Phys: Mechanics Of Breathing And Lung Volume Flashcards
(100 cards)
1
Q
What is responsible for gas exchange in the lungs?
A
Alveoli
2
Q
What helps pump air in the lungs?
A
The chest wall and respiratory muscles
3
Q
Which two zones are in the respiratory system?
A
Conducting and respiratory zone
4
Q
Does gas exchange occur in conducting zone? What is in this zone?
A
NO - includes nasal cavity, larynx, trachea, bronchi and bronchioles
5
Q
What is located in the respiratory zone?
A
-Respiratory bronchioles
-Alveolar ducts
-Alveoli
6
Q
Is there muscle or receptors in the trachea?
A
NO NO
7
Q
Where do the lungs divide in primary bronchi?
A
Sternal angle (carina)
8
Q
What is the trachea made up of?
A
Incomplete rings of hyaline cartilage
9
Q
Is there cartilage in the terminal bronchioles?
A
No
10
Q
All regions for gas exchange contain ________
A
Alveoli
11
Q
What causes the spongy appearance of the lung?
A
Alveolar packing
12
Q
What are the alveolar walls covered with?
A
Capillaries
13
Q
What are type Type I cells:
A
Main respiratory epithelial cells that cover 95% of surface area
14
Q
Type II cells are __________ cells
A
Granular
15
Q
What else is contained in the alveoli?
A
-macrophages
-lymphocytes
-mast cells
-plasma cells
16
Q
What are type II cells important for?
A
-production of surfactant
-cellular repair
17
Q
What is surfactant?
A
A mixture of phospholipids and proteins in the fluid coating the alveolar surface
18
Q
What is surfactant important for?
A
It reduces the surface tension within the alveoli
19
Q
What happens in babies with surfactant deficiency?
A
Infant respiratory distress syndrome (IRDS)
20
Q
Surfactant deficiency can increase surface tension which leads to ___________ compliance of lungs
A
Decreased
21
Q
What is atmospheric pressure? (Value)
A
760 mmHg
22
Q
What is the intra-pleural pressure? (Value)
A
756mmHg (-4 mmHg from atmospheric)
23
Q
What is intra-alveolar pressure? (Value)
A
760mmHg
24
Q
What is transpulmonsry pressure?
A
The difference between intra-alveolar pressure and intra-pleural pressure (760-756 =4mmHg)
25
What is the elasticity of the lungs?
The tendency of the lung to recoil after stretching
26
How is surface tension created in the lung?
Fluid molecules attract each other and collapse the lungs to push air out of alveoli
27
The elasticity of the chest wall allows the chest to…
Expand outward?
28
What three things contribute to the negative intrapleural pressure?
-elasticity of the lungs
-surface tension of fluid lining alveoli
-elasticity of chest wall
29
Which law gives the relationship between pressure and volume?
Boyle’s law
30
Volume and pressure have a(n) ___________ relationship
Inverse
31
How does air move?
By difference in pressures
32
What does the airflow direction depend on?
The differences between the atmospheric and the alveoli pressure
33
“What do we want” for the pressures?
The pressure inside the lungs to be lower
(She said this)
34
Which muscles are involved in breathing?
-diaphragm
-external intercostal muscles
-sternocleidomastoid
-scalenes
35
What is the function of the Diaphragm and external intercostal muscles?
Inhalation
36
Inspiration is normally an _________ process
Active
37
The diaphragm is responsible for ____% of inhalation
70%
38
How is intra-pleural pressure affected during inspiration?
Drops from -3 to -6 mmHg
39
What happens during inspiration?
Intra-pleural pressure becomes more negative, Intra-alveolar pressure decreases below atmospheric pressures and air rushes in to fill the expanded lungs
40
What happens when diaphragm relaxes?
Intra-alveolar pressure increases above atmospheric pressures, intra-pleural pressure more negative and lungs volume decreases and air moves out
41
What is Pneumothorax?
An accumulation of air in the intrapleural space due to penetrating injuries of the chest wall or destruction of the lung tissue
42
Expiration is normally __________
Passive
43
Only forced exhalation uses muscles. Those muscles are:
-internal intercostal muscles
-abdominal muscles
44
Pulmonary arteries:
Bring deoxygenated blood from right ventricle to the gas exchange area
45
Pulmonary veins:
Return oxygenated blood to the left ventricles
46
Bronchial arteries:
Bring oxygenated blood from the left ventricle to the airways
47
Bronchial veins:
Drain into pulmonary veins and form a left to right shunt
48
Pulmonary circulation:
-receives deoxygenated venous blood
-receives as all cardiac output from right side
-maintains continuous gas exchange
-empties oxygenated blood through pulmonary veins to L atrium
49
Bronchial circulation:
-receives oxygenated arterial blood from systemic circulation
-Receives 1-2% of CO
-supplies supporting lung tissue and provides nutrition for airways and pulmonary vessels
-empties in the bronchial veins or anastomose with pulmonary veins
50
At rest the pulmonary arterial pressure is ____
Low
51
When the blood flow is at rest, what happens to the capillaries?
Some capillaries will be open with blood flow, others open with no flow, and some closed
52
What happens when there is an increase in pulmonary arterial pressure?
