Biology: Lungs

Question 1

Lung disease

Answer 1

• Interpret information relating to the effects of lung disease on Gas Exchange and / or ventilation
• Interpret data relating to the effects of pollution and smoking on the incidence of lung disease
• Analyse and interpret data associated with specific risk factors and the incidence of lung disease
• Evaluate the way in which experimental data led to statutory restrictions on the sources of risk factors
• Recognise correlations and causal relationships

Question 2

Inspiration (Breathing in)

This is always an active process because it requires energy for the muscle movement

Answer 2

• The respiratory centre in the medulla of the brain generates electrical nerve impulses
• The nerve impulses travel to the external intercostal muscles and diaphragm
• The external intercostal muscles contract
• The rib cage is pulled upwards and outwards
• The diaphragm is also stimulated to contract, and this causes it to flatten (abdominal organs are pushed downwards)
• The movements of the ribcage and the diagram increase the volume of the thorax
• The pressure of the thorax decreases below that of atmospheric pressure
• Air flows down the pressure gradient into the lungs

Question 3

Expiration at Rest

A rest, expiration is mainly a passive process because muscle contraction is not required

Answer 3

• Nerve impulses stop being releases from the inspiratory section of the medulla
• The external intercostal muscles relax
• The ribcage falls down, and in as a result of gravity
• The diaphragm also relaxes and the pressure from the abdomen pushes the diaphragm back up into its some shape
• These movements decrease the volume of the thorax
• The pressure of the thorax increases above that of atmospheric pressure
• There is also elastic recoil of the lungs
• Air flows out of the lungs down the pressure gradient

Question 4

Expiration During Exercise

This is an active process as it involves the contraction of muscles

Answer 4

• Electrical nerve impulses are released from the expiratory section of the respiratory centre of the medulla
• These stimulate the internal intercostal muscles to contract
• The ribcage is pulled down and in
• They also stimulated muscle in the abdomen wall to contact (increasing pressure in the abdomen) so that that there is a force pushing the diaphragm upwards
• The movements causerie volume of the thorax to decrease
• The pressure of the thorax increases above that of atmospheric pressure
• There is also elastic recoil of the lungs
• Air flows out of the lungs down the pressure gradient