lecture 22: resp. 4

Question 1

definition of compliance

Answer 1

the reciprocal of elasticity, the ability to expand and stretch. (1/elasticity). compiance is change in volume over change in pressure (Dvolume/Dpressure)

Question 2

recoil force

Answer 2

how expiration occurs at rest
- consists of elasticity and surface tension

Question 3

elasticity

Answer 3

the ability to recover original size and shape after deformation. achieved int he lungs due to collagen and elastin

Question 4

surface tension

Answer 4

-skin on top of water (liquid gas interface), the top molecules have stronger attractive forces on their neighbours beside them since there is no molecules above. higher intermolecular forces between molecules on surface than those beneath.

Question 5

importance of surface tension

Answer 5

surface tension is trying to collapse the lung (thus a method of deflation). laplace’s law P = 2T/R
p= pressure
T= surface tension
R= radius of alveolus

Question 6

consequence of chronic obstructive pulmonary disease on lung compliance and ventilation

Answer 6

• increased compliance
• less pressure to inflate lungs
• for example in smokers where elastin content decreases
  -can’t take as deep a breath since lung is already partially inflated at functional Residual capacity/FRC (resting)

Question 7

consequence of fibrosis on lung compliance and ventilation

Answer 7

• compliance decreased
• more pressure to inflate lungs
• more collagen laid down from inflammation
• lung is stiff and FRC is smaller

Question 8

funnel effect

Answer 8

• highest resistance at generation 1(trachea)
• resistance decreases as more generations occur and surface area increases.
• airflow begins fast and turbulent and becomes slow and laminar (good for gas exchange)

Question 9

impact of dead space on ventilation

Answer 9

Dead space is the area in the lungs that doesn’t undergo gas exchange, if there is too much then the delivered volume of air for gas exchange will be less.

Question 10

autonomic control of airways in bronchioles

Answer 10

• parasympathetic (vagus): constriction via acetylcholine onf muscarinic receptor
• sympathetic causes dilation from nerves from spinal chord via norepephrine on beta-adrenoceptors

Question 11

control of airway an dimater and resisance pathway

Answer 11

• sensory receptos (mechano receptos in bronchioles recept stretch)
• through vagal afferents to medulla oblongata respiratory centres
• sympathetic efferent verve to effector or target organ to release norepinephrene and bronchioles dilate

Question 12

examples of diseases affecting airway resistance

Answer 12

asthma