1
Q
What are the functions of the respiratory system?
A
- Protection of respiratory surfaces – such as water loss, temperature, microorganisms and particulate matter
- Sound production
- Olfactory input – smell
- Blood pH regulation
2
Q
What is the importance of the elastic and collagen components of the lungs?
A
They allow for sthrength and passive recoil (elastic fibres).
3
Q
What are the two divisions of the respiratory system?
A
- Upper respiratory tract – nose, nasal cavities, paranasal sinuses and pharynx
- Lower respiratory tract – larynx, trachea, bronchial tree and lungs
4
Q
What are the two functional divisions of the respiratory system?
A
- Conduction part – involved with transfer of gases – nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles
- Respiratory part – respiration mechanisms – respiratory bronchioles, alveolar ducts and alveoli
5
Q
Histologically, how does the respiratory tract changes as we travel from the conducting part to the respiratory part?
A
The epithelium lining of the respiratory tract changes due to change in function mainly:
- Height of the epithelium changes – changes occur to the height of the cells, as we travel down to the respiratory part cells become more vertically challenged
- The complexity of the epithelium changes – there are less cells of different types present in the epithelium lining as we travel from the conduction to respiratory part of the respiratory tract.
6
Q
How can we describe the function of the ciliated cells in the respiratory tract?
A
Muco-ciliary escalator
7
Q
What type of epithelium is present in the upper part of the airway?
A
A pseudo-stratified ciliated epithelium
8
Q
What type of epithelium present in the parts of the airway that come in contact with food?
A
A stratified squamous epithelium
9
Q
What type of epithelium is present in the lower respiratory tract?
A
A pseudo-stratified ciliated epithelum
10
Q
What type of epithelium is present in the bronchioles?
A
Simple cuboidal
11
Q
What type of epithelium is present in the gas exchange area?
A
Simple squamous epithelium
12
Q
What are the 5 cells of respiratory epithelium?
A
- Pseudostratified columnar ciliated
- Mucous goblet
- Brush
- Basal
- Small granule
13
Q
What is the function of pseudostratified columnar cells?
A
They are the most common cell in the respiratory tract. There function is to be the muco-ciliary escalator.
14
Q
What is the function of the goblet cell?
A
To produce mucus.
15
Q
What is the function of the brush cells?
A
We don’t know but they are there.
16
Q
What is the function of the basal cell?
A
They act as stem cells
17
Q
What is the function of small granule cells?
A
They act as enteroendocrine (release hormones) cells.
18
Q
What are the major functions of conduction portion of the respiratory tract?
A
- Moisten / humidify – serous & mucous secretion
- Warm & humidify – vein network
- Trap dust / allergens – mucus
- Move trapped particles – muco-ciliary escalator
19
Q
What is the function of an epiglottis?
A
It prevents the entry of food from the pharynx to the larynx.
20
Q
What are the three function of the larynx?
A
- Prevent air entry to oesophagus
- Prevent food/liquid entry to lower respiratory tract
- Allow phonation
21
Q
What are anatomical significance of the trachea?
A
- The C shape hyaline cartilage which provides structure
- The muscle and ligament on the posterior surface which allows for contraction and change in shape of the cartilage and prevention of over extension.
22
Q
What type of cartilage present on the bronchus?
A
Irregular shaped hyaline cartilage.
23
Q
At which point does the transition between the conduction and respiratory part of the respiratory system occur?
A
This occurs when terminal bronchioles brunch into respiratory bronchioles.
24
Q
What is the pleura?
A
It is a double serous membrane with collagen and elastic CT. 2 layers – visceral and parietal.
25
What are the three different types of bronchioles?
1. Larger bronchioles
2. Terminal bronchioles
3. Respiratory bronchioles
26
What are the types of cells within the alveoli?
1. Type 1 alveolar cell – flat cell that is used in the blood gass barrier
2. Type 2 alveolar cell – produces surfactant
3. Alveolar macrophage – typical macrophage function – protection by engulfing pathogens and antigens
27
What are the structural part of the alveolar and what are their functions?
1. Respiratory bronchioles – carry gasses to and from the alveolar sacs, connect the alveolar sacs together.
2. Alveolar sacs – sac like collection of alveoli
3. Alveolar ducts – connect the alveoli together
4. Alveoli – respiratory conducting part that have a direction connection to blood gas barrier.
28
What are the functions of the club cells?
