Lecture 13 Flashcards
Define respiration
this is the exchange of O2 and CO2 between the tissues and the environment
What are three processes that respiration involves and what do these mean?
- external: exchange of O2 and CO2 between the atmosphere and blood flowing through the lungs
- transport of gases by the blood
- internal: gas exchange between capillaries and tissues (cellular respiration)
- overall regulation of respiratory function
What are the 5 steps of respiration?
- ventilation
- gas exchange
- gas transport
- gas exchange
- cellular respiration
Define ventilation
the process of moving air into and out of the lungs (supply O2 and to remove CO2 from the alveoli)
Ventilation occurs through what process?
bulk flow
Define gas exchange
Exchange of O2 and CO2 across alveolar membrane (air to blood) ie. into the body
Gas exchange occurs through which process? What does this depend on?
diffusion
this depends on the pressure gradient to get stuff across
Define gas transport
this is the delivery of O2 from the lungs to the tissues and transport CO2 produced by metabolism to the lungs
Gas transport occurs through which process?
bulk flow
Define cellular respiraton
when cells use O2 to produce CO2
Cellular respiration occurs through which process?
metabolism
What are 8 functions of the respiratory system?
- provide ______
- eliminate _______
- _______, ______ and _________ the air we breathe
- _________
- sense of _______
- regulate the ______ of the ________, in association with the _________
- defend against ___________
- temperature _________
- provide O2
- eliminate CO2
- filters, warms and humidifies the air we breathe
- communication
- sense of smell
- regulate the pH of the blood, in association with the kidneys
- defend against microbes
- temperature regulation
What are 6 things that make up the upper respiratory tract?
- nasal cavity
- pharynx consisting of:
- nasopharynx
- oropharynx
- laryngopharynx
- larynx
What are 7 things in the lower respiratory tract?
- trachea
- primary bronchi
- primary bronchioles
- secondary bronchioles
- tertiary (respiratory) bronchioles
- alveolar duct
- alveoli
What do we lose as we go from the bronchi to the bronchioles?
cartilage
The trachea is surrounded by what? Why is this?
cartilaginous rings to hold it open
What are the functional units for the respiratory system?
the alveolar sacs
What are the alveolar sacs surrounded by?
numerous capillaries
Describe the muscles required for quiet inspiration
The diaphragm contracts, moving it downwards. This gives enough space for the lungs to expand and inspiration is initiated.
Describe the muscles needed for inspiration during exercise
The diaphragm contracts but it is not enough to get enough O2 into the lungs. The external intercostals contract which increases the chest wall anteroposterior diameter to give more room for the lungs to expand. If this is still not enough, the sternomastoid (muscle of the neck) contracts to expand the ribs. There is also the pectorals minor
Expiration is a ________ process at _______
passive
rest
Describe the muscles required for expiration
The diaphragm stops contracting and it domes back and the internal intercostals help to pull down and reduce the anteroposterior diameter of this chest, aiding in expiration
Describe the muscles needed for expiration and inspiration during restful breathing
Inspiration caused by diaphragm contraction
Expiration caused by lung elastic recoil pulling
thorax and relaxed diaphragm inwards. No muscle contraction, therefore “passive”
Describe the muscles needed for expiration and inspiration during deeper breathing
Inspiration – diaphragm and external intercostal muscle contraction
Expiration – lung elastic recoil and internal intercostal muscle contraction
Describe the muscles needed for expiration and inspiration during forceful breathes
Inspiration – as above plus contraction of sternocleidomastoid and pectoralis minor muscles
Expiration – as above plus abdominal muscle contraction (external oblique abdominal rectus muscle)
Describe the nervous innervation of the lungs
There is the phrenic nerves which innervates the diaphragm which tells it to contract or relax during restful breathing.
The intercostal nerves supply the intercostal muscles which helps in additional inspiration or expiration.
Sympathetic and parasympathetic nerves play a role in respiration so damage at the level of the medulla means that you can’t control respiration.
The two lungs are covered in what?
pleura
The pleurae form what?
an envelope between the lungs and the chest wall
What are the two layers of the pleura called and where are these located?
- parietal pleura: the outer layer which lines inside of the chest wall and diaphragm
- visceral pleura: directly on the lung which lines the outside of the lungs
What is in between the two pleural layers?
the pleural cavity with pleural fluid
The visceral pleura is stuck to the _______ and the parietal pleura is stuck to the _______ ________ but this layer is very _____ so as the chest cavity _________, the lung also _________ along with it.
lungs chest cavity thin moves moves
What is the pleural cavity?
