expiration

Question 1

what type of process is quiet expiration?

Answer 1

passive

no muscle involvement

Question 2

what is expiration dependent on?

Answer 2

elasticity of lungs

Question 3

what is the equation and relationship for elasticity of lungs, in terms of pressures and volumes in thoracic cavity?

Answer 3

E = difference in P / difference in V

decrease in Volume, increases Elasticity

elasticity pulls visceral pleural away from parietal which tries to go with it as tethered together

Question 4

what happens to nerve impulses at peak inspiration?

Answer 4

nerve impulses from VRG are shut down at peak inspiration

Question 5

what causes the shut down of nerve impulses from the VRG?

Answer 5

specialised stretch receptors detect stretch of lungs at peak inspiration

send signals to medulla to inhibit inspiration signals from VRG

Question 6

what is the response in muscles due to the shut down of nerve impulses from the VRG?

Answer 6

decreased AP frequencies sent to inspiratory muscles

diaphragm
- goes back to original formation

external intercostals relax
- recoil back to origin formation of chest wall

DERCREASE IN THORACIC CAVITY VOLUME
pressures increase

Question 7

what is the effect of volume and pressures due to the shut down of VRG nerve impulses?

Answer 7

DERCREASE IN THORACIC CAVITY VOLUME
pressures increases

Ppul = +1mmHg
- so 761mmHg, above Patm so air flows out of alveoli until equal

Pip = -4 mmHg

Question 8

what muscles are involved in forced expiration?

Answer 8

internal intercostals

abdominal wall muscles

• external oblique
• internal oblique
• transverse abdominus
• recta abdominus

Question 9

what is the role of the internal intercostals in forced expiration?

Answer 9

upper rib downwards
push sternum and ribs inwards

helping to decreases thoracic cavity volume, so increasing Ppul and Pip

Question 10

what is the role of the abdominal wall muscles in expiration?

Answer 10

increases intrabdominal pressure
- pushes diaphragm upwards

helping to decreases thoracic cavity volume, so increasing Ppul and Pip

Question 11

what are the abdominal wall muscles and what do they do?

Answer 11

• external oblique
• internal oblique
• transverse abdominus
• recta abdominus

increases intrabdominal pressure
- pushes diaphragm upwards

helping to decreases thoracic cavity volume, so increasing Ppul and Pip