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Mechanisms of breathing Flashcards

1
Q

What is the primary purpose of the respiratory system?

A

Gas exchange - getting oxygen to tissues and removing carbon dioxide

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2
Q

In health, how much of our metabolic energy is used in ventilation?

A

1-2% - It has evolved to be very efficient.

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3
Q

what is the function of the oral and nasal cavity?

A

It is an Inlet and outlet that allows filtration (to catch particles we don’t want in our lungs), humidification (adding water) and warming of the air

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4
Q

Describe what should happen when a particle such as bacteria is inhaled into the oral and nasal cavity, to prevent it entering the lungs?

A

Secreted mucus traps participles such as bacteria and these are swept back into the pharynx (cavity behind the nose and mouth, connecting them to the oesophagus) where they can either be swallowed or coughed up.

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5
Q

what are nasal turbinate and what is their role?

A

They are structures on inside of the nose that project into the nasal passage as ridges of tissue and cause turbulence. Bouncing the air of the wall of the nasal cavity ensures that particles will get stuck in mucus.

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6
Q

on average, how many generations of airways does a human have? (where one airway branches into two or more smaller airways) and what are the first and last generation?

A

23
The trachea is generation 0 - the first airway.
The last generation are the alveoli.

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7
Q

what are the structures that supply the lung with air?

A

right and left primary bronchus

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8
Q

name two things that are found in the bronchi?

A

mucus and cilia

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9
Q

name the cells that secrete mucus in the trachea

A

goblet cells

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10
Q

some drugs decrease cilia motility, what can this lead to?

A

mucus congestion and infections

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11
Q

what happen to the bronchi and small bronchi in chronic bronchitis?

A

inflamed bronchi secrete more mucus, narrowing the diameter of the airway and making it more difficult to breathe.

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12
Q

name the structures that come after the small bronchi?

A

the bronchioles

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13
Q

what is present in the airways prior to generation 11 and what changes occur after this?

A

Prior to generation 11 airways are held open by cartilage. At generation 11, there is no longer cartilage which means airways can collapse and expand.

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14
Q

what forms the conducting airways and what generation are they? and what is their primary role?

A

the trachea, bronchi and bronchioles. these are generation 0-16. their primary role is to get air from the nasal and oral cavity down to the terminal respiratory unit, where gas exchange takes place.

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15
Q

what is meant by the term dead space ventilation?

A

this is ventilation that does not take part in gas exchange

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16
Q

roughly how much of every breath is dead space ventilation?

A

~100-150ml.

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17
Q

where will dead space ventilation be found and why will it be found here?

A

in the conducting airways as no gas exchange takes places here.

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18
Q

what makes up respiratory units and name two things that take place here?

A

respiratory bronchioles, alveolar ducts and alveoli. Air conduction and gas exchange.

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19
Q

what happens as you move from generation 16 to 23?

A

you get more and more alveoli.

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20
Q

around how many alveoli are there in the lungs?

A

300 millions

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21
Q

what is associated with each alveoli and what takes places here?

A

blood supply where gas exchange takes place.

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22
Q

how many respiratory units are then in our lungs? and how many alveoli are associated with each of these?

A

130,000

each of which have ~2,000 alveoli

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23
Q

name the structure that can close and help open up respiratory units?

