the respiratory system - uniba.sk...the respiratory system practical 1 objectives respiration,...
TRANSCRIPT
The respiratory system
Practical 1
Objectives
Respiration, ventilation
Intrapleural and intrapulmonary pressure
Mechanism of inspiration and expiration
Composition of the atmosphere and the expired air
Practical tasks
1. Hering´s model of the respiratory system
2. Paralellogram
3. Measurement of the vital capacity
4. Analysis of respiratory gases in exhaled air
5. Measurement of the expiratory peak flow with a peak
flow meter Vitalograph
© Katarína Babinská MD, PhD, MSc, 2017
Respiration – vital function
Respiration - exchange of the respiratory gasses
- the principal function of the respiratory system
⚫ supplying of O2 from atmospheric air for metabolism
⚫ removing excess CO2 (metabolic end-product) from the body
external respiration: exchange of gases between atmosphere and alveoli
internal respiration: exchange of gases between blood and cells of the body
cellular respiration – utilization of O2/ production of CO2 in the cell metabolism
atmosphere cells
- a rhythmic, automatic process (breathing cycle)
• inspiration
• air moves from the atmosphere into the lungs
• tidal volume VT – 500 ml (quiet breathing)
• expiration
• the same volume moves from the lungs into
the atmosphere
• external signs of breathing – movements of the
chest and abdomen
Inspiration and expiration
- the air flow into and out of the lungs is driven by the pressure differences
between the lungs and the atmosphere
Ventilation (Breathing)
© Katarína Babinská, MD, PhD. MSc., 2010
Atmospheric pressureatmosphere
the atmosphere (mass of air) exerts pressure
- at seal level approx: 100 kPa (1 atm, 760 mm Hg)
the atmospheric pressure is lower in higher altitudes
- lower density of the air
- thinner layer of the atmosphere
in physiology, pressures in the body
are related the atmosperic pressure
e.g. if pressure in the lungs= 0,1 kPa,
it means, it is by +0,1 kPa higher than
atmospheric pressure
https://i.ytimg.com/vi/O37XuRkS5UE/hqdefault.jpg
• lungs – lined with a thin membrane
pleura visceralis
• the internal side of the chest is lined with
pleura parietalis
• between both membranes is a thin space
- (intra)pleural space
• the space is filled with small volume of liquid
that surrounds the lungs
© Katarína Babinská, MD, PhD. MSc., 2010
Pleura, (intra)pleural space
Intrapleural pressure - the pressure(of the liquid) in intrapleural space
lungs - exert an elastic recoil directed inwards
thorax - exerts an elastic recoil directed outwards
due to elastic recoil of the lungs and the
chest the pressure in intrapleural space
is lower than the pressure in
atmosphere (= it is subatmospheric)
by – 0,5 to –1,0 kPa in quiet breathing
The negative pressure
prevents the lung to collapse
is effective in inspiration and expiration
intrapleural space –
negative pressure
© Katarína Babinská, MD, PhD. MSc., 2010
visceral
pleura
parietal
pleura
Intrapulmonary (alveolar) pressure
- pressure inside the lungs (i.e. in the lung alveoli)
- when the glottis is open and no air flows into/out of the respiratory
passageways, the pressures in all parts of the respiratory tree are equal to
the atmospheric pressure
© Katarína Babinská, MD, PhD. MSc., 2010
Physical laws in respiration
if two containers filled with air that differ in pressure
are connected, the air moves from the container
with higher pressure into the container with lower
pressure
pressure and volume of air within a closed
system is constant
⚫ i.e. if the volume increases, the pressure
decreases and vice versaV
p
V
p
P1 p2
P1 > p2
Boyle's law
Dalton's law
Forceful breathing
- e.g. in stress, physical activity
Quiet breathing
- in rest
1. Contraction of the inspiratory
muscles
= an active process
A. diaphragm – the main inspiratory muscle
- quiet breathing – by contraction it descends by 1-1,5 cm
- in forceful breathing – by a stronger contraction it descends by 6 -10 cm,
B. external intercostal muscles
- pull ribs up and out
- cause further increase in chest volume
C. accessory inspiratory muscles – active in forceful breathing
(m. sternocleidomastoideus, mm. scaleni, mm serrati ant.)
