Respiratory Flashcards
1
Q
Primary Function of respiration
A
Gas Exchange
2
Q
Inspiration vs Expiration
A
Inspiration: Breathe in air rich in O2
Expiration Breathe out air rich in CO2
3
Q
How is CO2 created in the body ?
A
Oxidative processes
4
Q
How are O2 and CO2 transported?
A
By the blood
5
Q
Why is it better to breathe in from nose rather than mouth ?
A
Nose has nasal turbinates which filter the air and trap big particles
6
Q
Describe the Respiratory tract?
A
- Breathe in through nose/mouth
- Air then goes through pharynx
- Air then goes through larynx
- Air then goes through the trachea
- Trachea splits into left and right main bronchi
- Bronchi then split into even smaller bronchi further in the lungs
- Gas exchange then occurs at the alveoli
7
Q
What is in the larynx?
A
Vocal cords
8
Q
Describe the alveoli
A
Covered by blood capillaries
9
Q
Where do alveoli send blood?
A
Blood rich in CO2 and poor in O2 is sent to the alveoli from the heart
Blood rich in O2 and poor in CO2 is sent from the alveoli to the heart
10
Q
Describe the pleural space
A
-Space located between the lungs and the ribcage
- Continuous bag of fluid
-Each lung has its own pleural space
-Pressure in the leural space is negative compared to the outside
11
Q
How does air flow into the lungs?
A
- Ribcage expands which increases the size of the lung volume, a larger volume = lower pressure, gas tends to flow from high pressure to low pressure
- Since the pressure inside the lungs is now lower than the outside pressure, the oxygen will flow into the lungs
12
Q
How does the pleural space inflate the lungs?
A
Creates suction between the lung and the ribcage. When the ribcage expands it pulls the lungs along with it and when the ribcage deflates the lungs are also deflated
13
Q
What is pneumothorax?
A
A collection of air outside the lungs but inside the pleural space
14
Q
How can pneumothorax occur?
A
If a stick enters through your ribcage but not into your lungs this causes pneumothorax because air from the outside will enter into the pleural space since it has a negative pressure than the outside
15
Q
What happens during pneumothorax?
A
When air enters into the pleural space the pressure in the space becomes equivalent to that of the outside this causes the lung to collapse since there is no longer a negative pressure holding the lung to the ribcage
16
Q
Describe the intercostal muscles and diaphragm during inspiration
A
When you inspire your diaphragm moves down and your intercostal muscles move outward to expand the ribs. As you diraphragm moves down the volume of the pleural space increases which pulls the lungs and causes them to expand. Since the volume of the lung has increased the pressure in the lungs is now lower than the outside and air will flow in.
17
Q
How many lobes on the left side of the lung vs the right?
A
Right = 3 lobes
Left = 2 lobes
18
Q
What makes up the conducting zone and describe the cartilage?
A
- Trachea(plaques of cartilage)
- Bronchi(plaques of cartilage)
- Bronchioles(no cartilage)
- Terminal bronchioles (covered by SM)
19
Q
Four main functions of the Conducting zone?
A
- Defense against bacterial infection and foreign particles
- Warm and Moisten inhaled air
- Sound and Speech
- Regulation of air flow
20
Q
What is the mucociliary defense system ?
A
Conducting zone does this
- Epithelial cells line the bronchi with cilia which beat upwards. The epithelial glands release mucous which lines the respiratory passages all the way down to the bronchioles. Foreign particles stick to the mucous and the cilia sweep the mucous up into the pharynx where it i coughed up/swallowed.
21
Q
What happens when cold air enters the respiratroy system?
A
Blood vessels around the airway dilate to bring more blood to the area to warm up the air
22
Q
How is sound/speech produced?
A
Movement of air passing over the vocal cords
23
Q
What is part of respiratory zone and describe the alveoli?
A
- Respiratory broncholes(start seeing alveoli in their walls)
- Alveolar Ducts (filled with alveoli in their walls)
- Alveolar sacs(just alveoli)
23
Q
How do the airways regulate flow?
A
Smooth muscle around the airways may contract/relax to alter resistance to air flow
24
Function of the respiratory zone
- This is the site of gas exchange between air in the alveoli and the blood in the pulmonary capillaries
-Roughly 300 million alveoli in lungs and each alveolus can be associated with up to 1000 capillaires
25
Two types of circulation systems
1. Pulmonary circulation
2. Systemic circulation(Bronchial circulation)
26
Describe the pulmonary circulation of blood?
1. Mixed venous blood from different organs with different metabolic activities enters the right atria via the vena cavas
2. The blood is then pumped from the right atrium to the right ventricle
3. The blood is then pumped to the pulmonary trunk (artery) which goes to the lungs and blood is oxygenated
4. Oxygenated blood then reenters the heart via the right and left pulmonary veins
27
Describe the systemic circulation
1. Oxygenated blood in the left ventricle is pumped into the aorta
2. This blood is then transported to various organs in the body which use up the oxygen and give off their metabolic waste(CO2)
28
Describe the bornchial circulation
Supplies oxygenated blood from the systemic circulation to the tracheobronchial tree which allows for the airways to get oxygenated
29
What is Anastomosis and where is this seen?
- Venous blood from the bronchial circulation is mixed with the oxygenated blood
-There is so little blood oxygenating the airways that there is not a separate venous system to bring deoxygenated blood back to the heart
30
What cells are found in the alveoli?
1. Epithelial type I
2. Epithelial type II
3. Endothelial cells
4. Alveolar macrophages
31
Epithelial type I
-Line the alveoli
-Little is known about their function
32
Epithelial type II
-Line the alveoli
-Produce pulmonary surfactant which decreases surface tension of the alveoli
33
Endothelial cells
-Consistute the walls of the pulmonary capillaries, can be as thin as 0.1 micron to allow for easy diffusion
34
Alveolar Macrophages
Remove foreign particles that may have escaped the mucociliary defense system of the airways and found their way into the alveoli
35
What is surface tension?
-Surface tension occurs at the air-liquid interface because water molecules attract each other more than air molecules attract each other
-The liquid molecules like to associate with themselves rather than with air molecules, this causes tension to be generated across the film surface
36
Why is surface tension bad for alveoli?
-Curved surface inside the alveolus causes the surface tension to produce a pressure that tends to collapse the alveolus
-Forces of attraction of the water molecules inside the alveoli add up to create a pressure that tends to collapse the alveoli
37
LaPlace's Law
P = 4T/r(T=surface tension)
38
How does radius affect pressure LaPlace's Law?
-As radius decreases(smaaller alveoli) the pressure increases
39
What does surfactant do for alveoli of varying sizes?