A

respiratory bronchioles

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24
Q

name 4 changes that occur as you move through the airway

A
  1. airways get progressively smaller in radius
  2. type of epithelial that lines airway changes: columnar in the trachea, cuboidal in the bronchi and squamous in the alveoli
  3. cilia and mucus production in the early parts of the airways (trachea, bronchi and bronchioles)
  4. cartilage present up until generation 11
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25
describe the pleural membrane
It is a serosal membrane of cells that folds back on itself and forms a cavity between the two sheets (pleural cavity). Partial pleural is attached to the chest wall and the visceral pleural is attached to the lungs.
26
which part of the pleura is heavily innovated (rich nerve supply) and thus will you feel pain in during pleurisy (pleural inflammation)?
the parietal pleura
27
what is found visceral pleura and what is its function?
network of lymphatic vessels that drain the pleural space.
28
what is intrapleural pressure?
the pressure within the pleural cavity
29
what is usually found in the pleural cavity and why?
and thin layer of fluid to prevent friction
30
how much fluid is should be found in the pleural space?
10ml
31
if there is fluid in the pleural space, why are the two membranes help together?
surface tension within the fluid
32
what is the pleural cavity?
its is a virtual space between the two pleural membranes containing a thin layers of fluid that acts as a lubricant.
33
what generates the intrapleural pressure at rest? and what affect does this have on the pleural membranes?
the elastic tissue of the lungs wanting to recoil and collapse and the chest wall wanting to spring out. these opposing forces are trying to pull the two membranes apart, generating a slightly negative pressure inside the cavity.
34
if the glottis is open, what will the pressure in the alveolar be?
the same as atmospheric pressure
35
if you had a pressure device why would you not want to put it into the pleural cavity?
puncturing the pleural membrane will disrupt surface tension, the two membrane will come apart, the lungs will collapse and the chest wall will spring out.
36
what conditions would you want to measure intrapleural pressure at?
under static conditions, where you have no breathing and the glottis is open, and so the alveolar pressure will = the atmospheric pressure
37
under static conditions, what will the pleural pressure be and why is this the case?
under static conditions the pleural pressure will be -0.5kPa, less than atmospheric pressure (0) as the lungs and chest wall pull away from each other.
38
how can we measure the intrapleural pressure and why can we do it in this way?
we can measure the intrapleural pressure by inserting a balloon ~30-35cm through the nose and into the oesophagus. The pleural pressure will be transduced throughout the thoracic cavity. The oesophagus is a thin walled and flaccid and so changes in pressure in the pleural space will be transferred to the oesophagus.
39
what is the intrathoracic pressure equal to?
the pleural pressure
40
name the two scenarios were intrapleural pressure is different (in health)
in different parts of the thorax and at different times of the respiratory cycle
41
during expiration, while standing, where is intrapleural pressure most negative?
at the apex of the lung
42
during expiration, while standing, what is the intrapleural pressure at the apex and the base of the lung?
- 0.8 kPa | - 0.2 kPa
43
why are the differences in intrapleural pressure at the apex and the base of the lung?
gravity is pulling the lungs (relatively heavy blood filled sacs) down, pulling the lungs away from the partial pleural more so than at the base, resulting in a more negative intrapleural pressure at the apex than at the base
44
how will intrapleural pressure change when we inhale?
it will become slightly more negative as muscles in the chest wall contract and pull out and the diaphragm pulls down, pulling the partial pleura away from the visceral pleura, volume of the thoracic cavity increases, driving the lungs to expand
45
how will intrapleural pressure change when we exhale?
it becomes slightly more positive, diaphragm and external intercostal muscles relax, volume of thoracic cavity decreases and the lungs passively recoil
46
how does intrapleural pressure change if you mechanically ventilate someone?
the opposite to what normally happens occurs. pushing air into the lungs pushes the visceral pleura out and so makes interpleural pressure less negative on inhalation.
47
what holds the two pleural membranes together?
surface tension
48
how does the chest wall expanding lead to the lungs expanding?
as the chest wall expands, the parietal pleura will follow. due to surface tension and the more negative intrapleural pressure, the visceral pleura will follow the parietal pleura, pulling the lung tissue out and causing them to expand
49
define biochemical respiration? (internal respiration)
ATP produced from ADP by oxidative phosphorylation of organic molecules, consuming oxygen and producing carbon dioxide and water.
50
define physiological respiration?
the process by which oxygen and carbon dioxide are exchanged between internal and external environments (ventilation and external respiration )
51
which process in the respiratory cycle requires energy? and what is it used for?
inspiration | contraction of chest wall muscles and the diaphragm (expanding thoracic cavity)
52
which process of the respiratory cycle should be passive i.e. in health? and what is this down to?
expiration. this is down to release of stored energy in recoil of elastic lung tissue, wanting to return lungs to their original size and shape.
