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MB prep: Physiology > Respiratory physiology > Flashcards

Respiratory physiology Flashcards

1
Q

What is the respiratory tract

A

The respiratory tract is the path of air from the nose to the lungs
Its structures include; nasal cavity, pharynx, larynx, trachea, primary bronchi and lungs

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2
Q

What are the divisions of the respiratory tract (divided structurally)

A

Upper and Lower

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3
Q

What structures are of the upper respiratory tract

A

Structures above the vocal cords:

👉 Nose
👉 Nasal passages
👉 Paranasal sinuses
👉 Larynx
👉 Pharynx

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4
Q

the respiratory system is composed of 2 parts :

A

a gas exchanging organ
ii) a pump that ventilates (process of gas exchange between the lungs and the environment, includes both inspiration and expiration) the lungs. This pump consists of;
* Chest wall
* Respiratory muscles (which increase or decrease size of the thoracic cavity)
* Brain areas that control these muscles
* Tracts and nerves which connect the brain to the muscles

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5
Q

what are the components of the ‘pump’ of the respiratory system

A
  • Chest wall
  • Respiratory muscles (which increase or decrease size of the thoracic cavity)
  • Brain areas that control these muscles
  • Tracts and nerves which connect the brain to the muscles
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6
Q

a normal person breathes how many times a minute

A

12-15

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7
Q

what is the volume of air breathed per minute

A

500mL of air/breath ie 6-8L/min

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8
Q

how much O2 enter the body/ min

A

250mL

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9
Q

how much CO2 is excreted from the body/ min

A

200mL

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10
Q

what structures are of the lower respiratory tract

A

portion of larynx below the vocal cord:
-trachea,
-bronchi-primary, secondary & tertiary, and
-bronchioles.
-Lungs can be included; (respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli)

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11
Q

functionally what are the divisions of the respiratory system

A

Conducting zone and Respiratory zone (transporting gases vs exchanging gases)

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12
Q

generation 0

A

Trachea

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13
Q

generation 1-2

A

Bronchi (Primary {2}, secondary, tertiary)

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14
Q

generation 3-4

A

bronchiole

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15
Q

generation 5-16

A

Terminal bronchioles

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16
Q

generation 17-19

A

respiratory bronchioles

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17
Q

generation 20-22

A

alveolar ducts

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18
Q

generation 23

A

alveolar sacs

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19
Q

what are the significance of the multiple divisions of the respiratory tree

A

-They greatly increase the cross sectional surface area of the respiratory tract from about 2.5cm2 in the trachea to 11,800cm2 in the alveoli

-They reduce the velocity of airflow in the small airways. This helps prevent the entry of large particles into the lungs.

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20
Q

what is the conducting zone

A

Includes the upper airways from the nose and mouth to the terminal airways (terminal bronchioles). Serve as conduit for the passage of air, but do not function in gas exchange
Structures in the conducting zone undergo an irregular branching for 16 generations, each subsequent generation of airway increasing the total cross-sectional area of the conducting zone. They begin as a relatively narrow passage way, the larynx having the smallest cross-sectional area

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21
Q

what are the structures in the conducting zone

A

-Upper airways (nose, mouth, pharynx and larynx)
-Trachea (0)
-Left & right bronchi (primary bronchus-singular; 1-2)
Secondary bronchi (1-2)
Tertiary bronchi/segmental bronchi (1-2)
-Bronchioles (3-4)
-Terminal bronchioles (5-16

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22
Q

what is the blood supply to conducting zone

A

bronchial arteries

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23
Q

What are the functions of the conducting zone

A

-conditioning of air
-removal of foreign materials
-reaction of foreign materials

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24
Q

explain the conditioning of air function of the conducting zone

A

inspired air is adjusted to body temperature and saturated with water vapour by the time it reaches the trachea during nasal breathing

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25
Q

explain the conditioning of air function of the conducting zone

A

inspired air is adjusted to body temperature and saturated with water vapour by the time it reaches the trachea during nasal breathing

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26
Q

explain the removal of foreign materials function of the conducting zone

A

particulate matter in inspired air is removed by several mechanisms:
-Filtration: as inspired gas passes through the nose, nasal vibrissae (coarse hairs) filters out particles that are larger than 50µ in diameter.

