Lung volumes
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Lung Volumes
Lung volume and lung capacities refer to the volume of air associated with different phases of
the respiratory cycle. Lung volumes are directly measured. Lung capacities are inferred from
lung volumes.
The average total lung capacity of an adult human male is about 6 litres of air, but only a small
amount of this capacity is used during normal breathing.
The breathing mechanism in mammals is called respiration. Tidal breathing represents the
volume of air that is inhaled and exhaled in normal, resting breathing.
An average human breathes some 12-20 times per minute.
Contents
[hide]
1 Factors affecting volumes
2 Values
3 Restrictive and obstructive
4 See also
5 References
6 External links
[edit] Factors affecting volumes
Several factors affect lung volumes; some can be controlled and some cannot. Lung volumes can
be measured using the following terms:
Larger volumes Smaller volumes
taller people shorter people
non-smokers smokers
people living at high altitudes people living at low altitudes
A person who is born and lives at sea level will develop a slightly smaller lung capacity than a
person who spends their life at a high altitude. This is because the partial pressure of oxygen is
lower at higher altitude which, as a result means that oxygen less readily diffuses into the
bloodstream. In response to higher altitude, the body's diffusing capacity increases in order to
process more air.
When someone living at or near sea level travels to locations at high altitudes (eg. the Andes,
Denver, Colorado, Tibet, the Himalayas, etc.) that person can develop a condition called altitude
sickness because their lungs remove adequate amounts of carbon dioxide but they do not take in
enough oxygen. (In normal individuals, carbon dioxide is the primary determinant of respiratory
drive.)
Specific changes in lung volumes occur also during pregnancy. Decreased functional residual
capacity is seen, typically falling from 1.7 to 1.35 litres,[citation needed] due to the compression of the
diaphragm by the uterus. The compression also causes a decreased total lung capacity (TLC) by
5% and decreased expiratory reserve volume. Tidal volume increases with 30-40%, from 0.45 to
0.65 litres,[citation needed] and minute ventilation by 30-40%[1] giving an increase in pulmonary
ventilation. This is necessary to meet the increased oxygen requirement of the body, which
reaches 50 mL/min, 20 mL of which goes to reproductive tissues. Overall, the net change in
maximum breathing capacity is zero.[2]
[edit] Values
These values vary with the age and height of the person. For males, the values that follow are the
average ones for a healthy 70 kg (154 lb), average-sized adult male [3]; for females, the editors of
this article have not yet produced data from primary sources; until they do, the data listed are
estimates obtained by reducing the values for males by 22.5% [4]:
Value
Measurement Calculation Description
(Male/Female)
The volume of air contained in the
lung at the end of maximal
Total lung TLC = IRV + Vt + ERV + inspiration. The total volume of the
= 6.0 / 4.7 L
capacity (TLC) RV lung. Values of between 80% and
120% of average value are
considered normal.[5]
Vital capacity = 4.6 / 3.6 L VC = IRV + Vt + ERV The amount of air that can be forced
(VC) out of the lungs after a maximal
inspiration. Emphasis on
completeness of expiration. The
maximum volume of air that can be
voluntarily moved in and out of the
respiratory system.[6]
The amount of air that can be
Forced vital maximally forced out of the lungs
= 4.8 / 3.7 L measured
capacity (FVC) after a maximal inspiration.
Emphasis on speed.[7][8]
The amount of air breathed in or out
Tidal volume during normal respiration. The
= 500 / 390 mL measured
(Vt) volume of air an individual is
normally breathing in and out.
The amount of air left in the lungs
after a maximal exhalation. The
amount of air that is always in the
lungs and can never be expired (i.e.:
Residual
= 1.2 / 0.93 L measured the amount of air that stays in the
volume (RV)
lungs after maximum expiration).
Values between 75% and 125% of
average value are considered normal.
[5]
The amount of additional air that can
be pushed out after the end
expiratory level of normal breathing.
(At the end of a normal breath, the
Expiratory
lungs contain the residual volume
reserve volume = 1.2 / 0.93 L measured
plus the expiratory reserve volume,
(ERV)
or around 2.4 litres. If one then goes
on and exhales as much as possible,
only the residual volume of 1.2 litres
remains).
The additional air that can be inhaled
Inspiratory after a normal tidal breath in. The
measured or IRV=VC-
reserve volume = 3.0 / 2.3 L maximum volume of air that can be
(Vt+ERV)
(IRV) inspired in addition to the tidal
volume.
The amount of air left in the lungs
after a tidal breath out. The amount
Functional
of air that stays in the lungs during
residual = 2.4 / 1.9 L FRC = ERV + RV
normal breathing. Values of between
capacity (FRC)
80% and 120% of average value are
considered normal.[5]
The maximal volume that can be
Inspiratory
= 3.5 / 2.7 L IC = Vt + IRV inspired following a normal
capacity (IC)
expiration.
Anatomical = 150 / 120 mL measured The volume of the conducting
airways. Measured with Fowler
dead space
method.[9]
Physiologic The anatomic dead space plus the
= 155 / 120 mL
dead volume alveolar dead space.
The tidal volume, vital capacity, inspiratory capacity and expiratory reserve volume can be
measured directly with a spirometer. These are the basic elements of a ventilatory pulmonary
function test. Determination of the residual volume can be done by radiographic planemetry,
body plethysmography, closed circuit dilution and nitrogen washout.