1. Produce one component of surfactant
2. Bronchiolar progenitor cells
3. Immune system regulation
4. Environmental protection function (thru use of GAGs, enzymes and other substances).
29
What is the structural importance of basement membrane in alveolar gas exchange?
In order to achieve the optimal diffusion of gasses – the distance between the alveolus and the capillaries need to be minimized.
This is done by fusing the basement membrane of the alveolar septum and the endothelium (capillaries) into 1 shared basement membrane. This means that instead of traveling through 2 seprate membrane, the gas only needs to diffuse through 1 basement membrane, which induces a higher rate of gas exchange between the alveoli and capillaries.
30
What is the function of type II pneumocyte?
Their function is to synthesize and release surfactant. The surfactant is able to reduce the alveolar surface tension and prevent alveolar collapse during expiration.
31
What connective tissue provide support to the alveoli?
1. A few fibroblasts
2. Reticular fibers
3. Collagen fibers
4. Elastic fibers (elastic recoil)
32
What is asthma and what are the potential implication for dental treatment it may cause?
Asthma – a chronic inflammation of the bronchioles.
Potential relation to oral health include:
• Increased caries development
• Reduced saliva flow
• Changes in oral mucosa
• Orofacial abnormalities
33
Why do dentist need to know about the respiratory system?
1. Mouth if part of the upper respiratory system thus dental procedures can impede airflow
2. LA and sedation can alter respiratory function
3. Potential to cause of respiratory episodes
4. Clients pre-existing respiratory conditions could interact with dental procedures
34
What are the function o the respiratory system?
1. Homeostasis of oxygen and carbon dioxide
2. Homeostasis of pH
35
What is cellular respiration?
It is a metabolic process in cells. Cells use oxygen for metabolism and excrete carbon dioxide.
36
What is external respiration?
It is the exchange of oxygen and carbon dioxide between atmosphere and cells of body. It has 4 steps.
37
What are the 4 steps of external respiration?
1. Ventilation or gas exchange between the atmosphere and air sacs in the lungs
2. Exchange of oxygen and carbon dioxide between air in the alveoli and the blood in the pulmonary capillaries
3. transport of oxygen and carbon dioxide by the blood between the lungs and the tissues
4. Exchange of oxygen and carbon dioxide between the blood in the systemic capillaries and the tissue cells
38
So what is the point of the cartilage in the trachea and larynx and why don’t we have in lower respiratory portion of the respiratory tract?
Cartilage provides structure to the upper airways which prevents if from deflating or collapsing when large forces are apply in respiration in order to have ultimate flow of gases.
The alveoli need an ability to stretch for ultimate gas exchange thus having cartilage around them will be counterintuitive. Rather they have elastic tissue for recoil.
39
What protect the lungs entry?
The laryngeal muscle that can open/close are able to provide protection for the glottis thus protecting the lungs from potential pathogens.
40
What are the 4 major aspects in terms of mechanics of breathing?
1. Muscle of respiration involved
2. Elastic properties of the lungs
3. Elastic properties of the chest wall
4. Airway resistance
41
What are the major muscles used in passive inspiration?
These muscles contract every inspiration and their relaxation causes passive expiration.
1. Diaphragm
2. External intercostal muscles
42
What are the major muscles used in forceful inspiration?
On top the diaphragm and the external intercoastal muscles we also have the:
1. Sternocleidomastoid muscles
2. Scalenus muscles
43
What muscles are used in active expiration?
Following muscle contract only during active expiration
1. Abdominal muscles
2. Internal intercoastal muscles
44
What are the 3 important pressure to consider?
1. Atmospheric pressure (pressure outside) – 760 mm Hg
2. Intra-alveolar pressure (pressure in the alveoli) – 760 mm Hg
3. Intrapleural pressure (pressure in the first cavity where the intrapleural fluid is) – 756 mm Hg
45
Why is the pressure in the alveoli and the atmosphere the same at rest?
Because, technically, the alveoli and the atmosphere are connected through the airway thus are they display the same pressure at rest.
46
What is Boyle’s law?
