Unit 5 Flashcards
1
Q
What does the respiratory system allow for?
A
- exchange of gases between the atmosphere and blood
- homeostatic regulation of body pH
- protection from inhaled pathogens and irritating substances
- vocalization
2
Q
What are the 4 main processes of the respiratory system?
A
- Gas exchange between atmosphere and lungs (ventilation)
- Air moves into lungs→inspiration (inhalation) lungs increase in size
- Air moves out of lungs→expiration (exhalation) lungs decrease in size - Gas exchange between lungs and blood → CO2 and O2
- Transport of gases by blood→ CO2 and O2
- Exchange of gases between blood and tissues
3
Q
What causes the lungs to expand in size?
A
inspiration (inhalation)
4
Q
What causes the lungs to decrease in size?
A
expiration (exhalation)
5
Q
What is the respiratory system involved in?
A
both ventilation and gas exchange
6
Q
What is the conducting system?
A
Passages or airways that lead from external environment to the exchange surface of the lungs
7
Q
What two parts can the respiratory system be divided into?
A
- Upper respiratory tract
- Lower respiratory tract
8
Q
What does the upper respiratory tract consist of?
A
mouth, nasal cavity, pharynx, larynx
9
Q
What does the lower respiratory tract consist of?
A
trachea, bronchi, bronchioles, lungs
10
Q
What is ventilation?
A
gas exchange between atmosphere and lungs
11
Q
What is ventilation?
A
gas exchange between the external atmosphere and lungs
12
Q
Where is the exchange surface?
A
the alveoli
13
Q
What are alveoli?
A
tiny hollow sacs found at the ends of the terminal bronchiole
14
Q
What is alveoli wrapped with?
A
wrapped with an extensive capillary network which covers 80-90% of the alveolar surface
15
Q
Where does gas exchange occur?
A
gas exchange occurs by diffusion between alveoli and capillary
16
Q
What are the two types of alveoli cells?
A
- Type I alveolar cells
- Type II alveolar cells
17
Q
What are Type I alveolar cells?
A
large but thin cells, allowing gas to rapidly diffuse through it
18
Q
What are type II alveolar cells?
A
small but thick cells, and they synthesize and secrete a chemical called surfactant
19
Q
What is the primary function of alveoli?
A
the exchange of gases between themselves and the blood
20
Q
What does the blood vessels of the pulmonary circulation allow for?
A
allows for gas exchange with the alveoli
21
Q
What is pulmonary circulation?
A
- low oxygen blood exits the right ventricle of the heart
- the low oxygen blood then goes into the pulmonary arteries via the pulmonary trunk
- there are two pulmonary arteries; one to each lung
22
Q
Why is the rate of blood flow through the lungs much higher than the rate in other tissues?
A
because the lungs receive the entire cardiac output of the right ventricle vs. the whole body receives the blood leaving from the left ventricle
this means that as much blood flows through the lungs in 1 minute as flows through the rest of the body in the same amount of time
23
Q
Why is pulmonary blood pressure low compared to the systemic circuit?
A
because the right ventricle does not pump as forcefully to create blood flow as the left ventricle because the resistance of the pulmonary circulation is low
24
Q
What allows for ventilation (inspiration and expiration)?
A
bones and muscles of the thorax (chest cavity)
25
What is the relation of the lungs to the chest wall?
the ribs and spine (chest wall) forms the sides and top of the cage
its a closed compartment; closed off at the top by neck muscles and connective tissue and closed off at the bottom by the diaphragm
the wall is formed by the ribs and intercostal muscles
26
What is the two lungs surrounded by?
the pleural sac
27
What does the pleural sac form around each lung?
a double membrane
28
What is pleura (the double membrane) filled with?
filled with pleural fluid which acts as a lubricant
29
What is Dalton's Law?
Total pressure of a mixture of gases = sum of the partial pressure of individual gases
30
Where do gases move from?
gases move from areas of high pressure to areas of low pressure
31
What is the relation of volume and pressure of a gas?
they are inversely related;
if volume of a gas is increased, pressure of a gas will be decreased
vise versa, if volume is decreased, pressure will increase
32
What is the amount of gas to dissolve in a liquid determined by?
a. partial pressure of the gas
b. solubility of the gas in the liquid
33
What does partial pressure mean?
the pressure of an individual gas in a mixture
34
What is the formula for partial pressure?
