Mucus-secreting cells trap dust and pathogens
  • • Cilia for sweeping action
  • • Spongy air sacs increase O₂ retention
  • • Dense capillary network for efficient diffusion

Respiratory System Diseases

Asthma

Description: Constriction of bronchi and bronchioles causing breathing difficulty

Cause: Allergic response to dust, pollen, sprays, grass, or mites

Signs: Wheezing, exhaustion due to low oxygen

Bronchitis

Description: Inflammation of bronchial tubes

Cause: Mucus buildup damages cilia

Signs: Persistent cough, mucus production

Pulmonary Tuberculosis (TB)

Description: Bacterial infection primarily affecting lungs

Cause: Mycobacterium tuberculosis, transmitted through airborne droplets

High-Risk Groups: Elderly, infants, immunocompromised individuals

Signs: Fever, persistent cough, fatigue, weight loss, chest pain, difficulty breathing

Lung Cancer

Description: Tumors form in alveoli due to abnormal cell division

Cause: Often stimulated by tar from tobacco smoke

Signs: Persistent cough, chest pain, difficulty breathing

Carbon Monoxide (CO) Poisoning

Description & Sources

Poisoning from inhaling carbon monoxide gas

Sources: Burning charcoal, running engines

Effect: CO forms carboxyhemoglobin, preventing oxygen transport

Signs & Symptoms

  • • Headache
  • • Nausea and vomiting
  • • Loss of hearing
  • • Cardiac arrest
  • • Weakness
  • • Blurred vision

First Aid

Mildly Affected:

  • • Stay calm and act quickly
  • • Get fresh air immediately
  • • Turn off CO source

Severely Affected:

  • • Move victim to open area
  • • Administer artificial resuscitation
  • • Call for medical help

Prevention

  • • General awareness
  • • Proper ventilation
  • • Install CO monitoring devices
  • • Avoid burning fuels in poorly ventilated areas

Effects of Smoking

Respiratory System

  • • Trachea irritation
  • • Reduced lung function
  • • Impaired lung clearance
  • • Air sac damage

Circulatory System

  • • Elevated blood pressure
  • • Increased heart rate
  • • Blood vessel constriction
  • • Reduced oxygen transport
  • • Increased clotting risk
  • • Artery damage
  • • Stroke and heart attack risk

Immune System

  • • Increased disease susceptibility
  • • Long-lasting respiratory diseases
  • • Low vitamin C levels

Tissue Respiration

Description

Complex biochemical process in cells involving glucose breakdown to release energy as ATP and heat. ATP serves as readily available chemical energy.

External Respiration

  • • Gas exchange (CO₂ and O₂) through diffusion
  • • Occurs in lung alveoli
  • • Physical process

Cellular Respiration

  • • Chemical process releasing energy
  • • Used for muscle contraction
  • • Enzyme and hormone synthesis
  • • Active nutrient uptake
  • • Heat generation

Types of Tissue Respiration

Aerobic Respiration

Conditions: Requires O₂

Process: Complete glucose oxidation

Location: Cytoplasm and mitochondria

Products: CO₂, H₂O, ATP, heat

C₆H₁₂O₆ + 6O₂ → 6H₂O + 6CO₂ + ATP + Heat

Anaerobic Respiration

Conditions: Occurs without O₂, produces less energy, occurs in cytoplasm only

Alcoholic Fermentation

Formation of alcohols

C₆H₁₂O₆ → C₂H₅OH + Energy

Lactic Acid Formation

In muscle cells when O₂ is low

C₆H₁₂O₆ → C₂H₄OHCOOH + Energy

Obligate Anaerobes

Organisms that can only perform anaerobic respiration

Facultative Anaerobes

Organisms that can perform both aerobic and anaerobic respiration

Aerobic vs Anaerobic Respiration

Aspect Aerobic Anaerobic
Oxygen Requirement Requires O₂ Does not require O₂
Location Cytoplasm and mitochondria Cytoplasm only
Glucose Oxidation Complete oxidation Incomplete oxidation
Energy Released More energy Lower energy
By-products Heat, H₂O, CO₂ Fermentation: ethanol, heat, CO₂
Muscle cells: lactic acid, heat