Viva Respiratory Flashcards
1
Q
Normal respiratory rate
A
12-16 per minute
2
Q
What are the types of respiration
A
• External respiration that involves exchange of respiratory gases, i.e. oxygen and carbon dioxide between the alveoli of the lungs and blood • Internal respiration that involves exchange of respiratory gases between blood and tissues.
3
Q
Define respiratory unit
Name the structures of respiratory
unit.
A
Respiratory unit is the terminal portion of respiratory tract where the exchange of gases occurs • Respiratory bronchiole • Alveolar ducts • Antrum • Alveolar sacs • Alveoli
4
Q
List the non-respiratory functions of
respiratory tract.
A
• Olfaction • Vocalization • Prevention of dust particles • Defense mechanism • Maintenance of water balance • Regulation of body temperature • Regulation of acid base balance • Anticoagulant function • Secretion of angiotensin converting enzyme (ACE) • Synthesis of hormonal substances.
5
Q
What are the characteristic features
of pulmonary circulation?
A
• The wall of pulmonary blood vessels is thin
• These blood vessels are more elastic
• Smooth muscle coat is not well developed
in these blood vessels
• True arterioles have less smooth muscle
fibers
• Pulmonary capillaries are larger than
systemic capillaries.
6
Q
What is the normal pulmonary blood
pressure?
A
Systolic pressure : 25 mm Hg
Diastolic pressure : 10 mm Hg
Mean arterial pressure : 15 mm Hg
Capillary pressure : 7 mm Hg
7
Q
Enumerate the factors regulating
pulmonary circulation.
A
- Cardiac output
- Pulmonary vascular resistance
- Nervous factors
- Chemical factors.
8
Q
Name the primary inspiratory and
primary expiratory muscles with the nerve
supply
A
Primary inspiratory muscles: • Diaphragm—innervated by phrenic nerve • External intercostal muscles—innervated by intercostal nerves. Primary expiratory muscles: Internal intercostal muscles—innervated by intercostal nerves.
9
Q
Name the accessory respiratory
muscles
A
The accessory inspiratory muscles are sternomastoid, scalene, anterior serrati, elevators of scapulae and pectorals. The accessory expiratory muscles are abdominal muscles.
10
Q
What is the role of lungs in defense
mechanism?
A
• Lung’s own defense: Secretion of immune
factors – defensins and cathelicidins
• Leukocytes: Neutrophils and lymphocytes
kill the bacteria and virus
• Macrophages: Engulf dust particles and
pathogens, act as antigen presenting cells;
secrete interleukins, tumor necrosis
factors and chemokines
• Mast cell: Produces hypersensitivity
reactions
• Natural killer cell: First line of defense
against virus
• Dendritic cells: Function as antigen
presenting cells.
11
Q
What is pump handle movement?
What is its significance?
A
During inspiration the upper costal series
(second to sixth pair of ribs) are elevated
and the sternum moves upward and
forward. This type of movement of ribs and
sternum is called pump handle movement.
Significance: It increases the anteroposterior
diameter of thoracic cage during inspiration.
12
Q
What are the movements of thoracic
cage during inspiration?
A
Thoracic cage enlarges during inspiration
and its size increases in all diameters.
Increase in anteroposterior diameter is due
to the elevation of upper costal series and
the upward and forward movement of
sternum. Increase in transverse diameter is
due to the elevation of lower costal series.
The increase in vertical diameter is due to
descent of diaphragm.
13
Q
What is the bucket handle movement
A
During inspiration the central portions
(arches) of upper costal series (second to
sixth pair of ribs) and lower costal series
(seventh to tenth pair of ribs) swing outward
and upward. This is called bucket handle
movement.
Significance: It increases the transverse
diameter of thoracic cage during inspiration
14
Q
What is pump handle movement?
What is its significance?
A
During inspiration the upper costal series
(second to sixth pair of ribs) are elevated
and the sternum moves upward and
forward. This type of movement of ribs and
sternum is called pump handle movement.
