pulmonary ventilation Flashcards
1
Q
What are the two forms of lung expansion?
A
- Movement of the diaphragm to lengthen and shorten the thoracic cavity. Normal breathing. 2. Expansion and depression of the rib cage. Heavy breathing-relies on the contraction of abdominal muscles.
2
Q
What are the 4 most important muscles involved in expanding the rib cage?
A
- External intercostal muscles. 2. Sternocleidomastoid 3. Anterior serrati 4. Scaleni
3
Q
What is the role of the sternocleidomastoid?
A
To raise the sternum.
4
Q
What is the role of the anterior serrati and scaleni?
A
To lift the ribs. The scaleni lift the first two ribs.
5
Q
What are the muscles of expiration?
A
- Abdominal recti 2. Internal intercostal muscles
6
Q
What is the midline of the thoracic cavity called?
A
Mediastinum
7
Q
What are the two pleural membranes called?
A
Visceral and parietal. Note they are the same membrane just on two different surfaces.
8
Q
What surface is the visceral pleura found on?
A
Superficial surface of the lungs
9
Q
What surface is the parietal pleura found on?
A
The inner surface of the thoracic cavity
10
Q
What is found in the mediastinum section of the thoracic cage?
A
The hilum of the lungs.
11
Q
What is the pleural pressure?
A
The pressure exerted by the pleural fluid between the visceral and parietal pleura.
12
Q
What is the value of the pleural pressure at the beginning of inspiration? ii. Why is this?
A
- -5cm of water pressure ii. Due to the slight suction of pleural fluid into the lymphatic system.
13
Q
What value does the pleural pressure reach on average during normal inspiration?
A
-7.5cm of water pressure
14
Q
How many litres does the lung volume increase by during inspiration?
A
0.5 L
15
Q
What does occlusion of a pathway mean?
A
BLOCKED- must remember this.
16
Q
What is the alveolar pressure at the beginning of inspiration?
A
0 cm of water pressure. (atmospheric pressure)
17
Q
In order for a pressure gradient to occur, what value does the alveolar pressure drop to?
A
-1 cm of water pressure.
18
Q
In order for expiration to occur what value does the alveolar pressure rise to?
A
+1 cm of water pressure.
19
Q
Define transpulmonary pressure.
A
It is the difference in pressure between the alveolar and pleural pressures. It is also a measurement of the elastic forces in the lungs which tend to collapse them at each instant of respiration. This is called recoil resistance.
20
Q
Define Lung compliance.
A
The ability to for the lungs to expand for each unit increase of Transpulmonary pressure. This is provided that the lungs are given time to reach equilibrium.
21
Q
What are the two types of elastic forces which affect lung compliance?
A
- Parenchymal elastic forces.I.e the collagen and elastin fibres found in the parenchyma of the lungs. 2. Elastic forces caused by surface tension.
22
Q
What is a surfactant?
A
A mixture of Phospholipids, proteins, and ions. It is a surface-active agent of water.
23
Q
Where is the surfactant secreted from?
A
Type ii alveolar epithelial cells. These cells are granular.
24
Q
What are the most important factors of the surfactants?
A
- dipalmitoyl phosphatidylcholine 2. surface apoproteins 3. calcium ions
25
what is the equation for pressure in regards to occluded alveoli caused by surface tension?
Pressure= 2\*surface tension/radius of alveolus
26
Define surface tension.
The characteristic of water particles on the surface to have a strong attraction to water particles on the inner surface due to cohesion. This maintains the rigidity of the shape and minimizes the surface area.
27
What is the average size of an alveolus?
100 micrometers
28
At roughly what period in gestation is surfactant made?
6-7 months
29
What is the name of the condition found in premature babies wherein the likelihood for their alveoli to collapse is 8 times greater then in normal people?
Newborn Respiratory distress syndrome.
30
What is the difference between the compliance of the lungs compared to the entire pulmonary system?
the pulmonary system's compliance is exactly half the value in comparison to the lungs. ~110ml/cm of water pressure to 200ml/cm of water pressure.
31
What are the three forms of work in which inspiration requires energy to battle against?
1. Elastic work - refers to the elastic fibres which prevent the expansion of lung. 2. tissue resistance work - refers to the viscosity of the lung and chest walls. 3. airway resistance work- refers to the resistance from the airways.
32
What machine can be used to measure pulmonary ventilation?
Spirometer.
33
i).What is the definition of tidal volume ii).What is its average value in a young man?
i.The volume of air inspired or expired with each normal breath; ii. 500 ml
34
i).What is the definition of inspiratory reserve volume? ii).What is its average value in a young man?
i.The extra volume of air that can be inspired over and above the normal tidal volume when the person inspires with full force. ii. 3000 milliliters.
