The Bio Brief

What is Respiration?

• Respiration is the process by which food (glucose) is broken down in cells to release energy needed for life activities.

Energy released is stored in the form of ATP

Why is Respiration Important?

• Provides energy for growth, movement, repair
• Needed for all life processes
• Occurs in every living cell

 Types of Respiration

 Flowchart: Types of Respiration

Respiration

    ↓

 ┌───────────────┬───────────────┐

 Aerobic        Anaerobic

 (with O₂)      (without O₂)

 First Step of Respiration (Common to All)

Glycolysis

• Glucose (6-carbon) → Pyruvate (3-carbon)
• Occurs in cytoplasm
• Does not require oxygen

Glucose (6C)

     ↓

Pyruvate (3C)

 Fate of Pyruvate

Pyruvate

   ↓

 ┌────────────┬─────────────┬─────────────┐

 No oxygen    No oxygen     Oxygen present

 (Yeast)     (Muscles)     (Mitochondria)

   ↓             ↓              ↓

 Ethanol +     Lactic        CO₂ + H₂O

 CO₂           Acid

 (Low energy)  (Cramps)     (High energy)

(A) Anaerobic Respiration

• Takes place without oxygen
• Occurs in:

Yeast → Ethanol + CO₂

Muscle cells → Lactic acid

 Lactic acid causes muscle cramps

(B) Aerobic Respiration

• Takes place with oxygen
• Occurs in mitochondria
• Produces:

Carbon dioxide

Water

Large amount of energy

Energy Currency – ATP

What is ATP?

• Adenosine Triphosphate
• Stores and supplies energy

ATP Cycle

ADP + Phosphate + Energy

        ↓

       ATP

        ↓ (energy released)

ADP + Phosphate

Breaking one ATP releases 30.5 kJ/mol energy

Uses of ATP

• Muscle contraction
• Protein synthesis
• Nerve impulse conduction
• Cell division

Exchange of Gases in Plants

• Takes place through stomata
• Occurs by diffusion
• Depends on: Day / Night

Requirement of plant

Time	Main Gas Exchange
Day	Oxygen released
Night	Carbon dioxide released

Respiration in Animals

• Aquatic Animals (Fish)
• Use dissolved oxygen
• Breathe faster
• Oxygen absorbed through gills

Terrestrial Animals

• Use atmospheric oxygen
• Special respiratory organs:
• Lungs (humans)
• Trachea (insects)

Human Respiratory System

Flowchart: Path of Air

Nostrils

  ↓

Nasal cavity

  ↓

Throat (Trachea)

  ↓

Bronchi

  ↓

Bronchioles

  ↓

Alveoli

Structure & Function

• Nostrils – filter air (hair + mucus)
• Trachea – cartilage rings prevent collapse
• Alveoli:
• Balloon-like sacs
• Very thin walls
• Rich blood supply
• Large surface area (~80 m²)

Breathing Mechanism

Inhalation

• Ribs move up
• Diaphragm flattens
• Chest cavity expands
• Air enters lungs

Exhalation

• Ribs move down
• Diaphragm relaxes
• Air goes out

 Lungs always contain residual air for continuous gas exchange

 Transport of Gases

• Oxygen Transport
• Carried by haemoglobin
• Present in RBCs
• Haemoglobin has high affinity for oxygen
• Carbon Dioxide Transport
• Mostly transported dissolved in blood

 Importance of Large Surface Area

• Alveoli provide huge surface area
• Makes gas exchange fast & efficient
• Diffusion alone would take 3 years for oxygen to reach toes

 Harmful Effects of Smoking

Smoking Damages:

• Lungs
• Heart
• Liver
• Tongue

Effects:

• Destroys cilia
• Dust and germs enter lungs

Causes:

• Cough
• Infection
• Lung cancer
•  Say NO to tobacco! Stay healthy!