Significance: It increases the anteroposterior
diameter of thoracic cage during inspiration
15
Q
What is the significance of contraction
of diaphragm during inspiration?
A
When the diaphragm contracts, it is
flattened. This increases the vertical diameter
of thoracic cage during inspiration.
16
Q
Daltons law
A
It states that total pressure exerted by a
mixture of gases is equal to the sum of the
partial pressures of all the gases present
within it.
17
Q
Henry’s law
A
It states that if temperature is kept constant,
amount of gas dissolved in any solution is
directly proportional to the partial pressure
of that gas.
18
Q
Give the normal value of intrapulmonary or intra-alveolar pressure.
A
760
19
Q
Why intra-alveolar pressure is equal
to that of atmospheric pressure? How
is it affected during inspiration and
expiration?
A
It is equal to the atmospheric pressure as during quiet breathing, at the end of expiration and at the end of inspiration, no air is going in and out of the lungs. During inspiration it decreases 3 mm Hg below its normal value, i.e. 757 mm Hg and during expiration it increases 3 mm Hg above its normal value, i.e. 763 mm Hg.
20
Q
What is Valsalva maneuver and
Muller’s maneuver?
A
Forced expiration against a closed glottis
may produce positive intrapulmonary
pressure of > 100 mm Hg above the atmospheric value. This voluntary act is known as
Valsalva maneuver.
Forced inspiration against closed glottis
can reduce the intrapulmonary pressure
to < 80 mm Hg below the atmospheric
value. This voluntary act to reduce the intrapulmonary pressure is known as Muller’s
maneuver.
21
Q
What is collapsing tendency of lungs?
What are the factors causing and preventing
collapsing tendency of lungs?
A
The constant threat of compression of the
lungs is called collapsing tendency of lungs.
Causing • Elastic property of lung tissues that induces the recoiling tendency of lungs • Surface tension exerted by the alveolar fluid. Preventing • Intrapleural pressure that overcomes elastic recoiling tendency of lungs • Surfactant that overcomes surface tension.
22
Q
What is surfactant? Name the cells
secreting surfactant.
A
Surfactant is the lipoprotein substance that
reduces the surface tension induced by the
fluid lining in the alveoli.
It is secreted by type II alveolar epithelial
cells of lungs and Clara cells situated in
bronchioles
Surfactant prevents collapsing tendency of
lungs by reducing the surface tension in the
alveoli.
23
Q
What is respiratory distress
syndrome or hyaline membrane disease?
A
It is the condition in infants with collapse of
lungs due to the absence of surfactant. In
adults it is called adult respiratory distress
syndrome (ARDS)
24
Q
Define and give normal values of
intrapleural or intrathoracic pressure.
A
The intrapleural or intrathoracic pressure is
the pressure existing in the pleural cavity.
It is always negative. During inspiration it is
– 6 mmHg and during expiration it is –
2 mmHg.
25
What is the cause for negative intrapleural pressure?
The intrapleural pressure is negative
because of constant pumping of fluid
(secreted by visceral layer of pleura) from
the intrapleural space into lymphatic vessels
26
What is the significance of intrapleural pressure?
The intrapleural pressure prevents collapsing tendency of lungs. It is also responsible
for respiratory pump that increases venous
return.
27
How is intrapleural pressure
| measured?
Intraesophageal balloon
28
Define and give normal values of
| intraalveolar or intrapulmonary pressure
```
The intraalveolar or intrapulmonary
pressure is the pressure existing in the
alveoli of lungs.
During inspiration it is – 4 mm Hg
During expiration it is + 4 mm Hg
```
29
What is the significance of intraalveolar pressure?
```
alveolar pressure?
• It causes flow of air into alveoli during
inspiration and out of alveoli during
expiration
• It helps in exchange of gases between
alveoli and blood.
```
30
What is transpulmonary pressure?
Transpulmonary pressure is the difference
between the intraalveolar pressure and
intrapleural pressure
31
What is compliance?
