Chapter 17: Mechanics of Breathing Flashcards
1
Q
what are the respiratory system functions?
A
- Exchange of gases between the atmosphere and the blood
- Contributing to the regulation of acid-base balance in the blood
- Vocalization
- Defense against pathogens and foreign particles in the airways
- Route for water and heat loss
- Enhancing venous return (respiratory pump)
2
Q
what does internal respiration involve?
A
oxidative phosphorylation
3
Q
what are the four processes of external respiration?
A
- Pulmonary ventilation
- Exchange between lungs and blood
- Transportation in blood
- Exchange between blood and body tissues
4
Q
- *airways from pharynx to lungs
- conducting zone
- respiratory zone
A
respiratory tract
5
Q
- consists of:
- larynx
- trachea
- bronchi
- secondary bronchi
- tertiary bronchi
- bronchioles
- terminal bronchioles
A
conducting zone
6
Q
consists of glottis and epiglottis
A
larynx
7
Q
- 2.5 cm diameter
- 10 cm long
- 15-20 C shaped bands of cartilage
A
trachea
8
Q
- Three on right side to three lobes of right lung
- Two on left side to two lobes of left lung
A
secondary bronchi
9
Q
20–23 orders of branching
A
tertiary bronchi
10
Q
less than 1 mm in diameter
A
bronchioles
11
Q
- Air passageway: 150 mL in volume (dead space)
- Increases air temperature to body temperature
- Humidifies air
A
functions of conducting zone
12
Q
consists of goblet cells and ciliated cells
A
epithelium of conducting zone
13
Q
secrete mucus
A
goblet cells
14
Q
- Cilia move particles toward mouth
- Mucus escalator
A
ciliated cells
15
Q
secrete saline and mucus
A
Epithelial cells lining the airways and submucosal
glands
16
Q
move the mucus layer toward the pharynx, removing trapped
pathogens and particulate matter
A
cilia
17
Q
creates 80 million bronchiooles
A
branching of airways
18
Q
- Exchange of gases between air and blood
- Mechanism of action: diffusion
A
function of respiratory zone
19
Q
what are the structures of the respiratory zone?
A
- Respiratory bronchioles
- Alveolar ducts
- Alveoli
- Alveolar sacs
20
Q
surrounded by elastic fibers and a network of capillaries`
A
each cluster of alveoli
21
Q
- Respiratory membrane
- Epithelial cell layer of alveoli
- Endothelial cell layer of capillaries
A
epithelium of respiratory zone
22
Q
- site of gas exchange
- 300 million in the lungs
- rich blood supply from capillary sheet
A
alveoli
23
Q
what are the types of alveoli?
A
- alveolar pores
- type I alveolar cells
- type II alveolar cells
- alveolar macrophages
24
Q
- make up wall of alveoli
- single layer of epithelial cells
- for gas exchange
A
type I alveolar cells
25
secrete surfactant
type II alveolar cells
26
ingests foreign material
alveolar macrophage
27
- airtight, protects lungs
- consists of:
- rib cage
- sternum
- thoracic vertebrae
- muscles (internal and external intercostals, diaphragm)
chest wall
28
- membrane lining of lungs and chest wall
| - sac around each lung
pleura
29
- filled with intrapleural fluid
| - volume = 15 mL
intrapleural space
30
how does air move in and out of the lungs?
bulk flow
31
what drives the flow of air?
pressure gradient
32
in what direction does air move?
from high to low pressure
33
pressure in lungs less than atmospheric pressure
inspiration
34
pressure in lungs greater than atmospheric pressure
expiration
35
Atmospheric pressure=
Patm
36
- Pressure of air in alveoli
| - Palv
intra-alveolar pressure
37
- pressure inside pleural sac
| - Pip
intrapleural pressure
38
what are the pulmonary pressures?
- Atmospheric pressure
- intra-alveolar pressure
- intrapleural pressure
39
- 760 mm Hg at sea level
- Decreases as altitude increases
- Increases under water
atmospheric pressure
40
are given relative to atmospheric pressure (set Patm= 0mmHg)
other lung pressures
41
- pressure of air in alveoli
- given relative to atmospheric pressure
- varies with phase of respiration
intra-alveolar pressure
42
when is intra-alveolar pressure negative (less than atmospheric)?
during inspiration
43
when is intra-alveolar pressure positive (more than atmospheric)?
during expiration
44
drives ventilation
Difference between Palv and Patm
45
- pressure inside pleural sac
| - varies with phase of respiration
intrapleural pressure
46
- Always negative under normal conditions
| - Always less than Palv
pressure inside pleural sac
47
what is the intrapleural pressure at rest?
-4mm Hg (vacuum)
48
prevents wall and lungs from pulling apart
surface tension of intrapleural fluid
49
keeps the lung adhered to the chest wall, in a normal lung at rest
pleural fluid
50
creates an inward pull
elastic recoil
51
tries to pull the chest wall outward
elastic recoil of the chest wall
52
-If the sealed pleural cavity is opened to the
atmosphere, air flows in. --The bond holding the lung to the chest
wall is broken, and the lung collapses
-air in thorax
pneumothorax
53
what is movement of air in and out of the lungs due to?
pressure gradients
54
describes mechanisms for creating pressure gradients
mechanics of breathing
55
force for flow=
pressure gradient (mechanics of breathing)
56
remains constant during breathing cycle
atmospheric pressure
57
do alveolar pressure changes affect gradients?
yes
58
pressure is inversely related to volume
Boyle's law
59
related to airway radius and mucus
resistance to air flow (R)
60
flow =
| mechanics of breathing
Patm-Palv/R
61
how can you change alveolar pressure?
by changing its volume
62
V=1/P
relationship says that if the volume of gas increases, the pressure decreases and vice versa
63
PV=nRT
ideal gas equation
64
P1V1=P2V2
boyle's law expresses the inverse relationship between pressure and volume
65
what are the determinants of intra-alveolar pressure?