Partial pressure of a gas = Patm( atmospheric pressure) x % of gas in atmosphere
eg. partial pressure of oxygen:
PO2 = 760 mm Hg x 21% = 160 mm Hg
35
What is Boyle's Law?
P1V1 = P2V2
36
In the respiratory system, what does changes in the volume of the chest cavity during ventilation cause?
causes pressure gradients that create air flow
37
What is the driving force for air flow?
changes in alveolar pressure
38
What happens when you increase chest volume?
decrease in alveolar pressure, and air flows into respiratory system
39
What happens when you decrease chest volume?
increase in alveolar pressure, and air flows out into the atmosphere
40
Do lungs have muscles?
No, thus lungs cannot change volume on their own
41
Where are the muscles located then, if not in lungs?
the muscles are located in the chest walls, and contraction will change thoracic volume
42
What is the structure of lungs?
passive elastic structures (like balloons)
43
What does the volume depend on?
1. the transpulmonary pressure
2. the degree of elasticity of the lungs
44
What is transpulmonary pressure?
difference between alveolar pressure and intrapleural pressure
45
What is alveolar pressure?
pressure inside the lungs
46
What is intrapleural pressure?
pressure outside the lungs, in the intrapleural fluids
47
What role does airways serve as?
they serve an important role in conditioning the air before it reaches the lungs
48
What do the airways need to do?
1. Warm air to 37 degrees C to maintain core body temperature and protect alveoli
2. Add water vapour to air to prevent drying of epithelia
3. Filter out foreign material
49
What are airways lined with?
Airways are lined with ciliated epithelia that secrete a watery saline solution
50
What are the steps of saline secretion by airway epithelial cells?
1. NKCC (Na+, K+, Cl-, Cl-) brings Cl- into epithelial cell from ECF.
2. Apical anion channels allow Cl- to enter the lumen.
3. Na+ goes from ECF to the lumen.
4. NaCl movement from ECF to lumen creates a concentration gradient so water followings into the lumen, creating the watery saline solution.
51
What is cilia covered with?
cilia is covered with a sticky layer of mucus that is secreted by goblet cells
- traps most inhaled particles
52
What does mucus contain?
contains immune cells that kill invaders
53
Where does mucus go?
Mucus is moved up to the pharynx, where it can then be spit out or swallowed.
54
If mucus is swallowed, how is the bacteria destroyed?
the mucus is transferred to the digestive tract where additional bacteria is destroyed
55
What is cystic fibrosis (CF)?
- inherited condition
- result of mutations in a Cl- channel
- the Cl- channel is defective
56
What does the defective Cl- channel cause?
prevents the appropriate secretion of water in the lumen to create the watery saline layer
- cilia are trapped in thick and slimy mucus, which blocks airways, creating difficulty breathing
- prevents proper removal of bacteria, causing repeated infections
57
What eventually happens to people with cystic fibrosis?
over-active immune cells start destroying the lung, which is lethal
58
What are the two steps of the respiratory cycle?
inspiration and expiration
59
What happens during inspiration?
1. Somatic motor neurons trigger contraction of diaphragm and inspiratory muscles
2. Thorax expands (thoracic volume increases)
3. Alveolar and intrapleural pressure decreases
4. lungs expand resulting in air flowing into lungs
60
What happens to the diaphragm during inspiration?
the diaphragm contracts and flattens
61
What happens during expiration?
1. Impulses from somatic neurons stop.
2. Diaphragm and thoracic muscles relax which returns thorax to their original positions (thoracic volume decrease, elastic recoil)
3. Alveolar and intrapleural pressure increases
4. Elastic recoil of the lungs decreases lung volume (air flows out of the lungs)
62
What type of process is expiration during quiet breathing?
expiration is a passive process (does not require energy)
63
What type of process is expiration during exercise or heavy breathing?
expiration is active
64
What does passive expiration depend on?
elastic recoil of the thoracic muscles and the lungs
65
What does active expiration depend on?
contraction of internal intercostals and abdominal muscles
66
What is intrapleural pressure normally?
sub-atmospheric (less/lower than that of the atmosphere) (arises during fetal development)
67
Why is the intrapleural pressure lower than the rest?
having lower pressure in the pleural fluid (outside the lung) than inside the lung (at rest) helps keep the lung expanded and open
68
What happens when air gets into the pleural cavity?
intrapleural pressure increases, causes the pressure difference broken, which results in lung collapsing (pneumothorax)
69
What is pneumothroax?
