Chapter 13- Respiratory System Flashcards
(193 cards)
1
Q
What is the respiratory system’s main function?
A
-Supply body tissues wit O2
-Dispose of CO2 produced by cellular metabolism
2
Q
What are the two main processes of the Respiratory system?
A
- Internal respiration
- External respiration
3
Q
What is external respiration?
A
Gas exchange between the external environment and the body cells
4
Q
What is internal respiration?
A
Cellular respiration
5
Q
What are the 4 steps of external respiration?
A
- Ventilation
- Exchange of O2 and CO2 in alveoli and pulmonary capillaries
- Transport of O2 and CO2 between lungs and tissues via blood
- Gas exchange between tissues and systemic capillaries
6
Q
What is ventilation?
A
Movement or air into and out of the lungs
7
Q
What is nonrespiratory function of the respiratory system?
A
Helps maintain normal acid-base balance
8
Q
What is the anatomy of the respiratory system?
A
Airways
Lungs and alveoli
Structures of the thorax involved in air movement
9
Q
What are the respiratory airways function?
A
Tubes that carry air between the atmosphere and the air sacs
10
Q
What are all the respiratory airways?
A
- Nasal passages
- Pharynx
- Trachea
- Larynx
- Right and left bronchi
- Bronchioles
11
Q
What are the lungs divided into and supplied by?
A
Two lungs divided into several lobes
Each supplied by one bronchi
12
Q
What do the lungs consist of?
A
-HIghly branched airways
-Alveoli
-Pulmonary blood vessels
-Large quantities of elastic connective tissue
13
Q
What do bronchioles walls contain?
A
Smooth muscle innervated by the autonomic nervous system
-NO CARTILAGE
14
Q
Where are alveoli located?
A
Clustered at the ends of terminal bronchioles
15
Q
What re bronchioles sensitive to?
A
Certain hormones and local chemicals
16
Q
What zone do the Trachea and bronchi belong to?
A
Convection zone
17
Q
What are the Trachea and bronchi?
A
Rigid, nonmuscular tubes made from cartilage rings (prevent collapse)
18
Q
What zone do the bronchioles belong to?
A
Diffusion zone
19
Q
What is the function of alveoli?
A
- Gas exchange (Air sacs)
- Increase surface area
20
Q
What are the types of alveoli?
A
Type I
Type II
21
Q
What are Type I alveoli?
A
Walls have a single layer of flattened epithelial cells
22
Q
What are Type II alveoli?
A
Secrete pulmonary surfactant
23
Q
What is the thorax/outer chest wall formed by?
A
12 pairs of ribs
Sternum
Thoracic vertebrae
24
Q
What is the function of the thorax?
A
Protect lungs and heart
Contains muscles involved in generating pressure that causes air flow
25
What are the main inspiratory muscles?
Diaphragm
External intercostal muscles
26
What nerve innervates the Diaphragm?
Phrenic nerve
27
What nerve innervates the External intercostal muscles?
Intercostal nerve
28
What are the expiratory muscles?
Internal intercostal muscles and abdominal muscles
29
What is the name of serous membrane sac for the Lungs?
Pleural sac
30
What is the pleural sac?
Double walled, closed sac
-separates each lung from the thoracic wall
31
What is interior to the pleural sac?
Pleural cavity
32
What do the surfaces of the pleura secrete?
Intrapleural fluid (Fills pleural cavity)
33
What is the function of intrapleural fluid?
Lubricate pleural surfaces
34
What are the two layers of the pleural sac?
Parietal membrane (Most external layer, by thoracic wall)
Visceral membrane (Surface of the lung)
35
What is the Pleural sac's function?
Allow lungs and thorax to slide past each other during breathing
36
What are the 4 different pressures important in ventilation?
1. Atmospheric (barometric) pressure
2. Intra Alveolar pressure
3. Intra Pleural pressure
4. Transpulmonary pressure
37
Example of an atmospheric pressure important in ventilation?
Sea level
38
What is the pressure of Sea level?
760 mmHg
39
What is the transmural pressure gradient?
Pressure gradient across the lungs
Inside pressure - outside pressure
40
What is the function of the Transmural pressure gradient?