Before the inspiration Inspiration
Mechanism of inspiration
© Katarína Babinská, MD, PhD. MSc., 2010
2. increase in chest volume
- by 0,5 L in quiet breathing,
(forceful breathing by 2-3 L)
3. decrease of intrapleural pressure
- becomes more negative
- parietal pleura follows the chest
movement, thus volume of pleural cavity , intrapleural pressure
4. decrease in intrapulmonary pressure
- before inspiration: pressure in lungs = pressure in atmosphere
- the increased negativity of intrapleural space
„pulls the lungs outwards“ therefore, lung expand
- during lung expansion – alveolar pressure becomes than atmospheric
5. the air moves
- from the place with higher pressure (atmosphere)
- to the place with lower pressure (lung)
- until the pressures get equal (end of inspiration)
Before inspiration inspiration
© Katarína Babinská, MD, PhD. MSc., 2018
Mechanism of expiration
a quiet expiration is passive
(i.e. it does not require
muscle contraction)
1. inspiratory muscles are relaxed
- the diaphragm moves upwards, ribs move downwards
(because of their elastic recoil)
2. chest size decreases
3. intrapleural pressure increases (less negative)
4. intrapulmonary pressure exceeds atmospheric pressure
5. air moves
- from the place with higher pressure (lung)
- to place with lower pressure (atmosphere)
- expiration is terminated when the pressures in lungs/atmosphere are equal
expiration
© Katarína Babinská, MD, PhD. MSc., 2010
Expiration
• in forceful breathing – active
(requires muscle contraction)
• involves:
Expiratory muscles- contraction
1. internal intercostal muscles
- move ribs downwards
- further decrease in thoracic volume
2. accessory expiratory muscles – abdominal muscles
expiration
© Katarína Babinská, MD, PhD. MSc., 2010
intrapleural space –
negative pressure
after exspiration / prior to next inspiration
- two recoil forces are in equilibrium( )
= relaxation position of the chest
- position whan the respiratory muscles
(inspiratory and expiratory) are relaxed
- optimum starting position for breathing –
least work of respiratory muscles
Inspiration
- starting from relaxation position is active
- activity=contraction of inspiratory muscles
Expiration
- above relaxation position is passive (quiet expiration)
- relaxation of inspiratory muscles
Expiration
- starting from relaxation position is active (forced expiration)
- activity=contraction of expiratory muscles
Inspiration
- up to relaxation position is passive (forced breathing)
- relaxation of expiratory muscles
relaxation
position –
respiratory
muscles are
relaxed
Non-relaxation positions
1. inspiratory position
- during inspiration, when inspiratory
muscles are contracted
2. expiratory position
- during forceful expiration when
expiratory muscles are contracted
- inspiratory and expiratory position are
a result of respiratory muscle activity
(contraction)
Pressures in the respiratory system
Intrapleural pressure – quiet breathing
• beginning of inspiration: - 0,5 kPa
• beginning of expiration: - 1,0 kPa
Intrapleural pressure - forceful breathing
• end of inspiration – more negative values
• end of expiration – may be a positive
beginning beginning
of inspiration of expiration
0
-1
0
0,5
0
Intrapulmonary (alveolar) pressure
• inspiration – negative values
a) at the beginning of inspiration – chest expands, decrease ofthe intrapulmonary pressure
b) later during inspiration - air moves into the lungs – pressureprogressively increases (from negative values to zero value)
• expiration – positive values
c ) at the beginning of expiration – chest volume reduces, increase in the intrapulmonary pressure
d) later during expiration - air moves out of lungs – progressivedecrease pressure (from positive values to zero value)
Volume of air in the lungs
- increase during inspiration, decrease during expiration
inspiration exspiration
ab
c
d
Inspiration
- starting from relaxation position is active
- activity=contraction of inspiratory muscles
Expiration
- above relaxation position is passive (quiet expiration)
- relaxation of inspiratory muscles
Expiration
- starting from relaxation position is active (forced expiration)
- activity=contraction of expiratory muscles
Inspiration
- up to relaxation position is passive (forced breathing)
- relaxation of expiratory muscles
relaxation
position
Relaxation position of the chest
- respiratory muscles (inspiratory and expiratory) are relaxed
-volume in the lungs = functional residual capacity (FRC=ERV+RV)
Task 1. The Hering´s model of respiratory system
Hering´s model
a glass bell represents the chest, the bottom is made of rubber
and it imitates the diaphragm
shows the function of diaphragm in breathing
Principle
pull down or push up the bottom of
Hering´s model, observe and
explain changes in pleural space,
lung and vena cava
© Katarína Babinská, MD, PhD. MSc., 2010
Procedure
Diaphragm – pulling down („inspiration“)
volume of the thoracic cavity is increasing
pressure in the pleural space is decreasing
pressure in alveoli (lung) is decreasing from atmospheric level
air moves from the atmosphere into the lungs
v. cava expands
Diaphragm – pushing up („expiration“)
volume of the thoracic cavity is decreasing
pressure in the pleural space is increasing
pressure in alveoli is increasing – exceeds the atmospheric
pressure
air is moving from the lungs into the atmosphere
blood flow in v. cava is decreased
© Katarína Babinská, MD, PhD. MSc., 2010
Valsalva manoeuvre
a forcible expiration against closed airways (nose, mouth)
a major increase in pleural pressure (that may get even positive)
it helps to normalize the middle ear pressure
it is used in some clinical examinations
Műller´s manoeuvre
after a forced expiration an attempt of deep inspiration with closed
airways (nose, mouth)
a major decrease in pleural pressure
the manoeuvre is used in some clinical examinations of respiratory tract
Result and conclusion: describe the observation
© Katarína Babinská, MD, PhD. MSc., 2010
Pneumothorax
„a hole“ in the pleura
⚫ due to injury of chest wall, lung disease, etc.