-Helps reduce surface tension and helps to make sure all of the alveoli are the same size
-If one alveoli was huge and another was small this would create an unstable system since all the air would go into the large one since it has a lower pressure
-If surfactant wasn't there the small alveoli would collapse and empty into the large alveoli
40
Two Roles of pulmonary Surfactant
1. Reduces overall surface tension so that we are able to breathe. If the surface tension was equal to that of water we would not be able to breathe
2. Makes surface tension inside the alveoli change in a way that prevents the pressure inside the small alveoli from exceeding that of the large (should be equal)
41
How would the same amount of surfactant affect a small alveolus vs a large one?
Smaller alveolus' surface tension would decrease more than the big alveolus' surface tension
42
Principal respiratory muscles used during inspiration
1. Diaphragm
2. External intercostal muscles
3. Parasternal intercartilaginous
43
Accessory Muscles used during inspiration
1. Sternacleidomastoid
2. Scalenus
44
Accessory vs Principal muscles?
Principal : used during normal inspiration
Accessory: used during heavy breathing
45
What nerves innervate the diaphragm?
Phrenic nerves from cervical segments 3, 4, and 5
46
Diaphram during inspiration?
- When it contracts it descends, increaseing the longitudinal dimension of the ribcage
-it is attached to the lower ribs and when it contracts it also causes the lower ribs to lift which increases the cross-sectional dimension of the ribcage
47
External Intercostal Muscles in Inspiration
When these muscles contract they lift the ribs and increase the cross-sectional dimension of the ribcage
48
Parasternal intercartilagenous muscles during inspiration
When these muscles contract they lift the ribs increasing the crosss-sectional dimension of the ribcage
49
Sterncleidomastoid and Scalenus during heavy breathing
Sternacleidomastoid: Contracted it elevates the sternum
Scalene's: Elevates/fixes the upper ribs
50
What happens during expiration of quiet breathing?
Relaxation of the inspiratory muscles:
- Diaphragm goes up
-Ribcage goes down (intercostals relax)
51
What happens during expiration of active breathing?
-Internal intercostals are recruited or abdominal muscles which helps push on the abdomen forcing the diaphragm to go back up
52
What is a spirometer?
Tool used to measure the amount of air that comes in/out of our lungs
53
How do we hook up a spirometer?
1. Nose clip
2. Place spirometer tube in the mouth, the other end is attached to a pen that moves up/down as the patient breathes
54
What can a spirometer measure?
1. Tidal volume
2. Vital capacity
3. Inspiratory capacity
4. Expiratory reserve volume
5. Inspiratory reserve volume
55
What canno be measured by the spirometer?
1. Functional residual capacity
2. Total lung capacity
3. Residual volume
56
Tidal volume
Volume of air inhaled or exhaled in one breath during quiet breathing
57
Vital capacity
Maximum amount of air you can forcibly exhale from your lungs after fully inhaling
-IRV + TV + ERV
58
Inspiratory Capacity
Maximum amount of air that can be inhaled after a normal tidal expiration
(TV + IRV)
59
Inspiratory Reserve Volume
Amout of air in excess of tidal inspiration that can be inhaled with max effort
60
Expiratory Reserve Volume
Amount of air in excess of tidal volume that can be exhaled with max effort
61
Functional Residual Capacity
Amount of air remaining in the lungs after a normal tidal expiration
(RV +ERV)
62
Total lung capacity
Maximum amount of air the lungs can contain
RV + VC
63
Residual Volume
Amount of air remaining in the lungs after maximum expiration : Keeps the alveoli inflated
64
How can Functional Residual Capacity be measured?
Helium Dilution
65
Helium Dilution
1. C1 is the helium concentration in a spirometer of volume V1. Let the subject breathe out to FRC(regular breath)
2. Then, open the valve and ask the subject to breathe in/out from the spirometer. This will equilibrate the helium concentration betweenn the spirometer and patients lung
3. Concentration after equilibration is measured as C2 and then we calculate V2 which is the system + FRC
66
Ventilation
amount of air inspired into the lungs over some period of time
67
Minute ventilation
Amount of air inspired into the lungs over a period of one minute (VE)
VE = VT X f (tidal volume times the number of breaths)
68
Anatomical Dead Space
Not all air inhaled into the lungs reaches the exchanging area. The air that remains in the conducting airways is called the anatomical dead space.
69
How to approximate the anatomical dead space?
About the subject's weight in lbs to mL
Ex. 100 lbs has an anatomical dead space of 100 mL
70
Physiological Dead Space
Under pathological conditions, a certain amount of inspired air, although reaching the respiratory zone does not take part in gas exchange because the alveoli either recieve a decreased blood supply or no blood at all. These alveoli are called alveolar dead space
71
How to calculate physiological dead space(VD)?
Physiological Dead Space(VD) = Anatomical Dead Space + Alveolar Dead Space
72
Normal Alveolar Ventilation
VA keeps the PaCO2 at a constant level
73
Alveolar Hyperventilation
When you ventilate more than your body needs it, more O2 supplies and more Co2 removed than the metabolic rate requires
-Results: Alveolar partial pressures of O2 rise and that of CO2 decreases
74
Alveolar Hypoventilation
When you don't ventilate enough for your metabolic rate. Less O2 is supplies and less CO2 is removed
Results: Alveolar partial pressures of CO2 rise and O2 decreases
75
When does alveolar hypoventilation occur
Diseases such as chronic obstructive lung disease, damage to the respiratory muscles, ribcage injuries
76
Why do people breathe in a bag when they hyperventilate?
By reathing in a bag, CO2 accumulates in the bag and restablishes your CO2 level
77
Why do we not hyperventilate when we exercise?
When we exercise we increase our metabolic requirements which allows us to use up the extra oxygen we recieve during exercise
78
Effects of breathing air with low PO2
- Alveolar partial pressures of O2 decrease
-Alveolar partial pressures of CO2 stay the same
79
Effects of an increase in alveolar ventilation and unchanged metabolism
-Increase in PO2
-Decrease in PCO2
80
Effects of a decrease in alveolar pressure and unchanged metabolism
-Decrease in PO2
-Increase in PCO2
81
Effects of an increase in metabolism and unchanged ventilation
- Decrease in PO2
-Increase in PCO2
82
Effects of a decrease in metaboloism and unchanged alveolar ventilation
-Increases PO2
-Decreases PCO2
83
Diffusion Rate
The transfer of gases across the alveolar-capillary membrane occurs by passive diffusion
84
Why is passive diffusion efficient enough in the lungs?
- Lungs have huge surface area and the capillaries have a very thin membrane
85
Diffusion rate is proportional and inversely proportional to...
