8. Respiration in Humans Flashcards
function of larynx
Voice box containing vocal cords
function of trachea (2)
• Breathing tube supported by C-shaped cartilage
which prevents the trachea from collapsing as the
air pressure in the lungs changes.
• branches into two bronchi, one to each lung.
function of bronchi (2)
• Branches repeatedly within the lungs to produce
numerous finer tubes called bronchioles.
• The bronchioles at the end of the branching
terminate in clusters of air sacs called alveoli
function of bronchioles
allow gas exchange with blood: their many branches branch out into the alveoli
function of alveoli (5)
- Sites of gaseous exchange in the lungs.
- Blood entering the lungs from the heart has a lower
concentration of oxygen and a higher concentration
of carbon dioxide than the atmospheric air entering
the alveoli in the lungs. - Oxygen diffuses from the alveolar air into the blood
capillaries - Carbon dioxide diffuses from blood capillaries to the
alveoli - Oxygen and carbon dioxide concentration gradients
are maintained by:
• Continuous flow of blood through the blood
capillaries.
• Movement of air in and out of the alveoli, caused by
breathing
function of associated capillaries
allow the movement of substances, mainly gases Oxygen and Carbon Dioxide into and out of the capillary.
State the characteristics and describe the role of the exchange surface of the alveoli in gas exchange (4)
ADAPTATION OF LUNG FOR GASEOUS EXCHANGE
1. The numerous alveoli in the lungs provide a large surface area to volume ratio for gaseous exchange.
2. The wall of the alveolus is only one cell thick. This provides a short diffusion distance for gases, ensuring a
faster rate of diffusion.
3. A thin film of moisture covers the surface of the alveolus. This allows oxygen to dissolve in it.
4. The walls of the alveoli are richly supplied with blood capillaries. The flow of blood maintains the steep
concentration gradient of gases
effects of tobacco smoke and (nicotine, tar and carbon monoxide)
- nicotine (5)
- tar (2)
- carbon monoxide (2)
- irritants
Nicotine
• Addictive substance that stimulates adrenaline release
• Increases heart rate and blood pressure
• Increase the risk of blood clot
• Blood clots in arteries leads to increased risk of heart attack
• Blood clots in blood capillaries in the brain increases risk of
stroke
Tar
• Carcinogenic substances that increases risk of cancer
• Paralyses cilia lining air passages. Dust and irritant are trapped in
the mucus which cannot be removed, increasing risks of chronic
bronchitis and emphysema
Carbon Monoxide
• Combines irreversibly with haemoglobin to form
carboxyhaemoglobin, which reduces eficiency of blood to
transport oxygen
• Increases the rate of fatty deposits on the inner arterial wall,
increasing risk of atherosclerosis
Irritants
• Paralyses cilia lining air passages, dust and irritant are trapped in
the mucus which cannot be removed, increasing risks of chronic
bronchitis and emphysema
define and state the equation for aerobic respiration in humans
Glucose + Oxygen ⟶ Carbon Dioxide + Water + Energy
define and state the equation for anaerobic respiration in humans
Glucose ⟶ Lactic Acid + Energy (small amount)
describe the effect of lactic acid in muscles during exercises (5)
Recovery period
• The body requires rest and the breathing rate continues to be fast for some time.
• This is to take in more oxygen to repay the oxygen debt.
• Lactic acid is removed from the muscles and transported to the liver.
• In the liver, oxygen is also used to oxidised some of the lactic acid to release energy. This energy is used to convert the remaining
lactic acid back into glucose.
• When all the lactic acid has been converted to glucose, the oxygen debt is repaid
describe anaerobic respiration in muscles (6)
• During vigorous muscular contractions, the muscle cells primarily respire aerobically.
• However, during strenuous exercise, there is a limit to the rate of breathing and heart rate, there may not be suficient oxygen supplied
to muscle cells to sustain aerobic respiration.
• Therefore, muscle cells also respire anaerobically for short durations in order to meet the energy demands of the activity.
• The extra energy released by anaerobic respiration supplements the energy released by aerobic respiration to allow continuous muscle
contraction
• When anaerobic respiration occurs, there is a buildup of lactic acid in the muscle cells.
• The muscles are incur an oxygen debt and lactic acid build up causes fatigue and muscular pains.
describe aerobic respiration (3)
- in the presence of oxygen, aerobic respiration can produce a large amount of
energy - Site of aerobic respiration is mitochondria
- Energy is needed
• Synthesising complex molecules from simpler molecules i.e. proteins from
amino acids
• Synthesis of new protoplasm and genetic material for cell growth and division
• Muscular contraction
• Active transport
• Transmission of nerve impulses
• Maintenance of constant body temperature as heat is released during
respiration
effects of smoking on health
- chronic brochities (5)
- emphysema (4)
- lung cancer (2)
CHRONIC BROCHITIS
- Chronic bronchitis is the inflammation of respiratory lining of the airways, caused by
irritation
- Prolonged exposure to tar and irritant particles leads to excessive mucus is secreted
by the epithelium.
- The cilia on the epithelium are paralysed thus mucus and dust particles cannot be
removed.
- The air passages become blocked, making breathing difficult.
- Persistent coughing is needed to clear air passages, in order to breathe. This
increases the risk of getting lung infections.
EMPHYSEMA
- Persistent and violent coughing due to bronchitis may lead to emphysema.
- alveolar walls break down due to persistent and violent coughing.
- This decreased surface area for gaseous exchange.
- Lungs lose their elasticity and reduce ability to expel air, causing severe
breathlessness result.
LUNG CANCER
- Risk of lung cancer increases when a person smokes tobacco due to carcinogens (tar)
present
- Cancer is the uncontrolled division of cells producing tumour.
