03. Respiration & Gas exchange

Release of energy from food [usually glucose]

1. Goes on in every cell in the body

2. Some energy is transferred by heat

3. Energy transferred by respiration can’t be used directly by cells [used to make ATP]

1. Stores the energy needed for cell processes

2. When cell need energy → ATP molecules are broken down and energy is released

1. Respiration with oxygen

2. Produces CO₂ + H₂O

3. Produces lots of ATP

4. Used most of the time

1. Respiration without oxygen

2. In animals : Produces lactic acid
   In plants/fungi : Produces ethanol + CO₂

3. Produces small amt of ATP

4. Glucose partially broken down

• Vigorous exercise

• Not enough oxygen even if heart & breathing rate increase

• Respire anaerobically to repay oxygen debt

• Lactic acid produced

• Lactic acid build up and leads to cramps

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Glucose + Oxygen → Carbon dioxide + Water + ATP

Glucose → Ethanol + Carbon dioxide + ATP

Glucose → Lactic acid + ATP

1. Trachea

2. Cartilage

3. Rib

4. Intercostal muscle

5. Bronchus

6. Bronchioles

7. Alveoli

8. Pleural membrane

9. Diaphragm muscle

• Tube linking nose & mouth to lungs

• Splits into 2 tubes - bronchi

Stop trachea from collapsing [support]

Support + protect the heart & lungs

• Shrink & expand chest cavity during breathing

• Form & move the chest wall

Carry air to & from the lungs

Tree of tubes spreading throughout the lungs

• Air sacs

• Site of gas exchange

• Alveolar air - high conc. of O₂, low conc. of CO₂

• Surround the lungs

• Contains lubricating fluid within membrane sac

• Sheet of tendon separating thorax & abdomen

• Contract & relax during breathing

• Found in lungs & trachea

• Catch dust & bacteria

• Keep trachea clear by sweeping mucus back

1. Deoxygenated blood arrives from rest of the body via blood capillary

2. Diffusion [high to low]
   O₂ diffuses out of alveoli into the blood
   CO₂ diffuse out of the blood into the alveoli

3. Oxygenated blood leaves

4. Blood reaches body cells
   O₂ is released from red blood cells and diffuse into body cells
   CO₂ diffuse from body cell into blood

5. Deoxygenated blood carried back into lungs [repeat]

1. Many - increase SA

2. Moist lining - gas can dissolve into lining [help diffuse]

3. One cell thick wall - short diffusion distance

4. Good blood supply - maintain conc. gradient

5. Permeable walls - gases can diffuse across easily

1. Intercostal muscles + diaphragm contract

2. Diaphragm muscles pull down + flatten diaphragm

3. Ribcage move up & out

4. Volume of thorax increase

5. Pressure decrease

6. Air dragged in by higher pressure outside

1. Intercostal muscles + diaphragm relax

2. Diaphragm return to domed state

3. Ribcage move down & in

4. Volume of thorax decrease

5. Pressure increase

6. Air forced out due to higher pressure inside

1. Damages alveoli walls - Reduce SA for gas exchange [emphysema]

2. Tar damages cilia in lungs & trachea

3. Tar irritates bronchi & bronchioles - Produce more mucus but cannot be removed due to damaged cilia [smoker’s cough, Chronic bronchitis]

4. CO [carbon monoxide] - binds irreversibly to haemoglobin - reduce amt of oxygen blood can carry

5. Carcinogens [tobacco smoke] can lead to cancer

6. Nicotine is addictive + narrows blood vessels [increase blood pressure]

1. Enzymes break down carbs in flour into sugars

2. Yeast use sugars in aerobic respiration [produce carbon dioxide]

3. Oxygen run out - anaerobic respiration [produce carbon dioxide & ethanol]

4. Carbon dioxide produced is trapped in bubbles inside dough

5. Gas pockets expand - dough rise

6. Dough is baked in the oven [increase heat - increase speed of reaction]

   1. Yeast ferment till optimum temp is reached

   2. Alcohol [ethanol] produced is boiled away

7. Bread stops rising [gas pockets still present]