Proportional to surface are
Proportional to concentration gradient
Inversely proportional to the membrane thickness
86
Fick's Law governs Diffusion
Diffusion rate is proportional to surface area
Diffusion rate is proportional to partial pressure gradient
Diffusion rate is inversely proportional to the thickness of the alveolar capillary membrane
87
Describe the process of diffusion of oxygen across the alveolar capillary membrane
1. Oxygen goes through the fluid layer surrounding the alveolus this contains surfactant
2. Oxygen then diffuses through the alveolar epithelium, epithelial BM, the interstitial space, capillary BM, endothelium, plasma and then to the RBC
**CO2 travels in the opposite direction**
88
Edema
The interstitial space can accumulate fluid which results in a thicker capillary and makes it harder for gases to diffuse
89
Henry's Law
-To diffuse through a liquid, a gas must be soluble
- The amount of gas dissolved is proportional to its partial pressure (greater PP = more gas dissolved = more diffusion)Henry's Law
90
CO2 vs O2 diffusion
-CO2: is more soluble than O2 in water and thus diffuses 20 times more rapidly than O2
-This is why the partial pressure of CO2 is much lower than O2
The PCO2 between the 2 sides of the alveolar-capillary membreane is 10 times smaller than that for PO2. Therefore , time required for equilibrium between alveolar air and capillary blood is the same for the two gases
91
What is the normal transit time of blood through the pulmonary capillaries at rest?
0.75 seconds
-Diffusion is so rapid that in a normal lung diffusion of both O2 and CO2 is accomplished within 1/3 of the RBC transit time
92
How does edema affect diffusion interms of transit time??
Since diffusion is soo fast a person with edema may still be able to diffuse O2 and CO2 across during the transit time. However during exercise blood flow increase and then not all of the CO2 and O2 will be diffused
93
What happens to transit time if you exercise a lot?
Transit time of the RBCs becomes faster to transport more O2 to your muscles
94
Normal partial pressures of O2 and Co2 in the lungs vs right heart vs left heart?
Lungs:
PO2: 105 mmHg
PCO2: 40 mmHg
Right Heart(deoxygenated):
PO2: 40 mmHg
PCO2: 46 mmHg
Left Heart(oxygenated):
PO2: 100 mmHg
PCO2: 40 mmHg
95
Why is the pressure gradient of PCO2 much lower than that of PO2?
CO2 is much more soluble in blood and therefore diffuses 20 times faster than O2 and thus needs a smaller pressure gradient to transport the same amount of CO2
96
Pressure gradient for O2 vs CO2?
CO2 is about 6 mmHg
O2 is about 65 mmHg
97
What are the partial pressures of CO2 and O2 in the air?
PCO2: 0.3 mmHg
PO2: 160 mmHg
98
The partial pressure O2 of air is 160 mmHg and that in the lungs is 105 mmHg why does it decrease som much from air to alveoli?
The air coming from the right heart is very low in O2 , as soon as fresh air enters the lung it will diffuse into the blood vessels to equlibrate/saturate them which leads to lower partial pressure in the alveoli. The opposite occurs for PCO2
99
Why is blood pressure in the pulmonary circulation lower than that of the systemic?
Pulmonary circulation only needs to bring blood to the top of the lungs whereas systemic circulation has to bring it to all major organs of the body
100
T/F: the pulmonary capillaries are thinner than those of similar vessels in the systemic circulation
True, this is also why pulmonary circualtion cannot be high pressure because more risk for leakage and edema
Thinner blood vessels with less smooth muscle
101
Right ventricle during systole ?
The right ventricle of the heart pumps blood through the pulomanry circulation and develops a pressure of about 25 mmHg during systole, the blood is transmitted to the pulmonary arteries to be oxygenated in the lungs
102
Right ventricle after systole?
After systole the right ventricle drops to atmospheric pressure and the pressure in the pulmonary circulation decreases gradually during diastole to a low of about 8 mmHg as blood flows through the pulmonary capillaries
103
Blood pressure in the right heart?
25/8
104
Left ventricle during systole?
When contracting the left ventricle is at a pressure of 120 mmHg the blood is thhen transmitted to the systems arteries where the pressure drops to 100 mmHg. As blood flows through. the tissue capillaries the blood pressure goes even lower , as blood returns to the right atria of the heart pressure is about 0 mmHg
105
Blood pressure in the right ventricle
120/80
106
What does blood flow depend on?
Flow = Pressure/Resistance
It depends on vascular pressure and resistance
Increase in pressure = increase in blood flow
Increase in resistance = decrease in blood flow
Resistance is inversely proportional to radius
107
T/F: blood flow in the pulmonary circulation = blow flow in the systemic circulation
true,
PC: has low vascular resistance (thin blood vessels with little SM) but low pressure
SC: has high pressure system but vessels contain more smooth muscle and therefore have higher resistance
108
T/F: Pulmonary resistance is 1/10 that of the systemic circulation
True
109
How do pulmonary blood vessels accomodate an increase in blood flow?
During exercise, we increase blood flow to our limbs but don't want to increase the pressure in our respiratory system
1. Open up closed capillaries since at rest some of our capillaries are closed.
2. Distention(expand the blood vessels). Expand blood vessels that are already open which increases radius and reduces resistance to allow more blood flow
110
Drugs that can decrease blood flow
Serotinin, histamine and norepinephrine cause smooth muscle to contract which increases resistance in large arteries and decreases blood flow
111
Drug that increase blood flow?
Acetylcholine and Isoproterenol relax smooth muscle decreasing resistance and increasing blood flow
112
What is the reflex vasoconstriction?
If a region of the lung is poorly oxygenated vasoconstriction will redirect the blood flow to regions that are better ventilated
113
Effects of nitric oxide on blood flow?
Endothelial cells produce nitric oxide which relaxes vascular smooth muscle leading to vasodilation and increases blood flow
114
How does gravity affect pulmonary blood flow?
In the upright position blood flow increases lineraly from top to bottom of the lungs (blood goes preferentially to the bottom of the lungs)
115
Why does blood go preferentially to the bottom of the lungs?
-Blood vessels are more distended toward the bottom of the lungs because gravity increases vascular pressure
-Near the top of the lungs, the pulmonary capillaries may be completely compressed
116
How do we measure the effects of gravity on blood flow?
Inject radioactive xenon into a peripheral vein it acts as an alveolar gas and we can see where it goes in the lungs
117
Top zone of the lungs
Pressure in the arterioles(Pa) is very low because blood does not preferentially flow to the top of the lungs. Pressure in the arterioles is the greatest and this causes the capillaries at both the arterial and venous sides to be compressed which fully restricts blood flow
118
Middle zone of the lung
Pressure in the arterioles(Pa) is higher than the alveolar pressure(PA) but pressure in the venules is lower than both. Since the alveolar pressure is greater than the venous pressure blood cannot go fully through the capillaries since they are shut down at the venous side. However, as blood keeps on pumping into the arterial side this raises the pressure which then becomes high enough to open the blood vessels all the way. As the pressure decreases again then shut down again.
Pa > PA > Pv
119
Describe the Bottom Zone of the lungs
Due to gravity blood flows preferentially to the botttom of the lungs this causes a higher arterial and venous pressure, since the pressure in the alveoli is constant and lower than both the venous and aterial pressures blood flows through the capillaries(Pa > Pv > PA)
120
How does gravity effect alveoli at the top of the lungs in an upright position?