-Impaction: by impaction on the walls of the upper airways (the momentum of these particles cause them to stick to the mucous lining of the airways), particles that are 2-50µm in diameter are removed from inspired gas

-Sedimentation: particles that are 0.01-2µm are largely deposited in the small airways (where flow velocity is very low) and alveoli because of the effect of gravity

-Diffusion: inflammation develops and thus the activation of macrophages when particles less than 0.01µm reach the walls of the terminal airways and alveoli by diffusion.

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27
Q

how does filtration remove foreign particles from the conducting zone

A

as inspired gas passes through the nose, nasal vibrissae (coarse hairs) filters out particles that are larger than 50µ in diameter.

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28
Q

how does impaction remove particles from the conducting zone

A

by impaction on the walls of the upper airways (the momentum of these particles cause them to stick to the mucous lining of the airways), particles that are 2-50µm in diameter are removed from inspired gas

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29
Q

how does sedimentation remove particles from the conducting zone

A

particles that are 0.01-2µm are largely deposited in the small airways (where flow velocity is very low) and alveoli because of the effect of gravity

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30
Q

how does diffusion remove particles from the conducting zone

A

inflammation develops and thus the activation of macrophages when particles less than 0.01µm reach the walls of the terminal airways and alveoli by diffusion.

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31
Q

explain the ‘reaction of foreign materials’ function of the conducting zone

A

-Irritant receptors are located in the large bronchi, they are stimulated by foreign materials

-This leads to reflex bronchoconstriction, cough, and increase secretion of mucous

-Foreign particles and vapour which reach the alveolar surface leads to the presence of increased alveolar macrophages which in turn releases proteolytic enzymes into the lung tissue (proteolytic enzymes are also called proteinase: they break long chain of protein molecules into shorter fragments-peptides-and eventually into amino acids).

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32
Q

draw a diagram of the divisions of the respiratory system

A

check the book

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33
Q

what are the divisions of the the respiratory zone of the respiratory system

A

Respiratory bronchiole (17-19)
Alveolar ducts (20-22)
Alveolar sac/alveoli (23)

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34
Q

what is the blood supply of the respiratory zone

A

branches of pulmonary artery

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35
Q

what is the function of the respiratory zone

A

Primarily in gas exchange across the respiratory membrane (ie between alveolar gas and pulmonary capillary blood, by the process of diffusion).

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36
Q

what are some non-respiratory functions of the respiratory tract

A

-Olfaction
-Vocalization
-Prevention of foreign particles entering the lungs: By filtration, macrophages, cough reflex, sneeze reflex.
-Immunity: leucocytes, macrophages, lung defensins, lung cathelidicins, mast cells, dendritic cells, Natural killer cells.
-Maintainance of water balance by expiration
-regulation of body temperature: by expiration
-regulation of acid-base balance
-anticoagulant: mast cells secrete heparin
-secretion of angiotensin converting enzyme
-secretion of hormones: serotonin, prostaglandins, acetylcholine

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37
Q

what is the respiratory tree

A

Also called the tracheobronchial tree. It refers to the branching structure of airways supplying air to the lungs, and includes:
Trachea
Main bronchus
Lobar bronchus
Segmental bronchus
Conducting bronchiole
Terminal bronchiole
Respiratory bronchiole
Alveolar duct
Alveolar sac
alveolus

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38
Q

what is the difference(s) between the respiratory tract and respiratory tree

A
  1. Location: The respiratory tract extends from the nose/mouth down to the lungs, while the respiratory tree is located within the lungs.
  2. Function: The respiratory tract is responsible for conducting air into and out of the lungs, while the respiratory tree is responsible for distributing air within the lungs and facilitating gas exchange.
  3. Structure: The respiratory tract includes several structures such as the nasal cavity, pharynx, larynx, trachea, bronchi and bronchioles. The respiratory tree is a network of progressively smaller tubes, starting with the main bronchi and branching out into smaller bronchioles.
  4. Size: The respiratory tract is generally larger in diameter than the respiratory tree, which consists of progressively smaller tubes as they branch out.
  5. Composition: The respiratory tract is lined with a variety of tissues including mucous membranes, cartilage, and smooth muscle. The respiratory tree is composed of smooth muscle, elastic fibers, and a thin layer of epithelial cells.
  6. Cross sectional area: The respiratory tract has a smaller cross sectional area than the respiratory tree. (2.5cm2 < 11800cm2)
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39
Q

the epithelial cell of the respiratory tract line what

A

The trachea and bronchus

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40
Q

the mesenchymal cells of the respiratory tract line what

A

The lungs

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41
Q

out of the 13 cells of the lung, how many are epithelial, how many are mesenchymal

A

11 are epithelial cells, and 2 are mesenchymal cells

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42
Q

whats the distrubution of the goblet cells in the respiratory tract

A

are abundant in the upper RT, but fewer down, and absent in the bronchioles.

