respiratory system part 2

Question 1

Pulmonary ventilation consists of two phases

Answer 1

Inspiration: gases flow into the lungs
Expiration: gases exit the lungs

Question 2

Atmospheric pressure (Patm)

Answer 2

Pressure exerted by the air surrounding the body

760 mm Hg at sea level

Question 3

Respiratory pressures

Answer 3

Negative respiratory pressure is less than Patm (inhale)
Positive respiratory pressure is greater than Patm (exhale)
Zero respiratory pressure = Patm

Question 4

Intrapulmonary (intra-alveolar) pressure (Ppul)

Answer 4

Pressure in the alveoli

Fluctuates with breathing

Question 5

Intrapleural pressure (Pip)

Answer 5

Pressure in the pleural cavity
Fluctuates with breathing
Always a negative pressure

Question 6

negative Intrapleural pressure is caused by

Answer 6

opposing forces

Question 7

what inward forces promote lung collapse

Answer 7

Elastic recoil of lungs decreases lung size

Surface tension of alveolar fluid reduces alveolar size

Question 8

what outward force tends to enlarge the lungs

Answer 8

Elasticity of the chest wall pulls the thorax outward

Question 9

transpulmonary pressure

Answer 9

intrapulmonary pressure minus intrapleural pressure
Keeps the airways open
The greater the transpulmonary pressure, the larger the lungs

Question 10

If Pip = Ppul

Answer 10

lungs collapse

Question 11

Atelectasis

Answer 11

lung collapse

Question 12

Atelectasis is die to

Answer 12

Plugged bronchioles leads to collapse of alveoli

Wound that admits air or excess fluid into pleural cavity

Question 13

Pulmonary Ventilation

Answer 13

inspiration and expiration

volume changes result in pressure changes which result in gas flow to equalize the pressure

Question 14

Boyle’s Law

Answer 14

The relationship between the pressure and volume of a gas - Pressure (P) varies inversely with volume (V): P1V1 = P2V2
Increased V = Decreased P
decreased V = increased P

Question 15

Inspiration process

Answer 15

An active process
Inspiratory muscles contract (diaphragm & external intercostals)
Thoracic volume increases
Intrapulmonary pressure drops (to neg 1 mm Hg)
Lungs are stretched and intrapulmonary volume increases
Air flows into the lungs, down its pressure gradient, until Ppul = Patm

Question 16

Expiration process

Answer 16

Quiet expiration is normally a passive process
Inspiratory muscles relax
Thoracic cavity volume decreases
Elastic lungs recoil
Ppul rises (to +1 mm Hg)
Air flows out of the lungs down its pressure gradient until Ppul = 0
and intrapulmonary volume decreases

Question 17

forced expiration is an

Answer 17

active process, uses abdominal and internal intercostal muscles

Question 18

positive pressure and negative pressure results in

Answer 18

positive presure exhale, negative pressure inhale

Question 19

three factors that hinder air passage and pulmonary ventilation

Answer 19

Airway resistance
Alveolar surface tension
Lung compliance

Question 20

change in pressure is the

Answer 20

change in P is the pressure gradient between the atmosphere and the alveoli (2 mm Hg or less during normal quiet breathing)
Increase the change in pressure = increase the rate of flow

Question 21

The relationship between flow (F), pressure (P), and resistance (R) is:

Answer 21

force= change in pressure divided by resistance

Question 22

what is the relationship between gas flow and resistance

Answer 22

Gas flow changes inversely with resistance (ie. less resistance produces more flow)

Question 23

Resistance is usually insignificant because

Answer 23

Large airway diameters in the first part of the conducting zone
Progressive branching of airways as they get smaller, increasing the total cross-sectional area
Resistance disappears at the terminal bronchioles where diffusion drives gas movement

Question 24

what bronchi size has least resistance

Answer 24

medium bronchi size due to fastest and largest drop in diameter

Question 25

what does epinephrine due for resistance

Answer 25

Epinephrine dilates bronchioles and reduces air resistance

Question 26

Surface tension

Answer 26

Attracts liquid molecules to one another at a gas-liquid interface
Resists any force that tends to increase the surface area of the liquid

Question 27

Surfactant

Answer 27

produced by type II alveolar cells

Reduces surface tension of alveolar fluid and discourages alveolar collapse

Question 28

Lung Compliance

Answer 28

A measure of the change in lung volume that occurs with a given change in transpulmonary pressure

Question 29

Lung Compliance is normally high due to

Answer 29

Distensibility of the lung tissue

Alveolar surface tension

Question 30

Lung Compliance diminished by

Answer 30

Nonelastic scar tissue (fibrosis)
Reduced production of surfactant
Decreased flexibility of the thoracic cage

Question 31

homeostatic imbalances that reduce Lung Compliance

Answer 31

Deformities of thorax
Ossification of the costal cartilage
Paralysis of intercostal muscles