The alveoli at the top of the lungs are more open than the bottom ones because the weight of the lung pulls them open
121
What happens to alveoli at top vs bottom when you breathe in, in an upright position?
When you breathe in the top alveoli will inflate less than the botoom ones because they were already opened more, fresh air goes preferentially to the bottom of the lungs where the alveoli were less opened, greather change in volume for the bottom alveoli
122
Ventilation-Blood flow ration
-Blood flow increase more rapidly than ventilation from top to the bottom of the lungs
-Ventilation blood flow ratio is high at the top of the lungs due to rapid increase in bloodflow and increase in ventilation
-Meanwhile, the ventilation-perfusion ratio at the bottom of the lung is low
123
T/F: blood flow is higher than ventilation at the bttom of the lungs?
True
124
T/F: Ventilation is higher than blood flow at the top of the lungs?
True
125
T/F: The amount of oxygen you inspire per minute(VO2) is equal to the amount of oxygen that is taken up by the blood in the lungs in one minute
True (oxygen consumed per minute by our cells = oxygen taken up by the blood at the level of the lung per minute)
126
CaO2 vs CvO2
CaO2: Measured from an artery this is the blood leaving the lungs
CvO2: Measured via a catheter in from the pulmonary artery this is the blood entering the lungs
127
Fick's Prinicipal to calculate blood flow
Pulmonary blood flow(Q) = (O2 consumption per minute)/ (arterial concentration of blood entering the lungs - venous concentration of blood leaving the lungs)
Q = VO2/ (CaO2-CvO2)
128
How do we measure VO2?
Oxygen consumption is measured by comparing concentration of O2 in expired air collected un a large spirometer and concentration of inspired air O2 level
129
In 100 mL of plasma how much O2 is dissolved if at a PO2 of 100 mmHg?
0.3 mL of O2 is dissolved in the plasma
130
How much O2 do the body cells consume per minute?
300 mL/min
131
Why do we nned Hemoglobin?
Since only 0.3 mL of O2 dissolves in the plasma and we require 300mL or O2/min we need Hemoglobin in order to reach our O2 needs
132
Where is hemoglobin located and what does it do?
Hemoglobin is located in our red blood cells and it allows the blood to take up to 65 times as much O2 as plasma at a PO2 of 100 mmHg
133
Desribe the heme molecules?
-Each Hb molecule consists of 4 subunits bound together
-Each subunit is made up of a heme joined to a global
- And each heme contains an Fe++ ion that can bind to 1 molecule of O2
134
How much O2 can one hemoglobin bind?
One hemoglobin molecule can bind 4 oxygen molecules
135
Oxyhemoglobin
Hb + O2 = HbO2
136
At PO2 of 100 mmHg what is the total amount of oxygen in the blood vs the hemoglobin?
At PO2 of 100 mmHg :
0.3% of O2 is dissolved in the blood
19.5% of the total amount of O2 is bound to Hb
Total amount of O2 in arterial blood is 20%
137
Does the Hb bound to O2 contribute to the PO2?
NO, only the dissolved O2 in the plasma contributes to the overall PO2. However PO2 of the plasma does determine the amount of O2 that combines with Hb
138
O2 dissociation Curve
-Sigmoidal shape
-Determines the amount of O2 carried by Hb for a given partial pressure of O2
139
O2 dissociation curve at high values of PO2
-Seen in the alveoli
-The curve is relatively flat at high values which means the amount of O2 bound to Hb stays roughly constant
-A drop from 100 mmHg to 80 mmHg does not change the concentration of HbO2
-The concentration of HbO2 doesn't really change until PO2 of 60 mmHg
140
O2 dissociation curve at low values of PO2
- At low PO2 seen in the peripheral tissues, a small drop in PO2 unloads the O2 from Hb to the tissue
-HbO2 dissociates more readily at lower PO2 because this occurs at the tissue level where metabolic processes need O2
-A drop in PO2 from 40 to 20 results in a decrease in HbO2% from 75% to 35%
141
Bottom dashed line
Shows the dissolved O2 in the plasma
Even if you increase PO2 to 600 mmHg you still have very little dissolved O2 in the plasma
142
Top dashed line
Shows how dependent we are on Hb compared to dissolved O2
143
Cooperative binding of hemoglobin
Combination of the first heme group with O2 increases the affinity of the second heme for O2(quarternary structure determines its affinity)
144
Transport of O2 from the alveolus to the RBC
1. O2 is inspired and brought to the alveoli, pressure of O2 is high in the alveoli
2. O2 moves from the alveoli into the pulmonary capillary
3. PO2 in the pulomnary capillary is low as the blood arrives from the venous side
4. Some O2 remains dissolved in the plasma of the blood
5. Other O2 moves into the RBCs and binds to Hb
6. RBCs now move toward the peripheral tissues
145
Transport of O2 from the RBCs to Cells
1. Hb arrives to the cells, PO2 is high in the blood and low in the ISF
2. O2 dissolved in the capillary moves into the ISF to be used by cells
3. O2 bound to Hb will dissociate and move into the plasma and then the ISF and get picked up by cells
146
What is Myoglobin?
Molecule found in skeletal muscle that binds only one O2 molecule
147
What shape is the Myoglobin dissociation curve?
Hyperbolic
148
When does myoglobin release its O2?
Myoglobin only releases O2 at very low PO2 and acts as a safety net.
149
O2 dissociation curve of someone with anemia?
-Anemia causes a lack of Hb concentration
-Even when your Hb is fully saturated your total content of O2 in the blood decreases
150
In a normal individual what is the concentration of Hb in the blood?
14g/ mL
151
What is the Bohr Effect?
The shift of the HbO2 dissociation curve to the right when blood CO2 and/or temperature increases, or blood pH decreases
152
Why does the curve shift to the right?
Ex. When we exercise we increase blood CO2 and lactic acid production (decrease in pH) and we generate heat. The curve shifting to the right means that now HbO2 will dissociate at a higher PO2 to prevent us from reaching a very low PO2 when exercising.
153
What happens when there is a decrease in temeprature, increase in pH and decrease in blood CO2?
The HbO2 dissociation curve moves to the left. At lower PO2 less HbO2 will dissociate
154
What happens when someone has carbon monoxide poisoning?
-CO has an extremely high affinity for the O2 binding sites in Hb greather than that of O2
-When CO is present it reduces the amount of O2 bound to Hb and shifts the dissociation curve to the left which decreases HbO2 dissocitation and increases Hb affinity for O2 which makes more CO bind to the Hb. The PO2 remains normal because CO is still binding to Hb and the brain cannot tell the difference between CO bound to Hb and O2 since it only sense the partial pressures which remain constant
155
How much CO2 does the average person at rest produce per day?
250mL/min
156
How is CO2 carried in the blood(three forms)?
1. Physically dissolved in the blood(10%)
2. Combined with Hb to form HbCO2(11%)
3. Bicarbonate(79%)
157
How does CO2 combine with Hb in the blood?