Keep lung and chest wall together
-Lungs= Distentible and have elastic recoil
-Thoracic wall= Rigid and recoils outward
41
The pleural sac always has what pressure?
Subatmospheric pressure
42
What is elastic recoil in the lungs?
How readily the lungs rebound after being stretched so lungs can return to preinspiratory volume
43
What 2 factors do the Lung's Elastic recoil depend on?
1. Elastic connective tissue in the lungs (Stretchability)
2. Alveolar surface tension
44
What creates alveolar surface tension?
The thin liquid film that lines each alveolus
45
What two aspects of alveolar surface tension produce the Lung's elastic recoil?
1. The liquid resists alveoli expansion making them less compliant
2. Liquid lining on alveolus shrinks alveoli making them recoil
46
What would happen if only water lined the alveoli?
They would collapse
47
What makes alveoli more likely to collapse?
Smaller size and greater surface tension
48
What two factors oppose the tendency of alveoli to collapse?
1. Pulmonary surfactant
2. Alveolar interdependence
49
What is pulmonary surfactant?
Complex mixture of phospholipids and proteins secreted by Type II alveoli
50
What does Pulmonary surfactant do?
Reduces surface tension
51
How does Pulmonary surfactant reduce surface tension?
By dispersing between the water molecules that line the alveoli therefore reducing the cohesive force between water molecules
52
What increases the secretion of Pulmonary surfactant?
Deep breathing
53
What are the two benefits of Pulmonary surfactant?
1. Reduces the work of the lungs
2. Reduces recoil pressure of smaller alveoli more than larger alveoli
54
What is the overall effect of pulmonary surfactant?
Equalize pressures of different size alveoli, minimising the tendency of smaller ones to empty into larger ones and avoid collapse
-Stabilize alveoli
-Maintain gas exchange
55
Why do premature babies have difficulty breathing?
They lack surfactant (IRDS or RDSN)
-Alveoli collapse
-Alevoli have to re inflate every time =Energy drain
56
When is pulmonary surfactant made?
Last two months of utero
57
What are prevention methods of IRDS and RDSN?
Give mother steroids to trigger surfactant production
Give baby artificial surfactant while on a ventilator
58
How does alveolar interdependence contribute to alveolar stability?
Because all alveoli are connected to each other when one starts to collapse surrounding alveoli recoil to keep it open
59
What force do the surrounding alveoli exert on the collapsing alveoli?
Expanding force
-triggered when walls of alveoli are stretched and pulled in direction of collapsing alveolus
60
What is a pneumothorax?
Abnormal condition of air entering the pleural space
61
What happens to pressure gradient during a pneumothorax?
It no longer exists across the lung or chest wall
-Pleural and alveolar pressure now equal atmospheric pressure
62
Why does the lung collapse during a pneumothorax?
Because there is no opposing negative pleural pressure to keep it inflated
63
What is Boyle's Law?
At any constant temp, the pressure exerted by a gas varies inversely with the volume of a gas
64
What is the formula for Boyle's Law?
P1V1=P2V2
or P=1/V
65
What produces flow of air into and out of the lungs?
Changes in alveolar pressure
66
What happens when alveolar pressure is less than atmospheric pressure?
Air enters the lungs
67
What happens when alveolar pressure is greater than atmospheric pressure?
Air exits from the lungs
68
What happens when lung volume is altered?
Pressure changes in lungs
Air flow is generated
69
What changes the volume of the thoracic cavity?
respiratory muscle activity
70
What inspiratory muscle is responsible for 75% of thoracic volume change at rest?
Diaphragm
71
What DECREASES the size of the chest cavity?
-Relaxation of the diaphragm and chest wall muscles + Elastic recoil of the alveoli
72
What begins by the relaxation of inspiration muscles?
Onset of expiration
73
Expansion during inspiration decreases which pressure?
Intrapleural pressure
74
What happens to the lungs during expansion?
They are drawn into an area of lower pressure and expand
75
What happens to alveolar pressure to allow air to enter the lungs?
It lowers to a pressure level below atmospheric pressure
76
What happens to alveolar pressure to allow expiration (air exits)?
It increases to a level above atmospheric pressure and air is driven out
77
What happens to idntraalveolar pressure to cease outward flow?
