Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

630: Medical Physiology > Respiratory Physiology (Part 2) > Flashcards

Respiratory Physiology (Part 2) Flashcards

(98 cards)

Start Studying
1
Q

What are the 3 muscles of inspiration?

A
  • diaphragm
  • external intercostal
  • accessory muscles such as the sternocleidomastoid

*diaphragm is the most important

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What drives expiration?

A

It is a passive process driven by the reverse pressure gradient between the lungs and atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What muscles drive forced expiration?

A
  • abdominal muscles

- internal intercostal muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The compliance of what 2 structures are of primary interest in the respiratory system?

A

the lungs and chest wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does compliance describe?

A

The change in lung volume for a given change in pressure, which can be defined as the system’s distensibility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The compliance of the lungs and chest wall are inversely correlated with what?

A

their elastic properties, or elastance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The greater the amount of elastic tissue, the greater the elastic force, but the _____ the compliance

A

lower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Pressures equal to atmospheric pressure are ____.

A

zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Pressures higher than atmospheric pressure are ____.

A

positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Pressures lower than atmospheric pressure are ____.

A

negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does the slope of the pressure-volume loop equal?

A

the compliance of the lung

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

As pressure outside of the lungs becomes more negative, the lung ____ and its volume _____.

A

inflates

increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the negative pressure outside of the lungs that causes them to inflate called?

A

expanding pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The lungs fill with air along the _____ limb of the pressure-volume loop

A

insipration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Once the lungs are expanded maximally, the pressure outside of the lungs is made gradually ____ negative, causing the lung volume to decrease along the _____ limb of the pressure-volume loop

A

less

expiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the phenomenon of hysteresis

A

The slopes of the inspiration and expiration limbs are different

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which limb on the pressure-volume loop is greater for a given outside pressure? Why?

A

the expiration limb, because compliance is higher during expiration than during inspiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Compliance is measured on the _____ limb

A

expiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why are the inspiration and expiration limbs of the lung compliance curve different?

A

Because of the surface tension at the liquid-air interface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

As surfactant density increases, surface tension decreases which causes a(n) _____ in compliance

A

increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

As surfactant density decreases, surface tension increases which causes a(n) _____ in compliance

A

decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is created when air is introduced into the intrapleural space?

A

a pneumothorax

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Normally the intrapleural space has a _____ pressure

A

negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What creates this negative intrapleural pressure?