35
i).What is the definition of expiratory reserve volume? ii).What is its average value in a young man?
i. The maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration. ii. 1100 milliliters.
36
i).What is the definition of residual volume? ii).What is its average value in a young man?
i. the volume of air remaining in the lungs after the most forceful expiration ii. This volume averages about 1200 milliliters.
37
i).What is the definition of inspiratory capacity? ii).What pulmonary volumes does it equal to?
i.This capacity is the amount of air (about 3500 milliliters) a person can breathe in, beginning at the normal expiratory level and distending the lungs to the maximum amount. ii. Equals the tidal volume plus the inspiratory reserve. volume.
38
i).What is the definition of the functional residual capacity? ii).What pulmonary volumes does it equal to?
i.This capacity is the amount of air that remains in the lungs at the end of normal expiration (about 2300 milliliters). ii. Equals the expiratory reserve volume plus the residual volume.
39
i).What is the definition of the vital capacity? ii).What pulmonary volumes does it equal to?
i.This capacity is the maximum amount of air a person can expel from the lungs after first filling the lungs to their maximum extent and then expiring to the maximum extent (about 4600 milliliters). ii. Equals the inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume.
40
i. What is the definition of total lung capacity? ii. What pulmonary volumes does it equal to?
i. is the maximum volume to which the lungs can be expanded with the greatest possible effort (about 5800 milliliters). ii. Equals to the vital capacity plus the residual volume.
41
What does DLO2 mean?
Diffusing capacity of lungs for oxygen.
42
what does VO2 mean?
Rate of oxygen uptake per minute.
43
what does Vs mean?
Shunt flow.
44
What does R mean?
Respiratory exchange ratio.
45
What does Cvo2 mean?
Concentration of oxygen in mixed venous blood.
46
What does Cao2 mean?
Concentration of oxygen in arterial blood.
47
What does So2 mean?
Percentage saturation of haemoglobin with oxygen.
48
What does Sao2 mean?
Percentage of haemoglobin with oxygen in arterial blood.
49
How do you measure the functional residual capacity? Why can you not measure it directly?
i A spirometer of known volume is filled with air mixed with helium at a known concentration. At the end of this expiration, the remaining volume in the lungs is equal to the FRC. At this point, the subject immediately begins to breathe from the spirometer, and the gases of the spirometer mix with the gases of the lungs. As a result, the helium becomes diluted by the FRC gases, and the volume of the FRC can be calculated from the degree of dilution of the helium, using the following formula: where FRC is functional residual capacity, CiHe is initial concentration of helium in the spirometer, CfHe is final concentration of helium in the spirometer, and ViSpir is initial volume of the spirometer. ii Residual volume remains in the lungs therefore cannot be measured directly using a spirometer.
50
What is the minute respiratory volume? ii. How can you calculate it?
i. It is the total amount of new air passing through the respiratory passages per minute. ii. Equal to the tidal volume times the respiratory rate per minute.
51
What is the normal respiratory rate?
12-20 breaths per minute.
52
Define what alveolar ventilation is.
The rate at which new air reaches the alveoli, alveolar sacs, alveolar ducts, and respiratory bronchioles.
53
Define what dead space air is. Why is it disadvantageous?
Refers to the air that doesn't fill the respiratory passages. It remains in the nose, pharynx, and trachea. ii. As it is the first portion of air to be expired and not the waste products from the lungs.
54
What is the normal dead space air in a young person?
150 ml. It increases slightly with air.
55
How can you measure the dead space air?
Person is 100 percent O2, which fills the entire dead space with pure O2. Then the person expires through a rapidly recording nitrogen meter. The first portion of the expired air comes from the dead space regions of the respiratory passageways, where the air has been completely replaced by O2. Therefore, in the early part of the record, only O2 appears, and the nitrogen concentration is zero. Then, when alveolar air begins to reach the nitrogen meter, the nitrogen concentration rises rapidly, because alveolar air containing large amounts of nitrogen begins to mix with the dead space air. After still more air has been expired, all the dead space air has been washed from the passages and only alveolar air remains. Therefore, the recorded nitrogen concentration reaches a plateau level equal to its concentration in the alveoli.
56
What is the non exchange areas where air may remain in the respiratory system refered to as?
Anatomical dead space.
57
What is the difference between anatomical dead space and physiological dead space. ii. Is there a difference in value?
i.Physiological dead space includes alveoli with poor ventilation or perfusion. Anatomical dead space does not. ii. In healthy individuals the values are equal. However, Unhealthy individuals can have physiological dead space being 1 to 2 litres greater.
58
How do you calculate alveolar ventilation?
