lecture 16

Question 1

what cells remove debris from the alveoli and why do we have them there

Answer 1

resident macrophages remove debris from the alveoli, we have them in the alveoli as alveoli are too small for other protective mechanisms involving goblet cells. as we want thin cells for good O2 exchange

Question 2

what are the boundaries of the thoracic cavity

Answer 2

anteriorly the sternum
laterally the ribs
inferiorly the diaphragm
posteriorly the thoracic vertebrae
superiorly the base of the neck

Question 3

whats the significance of having two pleural cavities

Answer 3

each lung is in a separate pleural cavity. this acts as a fail-safe mechanism as if one pleural cavity is damaged the other can still work to supply O2 to the body.

Question 4

what is pressure measured by

Answer 4

pressure is measured by particle collisions with the walls of the spaces they are in

Question 5

whats a sternocostal joint and whats it made of

Answer 5

the joint between the sternum and the costal cartilage. these are all synovial joints except for the first one which is cartilagenous joint

Question 6

whats a costochondral joint and whats it made of

Answer 6

the joint between ribs and the costo cartilage. they are all cartilagenous joints

Question 7

what are the interchondral joints and what are they made of

Answer 7

the joint between cartilages 8-12 to each other, as these ones don’t go right to the sternum, they are synovial joints

Question 8

whats the costovertebral joint and whats it made of

Answer 8

the joint between the rib and the body of the vertebrae, its synovial

Question 9

whats the costotransvere joint and whats it made of

Answer 9

the joint between the rib and the transverse process, also synovial

Question 10

what are the primary muscles of respiration

Answer 10

the diaphragm and the intercostals

Question 11

describe the intercostal muscle structure

Answer 11

internal and external muscles, arranged diagonally between the ribs

Question 12

what do the external intercostals do

Answer 12

they Lift ribcage and
expand cavity
* Inspiration- quiet and
forced

Question 13

what do the internal intercostals do

Answer 13

Depress ribcage and decrease cavity
* Expiration- forced only

Question 14

describe muscle action during inhilation quiet

Answer 14

During normal ‘quiet’ inspiration
* Diaphragm contracts = flattens
* External intercostals contract = lifts ribs

Question 15

describe muscle action during forced inspiration

Answer 15

diaphragm contracts and flattens, external intercostals contract and lift the ribs. and accessory muscles contract to further expand thoracic cavity

Question 16

describe muscle action during quiet exhalation

Answer 16

its all passive diaphragm relaxes and returns to dome shape.
external intercostals relax, lowering ribs

Question 17

describe muscle action during forced exhalation

Answer 17

diaphragm relaxes and returns to dome shape.
external intercostals relax, lowering ribs
internal intercostals contract to depress the ribs, accessory muscles contract to decrease cavity volume

Question 18

how do the lungs move with the expanding thoracic cavities

Answer 18

The pleura make the lungs ‘stick’ to the thoracic wall through a fluid bond. so the visceral pleura is bound to parietal pleura, therefore the lungs expand with the expanding thoracic cavity.