When 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.
70
What treatment is there for pneumothorax?
apply suction to remove the air and seal the hole
71
What are the factors for breathing (work required to breathe)?
1. Compliance (stretchability of the lungs)
2. The resistance to air flow in the airways
72
What does lung compliance mean?
the ability for the lung to stretch (more stretchability = more compliance)
73
What does low lung compliance mean?
it is harder to expand the lungs (harder to breathe)
74
How do people with low lung compliance breathe?
breathe shallowly and rapidly
75
How do people with high lung compliance breathe?
breathe easier (their lungs stretch easily)
76
What does lung elastance mean?
degree and/or speed of return to resting volume after lung is stretched
77
What happens when lung elastance is low?
the lung does not return to resting volume passively
78
What is resistance determined by?
airway diameter
79
What is the formula for airway diameter?
R = 8Lh/pir^4
80
Is the work need to overcome airway resistance low/high normally?
normally, air resistance is low in comparison to work needed to overcome resistance to stretch
81
When does work needed to overcome airway resistance increase?
when mucus accumulates from allergies or infections
82
What can bronchiole diameter be affected by?
the nervous system, hormones and paracrines
83
What is bronchodilation and what causes it?
bronchodilation is expansion of the bronchial air passages
caused by increased CO2
84
What is bronchoconstriction and what causes it?
bronchoconstriction is increased resistance to air flow and decrease in the amount of fresh air that reaches the alveoli (narrowing of the airways)
caused by release of Histamine in response to tissue damage or allergic reactions
- large amounts of histamine leads to widespread bronchoconstriction and difficult breathing
85
What is the neural control of bronchioles?`
primarily from parasympathetic neurons that cause bronchoconstriction
86
What is bronchoconstriction designed to do?
a reflex designed to protect the lower respiratory tract from inhaled irritants
87
Is there a significant sympathetic innervation of the bronchioles in humans?
no
88
What is the hormonal control of bronchioles?
primarily from circulating epinephrine
89
What do smooth muscles in the bronchioles do?
they have lots of beta-2 receptors that respond well to circulating epinephrine, and when they're stimulated, they relax airway muscles to dilate bronchioles, causing bronchodilation
90
What are hormonal control of bronchioles used for?
as a treatment for asthma
91
How do you assess a person's pulmonary function?
by measuring how much air the person moves during quiet breathing and maximal breathing effort
92
What do you use to test pulmonary function?
using a spirometer, an instrument that measures movement of air during breathing
93
What are the four lung volumes that can be measured as air moves during breathing?
1. Tidal Volume (Vt)
2. Inspiratory Reserve Volume (IRV)
3. Expiratory Reserve Volume (ERV)
4. Residual Volume (RV)
94
What is tidal volume (Vt)?
the volume of air that moves during a single normal inspiration or expiration
95
What is Inspiratory Reserve Volume (IRV)?
maximum amount of air that can be inspired above tidal volume
96
What is Expiratory Reserve Volume (ERV)?
amount of air forcefully exhaled after the end of a normal expiration
97
What is Residual Volume (RV)?
the amount of air left in the lungs after maximal expiration
98
What is capacity?
the sum of two or more lung volumes
99
What is vital capacity (VC)?
the maximum amount of air that can be voluntarily moved into or out of the respiratory system with one breath
the sum of the inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and tidal volume (TV)
VC = IRV + ERV + Vt
100
What is total lung capacity (TLC)?
TLC = vital capacity + residual volume
101
What is total pulmonary ventilation/minute volume?
the volume of air moved into and out of the lungs each minute
102
What is the formula for minute volume?
MV (mL/min) = Vt (mL/breath) x respiratory rate (breaths/min)
103
What is anatomic dead space?
air in trachea, bronchi, and bronchioles that does not participate in gas exchange; the air that does not reach the alveoli
104
What is the formula for alveolar volume?
Alveolar volume = Vt - dead space
105
What is effectiveness of ventilation determined by?
determined by the rate and depth of breathing
- because of the dead space, increase in depth of breathing is the most important
106
What is alveolar ventilation?
the volume of fresh air that reaches the alveoli each minute
107
Why is alveolar ventilation a more accurate indicator of efficiency of ventilation?