The expansibility of lungs and thorax is
known as compliance. It is defined as change
in volume per unit change in pressure
32
Define compliance in relation to
intraalveolar pressure and give normal
value.
```
In relation to intraalveolar pressure,
compliance is defined as the volume increase
in lungs per unit increase in intraalveolar
pressure.
Compliance of lungs and thorax = 130 ml/
cm H
2O. Compliance of lungs alone = 220
ml/cm H
2O.
```
33
Define compliance in relation to
intrapleural pressure and give normal
value.
In relation to intrapleural pressure, compliance is defined as the volume increase in
lungs per unit decrease in the intrapleural
pressure.
Compliance of lungs and thorax = 100 ml/
cm H2O. Compliance of lungs alone = 200
ml/cm H
2O.
34
# Define work of breathing.
What are the types of resistance for
which energy is utilized during work of
breathing?
The work done by respiratory muscles
during breathing to overcome the resistance
in thorax and respiratory tract is known as
work of breathing.
• Airway resistance – that is overcome by
airway resistance work.
• Elastic resistance of lungs and thorax –
that is overcome by compliance work.
• Nonelastic viscous resistance – that is
overcome by tissue resistance work.
35
Define and give normal values of
| lung volumes.
• Tidal volume: The volume of air breathed
in and out of lungs in a single normal quiet
breathing.
Normal value: 500 ml.
• Inspiratory reserve volume: The additional
amount of air that can be inspired
forcefully beyond normal tidal volume.
Normal value: 3,300 ml.
•
Expiratory reserve volume: The additional
amount of air that can be expired
forcefully after normal expiration.
Normal value: 1,000 ml.
• Residual volume: The amount of air
remaining in the lungs even after forced
expiration.
Normal value: 1,200 ml.
Figure 16.1 illustrates spirogram showing
lung volumes and capacities
36
What is lung capacity? Define and
| give normal values of lung capacities.
```
Two or more lung volumes together are
called lung capacity (Fig. 16.1).
Lung capacities:
• Inspiratory capacity: The maximum volume
of air that can be inspired from the end
expiratory position. It includes tidal
volume and inspiratory reserve volume.
Normal value: 3,800 ml.
• Vital capacity: The maximum volume of
air that can be expelled out forcefully after
a maximal (deep) inspiration. It includes
inspiratory volume, tidal volume and
expiratory reserve volume.
Normal value: 4,800 ml.
• Functional residual capacity: The volume of
air remaining in the lungs after normal
expiration (after tidal expiration).
It includes expiratory reserve volume and
residual volume.
Normal value: 2,200 ml.
• Total lung capacity: The amount of air
present in the lungs after a maximal
(deep) inspiration. It includes all the four
lung volumes i.e., inspiratory reserve
volume, tidal volume, expiratory reserve
volume and residual volume.
Normal value: 6,000 ml.
```
37
Why the 'Wheeze' sound is heard
during expiration but not in inspiration of
an asthma patient?
During inspiration the intrapleural and
mediastinal negativity rises and as a result
the bronchial diameter increases. Reverse
occurs during expiration. Therefore
resistance to airflow is normally low in
inspiration and high in expiration. This is
why in bronchial asthma inspiration may
not be difficult but expiration becomes
difficult. This explains why the "Wheeze" in
bronchial asthma is heard during expiration
but not in inspiration.
38
What is the significance of residual
| volume?
• It helps in the exchange of gases in
between breathing and during expiration
• It maintains the contour of the lungs.
39
What are the instruments used to
| measure lung volumes and lung capacities?
* Spirometer
| * Respirometer.
40
Name the lung volumes and capac
ities,
which can not be measured by spirometer
* Residual volume
* Functional residual capacity
* Total lung capacity.
41
How are residual volume and functional residual capacity measured?
* Helium dilution technique
| * Nitrogen washout method
42
Define vital capacity. What is its
| importance?
```
It is the maximum volume of air which can
be expired by forceful effort after a maximal
inspiration.
