Define aerobic respiration
It is the breakdown of food substances in the presence of oxygen, resulting in the release of a relatively large amount of energy. Carbon dioxide and water are formed as waste products.
Where does aerobic respiration occur in eukaryotic cells?
Mitochondria
What is the equation for aerobic respiration?
C6H12O6 + 6O2——> 6CO2 + 6H2O + relatively large amount of energy
Where does anaerobic respiration occur?
Cytoplasm of cells
Define anaerobic respiration
It is the breakdown of food substances without oxygen, resulting in the release of a relatively small amount of energy
What is the equation of anaerobic respiration in yeasts?
C6H12O6 ——> 2 C2H5OH (ethanol) + 2CO2 + relatively small amount of energy
What is the equation for anaerobic respiration in skeletal muscles of humans?
C6H12O6—->2 C3H6O3 (lactic acid) + relatively small amount of energy
Why does anaerobic respiration occur in humans?
During exercise, muscles contract vigorously to enable movement. This results in high energy demand.
Both the rate of breathing and heart rate increase to enable more oxygen to reach muscles and CO2 to be removed entirely.
If increased oxygen intake is unable to meet the oxygen demand, anaerobic respiration takes place to provide additional energy required.
This results in the accumulation of lactic acid in muscle cells (fatigue and muscle pain).
What is oxygen debt?
Anaerobic respiration results in the accumulation of lactic acid in muscle cells (fatigue and muscle pain).
In the liver, lactic acid is oxidised and converted to glucose.
This additional O2 needed to oxidised the-accumulated lactic acid is termed oxygen debt.
What is the function of the nasal cavity?
The fringe of hair and mucous layer on the walls of the nasal cavity trap dust and foreign particles.
As air passes through the air passages, it is warmed and moistened
What is the function of the trachea?
Contains C-shaped rings of cartilage which prevents trachea from collapsing and keeps airways open
What are the adaptations in the inner walls of trachea and bronchi?
- goblet cells secrete mucous that trap dust particles and bacteria in inhaled air
- ciliated cells have cilia that weep the trapped particles and bacteria up the bronchi and trachea, into the pharynx
What is the function of alveoli?
They are the site of gaseous exchange.
What are the adaptations of alveoli?
- Numerous alveoli in lungs increase total surface area for gaseous exchange
- Alveoli are well-supplied with blood capillaries to enable the efficient exchange of gases
- Alveolar epithelium and blood capillary wall is one cell thick. The short distance allows quick diffusion of gases between alveoli and blood capillary
- Thin layer of moisture on surface of alveoli allows gases to dissolve and easily diffuse into blood in capillaries
- Maintenance of a steep concentration gradient between alveoli and blood : blood constantly flowing in alveoli capillaries + constant breathing
Describe the removal of carbon dioxide at the lungs
- the concentration of carbon dioxide at lungs is low
- HCO3- in blood plasma reacts readily with H+ and is converted back into carbonic acid, H2CO3
- H2CO3 is converted into CO2 + H2O. However, this does not readily occur and is a slow process, has it requires the aid of carbonic anhydrase to catalyse the reaction
- Co2 molecules then diffuse from RBC(?) to plasma to alveoli to be removed via exhalation
What are the effects of nicotine of health?
- stimulant that cause release of Adrenalin
- this increases the heart rate, which increases blood pressure, which makes blood clot more easily. His increases he risk of coronary heart disease
- highly addictive
What are the effects of tar on health?
- contains carcinogens—->lung cancer because cigarette smoke is inhaled
- paralyses cilia lining the air passages
- dust particles rapped in mucus lining cannot b removed
Increased risk of bronchitis and emphysema
What are the effects of carbon monoxide on health?
- binds with haemoglobin to form carboxyhaemoglobin, which is a very stable compound
- there will be less haemoglobin available to transport oxygen
Describe what happens during inspiration (breathing in)
- diaphragm contracts and flattens down
- external intercostal muscles contract and internal intercostal muscles relax
- rib cage is raised upwards and outwards
- thoracic volume increases
- pressure in thoracic cavity decreases below atmospheric pressure, so air is drawn into/force into lungs
Describe what happened during expiration (breathing out)
- diaphragm relaxes and arches up
- external intercostal muscles relax and internal intercostal muscles contract
- rib cage is raised downwards and inwards
- thoracic volume decreases
- pressure in thoracic cavity increases below atmospheric pressure, so air is pushed/ forced out of the lungs