XO2 combines with the globin portion not the heme of the Hb, this makes sure that there is no competition between O2 and CO2
158
Describe how CO2 becomes bicarbonate
1. CO2 combines with H2O to produce carbonic acid(H2CO3). This reaction is aided in RBCs by carbonic anhydrase
CO2 + H2O = H2CO3
2. H2CO3 then ionizes into bicarbonate (HCO3-) and H+ ions
H2CO3 = H+ + HCO3-
3. All these reaction are reversible
159
When CO2 production is high what is high in the blood?
-H+
-HCO3-
-HbCO2
160
Where are HbCO2 and HCO3- usually the highest?
At the peripheral tissues and then they are transported to the lungs to be exxpired
161
Why are the HbCO2 and HCO3- reactions reversible?
At the level of the lungs we need to be able to exhale just CO2
162
Describe the process of bringing CO2 from the tissues to the blood?
1. CO2 is produced at the tissues due to metabolic activity
2. When blood comes by the tissue it has a low PCO2
3. CO2 will diffuse into the plasma of the blood
3. Some CO2 stays dissolved in the plasma,, some CO2 enters the RBC to combine with Hb and some CO2 combines with H2O and become H2CO3 and then ionizes into HCO3-
4. The membrane of the RBC is permeable to the HCO3- which will move into the plasma from the RBC. To keep the RBCs neutrality a Cl- ion moves into the RBC from the plasma.
163
Describe the process of getting CO2 from the blood to the lungs?
1. There is a lower PCO2 in the alveoli than in the blood which results in HCO3- moving back into the RBC and Cl- moving back into the plasma. HCO3- combines with H+ to give H2CO3 and then further converting into CO2 and H2O, and HbCO2 dissociates
2. This CO2 then enters the alveoli and is all exhaled
164
CO2 as a function of PCO2 curve
-The relationship is almost linear
-As CO2 content increases so does PCO2
165
What is the Haldane Effect?
The idea that in blood that has low O2 (venous blood) you can transport more CO2
166
Why does the Haldane Effect stand?
-In tissue capillaries(low PO2), free Hb can combine with H+ ions , this occurs because reuced Hb is less acidic than HbO2, acts as a buffer.
-By binding to H+ in the tissue capillaries this helps with blood loading of CO2, by pussing equation 1 and 2 forward since were taking more H+ ions (Le Chatelier's Principle)
Pushing these equations :
CO2 + H2O = H2CO3
H2CO3 = H+ + HCO3-
167
Describe transportation of CO2 in blood that is saturated 75% by HbO2 vs 97.5% saturated by HbO2?
When Hb is 75% saturated by O2 it transports about 51.8 % CO2
When Hb is 97.5% saturated by O2 it transports 49.8% CO2
168
What happens to CO2 when we hypoventilate?
Since the relationship between CO2 and PCO2 is almost linear this means that if we hypoventilate and PCO2 rises,then aterial, capillary tissue and venous CO2 will also rise. CO2 content will accumulate not only in the lungs but everywhere in the body.
169
What happens to PCO2 if you double alveolar ventilation?
If you double alveolar ventilation you will half alveolar PCO2
170
3 Possible causes of Respiratory Failure
1. Problem with the gas exchaning capabilities of the lungs (ex. edema)
2. Problem with the nueral control of ventilation
3. Problem with the Neuromuscular breathing apparatus(Ex. muscular dystrophy, innervation problems)
171
What is Arterial Hypoxia(Hypoxemia)?
Deficient blood oxygenation (low PaO2 and low % Hb saturation)
172
How does low PO2 cause hypoxemia?
Air is not rich in oxygen causing a low PaO2
Ex. high altitudes
173
How does hypoventilation cause hypoxemia?
Alveolar ventilation is reduced compared to metabolic CO2 production and O2 needs. This causes PaO2 to decrease and PaCO2 to increase
-Occurs due to diseases affecting the CNS, neuromuscular diseases, barbiturates
174
How does ventilation/pefusion imbalance in the lungs cause hypoxemia?
Amount of fresh gas reaching an alveolar region per breath is too little for the blood flow through the capillaries of that region
Ex. Asthma(contraction of the SM )
175
How do shunts of blood across the lungs cause hypoxemia?
Venous blood bypasses the gas exchaning region of the lung and returns to systemic circualtion, deoxygenated
176
How does O2 diffusion impairement cause hypoxemia?
Thickening of the alveolar-capillary membrane or pulmonary adema results in slower diffusion time
177
T/F: breathing is under both voluntary and involuntary control?
True
178
How is gas exchange controlled?
The CNS controls gas exchange by integrating all the information coming from the periphery which in turn, gives an adequate depth and frequency of breathing
179
What are the two systems that control breathing and which one is responsible for involuntary/voluntary?
1. The cerebral hemispheres control voluntary breathing
2. The brainstem(pons and medulla) control involuntary breathing
180
What happens when you stop ventilation voluntarily(ie. hold your breath)?
Despite your efforts to prevent breathing eventually you will start breathing again. This occurs because arterial PCO2 has reached about 50 mmHg and arterial PO2 has reached about 70 mmHg, this is the point at which the voluntary control is overridden. The over-riding depends on the information from the receptor that sense CO2 and O2 levels in the arterial blood or cerebro-spinal fluid
181
Whay is the breaking point?
Point at which voluntary breathing control is overriden by involuntary control
PCO2: 50 mmHg
PO2: 70 mmHg
182
What are the three basic elements in the respiratory control system?
1. Sensors
2. Controllers
3. Effectors
183
What is the role of sensors in the respiratory control system?
Snesors gather info about lung volume (pulmonary receptors). There are also other sensors the sense CO2 and O2 content (chemoreceptors)
184
What is the role of controllers in the respiratory system?
Controllers recieve info from the sensors, in the pons and medulla via the afferent neural fibers. This peripheral information and inputs from the higher strucutres of the CNS are integrated
185
What is the role of effectors in the respiratory system ?
Neuronal impulses from the controllers are then generated and sent via the spinal motorneurons to the effects which are thhe respiratory muscles
186
What is the Medulla and what is foundWhat is found in the medulla and what does the medulla control?
-The medulla consists of pacemaker cells which are a type of neuron
-The respiratory neurons in the medulla generate the basic respiratory rhythmicity
187
What are the two groups of pacemaker neurons?
1. Ventral Respiratory group:generates the basic rhythm
2. Dorsal respiratory group: recieves several sensory inputs
-Both groups connect to each other
188
What is the role of the upper pons?
-Cells in the upper pons are responsible for turning off inspiration (without it you breathe deeply and slowly)
-Upper pons is also called the pneumotaxic centre
- This leads to smaller tidal volume and increased breathing frequency(makes it so that you are not constantly taking deep breaths)
189
How does cutting the upper pons off affecting breathing?
It causes breathing to become deep and slow
190
What is the role of the lower pons?