Intralveolar pressure equals atmospheric pressure
78
What allows for forced expiration?
Contraction of expiratory muscles
79
What is air flow dependent on?
1. Pressure differences
2. Airway resistance
80
What is the formula for airflow?
F=ΔP/R
81
What is ΔP?
Difference between atmospheric and intra-alveolar pressure
82
What is airway resistance determined by?
Radius
83
What changes the radius of airways?
Autonomic nervous system controls smooth muscle contraction in airway walls
84
What does the Sympathetic nervous system do to airways?
Causes Bronchodilation
-releases NE (nerve endings in lungs) and Epinephrine
85
What does the Parasympathetic nervous system do to airways?
Causes bronchoconstriction
-releases ACh from nerve endings in the lungs
86
What happens to airways that are narrowed by disease states?
Flow is restricted
More work to breathe
87
Formula for flow in disease states?
F=↑ΔP/↑R
88
What abnormally increases airway resistance?
Chronic pulmonary disease
-Expiration is harder than inspiration
89
What are examples of diseases that increase airway resistance?
1. Asthma
2. COPD
90
What happens during an Asthma attack that narrows airways?
1. Smooth muscle spasm
2. Airway walls thicken (Inflammation, histamine-induced edema)
3. Muscous is secreted
---> can lead to infections
91
What is COPD?
Chronic obstructed pulmonary disease
92
What are COPD cases caused by?
Cigarette smoke (80%) or chemicals like coal dust, asbestos
93
What are the 2 types of COPD?
1. Chronic bronchitis
2. Emphysema
94
What is Chronic bronchitis?
A long term inflammatory condition of smaller airways
95
What is NOT the cause of obstruction in COPD?
Smooth muscle contraction is not the cause
96
What causes chronic bronchitis?
Prolonged exposure to smoke, allergens etc
97
How are airways obstructed by chronic bronchitis?
a. Edematous thickening of airway lining
b. Thick mucous secreted
98
Why do those with chronic bronchitis get bacterial infections?
Coughing can't remove the mucous out of the lungs
99
What is Emphysema?
Collapse of smaller airways and alveolar wall breakdown
100
What is most commonly responsible for emphysema?
Over release of destructive (proteolytic) enzyme Trypsin
101
What is the maximum lung volume of adult male and female?
Male= 5.7L
Female= 4.2L
102
What is lung volume at rest?
2.2L
-Lungs are still half-full to continue gas-exchange
103
What a spirometer?
Device that measures the volume of air breathed in and out
104
Capacities are equal to?
The sum of 2 or more lung volumes
105
What is Tidal volume? TV
Volume of air entering or leaving lungs during a single breath
500mL
106
What is residual volume? RV
Minimum volume of air remaining in the lungs even after a maximal expiration
1200mL
107
What is Vital capacity? VC
Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV)
4500mL
108
What is Total lung capacity? TLC
Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV)
5700mL
109
What are 2 categories of respiratory dysfunction that give abnormal spirometry results?
1. Obstructive lung disease
2. Restrictive lung disease
110
What is Forced expiratory volume in 1 second (FEV1) in obstructed lung disease?
Less than 80%
111
What does restrictive lung disease cause?
Reduced vital capacity
-Normal airway resistance
112
What causes restrictive lung disease?
Impaired respiratory movements
113
What is Pulmonary ventilation?
Volume of air breathed in and out in one minute
-aka Minute ventilation
114
Formula for Pulmonary ventilation?
Pulmonary ventilation (ml/min) = tidal volume (ml/breath) x respiratory rate (breaths/min)
115
What is alveolar ventilation?
Volume of air exchanged between the atmosphere and the alveoli per minute
116
Which kind of ventilation (pulmonary or alveolar) is more important?
Alveolar ventilation
117
What is the average airway volume in adults?
150ml
118
Why is alveolar less than pulmonary ventilation?
Because of anatomic dead space
-There is a volume of air in the conducting airways that is useless for exchange
119
Alveolar ventilation formula?
Alveolar ventilation= (Tidal volume- dead space) x respiratory rate
120
What amount of energy is required for normal work of breathing? (quiet breathing)
3% of total energy expenditure
121
What situations increase the work of breathing?