the intrapleural cavity communicates with
the atmosphere
air enters the intrapleural space
an increase of the intrapleural pressure
lack of underpressure, that prevents the
collapse of lungs – the lung collapses
decreased effectiveness of breathing – the
lung fails to expand
Task 2. Parallelogram – a model of intercostal muscles
Principle
imitate the contraction of mm. intercostales interni and externi
and observe movements of the ribs
sternum
ribs
backbone
miemii
© Katarína Babinská, MD, PhD. MSc., 2010
Procedure
Modelling the inspiratory movement
inspiration - contraction of m. intercostales externi
contract the rubber that is directed obliquely downward and medially
immitate both quiet and forceful inpiration
Modelling the expiratory movement
immitate both A/ quiet and B/ forceful expiration
⚫ A/ relaxation of the inspiratory muscles
⚫ B/ contraction of the m. intercostales interni (they are directed obliquely
downward and laterally)
Result and conclusion: describe the observation
© Katarína Babinská, MD, PhD. MSc., 2010
Task 3. Measurement of the vital capacity
© Katarína Babinská, MD, PhD. MSc., 2010
VC
vital capacity (VC)
- The volume of maximum forceful expiration that follows previous maximum inspiration
Procedure
close the nose with a clamp
insert a disinfected mouthpiece into the rubber tube
make maximum inspiration
make maximum expiration – exhale into the
spirometer
a spirometer – a metal jar with a smaller jar inside
the internal jar is pushed up by the expired air
read the volume of the expired air on the scale
repeat the measurement of VC 3 times
calculate the average of your measurements
1000
2000
© Katarína Babinská, MD, PhD. MSc., 2010
Procedure
make the BTPS correction
VC BTPS= VC x BTPS factor (find in tables)
BTPS correction = recalculation for standard body conditions
⚫ temperature – 37 °C
⚫ barometric pressure – 101.3 kPa
⚫ water vapour saturation – 6.3 kPa
Calculate the normal value of vital capacity: VCphys
Men: VCphys = 5,76 x H – 0,026 x A - 4.34
Women: VCphys = 4,43 x H – 0,026 x A - 2.89
H = height in m A = age in years
is your VC BTPS in the range of 90 – 110 % of the VC phys?