In absence of such , estimates of residual volume have been prepared as a proportion of body
mass for infants (18.1ml/kg), [10] or as a proportion of vital capacity (0.24 for men and 0.28 for
women)[11] or in relation to height and age ((0.0275*AgeInYears+0.0189*HeightInCentimetres-
2.6139) litres for normal-weight individuals and
(0.0277*AgeInYears+0.0138*HeightInCentimeters-2.3967) litres for overweight individuals).[12]
Standard errors in prediction equations for residual volume have been measured at 579ml for
men and 355ml for women, while the use of 0.24*FVC gave a standard error of 318ml.[13]
Definition: Vital capacity (VC) is the the maximum amount of air that can be inhaled or exhaled
from the lung. It is one of the measurements taken during spirometry or pulmonary function
testing. VC is measured using a spirometer.
PULMONARY FUNCTION AND RESPIRATORY
REGULATION
Lung Volumes and Hyperventilation
Sherwood reading: Chapter13, see especially, p. 466-480
Objectives:
1) Define the variou lung volumes and capacities under different conditions and understand how
to measure them.
2) To observe the effect of altering breathing patterns on breath hold duration.
Introduction
In physiology thus far, you have been introduced to the concept of cellular or internal respiration,
which refers to the cellular metabolic processes that break down nutrient molecules, using O2 and
producing CO2. The respiratory system of the body (lungs, airways and muscles) is not directly
involved in this process, rather it is involved in the exchange of O2 and CO2 between the blood
(brought to the alveoli in the lungs) and the inspired air (filling the alveoli in the lungs).
Respiration is composed of four steps: 1) ventilation (or breathing), 2) gas exchange in the lungs,
3) circulation of blood between the lungs and tissues and, 4) gas exchange at between the blood
and tissues. Spirometry is a method for measuring lung volumes during ventilation. It is used to
assess lung function and is particularly helpful for diagnosing obstructive lung diseases. During
this laboratory, we will be using spirometry to understand how lung volumes change during
exercise. During resting respiration, only a small portion (about one tenth) of the lung capacity is
used. This allows plenty of reserve capacity for those occasions (such as strenuous exercise)
when the body requires much greater flow of oxygen to generate energy. Furthermore, the lungs
are never completely empty. Even when a lung is removed, and collapses, sufficient air is
trapped inside to permit it to float in water.
Breathing
During inspiration, air is forced into the lungs due to expansion of the thoracic cavity. Expansion
of the thoracic cavity is caused by the contraction (flattening out) of the diaphragm at the bottom
of the rib cage and the contraction of the external intercostal (between rib) muscles, causing the
ribs to move upwards and outwards. The expansion of the thoracic cavity increases thoracic
volume and decreases thoracic pressure so that the net flow of air is down its pressure gradient
and into the lungs. During exercise, the body's need for oxygen increases dramatically and
ventilation rate is increased. The depth of breathing also increases during exercise during
exercise due to the anatomical dead space of the respiratory system. The anatomical dead space
is the air in the nose, mouth, larynx, tracheas, bronchi and bronchioles. This air reaches the
alveoli first upon inspiration. This air also has a higher concentration of CO2 because of its
prolonged exposure to the tissues. Therefore, increasing the depth of a breath increases the
proportion of "fresh air" that gets to the alveoli, increasing gas exchange.
VC capacity
Vital capacity: the volume change of the lungs between –a full inspiration and a maximal
Expiration. The manoeuvre may be performed in different ways:
The manuever is performed rather slowly:
The vital capacity is assessed during an inspiratory manoeuvre. Starting from end-tidal volume
the subject expires maximally and subsequently makes a full inspiration. This is the inspiratory
vital capacity.
The vital capacity is assessed during an expiratory maneuver. Starting from end-tidal volume the
subjects make a full inspiration
http://www.spirxpert.com/indices2.htm
Introduction
Breathing is one of those critical bodily functions that, for most of us, we carry on daily with hardly a
conscious thought. You know that your lungs deliver vital oxygen to the blood, and expire waste
carbon dioxide out of the body. This exchange occurs at the alveolar membrane, between the alveoli
and capillaries in the lungs. The alveoli are tiny sacs at the furthest ends of the branching airways of
the lungs. In adults, the total surface area of the alveolar membrane varies roughly between 100 and
200 square meters(!)—about the same area as one or two tennis courts (Petty, 2006).
You know from experience that your lungs can respond to the body's changing needs for oxygen.
When you exercise vigorously, you breathe deeper and faster to keep yourself going. Can a person's
lung capacity increase with regular aerobic exercise?
In this project you will use two different measures of lung capacity: tidal capacity, which is the volume
exhaled from a normal breath, and vital capacity, which is the volume that can be exhaled from a
deep breath. You will measure tidal capacity and vital capacity for two groups of volunteers: athletes
and non-athletes. (You will have to devise a short survey in order to assign your volunteers to the
appropriate group.)
Since people come in all different sizes, you would expect lung capacity to vary according to size. You
will need to control for this. The approach taken in this project is to relate the actual (measured) lung
capacity to the expected lung capacity, based on a person's height and weight (for details, see the
Experimental Procedure section). By taking the ratio of measured lung capacity to expected lung
capacity, you will obtain a normalized measure that can be compared between experimental subjects.
If the ratio is less than one, the subject has a below-average vital capacity for their size. If the ratio is
equal to one, the subject has an average vital capacity. If the ratio is greater than one, the subject
has an above-average vital capacity.
https://secure.coursework.info/cgi-
bin/community/community.cgi
Time/se Number of ventilation
Condition c Counts movements
In syringe 30 1st 29
30 2nd 34
30 3rd 26
Average - 23
Replace piston with cotton
wool 15 1st 50
15 2nd 45
15 3rd 40
Average - 45
After piston was pushed in
and out 30 1st 20
30 2nd 15
30 3rd 20
Average – 18.3
When placed in refrigerator 1st 12
2nd 16
3rd 18
Average – 15.3