Increased ventilation
Decreased pulmonary compliance
Increased airway resistance
Decreased elastic recoil
122
Example of situations where there is a need for increased ventilation?
Exercise
-10-15% of O2 consumption
123
Example of when there is decreased pulmonary compliance?
Fibrosis
124
Example of when there is increased airway resistance?
COPD
125
Example of when there is decreased elastic recoil?
Emphysema
126
What is gas exchange?
Simple diffusion of o2 and CO2 down partial pressure gradients until partial pressures are equilibrated
127
In what capillaries does gas exchange occur?
Pulmonary and systemic tissue capillaries
128
How much air moves in and out with each breath?
500ml/breath
129
What is a partial pressure?
The pressure exerted by an individual gas in a mixture
130
What is the partial pressure of H20 in airways?
47mmHg
131
What does the addition of water vapour in airways do to partial pressures?
"dilutes" all gases by 47mmHg
132
What is functional residual capacity?
~2.2L
133
What happens to oxygen and carbon dioxide partial pressure gradients in the LUNGS?
1. O2 diffuses from alveoli to pulmonary capillaries
2. CO2 diffuses from pulmonary capillaries to alveoli
3. Blood leaves high in O2 and low in CO2
134
What happens to oxygen and carbon dioxide partial pressure gradients in the TISSUES?
1. O2 diffuses from capillaries to tissue cells
2. CO2 diffuses from tissue cells to capillaries
3. Blood leaves low in O2 and high in CO2
135
As the partial pressure gradients increases, what happens to diffusion?
Diffusion also increases
136
What can cause inadequate gas exchange?
Increased thickness of the barrier separating the blood and air
137
When thickness increases what happens to the rate of gas transfer?
Rate of gas transfer decreases
138
What are conditions that cause the thickness to increase?
a. Pulmonary edema
b. Pulmonary fibrosis
c. Pneumonia
139
How much time does blood spend in a capillary?
~0.75 second
140
How much time is required for equilibration during O2 gas transfer?
0.25 sec
141
How much time is required for blood transit during excercise?
0.4sec
142
What happens to O2 equilibration in diseased states?
It is more impaired than CO2 equilibration
-CO2 has a larger diffusion coefficient
143
How is most O2 transported in the blood?
It is bound to hemoglobin
144
Hemoglobin + oxygen=____?
Oxyhemoglobin
145
Where is a small percentage of oxygen dissolved?
The plasma
146
What is the main factor determining the % of haemoglobin saturation?
Partial pressure of oxygen in blood
147
The % of haemoglobin saturation is high where the partial pressure of oxygen is ____? and location
High
-in the lungs
148
The % of haemoglobin saturation is low where the partial pressure of oxygen is ____?
Low
-Tissue cells
149
What happens to oxygen and hemoglobin in tissue cells?
Oxygen dissociates from haemoglobin
150
What is the Oxygen haemoglobin dissociation curve?
graphical representation of the relationship between the amount of oxygen bound to hemoglobin and the partial pressure of oxygen in the blood
-Not a linear relationship
151
What is the plateau phase of the Oxygen haemoglobin dissociation curve?
Where the partial pressure of oxygen is high (lungs)
-Good margin of safety
152
What is the steep phase of the Oxygen haemoglobin dissociation curve?
At the systemic capillaries where hemoglobin unloads oxygen to the tissue cells
153
What other factors increase the unloading of O2?
Increased CO2
Increased Hydrogen
Increased temperature
2,3 BPG
154
What is 2,3 BPG?
Acid produced in RBC with chronically under-saturated hemoglobin
-Altitude living, disease states
155
What is the name of the 2 effects of hydrogen on hemoglobin saturation?
Bohr Effect
Haldane effect
156
What is the Borh effect?
CO2 produces H+ or other sources of H+ change the pH of hemoglobin molecules
157
What happens when the pH decreases in hemoglobin molecules?
More O2 released from hemoglobin
-Hemoglobin saturation curve shifts to the right
158
What is the Haldane effect?
Increase in partial pressure pressure oxygen leads to less CO2 bound to hemoglobin
-More CO2 can be carried by hemoglobin during deoxygenated state
159
What three ways does carbon dioxide travel?