-Cells in the lower pons (apneustic centre) send excitatory impulses to the respiratory groups of the medulla and promote inspiration
191
What is the role of the Vagus Nerve, what happens when they are the only thing cut?
-Brings afferent information to the brain about the state of your lungs and ventilation
- slow deep breaths(no info from the periphery, the default is slow and deep breathing)
192
What happens when you cut both upper pons and vagus nerves?
-Apneuses
-Tonic inspiratory activity interrupted by short expirations
193
What happens if you remove the medulla, pon and the cerebral hemisphere(only left with spinal cord and below)?
-No more ventilation
-No more breathing
194
What happens when you only remove the cerebral hemisphere?
-Normal ventilation
-No involuntary control of breathing
195
What happens when you remove the upper pons and cerebralhemisphere?
-No control over lung volume
-Do have rhytmicity
-Slow deep breaths
196
What happens when you cut the vagi nerves?
-Rapid inspiration to total lung capacity, breath hold and then expiration and then right away deep inspiration again (tonic ispiratory activity)
197
Removal of both pons and the cerebral hemisphere?
-Left with only medulla and spinal cord = only have rhytmicity
- No control over lung volume
198
What is apneustic breathing?
Rapid inspiration to total lung capacity, breath hold and then expiration and then right away deep inspiration again
-Seen when vagus nerves are cut or when the upper pons is removed
199
What do chemoreceptors do?
-Detect PO2, PCO2 and pH in the arterial blood
-information from these is carried to the respiratory neurons in the medulla
200
Activity of respiratory neurons increases if...
PaO2 is < 60 mm Hg
PaCO2 is > 40 mmHg
201
Activity of respiratory neurons decreases if...
PaO2 > 100 mmHg
PaCO2 < 40 mmHg
202
Name the two types of chemoreceptors?
1. Central
2. Peripheral
203
Where are the central chemoreceptors located?
The ventral surface of the medulla
204
What do the central chemoreceptors do?
-Detect pH of the CSF surrounding them (PCO2 and pH of the CSF are influenced by those of the arterial blood)
-Give rise to the mainn drive to breathe under normal conditions
205
What happens when chemoreceptors sense a high PCO2?
The increase in PCO2 stimulates the chemoreceptors which causes minute ventilation to increase. The resulting hyperventilation will reduce PCO2 in the blood and thus the CSF
206
Hypercapnia
Elevated CO2 in the blood
207
Ventilatory response during hypercapnia?
As PCO2 increases, minute ventilation increases both the frequeucy of breaths and tidal volume increase
208
How does an increase in PCO2 cause a decrease in pH recognized by the central chemoreceptors?
Since the majority of CO2 is converted to bicarbonate in the blood :
CO2 + H2O = H2CO3
H2CO2 = H+ + HCO3-
This causes a decrease in arterial pH since H+ is one of the products of CO2 into HCO3-. Since H+ and HCO3- cannot cross the blood brain barrier into the CSF , the CO2 reduces the CSF pH. This decrease in pH stimulates the central chemoreceptors.
209
Where are the peripheral chemoreceptors located?
In the carotid bodies (bifurcation of the carotid artery (splittin))and in the aortic bodies(next to the ascending aorta))
210
What are the peripheral chemoreceptos sensitive to ?
Sensitive to changes in PO2, but are also stimulated by increased PCO2 and decreased pH
211
What are the carotid and aortic bodies made up of?
blood vessel structural supporting tissue, and numerous nerve endings of sensory neurons of the glossopharyngeal (carotid) and vagus nerves(aortic).
The afferent fibers of these receptors project to the dorsal group of the respiratory neurons in the medulla
212
How can we study hypoxia?
Have an individual breathe gas mixtures with decreased concentrations of O2
213
Minute ventilation in normocampia vs increased PCO2?
Normocampia: Alveolar PO2 can be reduced to 60 mmHg before appreciable changes in minute ventilation occur
At increased PCO2: a decrease in PO2 below 100 mmHg can already cause an increase in minute ventilation
214
What are the three types of mechanoreceptors in the lung(pulomnary vagal receptors)?
1. Pulmonary stretch receptors
2. Irritant receptors
3. Juxta-capillary or J receptors(C-fibres)
215
Afferent fibres from all of the pulmonary vagal receptors travel in which nerve?
The vagus nerve
216
Where are the pulmonary stretch receptors located and describe them ?
In the smooth muscles of the trachea down to the terminal bronchioles
-They are innervated by large myelinated fibres and they discharge in response to distention of the lung
217
What increases the activity of the pulmonary stretch receptors?
-As lung volume increases activity of these receptors increases during inspiration
-Their activity is sustained so long as the lung is distended
218
Main reflex effect of stimulating the pulmonary stretch receptors is
Hering-Breuer Inflation Reflex
219
What is the Hering-Breuer Inflation Reflex ?
A decrease in respiratory frequency due to a prolongation of expiratory time
- If you take a deep breath to total lung capacity you need more time to expire then if you took a tidal breath (you change the frequency of your breaths)
220
How does the Hering-Breuer Reflex change in adults vs children?
The reflex is weak in adults unless the tidal volume exceeds 1L (exercise) but noticeable in infants and animals
221
Where are irritant receptors located?
Between the airway epithelial cells in the trachea down to the respiratory bronchioles
222
What stimulates the irritant receptors?
Noxious gases, cigarette smoke, histamine, cold air and dust
223
Are irritant receptors innervated by myelinated fibers?
Yes
224
What does the stimulation of irritant receptors do?
Leads to bronchoconstriction and hypernea (increased depth of breathing)
-Important dueing bronchoconstriction triggered by histamine release during an allergic asthmatic attack
225
Where are the Juxta-Capillary receptors located?
In the alveolar walls close to the capillaries
226
Are Juxta-Capillary receptors innervated by myelinated fibres?
No they are innervated by non-myelinated fibres and have short lasting bursts of activity
227
What stimulates the Juxta-capillary receptors?
An increase in pulmonary ISF(occurs in pulmonary congestion and edema)
228
What does the stimulation of Juxta-Capillary Receptors do?
Causes rapid and shallow respiration, intense stimulation leads to apnea(breath holding), This is done as an attempt to improve oxygenation and ventilation
-Play a role in dyspnea(sensation of difficulty in breathing) associated with left heart failure and lung edema or congestion
229
How does minute ventilation and metabolic rate change during exercise?
Minute ventilation : increases linearly with metabolic rate up to about 50% to 65%(ventilatory deflection point)
(metabolic rate increasing prevents us from hyperventilation)
After these points minute ventilation will increase at a rate disproportionately greater than metabolic rate (causing hyperventilation)
230
What does endurance training due to the ventilatory deflection point?
Delays the ventilatory deflection point, you delay the increase in ventilation because we don't want to expend too much energy for nothing
231
Does PO2 change in arterial blood as you exercise?
No, it remains stable
232
How does PCO2 in arteral blood change during exercise?