It states that pressure of any gas varies inversely with the volume of the said gas. Basically if the same amount of gas is put in a contain with volume x, another with volume 2x and another with volume 4x, the container x will have 2 timer the pressure than container 2x and 4 times the pressure then container 4x.
47
What are the 5 steps of inspiration?
1. Diaphragm and external intercostal muscles contract
2. Thoracic cage expands up and out
3. Lungs expand
4. This causes a drop in intrapulmonary pressure
5. This cause a drop in intra-alveolar pressure thus movement of air from the atmosphere to the alveoli
48
What are the 6 steps of expiration?
1. Diaphragm and external intercostal muscles relax
2. Thoracic cage moves in and down
3. Lung’s recoil toward pre-inspiratory size
4. Air in lungs compressed
5. Pressure rises above atmospheric
6. Air flows out of the lungs down the pressure gradient
49
What is compliance?
Compliance is the effort required to expand the lungs. Some factors may reduce compliance thus making is hard to breathe. Some things, such as elastic connective tissue that facilitate alveolar recoil, increases elastic compliance.
50
What is surface tension?
Surface tension is a force that make it hard for the alveoli to expand. Basically there are water molecules on the epithelium lining of the alveoli which create the “air-water interface”, but those water molecules are more strongly attracted to each other than the air thus are able to resist the pulling apart while the alveoli expand.
51
How can we overcome the surface tension?
Through use of a surfactant released by type 2 alveolar cells. Surfactant can be released through tubular myeline. It reduces the attraction between the hydrogen bonds of the water molecules thus reducing their resistance to separation while the alveoli expand resulting in an increase in pulmonary compliance.
52
What effects bronchodilation?
1. Neural (sympathetic drive)
2. Chemical (increase carbon dioxide)
3. Hormonal (adrenaline)
53
What effects bronchoconstriction?
1. Neural (parasympathetic)
2. Chemical (reduction in carbon dioxide)
54
What is the anatomical dead space?
It is the air remaining in the airways that cannot participate in gas exchange – around 150ml.
55
What is alveolar ventilation?
It is the volume of air exchanged between the atmosphere and alveoli per min.
56
What is the difference between the alveolar and pulmonary ventilation?
The pulmonary ventilation includes the entirety of the gas injested by a person while alveolar ventilation only includes a part of the gas that is exchanged in the alveoli (pulmonary volume – dead space)
57
What is the significance of dead space?
It is basically constant. Thus if a person has shallow breathing that does not create tidal volume that exceeds the dead space value, they won’t actually perform alveoli respiration.
58
How do gasses move across the blood gas barrier?
Through net diffusion. Thus following appropriate gradients, gases move from area of high concentration to the area of low concentrations until dynamic equilibrium is reached. Note: particles can still move even if equilibrium is reached (hence why it is called dynamic equilibrium).
59
How are lungs specialized for diffusion?
Through used of hundreds and millions of alveoli that can expand, lungs are able to create high surface area which following Fick’s law is great for diffusion of substances.
60
How is partial pressure calculated?
Percentages of the gas times by the total atmospheric pressure.
61
Why is the partial pressure of oxygen slightly lower in the lungs than in the atmosphere?
Because as air passes through the nasal cavity and the mouth it get saturated with water molecules creating water vapor, thus total pressure of air coming in is altered lowering the oxygen partial pressure.
Also the fresh air that comes in contact and mixes with dead space air thus lowering partial pressure of oxygen even further.
62
So how does partial pressure help with diffusion?
Partial pressure in different mediums drive diffusion as the gasses will move down their partial pressure gradients. For example, the partial pressure in the alveoli upon inspiration is higher than the alveolar capillaries – thus oxygen moves into the capillary. It travels down the circulatory system and reaches target tissue which has lower partial oxygen pressure than the capillary – thus oxygen moves from the capillary into said tissue.
Carbon dioxide follows a similar blue print but in reverse.
63
What other factors influence rate of gas transfer?
1. Surface area – Fick’s law
2. Difussion coefficient of the molecule
3. Distance – that is why the basement membrane is fused to reduce the distance – can be increased by pathological conditions thus reducing the gas exchange rate
64
How is oxygen transported?
By physically dissolving in blood or bound to hemoglobin (majority transporter) in red blood cells. Deoxyhamoglobin (non-oxygen hemoglobin) is able to bind up to 4 molecules of oxygen (creating saturated oxyhamoglobin). Thus hemoglobin is way more effective way to deliver oxygen.