A

2 opposing elastic forces pulling on the intrapleural space: the lungs tend to collapse and the chest wall which tends to spring out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
When a pneumothorax is introduced, the normal negative intrapleural pressure becomes ____.
zero
26
What are the 2 consequences of a pneumothorax?
1) the lungs collapse | 2) the chest wall springs out
27
What is the problem keeping small alveoli open?
The attractive forces between adjacent molecules of liquid creates surface tension. As the molecules of liquid are drawn together, the surface area becomes as small as possible, forming a sphere. The surface tension generates a pressure that tends to collapse the sphere
28
What does the Law of Laplace state?
The pressure tending to collapse an alveolus is directly proportional to the surface tension generated by the molecules of liquid lining the alveolus and inversely proportional to alveolar radius
29
A large alveolus will have a ___ collapsing pressure, and therefore will require ____ pressure to keep it open
low minimal
30
A small alveolus will have a ___ collapsing pressure, and therefore will require ____ pressure to keep it open
high more
31
So, why are alveoli so small if they have a higher tendency to collapse?
They need to be as small as possible to increase their total surface area for gas exchange
32
How do small alveoli remain open under high collapsing pressures?
surfactant
33
What is surfactant?
a mixture of phospholipids that line the alveoli
34
How does surfactant reduce the collapsing pressure for a given radius?
By reducing surface tension
35
What is another advantage surfactant provides for pulmonary function?
It increases lung compliance, which reduces the work of expanding the lungs during inspiration
36
How do you calculate airflow?
Q = ΔP/R ``` Q = Airflow ΔP = Pressure gradient R = Airway resistance ```
37
What is the driving force for airflow?
pressure difference
38
What is the site of highest airway resistance?
the medium-sized bronchi
39
What innervates bronchial smooth muscle?
parasympathetic cholinergic nerve fibers
40
Parasympathetic stimulation of bronchial smooth muscle produces _____.
constriction
41
Sympathetic stimulation of bronchial smooth muscle produces _____.
relaxation
42
High lung volumes ____ airway resistance, whereas low lung volumes ____ airway resistance.
decreases increases
43
What are the 3 phases of the breathing cycle?
- rest - inspiration - expiration
44
What does alveolar pressure equal at rest?
zero (atmospheric pressure)
45
What does intrapleural pressure equal at rest?
It is negative at approximately -5
46
What happens to alveolar pressure during inspiration?
It becomes negative (lower than atmospheric pressure)
47
What happens to intrapleural pressure during inspiration?
it becomes even more negative than at rest (approximately -8)
48
What happens to alveolar pressure during expiration?
It becomes positive (higher than atmospheric pressure)
49
What happens to intrapleural pressure during expiration?
It begins to return to the value at rest (-5) so it becomes more positive
50
What does gas exchange in the respiratory system refer to?
Diffusion of O2 and CO2 in the lungs and in the peripheral tissues
51
The transfer of gases across cell membranes or capillary walls occurs by way of what?
simple diffusion
52
Net diffusion of a gas is dependent on what?
the concentration gradient
53
What does gas pressure in a mixture of gases equal?
Sum of the “Partial Pressures” of Individual Gases
54
What are the 2 factors that determine the partial pressure of a gas dissolved in a fluid?
- Concentration | - Solubility coefficient of the gas
55
Partial pressure of a gas dissolved in fluid is _____ related to concentration of the dissolved gas and _____ related to the solubility coefficient
directly inversely
56
For a given concentration, the less soluble the gas, the _____ the partial pressure
greater
57
The total gas concentration in solution is the sum of what 3 things?
- Dissolved gas - Bound gas - Chemically modified gas
58
In solution, only _____ gas molecules contribute to the partial pressure
dissolved
59
Where does gas exchange occur?
Between alveolar gas and the pulmonary capillary
60
__ diffuses from alveolar gas into pulmonary capillary blood, and __ diffuse from pulmonary capillary blood into alveolar gas.
O2 CO2
61
What is the PO2 and PCO2 in dry inspired air?
PO2 is approximately 160 mmHg PCO2 is zero, because there is no CO2 in dry inspired air
62
In humidified air the air is fully saturated with what?
water vapor
63
What happens to PO2 when air is humidified in the trachea?
It is reduced, because O2 is "diluted" by water vapor and equals approximately 150 mmHg
64
What is the PCO2 in humidified air in the trachea?
PCO2 is zero, because there is no CO2 in dry inspired air
65
What is the PO2 and PCO2 in alveolar air?
PO2 is 100 mmHg PCO2 is 40 mmHg
66
Why does PO2 decrease and PCO2 decrease in the alveoli?
Because O2 leaves alveolar air and is added to pulmonary capillary blood, and CO2 leaves pulmonary capillary blood and enters alveolar air
67
Blood entering the pulmonary capillaries is essentially ___ ____ blood
mixed venous blood
68
What does PO2 and PCO2 equal in the mixed venous blood of the pulmonary capillaries? Explain the reasoning behind each
PO2 is 40 mmHg because the tissues have taken up and consumed O2 PCO2 is 46 mmHg because the tissues have produced CO2 and added it to venous blood
69
The blood that leaves the pulmonary capillaries will become ___ ____ blood
systemic arterial blood
70
What is the PO2 and PCO2 in system arterial blood?
PO2 is 100 mmHg PCO2 is 40 mmHg
71
What are the 2 forms in which O2 is carried in blood?
- dissolved | - bound to hemoglobin
72
Dissolved O2 accounts for approximately _% of the total O2 content of blood
2%
73
Dissolved O2 produces what?
partial pressure
74
Is the amount of dissolved O2 sufficient enough to meet the demands of the tissues?
No
75
O2 bound to hemoglobin accounts for approximately _% of the total O2 content of blood
98
76
Describe the structure of hemoglobin
It is a globular protein that consists of 4 subunits, in which each contains a heme moiety made up of an iron-binding porphyrin and a polypetide chain, which is designated as either alpha or beta
77
What is adult hemoglobin called?
alpha2beta2
78
How many molecules of O2 can bind to a single hemoglobin molecule?
4, one per subunit
79
In order for hemoglobin to bind O2 it must be in what state?
the ferrous (Fe2+) state
80
What are 3 variants of the hemoglobin molecule?
- Methemoglobin - Fetal hemoglobin - Hemoglobin S
81
When is hemoglobin considered methemoglobin?
When the heme moieties is in the ferric state (Fe3+)
82
Does methemoglobin bind oxygen?
No, because it is not in the ferrous state, it is in the ferric state
83
Describe the fetal hemoglobin variant
The 2 beta chanins are replaced by gamma chains, giving it the designation of alpha2gamma2
84
What is the physiologic consequence of the fetal hemoglobin modification?
It has a higher affinity for O2
85
Hemoglobin S is an abnormal variant of hemoglobin that causes what disease?
sickle cell disease
86
Which subunits are abnormal in hemoglobin S?
the beta subunits
87
The deformation of hemoglobin S in its deoxygenated form can result in what?
occlusion of small blood vessels
88
The O2 affinity of hemoglobin S is ___ than the O2 affinity of hemoglobin A.
less
89
What is O2-binding capacity?
The maximum amount of O2 that can be bound to hemoglobin per volume of blood, assuming hemoglobin is 100% saturated
90
What is O2 content?
The actual amount of O2 per volume of blood
91
How is O2 content calculated?
O2 content = O2 binding capacity x % Saturation + Dissolved O2
92
What determines O2 delivery to tissues?
Blood flow and the O2 content of blood
93
What are the 2 ways O2 delivery to tissues can be calculated?
= Cardiac output x O2 content of blood = Cardiac output x (Dissolved O2 + O2 bound to hemoglobin)
94
If 4 molecules of O2 are bound to heme groups than saturation is __%
100%
95
If 3 molecules of O2 are bound to heme groups than saturation is __%
75%
96
If 2 molecules of O2 are bound to heme groups than saturation is __%
50
97
If 1 molecules of O2 are bound to heme groups than saturation is __%
25
98
Percent saturation of hemoglobin is a function of what?
PO2

630: Medical Physiology (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions