Week 5 SBL

Question 1

How do snoring and sleep apnoea occur?

Answer 1

• In sleep (particularly REM sleep), loss of muscle tone occurs
• This leads to soft palate and tongue falling posteriorly within the oral cavity due to the effects of gravity
• This narrows (snoring) or inhibits (apnoea) flow of air within the oropharynx, causing obstructive respiratory defecit
• Decreased oxygen saturation
• Detected by peripheral chemoreceptors, leading to neurological arousal
• Body partially awakens to restore muscle tone
• Patient may not perceive this awakening, but the patient moves to a shallower form of sleep
• This can disrupt the sleep cycle, leading to sleep deprivation

Question 2

How is sleep apnoea different from PND?

Answer 2

• It’s a trick question
• PND is not a condition; it’s a symptom: waking up in the night short of breath
• Sleep apnoea can cause PND, but PND cannot cause sleep apnoea

Question 3

Explain what can cause the oxygen saturation curve to shift to the right, and why.

Answer 3

• If curve shifts to the right, then more oxygen is needed to achieve the same Hb saturation levels.
• If this is the case, then something else must be taking up the slots on the Hb molecule (i.e. CO2)
• Therefore, this must occur under high CO2 concentration, and therefore lower pH
• Also, temp must be increased as well

Question 4

Explain what can cause the oxygen saturation curve to shift to the left, and why.

Answer 4

• If the curve shifts to the left, then less oxygen is needed to achieve the same Hb saturation levels
• If this is the case, then there must be more CO2 taking up slots on Hb, and a greater demand for the blood to be taking up oxygen.
• Therefore, CO2 must be high, and pH must be low
• Temp is also lower, as less likely to disrupt bonds

Question 5

PCO2 in arterial vs venous blood

Answer 5

Arterial: 40mmHg
Venous: 46mmHg

Question 6

PO2 in arterial vs venous blood

Answer 6

Arterial: 100mmHg
Venous 45mmHg

Question 7

Describe the hering-breuer reflex

Answer 7

In response to increased lung volume, inspiration is inhibited (or expiration is prolonged) to prevent lung overexpansion.

Question 8

Primary inspiratory muscles (relaxed)

Answer 8

• Diaphragm
• External intercostal muscles

Question 9

Primary expiratory muscles (relaxed)

Answer 9

• There are none
• Typically, it is a relaxed response that occurs due to the elastic recoil of the lung as various muscles

Question 10

Accessory inspiratory muscles

Answer 10

• Sternocaleidomastoid
• Scalene
• Latissimus dorsi

Question 11

Accessory expiratory muscles

Answer 11

• Abdominal muscles
• Oblique muscles
• Internal intercostals

Question 12

Lung base surface anatomy (all surfaces)

Answer 12

Anteriorly: 6th rib
Laterally: 8th rib
Posteriorly: 10th rib

Question 13

Horizontal fissure of right lung surface anatomy

Answer 13

4th costal cartilage right sternal edge to 5th rib mid axillary line

Question 14

Oblique fissures surface anatomy

Answer 14

Curved line:

Anteriorly: 6th rib sternal border
Laterally: 5th Rib
Posteriorly: T4 spinous process

Question 15

Central vs obstructive sleep apnoea

Answer 15

Central: brain doesn’t send proper signals to the muscles that control breathing

Obstructive: throat muscles relax, blocking airways

Question 16

Normal FEV1/FVC

Answer 16

> =0.70