anatomy of chest wall and mechanics of breathing

Question 1

what is boyle’s law?

Answer 1

the pressure exerted by a gas is inversely proportional to to its volume (P a 1/V).

Question 2

what is Dalton’s law?

Answer 2

the total pressure of a gas mixture is the sum of the pressures of the individual gases.

Question 3

what is Charles law?

Answer 3

the volume occupied by a gas is directly related to the absolute temperature (v a T)

Question 4

what is Henry’s law?

Answer 4

the amount of gas dissolved in a liquid is determined by the pressure of the gas and it’s solubility in the liquid

Question 5

what are the three lobes of the right lung?

Answer 5

superior, middle and inferior lobe

Question 6

what are the two lobes of the left lung?

Answer 6

the superior and inferior lobe

Question 7

what superficial membrane around the lung called?

Answer 7

the parietal pleural membrane

Question 8

what is the deep membrane around the lungs called?

Answer 8

the visceral pleural membrane

Question 9

what is pleurisy?

Answer 9

inflammation of the pleura

Question 10

what is the function of the pleural fluid?

Answer 10

• sticks the two pleural membranes together

- provides lubrication for the two membranes to slide over each other.

Question 11

which muscles are used for inspiration?

Answer 11

external intercostal muscles, diaphragm. scalenes, sternocleidomastoids

Question 12

which muscles are used for expiration (not at rest) ?

Answer 12

internal intercostal muscles, abdominal muscles

Question 13

what happens during expiration at rest?

Answer 13

the muscles that are used for inspiration relax and the thoracic volume decreases again increasing the pressure in the lung causing air to be leave the lungs

Question 14

In what directions do the external intercostal muscles increase the thoracic cavity?

Answer 14

anterioposteriorsally, mediolaterally

Question 15

explain the pathophysiology of asthma

Answer 15

during an attack the smooth muscles of the bronchioles contract and cause the diameter of them to decrease. this causes minimal problems on inspiration as bronchioles are forced open by the increase in lung volume.
however on expiration they close off more than normal, causing difficulty in exhaling as the resistance to air exiting increases.

Question 16

what is a pneumothorax?

Answer 16

air enters the pleural cavity. this prevents the pleural fluid acting to stick the pleural membranes together and the lung cant increase in volume with an increase in thoracic volume and it can’t inflate.

Question 17

what is intra-thoraci (alveolar) pressure (P subscript A)?

Answer 17

pressure inside the thoracic cavity, (essentially pressure inside the lungs). May be negative or positive compared to atmospheric pressure.

Question 18

what is Intra-pleural Pressure (P subscript ip) ?

Answer 18

): pressure inside the pleural cavity, ALWAYS negative (in healthy lungs at least!)

Question 19

what is transpulmonary pressure (PT) ?

Answer 19

difference between alveolar pressure and intra-pleural pressure, always positive as intrapleural pressure is always negative and more negative than intra-thoracic pressure