53
how does normal expiration vary from forced expiration?
it requires energy through the use of muscles
54
there is always air left inside the lungs, even after forces expiration, how much residual volume will be left inside the lungs? why is this important (2)?
1-1.5 L this is important to maintain gas exchange during expiration as blood flow wont stop and to prevent lungs form collapsing
55
even during pneumothorax, where the lungs collapse maximally, there will still be around 0.5 L of air in the lungs, why?
smaller bronchioles that don't have cartilage will collapse, trapping around 0.5 L of air in the lungs.
56
describe the respiratory system at rest?
respiratory muscle are at rest, there is a balance between forces of collapse (elastic recoil of the lungs) and expansion (elastic recoil of the chest wall) of the thoracic cavity
57
during inspiration, the inspiratory muscle contract, what affect does this have on thoracic volume, intrapleural pressure, lung volume and alveolar pressure, and what result does this have?
increases thoracic volume, decreases intrapleural pressure, increases lung volume and decreases alveolar pressure, which draws air into the lungs
58
during expiration, the inspiratory muscle relax, what affect does this have on thoracic volume, intrapleural pressure, lung volume and alveolar pressure, and what result does this have?
decreases thoracic volume, increases intrapleural pressure, decreases lung volume and increases alveolar pressure, which expels air out of the lungs up until their functional residual capacity
59
during forced expiration, the expiratory muscle contract, what affect does this have on thoracic volume, intrapleural pressure, lung volume and alveolar pressure, and what result does this have?
decreases thoracic volume, increases intrapleural pressure, decreases lung volume and increases alveolar pressure, which expels air out of the lungs below their functional residual capacity
60
what muscles are used in forced expiration?
abdominal muscles (e.g. internal and external oblique, rectoabdominal and transverse abdominal), internal intercostal muscles and some back and neck muscles
61
what nerves supply the diaphragm? and where does it originate?
the right and left phrenic nerve, originates in C3-C5 in the neck
62
describe the diaphragm during expiration
when the diaphragm is relaxed it is domed up into the thoracic cavity, reducing the size of the thoracic cavity
63
describe the thoracic cavity during inspiration
when the diaphragm is contracted it flattens out, pulling down, increasing the size of the thoracic cavity
64
when does the diaphragm work best and why?
when we are standing up as gravity will assist it in pulling down and increasing the size of thoracic cavity during inspiration
65
which intercostal muscles are used most in inspiration and what do they do?
the external intercostal muscles. when they contract the pull the ribs up and out, making the thoracic diameter bigger
66
which intercostal muscles will be used in force expiration and what do they do?
the internal intercostal muscles, when they contract they pull the ribs down and in, decreasing the thoracic diameter
67
which intercostal muscles are not involved in normal tidal breathing?
the internal intercostal muscles
68
name two accessory muscles of the neck that can be used in forced inspiration to use our inspiratory reserve and what do they do?
the scalenes lift the first two ribs up and sternocleidomastoid move the sternum out.
69
describe what happens in pneumothorax/haemothorax?
air/blood within the pleural space due to disruption of the pleural membrane. lung collapses due to elastic recoil as it is no longer held to rib cage by surface tension. when severe, the chest wall will also spring out through elastic recoil as there is no longer a balance of forces holding it where it should be.
70
how would you treat a pneumothorax/haemothorax and what affects should this have?
insert chest drain to remove air/blood, in the hope to realign the pleural membranes and re-expand the lung and get back to normal ventilation. in a less severe pneumothorax they may have spontaneous recovery where they do not require a chest drain (this relies on whatever caused the pneumothorax to have healed and for the lymphatic system in the visceral pleura to have drained any fluid that was in the pleural space)
71
what affect does a pneumothorax/haemothorax have on the ability to ventilate?
there is a reduced ability to ventilate as a lung has collapsed - pleural membranes no longer attached to each other
72
why may coughing lead to pneumothorax?
need to generate more pressure to force air out of the lungs, and this pressure may rupture the alveoli and the visceral pleural membranes
73
what may tall young males have in their pleural membranes and what might this lead to?
genetic imperfections in the pleural membranes called blebs, these are weaknesses that can easily rupture and leads to a spontaneous pneumothorax
74
what is a haemothorax and what is it commonly caused by?
blood in the pleural cavity. common cause by penetration and blunt trauma
75
how much blood can the pleural cavity hold in a haemothorax?
up to 3 L
76
what effect will inserting a chest drain in a pneumothorax have?
removing air from the pleural space will generate a more negative intrapleural pressure, this will pull the lungs back out towards the partial pleura.
77
what type of dressing needs to be applied after you have removed the drain and why?
an air tight dressing as you have created a disruption to the pleura and don't want to generate another pneumothorax.

Case 6 (3 decks)

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