PCO2 goes down as you increase O2 consumption during exercise
-This does not cause minute ventilation to increase since a drive to increase VE would be caused by a decrease in PCO2
233
How does pH change during exercise?
pH decreases during exercise due to lactic acid build up.
234
Why aren't peripheral chemoreceptors responsible for the increase in ventilation during exercise?
Peripheral chemoreceptors respond to changes in PO2 and decreased pH and increased PCO2. During exercise, pH increases and PCO2 decreases and PaO2 remains constant
235
Why aren't the central chemorecepotrs responsible for increasing minute ventilation during exercise?
During exercise, pH increases in the medullary ECF. This decreases the ventilatory responses not increases it.
236
Neural control of exercise?
Minute ventilation increases prior to exercise and at the end of exercise there is a rapid decrease in ventilation. This is throught to be controlled neurally since you know when you are going to start exercising and when you are going to stop
237
Humoral control of exercise ?
It is throught that during exercise ventilation is controlled by humoral control which leads to a gradual increase in minute ventilation
238
How do we evaluate the elastic properties of the respiratory system?
We measure the changes in the recoil pressure of each separate structure for a given change in volume
239
How do we measure lung volumes ?
Spirometry
240
How do we measure pressures?
Manometers referenced to atmospheric pressure
241
What is a Negative pressure vs a Positive pressure?
Negative Pressure: Indicates a pressure below atmospheric
Positive Pressure:
Indicates a pressure above atmospheric
242
What is recoil pressure give an example using the chest wall?
The pressure difference between the inside and outside of the structure
ex. Recoil pressure of the chest wall is the difference between the pressure in the pleural space and the pressure at the body surface(Pw = Ppl - Pbs)
243
What is transpulmonary pressure?
difference between the pressure in the lungs (alveoli) and the pressurre in the pleural space
Pl = Palv - Ppl (this is the recoil pressure of the lungs)
244
What is the body surface pressure?
Pbs = Patm
which is 0 mmHg
245
Explain how pleural space works when thinking about lungs in a jar?
Lungs in a jar that are open to the atmosphere have the same pressure as the atmosphere. If you decrease the pressure around the lungs in the jar the lungs will be pulled open.
246
How is pleural pressure measured?
1. Pleural pressure is equal to the pressure in the esophagus
2. To measure this we insert a ballon through the nose, mouth and into the esophagus the balloon is attached to a manometer to measure the pressure
247
What is the recoil pressure of the total respiratory system?
Difference between the alveolar pressure and the body surface pressure
Prs = Palv - Pbs
can also be written as Prs = Pl +Pw
248
How to measure the elastic properties of the lungs?
1. Tell a subject to breathe into total lung capacity and hold their breath
2. Measure the alveolar pressure which can be measured by finding the pressure in the mouth because when breath holding the mouth and alveoli pressures will equilibrate
3. Measure the pleural pressure by using the balloon in the esophagus.
4. Pl = Palv - Ppl
249
How do we characterize the elastic properties of the ribcage?
1. Find the pleural pressure with the esophageal balloon
2. Pw = Ppl - Pbs
3. Since Pbs = 0 we can say that Ppl = Pw
250
How to measure the total respiratory system pressure?
Just measure the alveolar pressure since Prs = Palv - Pbs
251
What is compliance?
Describes how easy/hard it is to inflate/distend the lungs, chest wall or total respiratory system
252
What is the equation for compliance?
C = change in value/change in pressure
253
How do we measure respiratory system compliance?
Determine the static pressure-volume relationship while lung volume is decreased step by step from TLC
254
Describe the pressure at various lung volumes(TLC, VCand RV)?
TLC: Deflection in water is 30 cm in pressure
At 50% vital capacity the deflection is 10 cm in pressure
At RV the water is a 2 cm in pressure
255
What does the slope of the pressure-volume curve represent?
Compliance
256
Why does the slope decrease as you reach TLC?
Compliance decreases as you reach TLC which means it becomes harder and harder to pull the lungs open
257
What is fibrosis?
Deposition of fibrotic tissues on the alveoli in the lungs causes the lung to become stiff(reducing compliance)
258
How does fibrosis affect the pressure volume curve?
Patients with fibrosis who under go the same pressure will have lower volume changes (lungs don't want to expand at all)
259
What is emphysema?
Destruction of the alveolar walls, alveoli are floppy and inflate easily
(increased compliance)
260
How does the pressure volume graph for thos with emphysema change?
People with emphysema will undergo the same pressure and yet their lungs will expand way more
261
Equation for compliance of the lungs?
Cl = change in volume / (Palv -Ppl)
262
Another name for compliance of the lungs and its equation?
Inverse elastance
Elastance = 1/compliance
263
T/F: The pressure needed to maintain a given volume of gas inside the lungs increases as the volume of the lungs increases
True at total lung capacity compliance is greater and thus more pressure is needed to maintain that volume in the lungs
264
The pressure reported when measuring the compliance of the lungs is always positive?
True, since we are measuring the compliance of the lungs the lungs must be inflated which only happens when the Palv is greater than Ppl
265
What causes the elastic recoil of the lungs?
1. The elasticity of the lung tissue
2. The liquid film lining the inside of the lungs creates surface tension that generates substantial force because the surface area of the film is very large
266
Compliance of the chest wall ?
Cw = Change in volume / (Ppl-Pbs)
267
Why is the pressure of the chest wall always negative below 60% vital capacity ?
Below 60% vital capacity the chest wall tends to want to spring out(negative pressure) because it is below its resting value
268
Why is the pressure of the chest wall always positive above 60 % vital capacity?
The ribcage tends to want to collapse above 60% vital capacity because it is beyond its resting value
269
What happens when the ribcage is a 60% vital capacity?
This is the ribcages resting volume here there is not pressure generated on the ribcage
270
What is the resting state of the lungs?
Collapsed
271
What is the FRC in regards to the volume-pressure relationship between the lungs and ribcage?
-Lungs want to collapse with a pressure of + 5 cm of H2O
-Ribcage wants to expand with a pressure of -5 cm H2O
These pressures are equal and opposite and result in a zero net pressure
This means Prs = 0 and the whole respiratory system is at rest
-Lungs are above their resting volume and the chest wall is below its
272
What happens to the lungs and ribcage during pneumothorax?
-Lungs collapse to their resting position
- Ribcage goes to 60% vital capacity
273
Describe the respiratory system at rest?
- Lungs are at FRC
-Ppl is negative due to the opposite forces acting on the lungs and chest wall
274
What occurs during inspiration?
Diaphragm contracts and the chest wall is pulled open, This creates a more negative Ppl that causes the expansion of the lungs. The inflation of the lungs decreases alveolar pressure because the alveoli are pulled open and causes air to flow into the lungs from the outside
275
What is the equation for flow?
Flow = (Palv - Patm)/R
R = resistance
276
Describe flow during inspiration vs expiration?