% VC = VC(BTPS) x 100/VCphys
© Katarína Babinská, MD, PhD. MSc., 2010
Respiratory passageways
A/ Conducting zone
upper respiratory tract (passageways)
⚫ nasal cavity, nasopharynx, larynx
lower respiratory tract
⚫ trachea, bronchi, bronchioles (most)
B/ Respiratory zone (gas exchange)
lower respiratory tract
⚫ respiratory bronchioles
⚫ alveolar ducts
⚫ alveolar saccules
⚫ alveoli
2. alveolar dead space
- involves alveoli where no gas exchange takes place
- in a healthy human:
- all alveoli serve for gas exchange
- alveolar dead space 0
- in people with a lung disease - alveoli are malfunctioning
- alveolar dead space > 0 (e.g. in pneumonia, fibrosis)
- parts of respiratory passageways where no significant
gas exchange occurs between lungs and blood
1. anatomical dead space – approx 150 ml
= conductive part of airways
- function: the inspired air is heated, cleaned, moisturized
Physiological dead space = anatomical dead space + alveolar dead space
Dead space (VD)
- alveolar dead space
- pneumonia, x- ray exam
- lungs are blocked with
fluid and bacteria
- the atmosphere exerts atmospheric pressure- pressure of individual gasses is proportional to their content (%)
partial pressure of a gas
= atmospheric pressure x percent of the gas
e.g. if the atmospheric pressure is 100 kPa
O2 content in atmosphere 21% partial pressure of O2 = 100 x 0,21=21 (kPa)
CO2 content in atmosph. 0,04 % partial pressure of CO2=100 x 0,0004=0,04 (kPa)
- gasses dissolved in fluids also exert partial pressures
Partial pressures of O2, CO2
- diffusion O2 and CO2 from lungs into blood is based on differences in pO2, pCO2
Composition of atmosphere (inspired air):
N2 78 %
O2 21 %
CO2 0,04 %
H2O vapour 0,5% (non constant component)
N2 O2
atmosphere
CO2
inspiration(atmospheric air)
O2 21%
CO2 0,04%
expiration
O2 16,3%
CO2 3,8%
alveoli*
O2 14% 13,3 kPa
CO2 5,6% 5,3 kPa
pO2 5,3 kPa
pCO2 6,1 kPa
pO2 12,6 kPa
pCO2 5,3 kPa
the inspired air is mixed with the air
from previous expiration
the expired air is mixed with the air
from previous inspiration
* in alveoli O2 is
instantly diffusing into
blood and CO2 from
blood, therefore their
% differ from % in
inspired and expired
air
rection of
blood flow
Task: Analysis of the respiratory gases
gas analyzer SPIROLYT is used
the analyzer continuously measures and records atmospheric
⚫ concentration of O2
⚫ concentration of CO2
since composition of atmosphere is constant straight (zero) lines are
recorded on a sheet of paper (blue for CO2, red for O2 )
Task: Into a sampler (balloon) collect a sample of expired air from
the beginning of expiration
the end of expiration
and analyze the O2 and CO2 content
O2CO2
Analysis of the expired air:
attach the sampler to the SPIROLYT analyzer
observe the blue and red lines
if the blue and red lines move upwards = a change in O2 a CO2 is detected
proceed with the measurement until a „new“ straight line is recorded again
distance between lines = difference in O2 a CO2 % between the sample and
atmosphere
read the results by using a ruler (blue for CO2, red O2 )
DO2DCO2
Result: calculate the % O2 and CO2 in the sample
%O2 = decrease in O2 in the sample in contrast to atmospheric air
O2 in expired air = O2 in atmospheric air - DO2
% CO2 = increase in CO2 in the sample in contrast to atmospheric air
CO2 in expired air = CO2 in atmospheric air + DCO2
Conclusion: is the result normal? Explain
DO2DCO2
Task: Measurement of the expiratory peak
flow with a peak flow meter
Forced expiratory volume (FEV) measures how much air a person can exhale
during a forced breath. The amount of air exhaled may be measured during the
first (FEV1), second (FEV2), and/or third seconds (FEV3) of the forced breath.
- FEV1 normal value: 80 - 85% of VC
- FEV 3: normal value 97-100 % of VC
The peak air flow
It measures the fastest rate of air (airflow) that a person can blow out of lungs.
(airflow in litres per minute - L/min).
Procedure
Put the marker to zero.
Take a deep breath.
Seal your lips around the
mouthpiece.
Blow as hard and as fast as you
can into the device.
Note the reading.
Repeat three times.
The 'best of the three' is the
reading to record on the chart.
Normal peak flow
readings vary,
depending on
⚫ Age
⚫ Body size
⚫ Gender
The range of
normal peak flow
readings is
published on a
chart
Measurement of peak flow
- often used in asthma
- regular readings can be used to help
assess how well treatment is working.
- readings improve if narrowed airways
open up with treatment.
Air flow in the respiratory passageways
air flow through the respiratory passageways depends on their diameter
Normal breathing
Inspiration - bronchi dilated and prolonged „easier air flow
Expiration - bronchi narrower and shorter „more difficult“
expiration normally longer 2:1
in disease (e.g. asthma, bronchitis, etc.)
the air flow may be limited by
⚫ Bronchocinstriction (contraction of the
smooth muscle in the wall of bronchi –
mainly smaller bronchi and bronchioles)
⚫ Inflammed and swollen mucosa
⚫ Presence of mucus