Because a significant portion of inspired air never reaches the exchange surface, thus, alveolar ventilation is more accurate because it measures the amount of fresh air that reaches the exchange surface
108
What is the formula for alveolar ventilation?
Alveolar ventilation = ventilation rate x alveolar volume
109
Why is ventilation matched to alveolar blood flow?
the body attempts to match air flow and blood flow to maximize gas exchange in the capillary beds that surround the alveoli
110
What does alterations in blood flow in the lungs depend on?
primarily on local control exerted by O2 levels in the interstitial fluid around the arteriole surrounding the alveoli
111
What does increase in tissue PO2 result in?
results in vasodilation in the arteriole
112
What does decrease in tissue PO2 result in?
result in vasoconstriction in the arteriole, which reduces blood flow
113
What does local vasoconstriction divert?
diverts blood away from the under-ventilated areas
- ensures that blood travels to areas of the lungs that would ensure that oxygen is available to be picked up
114
What does gas exchange occur by?
diffusion
115
Rate of diffusion across lungs is:
1. Proportional to partial pressure gradient (gases move from regions of higher partial pressure to regions of lower partial pressure)
2. Proportional to the available surface area (high surface area = high rate of diffusion)
3. Inversely proportional to the thickness of the membranes (thick membrane = low rate of diffusion; thin membrane = high rate of diffusion)
4. Greatest over short distances (when distance increases, rate decreases)
116
What is partial pressure gradient influenced by?
1. Composition of inspired air
- affected by altitude (partial pressure of oxygen in air decreases along with total atmospheric pressure as you move from sea level to higher altitudes)
2. Alveolar Ventilation
- changes in airway resistance (eg. asthma)
- changes in lung compliance (eg. fibrosis)
117
What is the PO2 levels in normal alveoli?
The PO2 will be normal on the inside of the alveoli and inside the capillary
118
What happens during Emphysema?
destruction of the alveoli results in less surface area for gas exchange
- there's normal/low PO2 inside alveoli and low PO2 in the capillary
119
What happens during Fibrotic Lung Disease?
scaring thickens the alveolar membrane slows gas exchange, and loss of lung compliance may decrease alveolar ventilation (making air hard to come in)
- theres normal/low PO2 in alveoli, and low PO2 inside capillary
120
What happens during Pulmonary Edema?
increase in interstitial fluid (fluid in tissues of body) in lungs leads to increase in diffusion distance
- PO2 is normal inside alveoli and PO2 is low inside capillary
121
What happens during Asthma?
increased airway resistance decrease ventilation (bronchioles constricted)
-PO2 is low inside alveoli and low inside capillary
122
How are gases transported throughout the body?
dissolved in plasma or in the RBCs
123
How is oxygen transported?
oxygen has low solubility in plasma, thus most of oxygen is transported by RBC, which is bound to haemoglobin
124
What is haemoglobin?
the oxygen-binding protein that gives RBCs their color
125
What is O2 bound to in RBCs?
haemoglobin
126
What does blood loss result in?
there is less O2 carrying capacity (blood transfusion is required to restore capacity, but in emergencies this is not always possible)
127
How many oxygen molecules can each haemoglobin molecule bind to?
4 oxygen molecules
128
What does oxygen bind reversely to?
iron in haeme group
129
What is oxyhaemoglobin?
haemoglobin bound to oxygen (HbO2)
130
What is deoxyhaemoglobin?
unbound haemoglobin (Hb)
131
What is percent saturation of haemoglobin?
% of available binding sites that are bound to oxygen
132
What is a competitive inhibitor of O2 binding?
carbon monoxide; it prevents oxygen binding
133
How is carbon dioxide transported?
1. dissolved in plasma
- CO2 is more soluble in body fluids than oxygen; however, cells produce more CO2 than can be carried in plasma (diffuses from cell to plasma)
2. interact with proteins (including haemoglobin via 4 terminal amine groups on the protein)
- forms carbaminohaemoglobin (Hb CO2)
- deoxy-haemoglobin interacts more readily with CO2 than oxy-haemoglobin
3. converted to bicarbonate
- the majority of CO2 entering the blood is converted by reaction catalyzed by carbonic anhydrase (present in RBCs)
- the bicarbonate ions are moved out the RBC by a transporter protein which exchanges HCO3- for Cl- in a process known as the chloride shift
134
What is chloride shift?
a transporter protein that moves bicarbonate ions out of the RBC by exchanging the HCO3- for Cl-
135
When venous blood reaches lungs, the PCO2 of alveoli is higher or lower than blood?
lower than blood
136
How are CO2 diffused into alveoli?
