Anatomy of the chest wall & mechanics of breathing

Question 1

What is the pressure in the pleural cavity when compared to Patmos ?

Answer 1

Always -ve

Question 2

What is the pressure in the Alveoli when compared to Patmos ?

Answer 2

Can be +ve or -ve as the person breathes in & out

Question 3

Is Transpulmonary pressure +ve or -ve ?

Answer 3

Always +ve

Question 4

What muscles are used for inspiration ?

Answer 4

Diaphragm & external intercostal muscles

Question 5

What muscles are used for expiration ?

Answer 5

Internal intercostal muscles (forced expiration include abdominal muscles)

Question 6

What is Boyle’s law ?

Answer 6

That gas will move from an area of high pressure to an area of low pressure.

Question 7

What is respiratory minute volume ?

Answer 7

The amount of gas inhaled and exhaled from a person’s lungs each minute.

Question 8

What is the definition of pulmonary ventilation ?

Answer 8

The total air movement in and out of the lungs.

Question 9

What is the definition of Alveolar ventilation ?

Answer 9

The fresh air that enters the Alveoli & is therefore available for gas exchange.

Question 10

What is the ‘law of Laplace’ ?

Answer 10

P=2T/r (when T is surface tension & r is Radius of Alveoli)

Question 11

What is the definition of Compliance ?

Answer 11

Change in volume is relative to the change in pressure.

Question 12

In what part of the brain is the DRG & the VRG found ?

Answer 12

The medulla

Question 13

What is the DRG & what is it responsible for with regards to respiration ?

Answer 13

The Dorsal Respiratory Group is found in the Medulla and is responsible for inspiratory muscles via the phrenic and intercostal nerves.

Question 14

What is the VRG & what is it responsible for with regards to respiration ?

Answer 14

The Ventral Respiratory Group is found in the medulla and is responsible for expiratory muscles and the tongue (stops it from blocking airway)

Question 15

What type of receptors are the DRG & VRG ?

Answer 15

Central chemo receptors

Question 16

How does chemicals influence the behavior of these central chemo-receptors ?

Answer 16

When CO2 rises or falls within the blood stream this drop or rise in H ions will be detected within the CSF and the central chemo receptors. This leads to increased or decreased respiratory drive as suitable.

Question 17

What is the term used to describe plasma with too many H ions ?

Answer 17

Acidosis

Question 18

What is the term used to describe plasma with too little H ions ?

Answer 18

Alkalosis

Question 19

Where are the peripheral chemo-receptors found ?

Answer 19

In the Carotid & Aortic bodies

Question 20

What are these peripheral chemo-receptors responsible for ?

Answer 20

Secondary ventilatory drive

Question 21

What do peripheral chemo-receptors respond to ?

Answer 21

Changes in H ion levels not solely from CO2 but they also monitor O2 levels

Question 22

What kind of motor neurons relay the message to the muscles for inspiration and expiration ?

Answer 22

Somatic motor neurons

Question 23

The lungs and ribs are constantly trying to pull apart, what prevents this ?

Answer 23

The pleural fluid in the pleural cavity

Question 24

What is the pressure within the pleural cavity ?

Answer 24

-3mmHg (sub-atmospheric)

Question 25

What determines how much air flows in & out of the lungs at any given pressure ?

Answer 25

Airway resistance

Question 26

What is the major determinant of airway resistance ?

Answer 26

Radii of airways