It provides useful information about the
strength of respiratory muscles and also
provides useful information about other
aspects of pulmonary function through
FEV1
```
43
n which posture VC is highest and
| why?
```
In standing posture it is the highest as in
standing position diaphragm descends
down thereby increasing intrathoracic
volume. This increases intra-alveolar
volume during inspiration
```
44
8 In whom the vital capacity is more?
• Heavily built persons
• Athletes
• People playing musical wind instruments
like bugle
45
Name the pathological conditions
| when vital capacity is reduced.
```
• Asthma
• Emphysema
• Weakness or paralysis of respiratory
muscle
• Congestion of lungs
• Pneumonia
• Pneumothorax
• Hemothorax
• Pyothorax
• Hydrothorax
• Pulmonary edema
• Pulmonary tuberculosis.
```
46
Why does VC decrease during
| pregnancy?
During pregnancy diaphragm is pushed up
by the growing fetus resulting in decrease
of intrathoracic volume and thereby
decrease of capacity to inspire air and there
by VC is decreased.
47
What is respiratory minute volume
| (RMV)? Give its normal value
Respiratory minute volume is the amount
of air that is breathed in and out of lungs
during each minute. It is the product of tidal
volume and respiratory rate.
Normal value: 6,000 ml (500 ml × 12).
48
What is maximum breathing capacity
(MBC) or maximum ventilation volume
(MVV)? What is its normal value?
```
It is the maximum amount of air that can be
breathed in and out of lungs by forceful
respiration (hyperventilation).
Normal value:
In healthy – 150 to 170 liters/minute
adult male
In females – 80 to 100 liters/minute
```
49
What is forced expiratory volume
| (FEV) or timed vital capacity?
The amount of air that can be expired
forcefully (after deep inspiration) in a given
unit of time is called forced expiratory
volume (FEV) or timed vital capacity
50
Fev1
The amount of air that can be expired
forcefully after deep inspiration in the first
second is called FEV1 (1 stands for ‘first
second’).
51
What is the significance of determining FEV?
Vital capacity may be almost normal in
some of the respiratory diseases. However
determination of FEV has greater diagnostic
value, as it is decreased significantly in
some respiratory disorders, particularly in
obstructive diseases like asthma and
emphysema.
52
Define and give normal value of
| peak expiratory flow rate (PEFR).
The maximum rate at which air can be
expired after deep inspiration is known as
peak expiratory flow rate (PEFR).
Normal value: About 400 liters/minute.
53
What is the significance of measuring PEFR?
Measurement of PEFR is useful in assessing
the respiratory diseases, especially to
differentiate the obstructive and restrictive
diseases. It is about 200 liters/ minute in
restrictive diseases and it is only 100 liters/
minute in obstructive diseases. It is valuable
when measured serially to establish the
pattern of airway obstructive disease and
to monitor its responses in treatments,
especially asthma.
54
What is pulmonary ventilation? Give
| its normal value.
Pulmonary ventilation is the cyclic process
by which fresh air enters the lungs and an
equal volume of air is expired. It is defined
as the amount of air breathed in and out of
lungs in one minute. It is the product of tidal
volume and respiratory rate. It is otherwise
known as respiratory minute volume.
Normal value: 6,000 ml/minute.
55
What is alveolar ventilation? Give
| its normal value.
Alveolar ventilation is the amount of air
utilized for gaseous exchange every minute.
Alveolar = (Tidal volume – Dead space
ventilation
volume) × Respiratory rate.
Normal value: 4,200 ml.
56
What is dead space? Give normal
| value.
```
The part of respiratory tract where the
gaseous exchange does not occur is known
as dead space. The air present in the dead
space is called dead space air.
Normal value: 150 ml.
```
57
What are the types of dead space?
• Anatomical dead space, which includes the
volume of respiratory tract from nose up
to terminal bronchiole.
• Physiological dead space which includes
anatomical dead space and two additional
volumes:
– The volume of air in those alveoli, which
are not functioning
– The amount of air in those alveoli, which
do not receive adequate blood flow
58
Why the physiological dead space is
equal to anatomical dead space in normal
conditions?
