physiology of the pulmonary system

Question 1

what are the four steps involved in gas transport from atmosphere to the tissue

Answer 1

• ventilation: inspired air to alveoli
• external respiration: transfer from alveoli to capillary (diffusion)
• Transport: gas transport in blood to tissue
• internal respiration: exchange of gases between the capillary and tissue mitochondria

Question 2

Circulation

Answer 2

• passage of blood through the heart, blood vessels, organs and tissue
• transport system

Question 3

perfusion

Answer 3

• refers to the blood flow at the capillary level
• without this you get cyanotic

Question 4

ventilation

Answer 4

mechanical movement of gas in and out of the lungs (getting to and from alveoli)

Question 5

respiration

Answer 5

• exchange of O2 and CO2 across a membrane at the cellular level
• occurs via diffusion across a semipermeable membrane

Question 6

compliance

Answer 6

• a measure of the lungs ability to stretch and expand
• COPD = high compliance
• decreased compliance in restrictive pulmonary diseases

Question 7

Elasticity

Answer 7

• refers to the lungs ability to return to initial size after distension

Question 8

Surfactant

Answer 8

• a lipoprotein that REDUCES surface tension to keep alveoli open

Question 9

Partial pressure

Answer 9

• portion of the total pressure exerted by the presence of a single gas molecule

Question 10

Neural control of breathing

Answer 10

• automatic by pons (rate) and medulla (depth)
• voluntary = cerebal cortex (integrates with singing, talking, laughing)
• influenced by the hypothalamus (pH) and limbic system (emotion)

Question 11

Vagus nerve and respiration

Answer 11

• has stretch receptors to monitor when it is overstretched
• irritant receptors to initiate coughing
• j receptors
• hiccups stem from stimulation of the vagus nerve

Question 12

chemical control

Answer 12

• chemoreceptors in the brainstem, peripheral arteries, carotids and aorta
• sense changes in oxygen and carbon dioxide and pH
• more sensitive to CO2 changes
• feed into pons and medulla

Question 13

when is dyspnea most likely to occur

Answer 13

• when there is a discrepancy between neural drive to breathe and the level of ventilation achieved

Question 14

Describe the pump handle and bucket handle effects

Answer 14

• pump handle: refers to the up/anterior movement of the sterum and ribs
• bucket handle: refers to the lateral movement of the rib cage

Question 15

Mechanisms of inhalation

Answer 15

• the diaphragm contracts and moves down
• external intercostals contract lifting/rotating ribs, lift sternum and thoracic vertebrae
• lungs stretch
• pressure inside lungs is lower than pressure outside
• air gets pulled into lungs
• diaphragm pushes down into abdominal contents = abdomen expands

Question 16

Mechanics of exhalation

Answer 16

• lungs recoil
• rib cage gets pulled inward
• diaphragm gets pulled upward
• pressure inside lungs is higher than pressure outside
• air is forced out of respiratory tract
• diaphragm no longer pushes abdominal contents
• abdomen is pulled in

Question 17

TV

Answer 17

• tidal volume
• air inhaled and exhaled during quiet breathing

Question 18

IRV:

Answer 18

air that can be forcefully inhaled over normal breathing

Question 19

ERV:

Answer 19

air that can be forcefully exhaled over normal breathing

Question 20

RV:

Answer 20

the amount of air that cannot be forcefully exhaled

Question 21

Capacities:
TLC:

Answer 21

the total amount of air that the lungs can hold (IRV+TV+ERV+RV)

Question 22

IC:

Answer 22

maximum amount of air that can be inhaled following a normal expiration

Question 23

VC:

Answer 23

amount of air that can be forcefully exhaled following max inspiration

Question 24

FRC:

Answer 24

amount of air remaining in the lungs following a normal expiration

Question 25

Minute ventilation
- norms

Answer 25

= respiratory rate x tidal volume
- normal 4-6 L/min
- tidal volume can increase more than RR

Question 26

Describe pressures in the lungs during
1) resting
2) inspiration
3) expiration

Answer 26

1) atmospheric pressure = intrapulmonic pressure and intrapleural pressure is lower than atmospheric pressure
2) Atmospheric pressure>intrapulmonic pressure (air flows in) intrapleural pressure becomes more negative
3) atmospheric pressure <intrapulmonic pressure (air pushed out) intrapleural pressure remains negative

Question 27

Describe transport and cellular respiration

Answer 27

• at alveoli: capillary Po2<alveoli Po2
• at tissue: capillary Po2>tissue pO2

Question 28

Ventilation/perfusion ratio

Answer 28

• Ratio of the amount of air entering the alveoli and the blood flowing available to the alveoli
• Norm is 0.8 or greater
• Alterations result in hypoxia

Question 29

Types of barriers in V/Q

Answer 29

• dead space
• shunt

Question 30

Dead space as a barrier

Answer 30

• Air that does not participate in gas exchange
• Ventilation but not perfuses
• Anatomic dead space such as trachea and bronchi
• alveolar/physiologic dead space: ex = pulmonary embolism that blocks blood flow to the lung

Question 31

Shunt as a barrier to V/q

Answer 31

• Blood flow that returns to the left side of the heart without picking up oxygen
• Perfused but not ventilated
• Pneumonia (lung has gunk in it and get clogged so gas does not diffuse as well)

Question 32

V/Q in relation to body position

Answer 32

• Air and pulmonary blood flow are related to gravity
• Body position has a significant effect on the distribution of pulmonary blood flow
• Greatest volume of pulmonary blood flow will occur in gravity dependent areas of the lungs
• More in the bases than apices in upright position
• Patients that are bed bound need to be put in different positions to use different portions of their lungs → we normally change positions throughout our day