65
How does haemoglobin help to increase the diffusion of oxygen into the alveolar capillaries?
1. Hemoglobin is able to carry the oxygen molecules that are dissolved in blood]
2. This uptake of oxygen reduces the partial pressure of oxygen within the blood capillaries
3. This decrease in partial pressure of oxygen changes the concentration gradient
4. Lower concentration of oxygen leads to a higher uptake of oxygen by diffusion from the alveolar
66
What is the Bohr effect?
It is a description of factors that influence the release of Oxygen from haemoglobin
These are
1. Carbon dioxide levels – reduces affinity
2. Acidity – reduces affinity
3. Temperature – reduce cell metabolism
4. BPG – changes affinity by binding
67
How much carbon dioxide does our body excrete?
It is usually the same amount as the oxygen we consume
68
How is carbon dioxide transported through the body?
10% - physically dissolved
30% - bound to haemoglobin – carbamino haemoglobin
60% - as bicarbonate – combining with water in RBC and carbonic anhydrase (catalyst) – thus bicarbonate and hydrogen ions. Bicarbonate is moved though the chloride counter pump and hydrogen ions combine with haemoglobulin (Haledon effect at the alveolar)
69
What causes an increase in affinity between hemoglobin and oxygen?
At the lungs, carbon dioxide is given up by red blood cells into the alveoli. Carbon dioxide concentration falls, thereby shifting the oxygen equilibrium curve to the left; the increase in hemoglobin oxygen affinity enhances uptake of oxygen from the alveoli.
70
How is breathing sustained?
Breathing is sustained through rhythmic contraction of the skeletal muscles that are innovated with nerves and involved in inspiration and active expiration.
71
What are the two respiratory centers in the brain?
1. Pons respiratory center – smooth breathing – vagal efferent fibres
2. Medullary respiratory center – quite breathing – contains the dorsal respiratory group with respiratory neurons that connect to the motor nerves of the inspiratory muscles – also contains ventral respiratory group – used for active breathing.
72
What is the role of the Pre-Botzinger complex?
It is thought to be a pacemaker center of the respiratory system
73
What is the function of the pneumotaxic center?
Fires signals to DRG to reduce breathing
74
What is the function of the apneustic center?
Fires signals to the DRG to increase breathing
75
How does the respiratory center in the brain able to control oxygen and carbon dioxide level to meet metabolic demand?
Chemical control:
Chemoreceptors:
1. Peripheral chemoreceptors – carotid bodies and aortic bodies – respond within second to blood gas and pH changes (H+ ions)
2. Central chemoreceptor – located in medulla – detect changes in pH in brain extracellular fluid
76
Why is ventilation not primarily regulated by arterial Po2?
Because, chemoreceptors are unable to appropriately measure the amount of oxygen in the body as majority of it is bound with haemoglobin. It is only used as the emergency mechanism.
77
How does oxygen act as a emergency mechanism to trigger a increased respiratory function?
Basically when arterial partial pressure of oxygen drops bellow a threshold of 60 mm Hg, the peripheral chemoreceptors are able to detect it and fire a signal to the medullary respiratory center. The medullary respiratory center is able to increase ventilation thus increasing the arterial partial oxygen pressure.
78
How does the arterial partial pressure of CO2 influence respiratory function?
1. The peripheral chemoreceptors have a very weak response to the increase of carbon concentration in blood
2. The central chemoreceptors are the main receptors in the cascade that relates to the increase in respiration in response to increased carbon dioxide levels.
79
How does the central chemoreceptors actually detect the changes in carbon concentration in blood?
The central chemoreceptors are very sensitive to the amount of H+ ions in the brain ECF.
Thus:
1. CO2 travels in the blood
2. It is able to convert into bicarbonate and a hydrogen ion with use of carbonic anahydrase near the brain ecf
3. The increased H+ concentration results in chemoreceptor detection and triggering the firing of neurons and increase in respiration
80
What happens during the period where you hold your breath?
1. Decrease PoO2 and and increate in PoCO2 in the arterials
2. Increased extreccular fluid CO2 in the brain
3. This triggeres an increase in H+ in the brain
4. Stimulation of central chemoreceptors activate MRC
5. Inspiration occurs
81
What happens during hyperventilation?