Because all the alveoli of both lungs
are functioning and all the alveoli receive
adequate blood supply in normal conditions
59
How is dead space measured
By single breath nitrogen washout method.
60
What is ventilation perfusion ratio?
| Give its normal value
```
It is the ratio of alveolar ventilation (VA)
and the amount of blood (Q) flowing
through the lungs.
Ventilation perfusion ratio = VA/Q =
4,200/5,000.
Normal value: About 0.84.
```
61
What are the differences between
| inspired air and alveolar air?
• Oxygen content is more in inspired air
than in alveolar air
• Carbon dioxide is less in inspired air than
in alveolar air
• Inspired air is dry whereas alveolar air is
humid.
62
What is respiratory membrane
The alveolar membrane and the capillary
membrane in the lungs through which
diffusion of gases takes place are together
called respiratory membrane
63
What is diffusibg capacity
Diffusing capacity is the volume of gas that
diffuses through respiratory membrane
each minute for a pressure gradient of 1
mmHg
64
Mention the diffusing capacity for
| oxygen and carbon dioxide.
```
Diffusing capacity for oxygen is 21 ml/
minute/mmHg and for carbon dioxide it is
400 ml/minute/mmHg. Thus, the diffusing
capacity for carbon dioxide is about 20 times
more than that of oxygen.
```
65
What are the factors affecting the
| diffusing capacity?
```
Diffusing capacity is directly proportional to
• Pressure gradient of gases between
alveoli and blood in pulmonary capillary
• Solubility of gas in fluid medium
• Total surface areas of respiratory
membrane.
Diffusing capacity is inversely proportional
to:
• Molecular weight of the gas
• Thickness of respiratory membrane.
```
66
Hooks law in relation to lung
Length is directly proportional to force
| within a physiological limit.
67
Define lung compliance. What is
| 'hysteresis' curve of lung compliance?
The change of lung volume per unit
change in airway pressure is called as lung
compliance.
In compliance curve, at identical intrapleural pressure, the volume of lung is less
in inspiratory phase than in the expiratory
phase. This different pressure volume
relationship curve during inspiration and
expiration is known as 'hysteresis 'curve as
68
What is specific compliance? What is
| its advantage to use?
The compliance when expressed as a
function of FRC is known as specific
compliance.
In individuals with one lung only, lung
compliance is approximately half of the
normal even if the normal distensibility of
normal lung is present. Similarly in children
compliance is lower than normal though the
distensibility of lung remains normal. This
fallacy is removed with specific compliance
since FRC is proportionately reduced and
specific compliance remains essentially
constant.
69
What is the oxygen content and
partial pressure of oxygen (PO2) in the
blood?
```
Arterial blood:
Oxygen content = 19 ml%
PO2
= 95 mm Hg
Venous blood:
Oxygen content = 14 ml%
PO2
= 40 mm Hg
```
70
What is the carbon dioxide content
and partial pressure of carbon dioxide
(PCO2) in the blood?
```
Arterial blood : Carbon dioxide content
= 48 ml%
PCO2
= 40 mmHg
Venous blood :
Carbon dioxide content
= 52 ml%
PCO2
= 45 mmHg.
```
71
Coefficient of utilization
The percent of blood that gives up its O
2 as
it passes through the tissue capillaries is
called as the coefficient of utilization. At rest
it is about 25 percent and during heavy
exercise it increases up to 75 percent.
72
Which form is co2 transported in the blood
```
Mainly in 3 forms:
• In dissolved form in plasma and RBC -
0.3 ml%
• As bicarbonate form of Na+ and K+
- 3 ml%
• As carbamino compound form - 0.7 ml%
```
73
What is the CO2 content and partial
pressure of CO2 in arterial and venous
blood?
CO2 content
PCO2
Arterial blood-48 ml% 40 mm Hg
Venous blood-52 ml% 46 mm Hg
74
In which form the venous CO2 is
| mostly found?