-recruitment of capillaries
-dissension of capillaries
-increased blood flow
53
What is the primary mechanism that the body uses to regulate blood flow?
Changes in pulmonary vascular resistance
54
What does increased pulmonary arterial pressure do?
-reduces pulmonary vascular resistance
-increase flow due to recruitment and distention
55
Minute ventilation:
The total volume of gas inhaled or exhaled from lungs per minute VE = VT X f
56
VT
Tidal volume
57
f
Respiratory rate (12-16 breaths per minute)
58
Alveolar ventilation:
The amount of air that reaches the alveoli and is available for gas exchange with T he blood per unit time
VA=(VT - VD) X f
59
VD
Dead space volume (150mL)
60
What is the anatomical and physiological dead space?
The part of the respiratory tract where gaseous exchange does not take place
61
What is the function of the dead spaces?
Purification, humidification, and filtration
62
What is the anatomical dead space?
Volume of gas in respiratory tract (nose-terminal bronchiole)
63
What is the physiological dead space?
Total dead space volume (should be same as anatomical dead space in a healthy person)
64
Where is the most perfused part of the lung?
The base
65
Where is the most ventilated part of the lung?
Also the base
66
What is the ideal alveolar ventilation/perfusion ratio (VA/Q)?
0.8
67
In a standing position from apex to base of the lung, what happens?
-ventilation increases
-perfusion increases
-VA/Q decreases
68
Pulmonary ventilation and blood flow are __________ dependent
Gravity
69
Ventilation is greater than blood flow at the ______
Apex
70
What happens in under-ventilated alveoli, hypoxia, and CO2 accumulation?
Vasoconstriction -> shunting blood away from the hypoxia area
71
What happens in a poorly perfused area with low alveolar PCO2?
Bronchoconstriction
72
Where does a shunt unit occur and what is going on?
Completely blocked airways (normal perfusion, no ventilation)
73
Where does dead space occur and what is going on?
Pulmonary embolism (normal ventilation, no perfusion)
74
What happens in a silent unit?
No ventilation, no perfusion
75
What three factors affect ventilation?
-compliance (distensibility)
-elasticity
-airway resistance
76
What is compliance?
The change in volume / unit change in pressure (measure of stretchability)
77
The greater the compliance, the __________ it is for a change in pressure to cause expansion
Easier
78
What does a lower-than-normal compliance mean?
Lungs and thorax are harder to expand
79
What decreases lung compliance?
-small lung size
-pulmonary fibrosis
-pulmonary congestion or pulmonary edema
-high surface tension
80
What increases lung compliance?
-emphysema
-age
81
Why does a barrel shaped chest occur in emphysema?
There is an over-inflation of the lungs due to air trapping due to loss of elasticity and increased compliance in lung tissue
82
What is a spirometer?
A tool used to determine lung volumes and capacities
83
Tidal volume (TV)
Volume of air inspired or expired in each breath (0.5 L in adults at rest)
84
Inspiration reserve volume:
Volume inspired by maximum effort after normal inspiration
85
Inspiration capacity (IC):
Volume inspired by maximum effort
86
Expiratory reserve volume (ERV):
Volume expired by maximum effort after normal expiration
87
Residual volume (RV):
Volume of air that remains in the lung at the end of maximum expiration (1.2 L in adult male, increase w age)
88
Functional residual capacity (FRC):
-volume of air that remains in the lungs after normal expiration (2.4 L)
89
Vital capacity (VC):
Volume expired by maximum effort starting from maximum inspiration (5 L in adult males)
90
Total lung capacity (TLC):
Volume of air present in lung at the end of maximum inspiration (6L in adult male)
91
Forced vital capacity (FVC):
true amount of gas expelled when taking a deep breath and then forcefully exhaling maximally and as rapidly as possible
92
Forces expiratory volume (FEV1):
The amount of air expelled during the first second of expiration (healthy person can expel 80% in 1 sec)
93
FEV1 / FVC
-normally 80%
-if greater then restrictive disease
-if lower then obstructive pulmonary disease
94
What is seen in obstructive pulmonary disease?
-increases airway resistance
-COPD (asthma or bronchitis)
95
What increases in obstructive pulmonary disease? Why?
-total lung capacity
-function residual capacity
-residual volume
**due to HTN of lungs
96
What is seen in restrictive disease?
-Reduction in total lung capacity due to structural or functional changes in the lungs
-tuberculosis, fibrosis from smoking
97
What is reduced in restrictive disorder?
-vital capacity
-total lung capacity
-functional residual capacity
-residual volume
98
What is the mechanism of beta-2 agonists?
They bind to beta-2 adrenergic receptors on bronchial smooth muscle and activate adenylate cyclase -> increase cAMP -> activate protein kinase A -> bronchodilation
99
How do beta-2 agonists affect pulmonary vascular resistance?
-relax smooth muscles in the pulmonary arteries -> reducing PVR
-improves pulmonary hemodynamics
100
How do beta-2 agonists affect alveolar ventilation?
-Cause bronchodilation which reduces airway resistance by increasing alveolar ventilation
-enhance oxygen exchange and more efficient ventilation-perfusion matching
