Mechanics of Respiration Flashcards
what are the two meanings of respiration
breathing and tissue respiration
what is tissue respiration
aerobic metabolism in cells
what is breathing
gas exchange and its associated processes
what is the physiology of breathing interlinked with
tissue respiration
what are the roles of the lungs
- bring in fresh air rich in oxygen needed to fuel the body
- expel waste gas produced from cells in the body
what does the amount of oxygen and carbon dioxide depend on
energy requirements eg exercise
how can the brain affect lung ventilation
some issues with the lungs can begin neurologically, as there are neurons in brain that produce the rhythm transported to the diaphragm
what do almost all lung diseases affect
the mechanical properties of the lungs
why is death from lung disease common
there is an inability to overcome changes in the lung and chest mechanics
what is the partial pressure of oxygen at rest in a healthy individual
100mmHg
what is the partial pressure of carbon dioxide in a healthy individual at rest
40mmHg
what is the concentration of oxygen in one breath for a healthy individual at rest
250ml of oxygen per minute
what is the rest exchange of carbon dioxide in a healthy individual
200ml of carbon dioxide per minute
what is the main point of breathing
blood gas homeostasis
is there more oxygen or more carbon dioxide at rest
more oxygen
how can ventilation in a healthy individual change during exercise
go from 250ml at rest, to 800ml when walking, to 5000 when exercising
what is the function of the nasal cavities and paranasal sinuses in breathing
filter, warm, humidify air, and detect smells
what is the function of the pharynx in breathing
conduct air to the larynx
shared with the digestive tract
what is the function of the larynx
protects the opening to the trachea
contains vocal folds
what is the function of the trachea
filter air
trap particles in mucous
cartilages keep the airway open
what is the function of the bronchi
the same as the trachea
what is the definition of breathing in the lungs
air movement through volume changes during movements of the ribs and diaphragm
includes the airways and the alveoli
what is the function of alveoli
act as sites of gas exchange between air and blood
what is the major function of the upper respiratory tract
humidify, warm and filter air
why is it important to humidify and warm air
Air should be saturated with water, breathing in dry air can be irritating and can damage the epithelial lining of the upper airways. Therefore it is important it is humidified.
Also want it to be warm, and if we breathe in cold air it is irritating to the upper airways.
what lines the upper airways
pseudostratified, ciliated, columnar epithelium
what is the function of mucous in the upper airways
trap particules and move up to the mouth via cilia for expulsion
how many litres of air is inhaled with each breath
half a litre
on average how many breaths do we do a minute
12-15
how many litres on average do we breathe in per minute
6-7
what is the maximum ventilation
160 litres per minute
maximum ventilation per breath
4 litres
how many breaths can we breathe in maximum
40
describe inspiration and expiration during quiet breathing
inspiration is active
expiration is passive
describe active inspiration
- diaphragm contracts downwards, pushing abdominal contents outward
- external intercostals pull the ribs outward and upward
describe passive expiration
elastic recoil
describe inspiration and expiration during strenuous breathing
active inspiration and active expiration
describe active inspiration during strenuous breathing
greater contraction of the diaphragm and external intercostals
the inspiratory accessory muscles are active
what are the inspiratory accessory muscles
- sternocleidomastoid
- alae nasi
- genioglossus
what are the abdominal muscles involved in active expiration
rectus abdominus
internal oblique
external oblique
transversus abdominus
what are the internal intercostal muscles
these muscles oppose the external intercostals by pushing the ribs down and inward
what is the major inspiratory muscle
diaphragm
when are the other respiratory skeletal muscles active in order to aid the diaphragm
during more strenuous breathing
what happens during inspiration to increase the lung cavity capacity
diaphragm contracts downward
intercostals pull the ribs outward
chest wall moves outward
what does it mean to describe quiet expiration as passive
there is no muscle involvement
how far does the diaphragm move during quiet breathing
1cm
how far does the diaphragm move during strenuous breathing
10cm
what is intrapulmonary pressure
pressure in the lungs
what is the value of the intrapleural pressure in the course of inspiration
negative
what is the tidal volume
the change of volume occurring in inspiration
what are the pleural spaces
the small spaces between the lung and the chest wall
pressure is important because it is the pressure that drives breathing
what is the pressure in the pleural space
the pleural pressure
what is the alveolar pressure
the pressure within the lung
what is the transpulmonary pressure
the difference between pleural pressure and alveolar pressure
what is elastic recoil pressure
quiet breathing during expiration
is there flow of air at the beginning of a breath
no
what is the alveolar pressure at the beginning of a breath and why
0 because there is no flow of air into the lung
what happens to pleural pressure when inspiration is about to occur
pleural pressure becomes more negative
why does pleural pressure become more negative when we inspire
the pleural space gets bigger but there is no change in volume yet. lung expands into the larger space, which then leads to decreased pressure in the lungs.
what triggers air flow into the lungs
decrease in pressure in the lungs when the pleural pressure decreases
why is pressure always negative in the pleural cavities
chest wall is always moving out and the lung is trying to collapse
when does air flow stop
when barometric pressure is equal to the alveolar pressure
what happens to thoracic volume when the inspiratory muscles contract
the volume increases
describe the full series of events when breathing, including pressure changes (you are so strong and brave)
- Beginning of inspiration, no flow: PA=0 PB=0.
- Inspiratory muscles contract – inc. thoracic volume.
- Pleural pressure becomes more negative.
- Increase in transpulmonary pressure.
- Lungs expand and alveolar volume increases.
- PA becomes negative (below PB).
- Air flows into alveoli (from higher to lower pressure).
- End inspiration - Muscles stop contracting, thorax and alveoli stop expanding, PA = PB (no flow).
- Beginning expiration: Thoracic volume decreases. .
- Ppl & PL return to pre-inspiration values.
- Thorax and lungs recoil (elastic recoil pressure).
- Air in alveoli compressed.
- PA becomes greater than PB.
- Air flows out of lungs.
is low level breathing efficient in healthy lungs
yes, as there is low muscle effort
how many ml of oxygen per litre of air
1
how much resting energy expendenture is used in breathing at rest in healthy people
2%
why is higher intensity breathing less efficient
gas flow is turbulent and uses more muscles
accessory muscles can fatigue easily
what is the functional residual capacity
the volume of air in the lung at the end of the expiration during quiet breathing
what decreases lung volume
elastic recoil forces
what increases lung capacity
outward recoil of the chest wall
how are the elastic recoil and outward recoil when muscles at the functional residual capacity
they are equal and opposite as the muscles are relaxed
are lungs emptied entirely after respiration
yes
why can neuromuscular disease affect breathing
if the chest wall muscles are weak, the functional residual capacity decreases as the lung elastic recoil is greater
what determines the ease or difficulty of air movement into the lungs
mechanical properties of the lung and chest wall
why is measurement of lung volume important
to understand normal and diseased lung function