Bicarbonate form
75
What do you mean by maximum
| venous point and arterial point?
```
venous point and arterial point?
In deoxygenated blood with maximum
PCO2, 60-67 mm Hg, CO2 content is 65 ml%
called as the maximum venous point as
represented by Figure 16.4. In oxygenated
blood at PCO2 40 mm Hg, CO2 content is
48 ml% called as the arterial point
```
76
What are the effects of CO2 addition
| to blood?
It causes increase in plasma bicarbonate ion,
decrease in plasma chlorides and increase
in RBC chlorides.
77
What do you mean by physiological
| CO2 dissociation curve?
If we join maximum ‘venous point’ and
‘arterial point’ which corresponds to
extreme CO2 level in the body respectively,
it will roughly reflect changes between
PCO2 and CO2 content in the blood and
called the physiological CO2 dissociation as
represented by curve C of Figure 16.4.
78
What are the factors affecting CO2
| dissociation curve?
These are:
• Increase in body temperature shifts the
curve to the left, i.e. at increased body
```
temperature larger amount of CO2 can
be taken by the blood at a given PCO2.
• Decrease in PO2 shifts the curve to the left
and there by helps in loading of CO2 in
blood.
```
79
What is respiratory exchange ratio?
| Give its normal value
It is the ratio between the amount of oxygen
consumed (uptake) and the amount of
carbon dioxide given out by the tissues.
It is 1.00 if only carbohydrate is utilized,
0.70 if only fat is utilized and 0.8 if only
protein is utilized
80
How is oxygen transported by
| blood?
As physical solution
| • In combination with hemoglobin
81
What is oxygen hemoglobin dissociation curve? What is its normal shape?
It is the curve that demonstrates the
relationship between the partial pressure of
oxygen and percentage saturation of
hemoglobin with oxygen.
Normally, it is ‘S’ shaped or sigmoidshaped (Fig. 16.5).
82
What is the oxygen carrying capacity
| of hemoglobin and blood?
Oxygen carrying capacity of hemoglobin is
1.34 ml/g of hemoglobin. The oxygen
carrying capacity of blood is 19 ml/100 ml
of blood when the hemoglobin content in
blood is 15 g%.
The oxygen carrying capacity of blood is
only 19 ml% because the hemoglobin in the
blood is saturated with oxygen only for
about 95%.
83
Why this curve is sigmoid - haemoglobin dissociation curve
Hb molecule contains 4 atoms of Fe++ each
of which combines with O2 in varied affinity.
The combination of 1st heme in the
hemoglobin molecule with O2 increases the
affinity of the 2nd heme for O
2 and
oxygenation of 2nd heme increases the
affinity of the 3rd and so on. This shifting of
affinity of Hb for O2 produces sigmoid shape
84
What is the significance of the sigmoid shape of O2 dissociation curve?
```
• O
2 dissociation curve has the plateau
above 60 mm Hg. This flat upper part
indicates that even if the PO2 increases
from 60 mm Hg to 300 mm Hg, the O2
content of the blood will not vary
significantly. Similarly the effect of O2 lack
on the body will not be manifested until
the PO2 goes down below 60 mm Hg.
• The steep slope of the curve indicates that
the slight decrease of PO2 will cause
greater release of O2 from hemoglobin.
```
85
What is the O2 content in arterial and
| venous blood?
Arterial blood-19 ml%; venous blood - 14
| ml%.
86
What is the partial pressure of O2 in
| arterial and venous blood?
Arterial blood - 100 mm Hg; Venous blood-
| 40 mm Hg
87
8 In which form O2 is carried from
| lungs to tissues and in what amount?
• In dissolved form in plasma and RBC—
0.3 ml %
• In oxyhemoglobin form—18.7 ml %
88
What do you mean by O2 carrying
| capacity of blood?