1. Physically dissolved
2. Bound to hemoglobin
3. as Bicarbonate
160
How is most CO2 transported?
As bicarbonate HCO3-
-80%
161
What enzyme facilities the combination of CO2 and water (carbonic acid)?
Carbonic anhydrase
162
How is bicarbonate ions formed?
Carbonic acid dissociates into hydrogen ions and bicarbonate ion
163
How much of CO2 is transported by hemoglobin?
~10%
164
How much of CO2 is dissolved in the plasma?
~10%
165
What are conditions that cause abnormalities in arterial P O2 ?
Hypoxia
Hyperoxia
166
What is Hypoxia?
Condition of having insufficient O2 at the cell level
167
What are the 4 categories of Hypoxia?
Hypoxic
Anemic
Circulatory
Histotoxic
168
What is Hypoxic hypoxia?
Low arterial PO2 caused by respiratory malfunction or low environmental O2 e.g low altitude, suffocation
169
What is Anemic hypoxia?
reduced O2-carrying capacity of the blood despite normal PO2 levels
Causes by: reduced RBC
reduced Hemoglobin
CO poisoning
170
What is circulatory hypoxia?
Delivery of O2 to tissues is insufficient
Caused by:
Local (heart attack)
Congestive heart failure
Circulatory shock
171
What is Histotoxic hypoxia?
Cells cannot use O2 despite normal O2 delivery
caused by Cyanide poisoning (blocks ETC)
172
What is Hyperoxia?
Condition of having an above-normal arterial PO2
Can cause brain problems and retinal damage (possibly blindness)
173
When can Hyperoxia occur?
Only when breathing supplemental oxygen
174
What happens if someone with a pulmonary disease with reduced arterial P O2 has Hyperoxia?
Can improve their O2 gradient from alveoli to blood
175
What is Hypercapnia?
Condition of having excess CO2 in arterial blood
Caused by:
Hypoventilation
Lung disease
-aka Respiratory acidosis
176
What are the conditions that cause abnormalities in arterial P CO2?
Hypercapnia
Hypocapnia
177
What is Hypocapnia?
Condition of having below-normal arterial PCO2 levels
Caused by:
Hyperventilation (anxiety, fever, aspirin poisoning)
aka Respiratory alkalosis
178
What controls respiration?
respiratory centers in the brain stem establish a rhythmic breathing pattern
179
What are the respiratory centers in the brain stem?
1. Medullary respiratory centre
2. Pneumotaxic centre
3. Apneustic centre
180
What 2 groupsmis the medullary respiratory centre divided into?
a. Dorsal respiratory group (DRG)
b. Ventral respiratory group (VRG)
181
What is the Dorsal respiratory group composed of?
Mostly inspiratory neurons
182
what is the Ventral respiratory group (VRG) composed of?
Inspiratory and expiratory neurons
-Used when increased ventilation is required
183
What is the pneumotaxic centre?
-Sends impulses to DRG that help “switch off” inspiratory neurons –“fine-tuning”
-Dominates over apneustic centre
184
What is the Apneustic centre?
-Prevents inspiratory neurons from being
switched off
-Provides extra boost to inspiratory drive
185
What chemical factors play a role in determining magnitude of ventilation?
P O2 (peripheral detection)
P CO2 (central detection)
Arterial H+ (pH)
186
What are the peripheral chemoreceptors?
Carotid bodies in the carotid sinus
Aortic bodies in the aortic arch
187
Are peripheral chemoreceptors sensitive?
No
Hb still at 90% sat at 60mmHg
188
How is a rise in H+ concentration detected?
Decrease in pH stimulates ventilation by the carotid chemoreceptors
189
What is the most important regulator of ventilation?
PCO2
190
What happens to ventilation when PCO2 increases?
Respiratory centre is stimulated which increases ventilation
191
What happens to ventilation when PCO2 decreases?
Respiratory drive is reduced
192
Where are central chemoreceptors located?
Near respiratory centre
responsible for ~70% of ventialtion
193
Generally, an increase in arterial PCO2 triggers?
Peripheral/central chemoreceptors and the medullary respiratory centre
----> Ventilation increases (PCO2 decreases)
