basics of respiratory system

Question 1

functions of respiratory system

Answer 1

1) metabolic & acid base regulation (main)
- transport O2 to tissues for metabolism
- remove CO2, regulate pH

2) endocrine function
- produce hormones (AG II)

3) immunological function
- clear irritants & potential pathogens

4) voice production
- larynx (voice box)

Question 2

innervation & musculature of airways

Answer 2

1) trachea & bronchi
- mainly cartilage, little smooth muscles
2) bronchioles to terminal bronchioles
- mainly smooth muscles

. bronchi & bronchioles
- can constrict/dilate
- innervated by ANS & non-cholinergic nerves
- excessive bronchoconstriction in asthma = difficulty breathing

Question 3

components involved in ventilation

Answer 3

. chest wall
1) skeletal: rib, sternum, clavicle
2) muscle: diaphragm, intercostal, neck muscles

Question 4

process of inspiration

Answer 4

. active process
1) diaphragm and inspiratory chest wall muscles contract
2) increase in intra-thoracic volume
3) decrease in thorax & pleural cavity pressure (< atmospheric pressure)
4) air flows in

Question 5

process of expiration

Answer 5

. passive process
1) diaphragm and inspiratory chest wall muscles relax
2) decrease in intra-thoracic volume
3) increase in thorax & pleural cavity pressure (> atmospheric pressure)
4) air flows out

Question 6

what happens in cases of intense activities

Answer 6

. active process
. ventilation stimulated -> other muscles recruited (intercostal, abdominal) -> enhance chest wall movements
. stronger inspiratory effect
- neck muscles + increase diaphragm contraction = further increase in lung volume
. stronger expiratory effect
- abdominal contraction = further decrease in lung volume

Question 7

factors affecting gas exchange - diffusion

Answer 7

1) partial pressure
- partial pressure: proportion of pressure exerted by gas in mixture of gases
- move from high partial pressure to low partial pressure until equilibrium achieved

2) membrane thickness
- epithelium barriers: alveolar epithelium, basement membrane, capillary endothelium

3) surface area
- more alveoli = greater SA

Question 8

factors affecting gas exchange - blood flow

Answer 8

1) blood flow rate
- faster blood flow = lesser time for exchange
- exercise increase blood flow rate

2) blood volume
- larger volume = more diffusion

Question 9

route for pulmonary circulation

Answer 9

Right ventricle -> pulmonary artery -> branch into smaller pulmonary arterioles (w bronchioles) -> arterioles -> capillaries around alveoli -> small pulmonary vein -> 4 larger pulmonary veins -> left atrium

Question 10

features of pulmonary circulation

Answer 10

1) low pressure system (way lower than systemic circulation)
2) high blood volume
3) blood not uniformly distributed through lungs
- affected by gravity and muscular tone
- distention: lesser muscles so can distend more
- vasoconstriction: lesser blood flow