It is the O2 carrying capacity of the total
hemoglobin of blood. If the Hb content of a
person is 16 gm% then his O2 carrying
capacity will be 16 × 1.34 ml (each gram Hb
carry 1.34 ml O2), i.e. 21 ml per deciliter of
blood
89
What is the difference between O2
| content and O2 capacity?
The O2 content refers to the amount of O2
actually present in a given sample of blood
where as O2 capacity refers to the total
amount of O2 that can be carried by blood
when the hemoglobin is fully saturated with
O2.
90
What is the indication of shift to the
right of oxygen dissociation curve? Name
some factors causing it.
Shift to the right of oxygen dissociation
curve indicates the dissociation or release
of oxygen from hemoglobin.
It is caused by:
• Decrease in partial pressure of oxygen in
blood
• Increase in partial pressure of carbon
dioxide
• Increase in hydrogen ion concentration
and decrease in pH (acidity)
• Increase in body temperature
• Excess of 2, 3 DPG (2,3, diphosphoglycerate)
91
What is the indication of shift to the
left in O2 dissociation curve? When does it
occur?
```
Shift to the left of oxygen dissociation curve
indicates the acceptance (association or
retention) of more amount of oxygen by
hemoglobin.
It occurs:
• In fetal blood since fetal blood has more
affinity for O2 than the adult blood
• When hydrogen ion concentration in the
blood decreases causing increase in pH
(alkalinity).
```
92
What is P50?
The partial pressure of oxygen at which the
hemoglobin saturation is 50% is called P50.
It is 25 mm Hg.
93
What is bohr effect
The presence of carbon dioxide decreases
the affinity of hemoglobin for oxygen and
enhances further release of oxygen to the
tissues and oxygen dissociation curve is
shifted to right. This is Bohr’s effect.
94
How is carbon dioxide transported
| in the blood?
* As physical solution
* As carbonic acid
* As bicarbonate
* As carbamino compounds.
95
Name the method by which maximum
amount of carbon dioxide is transported
in the blood.
As bicarbonate (about 63%)
96
What is chloride shift?
The negatively charged bicarbonate ions
formed in the red blood cells diffuse out
into the plasma. To maintain the electrolyte
equilibrium, the negatively charged
chloride ions move into the cells from
plasma. This is known as chloride shift (Fig.
16.6).
97
What is reverse chloride shift?
When the blood reaches the alveoli of lungs,
the bicarbonate ions diffuse into the red
blood cells from plasma. To maintain
electrolyte equilibrium, chloride ions move
out of the cells into the plasma. This is
known as reverse chloride shift.
98
What is carbon dioxide dissociation
| curve
```
The curve that demonstrates the relationship
between the partial pressure of carbon
dioxide and the amount of carbon dioxide
combined with blood is called the carbon
dioxide dissociation curve.
```
99
What is Haldane’s effect? What is its
| cause?
Excess of oxygen content in the blood
displaces carbon dioxide from hemoglobin
and shifts the carbon dioxide dissociation
curve to right. This is called Haldane’s effect.
This is because, when more amount of
oxygen combines, the hemoglobin becomes
acidic. The highly acidic hemoglobin causes
the displacement of carbon dioxide from
hemoglobin
100
Name the mechanisms involved in
| the regulation of respiration.
Nervous and chemical
101
What are the respiratory centers
```
Two medullary centers situated in med
ulla
oblongata:
– Inspiratory center or dorsal group of
neurons
– Expiratory center or ventral group of
neurons.
• Two pontine centers situated in pons:
– Pneumotaxic center
– Apneustic center
```
102
Mention the functions of each
| respiratory center.
nspiratory center is concerned with
inspiration. Expiratory center is concerned
with expiration.
Expiratory center is inactive during quiet
breathing and becomes active during forced
breathing or when inspiratory center is
inhibited.
activating the inspiratory center.
Apneustic center increases inspiration by
Pneumotaxic center decreases inspiration
by inhibiting apneustic center. By inhibiting
the apneustic center, it reduces the duration
of inspiration and thereby increases the rate
of respiration.