CO2 dissolved into plasma diffuses into alveoli and then CO2 in RBC diffuses into plasma and then diffuses into alveoli
137
What doesn't contract spontaneously?
diaphragm and intercostals aka. skeletal muscles
138
How are skeletal muscle contractions initiated?
they must be initiated by somatic motor neurons
139
What are the steps of carbon dioxide transport?
1. CO2 diffuses out of cells into systemic capillaries.
2. Only 7% of the CO2 remains dissolved in plasma.
3. Nearly a fourth of the CO2 binds to hemoglobin, forming carbaminohemoglobin.
4. 70% of the CO2 load is converted to bicarbonate and H+. Hemoglobin buffers H+.
5. HCO3- enters the plasma in exchange for Cl- (chloride shift)
6. At the lungs, dissolved CO2 diffuses out of the plasma.
7. By the law of mass action, CO2 unbinds from hemoglobin and diffuses out of the RBC.
8. The carbonic acid reaction reverses, pulling HCO3- back into the RBC and converting it back to CO2.
140
What is contraction of the respiratory skeletal muscles initiated in?
the medulla oblongata (brain)
141
What is the central pattern generator?
a network of neurons in the medulla oblongata that intrinsic rhythmic activity (eg. fire a signal at a rhythmic rate)
142
What are the two nuclei that are associated with respiration?
1. Dorsal respiratory group (DRG)
2. Ventral respiratory group (VRG)
143
What is the Dorsal respiratory group (DRG)?
neurons that control mostly muscles of inspiration (I neurons)
144
What do the Dorsal respiratory group (DRG) control?
control external intercostal muscles and diaphragm (muscles of inspiration)
145
What is the Ventral respiratory group (VRG)?
neurons that control muscles used for active expiration (E neurons)
146
What does the Ventral respiratory group (VRG) control?
control internal intercostal and abdominal muscles (active expiration)
147
What do chemoreceptors do?
modify or adjust the rhythmicity of the central pattern generator neurons
148
What are the two types of chemoreceptors?
1. Peripheral Chemoreceptors
2. Central Chemoreceptors
149
What are glomus cells?
the primary periopheral chemoreceptors, they are cells located in carotid bodies which are activated by a decrease in PO2 or pH or by an increase in PCO2, and triggers reflex the increase ventilation
150
What do peripheral chemoreceptors do?
sense changes in PO2, pH, and PCO2 of the plasma
- when there's a decrease in PO2, pH, or increase in PCO2, it will trigger a reflex to increase ventilation
151
Where are peripheral chemoreceptors located?
outside the CNS
152
Under normal circumstances, what is not an important factor in modulating ventilation"?
PO2; there must be a significant change before a signal is sent
most circumstances pH and PCO2 are important
153
Where is the central chemoreceptors located?
in medulla oblongata (brain)
- they are the most important chemical controller of ventilation
154
What happens when the arterial PCO2 increases for central chemoreceptors?
CO2 crosses the blood-brain barrier and activates the central chemoreceptors, then then the receptors signal the control network to increase ventilation and remove CO2 from the blood
155
What activates central chemoreceptors?
changes in pH in the cerebrospinal fluid (CSF) caused by the production of carbonic acid (H2CO3)
156
What initiates the chemoreceptor reflex?
H+ produced from the conversion of CO2 into bicarbonate and H+
157
Whats the formula of conversion of CO2?
CO2 + H2O <-> H2CO3 <-> HCO3- + H+
158
What are the two types of mechanoreceptors?
1. Irritant receptors
2. Stretch receptors
159
What is the receptor that controls ventilation to protect the lungs?
mechanoreceptors
160
Where are irritant receptors located?
in airway mucosa
161
What do irritant receptors do?
send signals through parasympathetic neurons that triggers bronchiolar smooth muscles to bronchoconstrict
162
Where are stretch receptors located?
in airway smooth muscles
163
When are stretch receptors triggered?
if the lungs are over-inflate
164
When are stretch receptors triggered?
if the lungs are over-inflated, and they send signals to terminate ventilation (Hering-Breuer inflation reflex)