This is a slit-like potential space filled with pleural fluid
Do the players of pleura normally separate?
no, the pleural cavity isn’t really there
The fluid layer between the pleura is so minimal, that it creates what?
negative pressure
What is the abbreviation for atmospheric pressure or barometric pressure?
P(atm)
P(b)
What is the abbreviation for alveolar pressure?
P(alv)
P(A)
What is the abbreviation for intra-pleural pressure?
P(ip)
P(pl)
What is the abbreviation for transpulmonary pressure or lung pressure?
P(tp)
P(L)
What is the abbreviation for elastic recoil pressure?
P(el)
What is the abbreviation for resistance?
R
What is the alveolar pressure/intrapulmonary pressure?
pressure inside the lung
What is the intrapleural pressue?
The pressure between the two layers of pleura (in the cavity)
What is the transpulmonary pressure?
The difference between the pressure inside (alveolar pressure/intrapulmonary pressure) and outside the lung (pleural pressure)
Define ventilation
the exchange of air between the atmosphere and alveoli
Air moves by _____ from the region of ______ pressure to _______ pressure
bulk
high
low
What is the equation for bulk flow (F)? What do these symbols mean?
What does this mean for the air flow into or out of the lungs?
F = ΔP/R
where ΔP = pressure difference between two points
R = resistance
F=(Palv-Patm)/R
All pressures in the respiratory system are given relative to atmospheric pressure which is given as what?
760mmHg
When there is no air flow, what assumption can we make about alveolar pressure and atmospheric pressure?
they are equal
We need a pressure gradient to generate air flow. This means we need to create a pressure difference between the ______ and the _______. How can we do this?
lungs
atmosphere
by changing the lung volumes
What is Boyle’s law?
At constant temperature, the volume of a gas varies inversely with absolute pressure.
What happens to the lung volume and pressure during inspiration?
During inspiration – volume of lung (container) is increased – decreased pressure
What happens to the lung volume and pressure during expiration?
During expiration – volume of lung (container) is decreased – increased pressure
What are the two determinants of lung dimension?
Difference in the pressure between the inside and outside of the lung (transpulmonary pressure (Ptp or PL ))
Stretchability of the lungs (compliance) – how much the lungs expand for a given change in Ptp
What is the equation for transpulmonary pressure and what do these components mean?
Ptp = Palv-Pip
where Pressure inside the lung - pressure inside the alveoli (Palv)
Pressure outside the lung - pressure of the intrapleural fluid surrounding the lung (Pip)
Transpulmonary pressure resists the what?
elastic recoiling of the lung
We want a _________ transpulmonary pressure to _________ the volume of the lung
positive
increase
In fibrosis, the lung becomes _______ so it is going to be difficult for the lung to ________
stiff
expand
In emphysema, the alveolar structures become distorted so the lung becomes _________ so it expands but it is going to be difficult to __________ because it loses its _________
flaccid
collapse
elasticity
What is the pressure across the chest wall?
What is the equation?
Pcw =Pip – Patm
Difference between pleural pressure and the atmospheric pressure
During quiet breathing Pip is __________, hence Pcw is __________
negative
negative
The transpulmonary pressure is always
positive
The intrapleural pressure is always
negative
Why is the intrapleural pressure always negative?
The lung always tries to collapse (when there is no airflow in between breaths) but the chest wall always tries to pull open. As these are trying to go the opposite way, the pleural cavity with the fluid doesn’t allow the lungs to collapse or the chest to expand. This means the pressure becomes negative.
For Ptp to be positive Pip should be __________
negative
To keep the lungs open Ptp should be __________- – which opposes elastic recoil
positive
If the parietal pleura or visceral pleura is damaged, what can happen?
The balance is gone so it changes the pressure in the pleural cavity so now the pleural pressure becomes the same as the atmospheric pressure. This means it becomes positive. If the pleural pressure becomes positive, the transpulmonary pressure won’t be positive and so the lungs will collapse
How can the parietal pleura be damaged?
knife wound
How can the visceral pleura be damaged?
you give more O2 to the patient, we increase the positive pressure which can damage the visceral pleura
Which ONE of the following is the key for achieving stable balance between the breaths?
A. Transpulmonary pressure should always be positive
B. Intrapleural pressure should become positive at the
end of inspiration
C. Intrapleural pressure should become positive at the
end of expiration
D. Alveoli should expand in size to its maximum during
inspiration
E. Chest wall should maintain its elastic recoiling in-
between the breath
A. Transpulmonary pressure should always be positive