Inspiration: flow is negative since Palv is more negative than Patm
Expiration: flow is positive since Palv is more positive than Patm
277
Describe inspiration?
1. Pleural pressure is initially negative and when you inspire the ribcage expand which decreases the pleural pressure even more. When we decrease Ppl this pulls the alveoli open. This decompresses the air in the alveoli causing Palv to be lower than Patm. Since Palv is lower than Patm we have a negative gradient which causes air to flow from the atmosphere into the lungs. As inspiration proceeds, the lungs fill up with air and the pressure gradients and air flow gradually decrease Air flow stops at the end of inspiration because Palv is equal to atmospheric pressure.
278
Describe Expiration?
Since air has accumulated in the lungs during inspiration the pressure gradient has decreased and flow is almost 0. When max tidal volume is reached the respiratory muscles relax. The diaphragm relaxes, elastic recoil of the respiratory system compresses the gas in the lungs and Ppl goes back to its pre-inspiratory value. Since Ppl is not decreasing anymore we are no longer pulling on the alveoli which means they start to collapse. This causes the Palv to increase(positive) and now there is a positive pressure gradient from the alveoli to the atmosphere. This causes air to flow out of the lungs. As lung volume decreases, Ppl slowly returns to it higher negative. At the end of expiration, at FRC, air flow = 0 mL and Palv = 0 (equivalent to Patm) and Ppl is about -5 cmH2O
279
Describe Palv during inspiration?
Prior to inspiration: Palv is equal to Patm (0 mmHg)
When Ppl is decreased: We pull the alveoli open which decreases Palv
After inspiration: Lungs are full of air and Palv is greater than Patm
280
Does tidal volume increase as air flows into the lungs?
Yes
281
What affects the time course of changes in pleural pressure during inspiration and expiration?
Depends on contraction of the respiratory muscles and airway resistance
282
How would pleural pressure change during inspiration/expiration if we had no airways only alveoli?
If we only had alveoli there would be much less resistance which means during inspiration pleural pressure would not need to be so negative and during expiration it wouldn't need to be so positive
283
What is airway resistance?
Raw = (Palv-Pao)/Flow
-The resistance of the airways to gas flow ins the ratio of the pressure in the alveoli minus the pressure at the airway opening
-These two pressures must differ in order to have flow
284
T/F: Larger diameter airways have lower resistance and can carry more flow?
True
285
What happens when someone allergic to pollen comes into contact with it?
Their mast cells will bind to the pollen and secrete histamine. Histamine receptors on SM will be bound by the histamine and cause the SM to contract and constrict the airways by creating a smaller radius in the airways Air flow will thus decrease
286
What happens when someone inspires to TLC and exhales to RV?
Flow rises very rapidly during inspiration and then declines over the rest of expiration at a constant rate
287
Describe the descneding/ascending portion of the flow volume curve?
The descending portion of the flow volume curve is independent of effort
The ascending portion of the flow-volume curve depends on effort
288
Describe the flow-volume curve of someone who breathes in with less effort?
The ascending portion of the curve will not reach max flow but will descend along the same path as someone who did breathe using max effort
289
Describe Palv and Ppl pre inspiration?
Palv = 0 (same as atm and pressure in mouth(no flow))
Ppl = -5 cm H2O (lungs are at rest)
290
Describe Palv and Ppl during inspiration?
Palv is negative compared to the Patm to draw in air
Ppl is negative in order to pull the lungs open
291
Describe Palv and Ppl at the end of inspiration?
Palv: Equal to Patm no more flow of air
Ppl: Still negative
292
Describe Ppl and Palv during forced expiration?
Palv is positive so air flows into the air
Ppl can also be positive due to the compression of the lungs and chest wall when the muscles contract strongly
293
Pressure drop during force expiration?
As air moves out of the lungs, it encounters resistance in the airways which causes the pressure to drop from a high positive to a lower positive. The pressure decreases as you reach your mouth. As Palv increaases due to the resistance the Ppl still stays highly positive this causes smaller airways to close which limits how quickly you can exhale. This is why you always exhale at the same rate in forced expiration.
294
Normal TLC, Max flow and RV?
TLC: 7L
Max Flow: 9 l/min
RV: 2.5 L
295
How do restrictive diseases such as Fibrosis affect the flow-volume curve?
-Total lung capacity decreases (harder to expand lungs)
-RV decreases(lungs have lots of recoil)
-Max flow decreases
-Flow is greater due to large recoil
296
How do obstructive diseases such as emphysema affect the flow-volume curve?
-Total lung capacity increases
-RV increases
-Max flow decreases
-Flow rate is scooped out
297
Summary of events in inspiration?
1. Diaphragm and intercostal muscles contract
2. Thoracic cage expands
3. Intrapleural pressure becomes more negative(Pressure exerted within the pleural space)
4. Transpulmonary pressure increases(pressure that keeps the lung expanded, if = 0 the lung will collapse(Palv-Ppl))(pleural pressure should always be less than alveolar pressure)
5.Lungs expand
6.Alveolar pressure decreases below atmospheric pressure
7.Air flows into the alveoli
298
Summary of of expiration?
1. Diaphragm and external intercostal muscles stop contracting
2. Chest wall moves inwards
3. Intrapleural pressure goes back toward pre inspiratory value(-5)
4. Transpulmonary pressure goes back towards pre inspiratory value (0)
5. Lung recoils towards pre inspiratory volume
6. Air in lungs is compressed
7. Alveolar pressure becomes greater than atmospheric pressure
8. Air flows out of the lungs
299
How does exercise impact tidal volume and breathing frequency?
Increase both tidal volume and breathing frequency proportionally
300
During hard exercise what happens to tifal volume?
During hard exercise tidal volume plateaus and therefore high ventilatory rates during hard exercise are caused by an increase in breathing frequency. This is due to the idea that compliance causes it to be harder to expand already full lungs.
301
What does increased breathing frequency do?
Decreasing the time of inspiration and expiration. However during progressive exercise expiratory times all more than inspiratory times
302
T/F: At rest, time of inspiration is less than expiration?
True
303
T/F: At heavy exercise, time of inspiration and expiration are roughly the same?
True
304
T/F: flow of expiration during exercise increases?
True
305
How much can minute ventilation increase during exercise?
-By 35 folds
-From 5L/min to 190L/min
306
How much can cardiac output increase during exercise?
-5-6 folds
-From 5L/min to 25-30L/min
307
What is the ratio of minute ventilation to blood flow at rest?
Approximately 1
308
Why do we believe blood flow limits aerobic performance?
Since Ve can increase more than Q during exercise there is an increase in VE/Q. The increase in this ratio is one reason why ventilation is not believed to limit aerobic performance.
309
Additonal reason ventilation does not limit aerobic performance?
Alveolar surface area is 50 m squared
Average blood volume is 5L. Only 4% of this 5L is in the pulmonary system at any one time during maximal exercise
Therefore there is a large capacity for gas exchange but blood is limited.