- factors determining intra-alveolar pressure
- lungs expand-alveolar volume increases
- lungs recoil-alveolar volume decreases
66
what are the factors determining intra-alveolar pressure?
- quantity of air in alveoli
| - volume of alveoli
67
- alveolar volume increases
- Palv decreases
- pressure gradient drives air into lungs
lungs expand
68
- alveolar volume decreases
- Palv increases
- pressure gradient drives air out of lungs
lungs recoil
69
moves
| sternum upward and outward
expansion of ribs during inspiration
70
when does the diaphragm and external intercostals contract?
during inspiration
71
when do the chest wall and lungs expand?
during inspiration
72
when do the external intercostals and diaphragm relax?
expiration
73
when do the internal intercostals and abdominals contract?
only for active expiration
74
when do the chest cavity and lungs contract?
during expiration
75
when do the ribs and sternum depress?
during expiration
76
what are the factors affecting pulmonary ventilation?
- lung compliance
| - airway resistance
77
-Change of volume (V) that results from a given force or pressure (P) exerted on the lung
=ΔV/ΔP
-ease with which lungs can be stretched
lung compliance
78
when is it easier to inspire?
when there is a larger lung compliance
79
requires more force from inspiratory muscles to stretch
low compliance lung
80
what are the factors affecting lung compliance?
- elastance (elastic recoil)
| - surface tension of lungs
81
- Low elastance → high compliance
| - Balloon vs plastic bag
elastance
82
- Thin layer of fluid lines alveoli
- arises due to attractions between water molecules
- Greater tension → less compliant
surface tension of lungs
83
how can surface tension be overcome?
-surfactant secreted from type II cells
84
- detergent that decreases surface tension
- more concentrated in smaller alveoli
- increases lung compliance, makes inspiration easier
surfactant
85
what happens when airways get smaller in diameter?
-they increase in number, keeping overall resistance low
86
what does an increase in resistance result in?
- make it harder to breath
- contraction activity of smooth muscle
- mucus secretion
87
what is the role of bronchiolar smooth muscle in airway resistance?
- bronchoconstriction
- bronchodilation
- contractile state of bronchiolar smooth muscle under extrinsic and intrinsic controls
88
smooth muscle contracts, causing radius to decrease
Bronchoconstriction
89
smooth muscle relaxes, causing radius to increase
Bronchodilation
90
what is involved in the extrinsic control of the bronchiole radius?
- autonomic nervous system
| - hormonal control
91
-parasympathetic
-contraction of smooth
muscle
-bronchoconstriction
autonomic nervous systems
92
* epinephrine
- relaxation of smooth muscle
- bronchodilation
hormonal control
93
what is involved in the intrinsic control of the bronchiole radius?
- CO2: bronchodilation
| - histamine: bronchoconstriction
94
- Released during asthma and allergies
| - Also increases mucus secretion
Histamine: bronchoconstriction
95
what is involved in total lung capacity?
- tidal volume
- inspiratory reserve volume
- expiratory reserve volume
- residual volume
96
- 500 mL
| - single,unforced breath
tidal volume (Vt)
97
- 3000mL
| - after breathing in, volume you can still inspire
inspiratory reserve volume (IRV)
98
- 1000mL
| - after breathing out, volume you can still expire
expiratory reserve volume (ERV)
99
- 1200 mL
| - volume left after ERV
residual volume (RV)
100
= VT + IRV = 3500 mL
Inspiratory capacity (IC)
101
- maximum volume expired after maximum inspiration
| - VC = VT + IRV + ERV = 4500 mL
vital capacity
102
= volume remaining after resting tidal volume
| -FRC = ERV + RV = 2200 mL
functional residual capacity
103
- volume air in lungs after maximum inspiration
| - TLC = VT + IRV + ERV + RV = 5700 mL
total lung capacity
104
- difficulty expelling air
- associated with increased airway resistance
- residual volume increases (making it more difficult to expire)
- vital capacity decreases
obstructive pulmonary diseases
105
what are some major obstructive pulmonary diseases?
- COPD (chronic bronchitis and emphysema)
| - asthma
106
- difficulty expanding lungs
| - involve structural damage to the lungs
restrictive pulmonary diseases
107
what happens when the lungs are damaged structurally due to restrictive pulmonary diseases?
- decrease in lung compliance
- total lung capacity decreases
- vital capacity decreases
- pulmonary fibrosis (fibrous scar tissue)
- asbestos
108
maximum-volume inhalation followed by exhalation as fast as possible
forced vital capacity (FVC)
109
what does a low FVC indicate?
restrictive pulmonary disease
110
percentage of FVC that can be exhaled within certain time frame
forced expiratory volume (FEV)
111
percentage of FVC that can be exhaled within 1 second
FEV1
112
what is a normal FEV1?
80%
113
what does a FEV <80% indicate?
obstructive pulmonary disease
114
total volume of air entering and leaving the respiratory system each minute
minute ventilation
115
= VT × RR
minute ventilation
116
Normal respiration rate =
12 breaths/minute
117
Normal VT =
500 mL
118
Normal minute ventilation =
500mL x 12 breaths/min= 6000 mL/min
119
Air in conducting zone does not participate in gas exchange
anatomical dead space
120
- equals the anatomical dead space
| - about 150 mL
conducting zone
121
-Volume of fresh air reaching the gas exchange areas per minute
=(VT × RR) – (DSV × RR)
-normal is 4200 mL/min
alveolar ventilation
122
why are the conducting airways known as anatomic dead space?
because they don't exchange gases with the blood