Respiratory rate times the amount of new air
59
What maintains the structure of the trachea? (bronchi too)
Multiple cartilage rings five sixths of the way around it. smaller for bronchi and less extensive.
60
What keeps the bronchioles structure rigid?
Transpulmonary pressures which expand the alveoli.
61
What is also present in the walls of the trachea,bronchi and the majority of the bronchioles?
smooth muscle.
62
What do the respiratory bronchiole's walls consist of ?
Mainly pulmonary epithelium and underlying fibrous tissue plus a few smooth muscle fibers.
63
Why is there a greater amount of airflow resistance from the large trachea and bronchi and large bronchioles then there are from the terminal bronchioles?
As there are more bronchioles then bronchi and trachea.
64
In what three ways may the smaller terminal bronchioles add to airflow resistance in certain conditions?
1. muscle contraction in their walls. 2. oedema occurring in the walls. 3. Mucus collecting in the lumens of the bronchioles.
65
The sympathetic system releases what chemicals to assist in bronchial dilation?
Noradrenaline and adrenaline.
66
Where is adrenaline secreted from? Why is it effective for bronchial dilation?
i.Adrenal gland medulla. ii. More effective at causing a stimulation of beta-adrenergic receptors then noradrenaline.
67
What is the role of acetylcholine?
Used for bronchial constriction.
68
Give examples of what may cause cause the parasympathetic constriction reflex?
Irritation of the epithelial membrane of the respiratory passageways are caused by: 1. Cigarette smoke 2. bronchial infection 3. dust 4. noxious gases. 5. Microemboli occlude small pulmonary arteries.
69
What are the two main substances which are formed in the lungs and cause non nervous reflex bronchial constriction? ii. What are they released by?
1. histamine 2. slow reactive substance of anaphylaxis. ii). Mast cells.
70
Where is mucus secreted from on the surface of the respiratory passages?
1. Goblet cells on the epithelium lining. 2. Submucosal glands.
71
What is the role of mucus?
Traps small particles from inspiration and prevent them from reaching the alveoli.
72
How many cilia are there on one epithelial cell?
200
73
What direction is the 'power stroke' of the cilia?
Towards the pharynx. Therefore upwards in the lungs and downwards in the nose.
74
What is the carina?
Point where the trachea divides into the bronchi.
75
What are the stages of the cough reflex?
1. Up to 2.5 liters of air are rapidly inspired. 2. The epiglottis closes, and the vocal cords shut tightly to entrap the air within the lungs. 3. The abdominal muscles contract forcefully, pushing against the diaphragm while other expiratory muscles, such as the internal intercostals, also contract forcefully. Consequently, the pressure in the lungs rises rapidly to as much as 100 mm Hg or more. 4. The vocal cords and the epiglottis suddenly open widely, so that air under this high pressure in the lungs explodes outward.
76
What are the differences between the sneeze reflex and the cough reflex?
For sneeze reflex the uvula is depressed, so large amounts of air pass rapidly through the nose.
77
What are the three main roles of the nasal cavities? ii. What are they together defined as?
1. Warm the air by the conchae and the septum/ 2. Humidify the air. 3. Partially filter the air. ii. These functions together are called the air conditioning function of the upper respiratory system.
78
What are the roles of nose hairs?
1. Filter out large particles. 2. Turbulent precipitation- forces air to change direction and momentum when it hits the hairs however, the particles suspended can;t change as quickly and so hit them.
79
What happens to particles that are: i Greater than 6 micrometers (nasal entrance) ii 1-5 micrometers iii 0.5 micrometers
i. Blocked off by nasal filtration. ii. Lie on the surface of smaller bronchioles via gravitational precipitation. iii. Either diffuse into alveolar fluid or remain in alveolar air and is expired.
80
What are the two mechanical functions which make up speech?
1. Phonation- by the larynx 2. Articulation- by the structure of mouth
81
What is alveolar interdependence?
1. When a collapsing alveolus stretches the ones around it. 2. This in turn causes the alveoli surrounding it to recoil and pull it open.
82
Name the 4 muscles, 2 cartilages and 1 ligament present in the ligament.
ii. Name the 5 movements of the vocal cords.
iii. What causes the pitch of vibrations?
i. thyroarytenoid muscle
lateral cricothyroid muscle
posterior cricothyroid muscle
transverse arytenoid muscle
arytenoid cartilage
thyroid cartilage
Vocal ligament
ii. 1.Full abduction
2. Gentle abduction
3. intermediate position,
4. stage whisper
5. phonation.
iii. The pitch of the vibration is determined mainly by the degree of stretch of the cords, but also by how tightly the cords are approximated to one another and by the mass of their edges
