• Learning objectives
    • define aerobic respiration
    • state the word equation for aerobic respiration
    • list uses of energy in the body
    • list uses of energy in the body
    • state the word equations for anaerobic respiration in plants and animals
    • describe the production and effects of lactic acids on muscles during exercise

Definition

  • is the oxidation of food substances eg carbohydrates with the release of energy.
  • it occurs in living cells.

 

Uses of energy

  • maintenance of constant body temperature
  • active transport
  • making protein molecules
  • muscle contraction
  • cell division
  • transmitting nerve impulses

 

Types of Respiration

  1. Aerobic respiration
  2. Anaerobic respiration

 

Aerobic Respiration

  • breakdown of glucose to carbon dioxide and water to release large amounts of energy in the presence of oxygen;
  • C6H12O6 + 6O2 → 6CO2 + 6H2O

 

Anaerobic Respiration

  • oxygen is not required.
  • small amounts of energy is released.
  • lactic acid produced in mammals;
  • ethanol and carbon dioxide produced in yeast
Alcoholic Fermentation- in yeast cells
  • Glucose → ethanol + CO2 + energy
Lactate/acidic Fermentation- eg in muscle cells
  • Glucose → lactic acid

 

Differences between anaerobic and anaerobic respiration

Aerobic Anaerobic
occurs in mitochondrion in cytoplasm
large amounts of energy released small amounts of energy released
water + carbon dioxide lactic acid or CO2 + ethanol
require oxygen oxygen not required

HUMAN GAS EXCHANGE

The organs for gaseous exchange are the lungs found inside the ribcage. Gases exchanged are oxygen and carbon dioxide.

 

Lungs

 

 

Air Passage

Nasal Passage

  • the anterior most part which opens through external nostrils to the outside
  • it has hairs lining the nasal cavity- filter the air and trap large particles
  • moisture ie keeps the hairs moist
  • blood capillaries warm the incoming air.

 

Trachea

  • trachea splits into two bronchi-one goes to each lung.
  • It contains cartilage rings which keep it open and prevent it from collapsing
  • is lined with a mucus layer and cilia
  • mucus trap pathogens like bacteria and dust particles
  • cilia move in a sweeping motion to keep the air passage clean
  • The bronchi split further into bronchioles
  • the bronchioles finally end at alveoli, where gas exchange take place

 

The process of diffusion

  • there will be more oxygen inside the alveoli than there is in the surrounding blood capillaries.
  • oxygen diffuses from the air sacs into the blood capillaries
  • it will be absorbed by red blood cells
  • There will be more carbon dioxide inside the blood capillaries than there is in air sacs
  • carbon dioxide will diffuse from the blood into the air sacs

 

Differences between inhaled and exhaled air

Inhaled air % Exhaled air %
Oxygen 20 16
Carbon dioxide 0,04 4
Nitrogen 79 79
Water vapor varies saturated
  • Oxygen is used during respiration.
  • Carbon dioxide is the product of respiration.
  • Nitrogen is not used directly by the body
  • water vapor is saturated because it is a product of respiration

 

TEST FOR CARBON DIOXIDE
  • lime water changes from clear to milky in the presence of carbon dioxide.
  • Bicarbonate indicator changes from red to yellow in the presence of carbon dioxide.

 

Breathing Mechanism

Inspiration

  • external intercostal muscle contract
  • internal intercostal muscle relax
  • ribs moves upwards and outwards
  • diaphragm contracts and flattens
  • volume of thorax decreases
  • air flows into lungs

 

Expiration

  • external intercostal muscle relax
  • internal intercostal muscle contract
  • ribs moves downwards and inwards
  • diaphragm relaxes and arches upwards
  • volume of thorax decreases
  • air flows out lungs

 

The Alveoli

  • gaseous exchange takes place between the air sacs and the blood

 

Gas Exchange between the alveolar space and the blood

  • the O2 from the air sac diffuse into the moist layer-increases the concentration of O2
  • it diffuses through the alveolar epithelium into the blood capillaries
  • Blood continuous circulation maintaining the lower conc O2 in the blood capillaries, so it diffuses into blood capillaries
  • O2 combines with hemoglobin in the red blood cells
  • Oxygenated blood is transported out of the lungs
Diffussion across the alvoeli is enhanced by;
  • thin- shorter distance to diffuse
  • moist- allow gases to dissolve
  • large surface area
  • have a concentration gradient across surface-maintained by movement of air and transport
  • ability of blood to carry oxygen and carbon dioxide

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