- 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
- Aerobic respiration
- 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