Ventilation and the mechanisms of breathing

Question 1

Define ventilation

Answer 1

the exchange of air between the lungs and the atmosphere so that gas exchange can occur in the alveoli

Question 2

What is the role of ventilation?

Answer 2

-maintains blood gases and PH
-ventilation brings air from the atmosphere to the terminal bronchioles
-bring gas and blood into contact
-permits gas exchange of oxygen and carbon dioxide

Question 3

What two things must match in order for efficent gas exchange?

Answer 3

ventilation and perfusion

Question 4

What generates a total pressure gradient?

Answer 4

respiratory muscles

Question 5

Name the four main respiratory muscles

Answer 5

-diaphragm
-intercostal muscles
-accessory muscles
-muscles of the abdominal wall

Question 6

Name the intercostal muscles

Answer 6

-internal
-external

Question 7

Name the accessory muscles

Answer 7

-scalenus
-sternocleidomastoid
-pectoralis major and minor
-trapezius

Question 8

Name the muscles of the abdominal wall

Answer 8

-rectus abdominus
-external abdominis obliquus
-internal abdominus obliquus
-transversus abdominis

Question 9

What is the structure of the diaphrgam?

Answer 9

-membranous domed shaped muscle
-composed of two muscles (hemidiaphragms) joined at the centre
-innervation from phrenic nerves
-surface area about 900cm2

Question 11

What are some functions of the diaphragm?

Answer 11

-can shorten by 40%
-spend 45% of the day contracting
-unilateral paralysis causes little detriment and bilateral paralysis still consistenet with good ventilation

Question 12

Where do you find the sternocleidomastoid muscles?

Answer 12

either side of the neck

Question 13

where do you find your pectoralis major muscles?

Answer 13

chest

Question 14

Where do you find your trapezius muscles?

Answer 14

top of your back

Question 15

Where is the transverse abdominis located?

Answer 15

under the obliques, it is the deepest abdominal muscle and wraps around your spine for protection

Question 16

Where is the internal abdominal oblique located?

Answer 16

under the external obliques running in opposite directions

Question 17

where are external abdominal obliques located?

Answer 17

side and front of the abdomen

Question 18

Where is the rectus abdominis muscle located?

Answer 18

along the front of the abdomen.

(known as the six pack)

Question 19

What muscles are used during active forced respiration when inhaling?

Answer 19

-diaphragm
-external intercostals
-pectorals
-sternocleidomastoid
-scalene
-trapezius

Question 20

What muscles are used during active forced respiration when exhaling?

Answer 20

-internal intercostals
-rectus abdominus
-internal/external oblique muscles
-transverse abdominal muscles

Question 21

Describe accessory muscles of inspiration

Answer 21

-sternocleidomastoid-elevates sternum
-scalenes group-elevaate upper ribs
-pectoralis minor

Question 22

Describe the principal muscles of inhalation

Answer 22

-external intercostals interchondral part of internal intercostals-elevates ribs
-diaphragm-dome descends thus increasing vertical dimensions of thoractic cavuty-elevates lower ribs

Question 23

Describe quiet breathing using muscles of expiration

Answer 23

-passive elastic recoil of the lungs
-rib cage and diaphragm

Question 24

Describe active breathing with muscles of expiration

Answer 24

-internal intercostals except interchondrial part pull ribs down
-abdominals-pulls ribs down, compress abdominal contents thus pushing diaphragm up
-quadratus lumborum
-pulls ribs down

Question 25

describe the basics of breathing in

Answer 25

-increase in volume, decrease in pressure
-ribs move up and out
-diaphragm flatterns
-volume of chest increases

Question 26

Describe the basics of breathing out

Answer 26

-decrease in volume,higher pressure
-ribs fall
-diaphragm moves up
-volume of chest decreases

Question 27

atmospheric pressure is 101kpa what is the lung pressure if its the same as atmospheric?

Answer 27

0kpa

Question 28

what is the pressure of the lungs when its less than atmospheric?

Answer 28

-1kpa

Question 29

if the pressure is greater than atmospheric what is the pressure in the lungs?

Answer 29

+2kPa

Question 30

Why does air flow into lungs because the thoracic cage expands?

Answer 30

-inspiratory muscles contract and increase the thoracic cavity volume
-gas moves from areas of high to low pressure
-gas flows from outside to inside of the thoracic cavity
-only small pressure changes of about +/ - 0.1kPa are needed

Question 31

What does FRC stand for?

Answer 31

functional residual capacity

Question 32

Define FRC

Answer 32

the volume of gas in lungs and airways at the end of a normal expiratory breath
-measured in litres

Question 33

How do lungs balance at the FRC?

Answer 33

outward recoil of the chest wall is balanced by the inward recoil of the lung

Question 34

Describe the mechanisms of ventilation

Answer 34

-thoracic wall and lungs are held closely together by pleural membranes
-lungs and chest wall pull in opposite directions creating a negative pressure in pleural space
-lung is pulled outwards
-chest walls inwards
-intrapleural pressure is usually negative
-when thoracic cavity expands, vaccum in the interpleural space forced lungs to follow

Question 35

What is alveoli pressure at FRC?

Answer 35

-at FRC there is no flow so alveoli pressure is the same as atmospheric

Question 36

Describe pressure changes during inspiration

Answer 36

-thorax expands following contractions of inspiratory muscles
-lungs stretch to fill expanded thorax
-air flows into lung down pressure gradient

(alveolar pressure drops as volume of thorac increases, pleural pressure becomes more negative)

Question 37

Describe pressure changes during expiration

Answer 37

-thorax decreases in size following relaxation of inspiratory muscles
-lungs decrease in size as they recoil
-increased alveolar pressure

Question 38

Give an overall description of pressure change during breathing

Answer 38

-pleural pressure is sub atmospheric
-becomes more negative at higher volumes
-intrapleural pressure helps to prevent lung from completley deflating