Alkalosis by decrease of CO2
82
What are some of the signs of breathing difficulties?
1. Use of accessory muscles
2. Dyspnea – mental anguish associated with lack of air – elevated levels of CO2 or feedback from muscles
3. Wheezing – due to narrow airways
4. Cyanosis – very late sign – blue color of nail beds – remember that hemoglobin level is the same it is just the ability to acquire oxygen form the atmosphere is reduced
83
What are some of the more common pathophysiological changes related to major respiratory diseases?
1. Airways obstruction and loss
2. Alveoli loss
3. Restrictive – loss of compliance due to fibrosis and loss of elasticity – could also be due to scoliosis or kyphosis which restricts the ability of the thoracic cage to inlarge
84
What is COPD?
It is an umbrella term that stands for chronic obstructive pulmonary disease. These disease are able to increase airway resistance in a multitude of way – but primarily through narrowing of lower airways.
85
What diseases can be classified as COPD?
Asthma, Chronic bronchitis and emphysema.
86
What are causes of asthma?
Asthma can be triggered by irritants, allergens, respiratory infections or vigorous exercise.
Asthma is a result of over secretion of thick mucus as well as airway hyper responsiveness – spasm of smooth muscles.
87
What are the causes of chronic bronchitis?
It is a disease that is caused by air allergen of cigarette smoke. Airway oedema and thick mucus over production. As well as impaired cilia, so mucous not cleared even with coughing. This results in frequent bacterial infection. Not able to use bronchodilators.
88
What are the causes of emphysema?
It is caused by irritants and is mediated by a sever respiratory macrophage response. Macrophage produce trypsin, an enzyme that degrades protein in excessive mounts thus damaging the elastic fibers reducing the alveolar recoil.
89
How to COPD influence energy expenditure for the respiratory function?
Patients with COPD need to use more energy to perform appropriate respiratory function due to
1. Decreased compliance of the lungs
2. Increased airway resistance
3. Decrease elastic recoil
Thus they use accessory respiratory muscles thus requiring more energy.
90
What is the relationship between the resistance and the radius of the airways?
The reduction in airway radius increases the resistance
91
With a patient with COPD how can airway collapse?
1. Under normal circumstance the airway pressure remains slightly above the intrapleural pressure
2. During force inspiration by a patient with COPD – there is an increase in intra-alveolar and intrapleural pressure
3. Airway pressure drops below pressure in chest
4. Thus the airway that are not supported by cartilage collapse
5. That is why COPD patient find it harder to breath out than breath in as collapsed airway lead to loss of elastic recoil and increased airway resistance
92
What is the big differences between a person with obstructive and restrictive lung disease?
A person with COPD can inspire normally but expire poorly.
While a person who have restricted elasticity in alveoli inspires poorly and expires fine.
93
How does parasympathetic nervous system regulate the respiratory function?
Parasympathetic nervous system cause the contraction of bronchiolar smooth muscle thus causing a constriction of airway and increased airway resistance.
94
How can we upregulate the function of the respiratory system?
Through relaxation of smooth muscle by adrenaline and sympathetic signaling which will cause dilation of the airway and decreased airway resistance.
95
So how does hypoventilation influence respiratory function?
Hypoventilation is able to change pressure gradients for both oxygen and carbon dioxide.
It reduces the partial pressure of oxygen in the alveoli due to dead space air, thus less oxygen is able to diffuse into blood capillaries – reducing the overall oxygen saturation in the organism.
It reduces the excretion of carbon dioxide thus increasing the carbon saturation of blood.
96
What is hypoxia?
Inadequate amount of O2 at the level of the cells – limits cellular energy production.
97
What are the 4 types of hypoxia?
1. Hypoxic hypoxia – low arterial PO2 and Poor Hb saturation – caused by insufficient gas exchange and high altitude
2. Anemic hypoxia – diminished capacity to transport oxygen in blood – low RBC, insufficient Hb, CO poisoning
3. Circulatory hypoxia – limited transport of O2 – potential local blockage in the vasculature or congestive heart failure
4. Histotoxic hypoxia – cells can not utilize O2 – cyanide poisoning
