Pharmacology - Lung Structure & Function, Smoking

Question 1

Role of respiratory system

Answer 1

Ensure adequate intaake of O2 and removal of CO2

Question 2

Structure

Answer 2

Trachea
Bronchi
Bronchial Cartidge
Bronchioles
Alveoli

Question 3

Cystic fibrosis

Answer 3

Struggle with releasing fluids into lumen
Thick mucus that’s hard to move
Trap bacteria and viruses
Cause infections

Physiotherapy to remove mucus

Question 4

Effect of SNS

Answer 4

opening up of airways
increase in heart rate
Adrenaline and NA at adrenoceptors

Question 5

Effect of PNS

Answer 5

Constriction of airways
Increase GI motility
ACh at muscarinic receptors

Question 6

α-adrenoceptor subtypes

Answer 6

α1: smooth muscle contraction

α2: smooth muscle contraction, pre-junctional regulation of NA release (negative feedback mechanism to control itself)

Question 7

β-adrenoceptor types

Answer 7

β1: heart force and rate
β2: airway muscle relaxation
β3: skeletal muscle, adipose tissue

Question 8

Muscarinic Receptor Types

Answer 8

M1: CNS, slivary glands, gastric glands
M2: Heart rate of contraction, GI smooth muscle contraction, CNS
M3: salivary glands, GI and airways smooth muscle
M4 & M5: CNS

Question 9

Pathways of innervation in airways

Answer 9

Sympathetic:

• Adrenaline at β2-adrenoceptors –> muscle relaxation –> more O2
• Inhibition of inflammatory mediators release from mast cells –> beneficial for treating lung inflammation etc.
• Inhibition of mucus

Parasympathetic:

• ACh at M3 receptors
• Bronchoconstriction
• Increase mucus secretion

Sensory nerves:

• Local reflexes respond to irritants
• Coughing
• Bronchoconstriction
• Increase mucus secretion

Question 10

Sensory nerves in exercise-induced asthma:

Answer 10

• cooling and dehydration –> activation of sensory nerves immune response –> bronchoconstriction –> coughs

Question 11

Sensory nerves up-regulation

Answer 11

by inflammatory cytokines (ex: capsicum in chillis)

Question 12

Sensory nerves in cold-induced asthma

Answer 12

TRPM8 receptors detect changes in temperature –> activation of mast cellls –> secretion of mucus

bronchoconstriction

Question 13

Breathlessness causes

Answer 13

Cystic fibrosis
Inflammation; asthma & anaphylaxis 
Psychological; panic attacks
Pregnancy, obesity, altitude
Cancer
Pulmonary embolism
Side effect of drugs (β-blockers, NSAIDs etc.)

Question 14

Normal breathing

Answer 14

12 breaths/min
0.5 L/breath

eupnoea (normal rythm of breathing):
2 secs inhalation
3 secs exhalation

1/3 of air remain in main airways
Deeper breaths: more air pass into alveoli for gas exchange

Question 15

Airway resistance

Answer 15

depend on friction & airway cross section

• contraction of airway smooth muscle
• remodelling: increased growth of smooth muscle
• reduced size of lumen (asthma, COPD etc.)
• excess mucous production (chronic bronchitis etc.)

Question 16

Compliance

Answer 16

ability of lung to stretch

Question 17

Elastance

Answer 17

ability of lung to recoil

Question 18

Fibrosis

Answer 18

struggle to stretch the lung, but high recoil –> reduced capacity

Question 19

Emphysema/COPD

Answer 19

loss of elastance

Question 20

Control of Breathing

Answer 20

ANS

can be overridden by CNS

Question 21

Spirometry

Answer 21

measure lung volume

VC = FVC = forced vital capacity

VT = tidal volume

TLC = total lung capacity

IRV = inspiration reserve volume

Question 22

Spirometry normal result

Answer 22

FEV (4.0 L)

FEV1:FVC = 0.8

Question 23

Spirometry obstructive disease (COPD, asthma etc.)

Answer 23

FEV1 (1.3 L) (struggling to force air out)
FEV1:FVC = 0.3

FEV1 = 32% of normal –> severe

FVC normal or slightly decreased

Question 24

Spirometry restrictive disease (fibrosis etc.)

Answer 24

FEV1 = normal or slightly decreased

FEV1:FVC = normal

FVC decreased (cannot fill up lungs with air)

Question 25

Peak flow meter

Answer 25

PEF - rise rapidly during forced expiration then drops Constriction --> reduced peak flow --> lower number of peak flow meter

Question 26

Respiratory acidosis

Answer 26

impaired expiration fo CO2 --> build up of CO2 --> CO2 react with water to release H+ ions --> drop in pH long-term/chronic --> buffering with Hb in RBCs --> increase in HCO3- (bicarbonate) acidosis vs. alkalosis? --> measure blood pH acute vs. chronic --> HCO3- levels in plasma breathing rate: - acidosis --> increase in breathing to limit hypoxia - hyperventilation --> loss of CO2 --> alkalosis --> drop in CO2 and inhibition of ventilation - metabolic acidosis (ex: diabetes) --> drop in pH --> stimulation of ventilation - metabolic alkalosis (ex: vomiting) --> loss of H+ --> depression of ventilation

Question 27

Smoking

Answer 27

- one-third of all cancer deaths | - half of long-term smokers die prematurely due to smoking

Question 28

Cigarette smoke contents

Answer 28

- Tar - solid material, form sticky brown residue - Carcinogenics (ex: benzopyrenes --> DNA damage) - Oxidatives - Heavy metals (ex: cadmium)

Question 29

Decline of lung function because of smoking

Answer 29

keeps declining even if stopped smoking before seeing any symptoms