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43
Q

from the nose to the bronchi, the epithelium is

A

most of the epithelium is covered in ciliated pseudostratified columnar epithelium

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44
Q

cilia moves mucus towards

A

the throat

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45
Q

cartilage is present until …

A

the bronchioles, where it is replaced with smooth muscle

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46
Q

what type of cartilage is in the bronchi (left and right)

A

hyaline cartilage (the rigid cartilage prevents the bronchi from collapsing and blocking airflow to the lungs)

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47
Q

what epithelium lines the bronchi (left and right)

A

ciliated pseudostratified epithelium

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48
Q

the right bronchi branches into how many secondary bronchi

A

3

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49
Q

the left bronchi branches into how many secondary bronchi

A

2

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50
Q

when do the bronchioles constrict

A

They constrict to prevent pollution from dust and other pollutants.

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51
Q

when do the bronchioles dilate

A

during exercise, to let more air in

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52
Q

what are the functions of the lungs?

A

-Respiration
-Alter the pH of blood by facilitating alterations in the partial pressure of CO2
-Converts angiotensin I to angiotensin II by the action of angiotensinogen-converting enzyme
-Serves as a reservoir of blood in the body, blood volume of the lung is about 9% of the total blood volume of the entire circulatory system.
-Serves as a layer of soft, shock-absorbent protection for the heart which the lungs flank and nearly enclose

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53
Q

what cells line the alveoli

A

simple squamous epithelium, (TYPE I)

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54
Q

what is the function of septal cells (type II cells)

A

Septal cells produce alveolar fluid/pulmonary surfactant which coats the inner surface of the alveoli, helps to maintain the elasticity of the lungs, and prevents the thin alveolar walls from collapsing.
-They also help stabilise the alveoli

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55
Q

what is the function of macrophages in the alveoli

A

Macrophages in the alveoli keep the lungs clean and free of infections by capturing and phagocytizing pathogens and other foreign matter that enter the alveoli along with inhaled air

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56
Q

what is the percentage of oxygen in inspired air

A

20.95

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57
Q

what is the percentage of CO2 in inspired air

A

0.04

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58
Q

what is the percentage of nitrogen in inspired air

A

79.01

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59
Q

what is the percentage of CO2 in the alveoli air

A

5.5

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60
Q

what is the percentage of O2 in the alveoli air

A

13.8

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61
Q

what is the percentage of nitrogen in alveoli air

A

80.7

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62
Q

what is the percentage of oxygen in expired air

A

16.4

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63
Q

what is the percentage of CO2 in expired air

A

4.0

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64
Q

what is the percentage of nitrogen in expired air

A

79.6

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65
Q

what is residual volume

A

the volume of air left in the respiratory tract after the most forceful expiration. (1200mL)

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66
Q

what is the significance of residual volume

A

-Prevents collapse of the airways/lungs
-It allows for gas exchange even in periods of low ventilation (such as in sleep)

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67
Q

in normal quiet breathing, what volume of air is drawn in

A

500mL

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68
Q

Out of the amount of air inhaled in normal quiet breathing, what volume mixes with residual volume

A

350mL

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69
Q

what air is concerned with the gas exchange

A

alveoli air

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70
Q

the movement of air, in and out of te lungs is due to…

A

the air pressure changes within the lungs

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71
Q

what is inspiration

A

inspiration also called inhalation is the active process of breathing air from the mouth/nose, through the respiratory tract, and into the lungs

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72
Q

what is normal quiet breathing

A

Normal quiet breathing, also known as resting or tidal breathing, is the process of breathing that occurs during rest or light activity.
During normal quiet breathing, the diaphragm and other muscles involved in respiration contract and relax in a rhythmic pattern to move a small amount of air in and out of the lungs. The volume of air moved in and out with each breath is relatively small, typically around 500 mL, and the frequency of breaths is relatively low, typically around 12-20 breaths per minute.
Normal quiet breathing is sufficient for maintaining normal levels of oxygen and carbon dioxide in the blood during rest or light activity. It is an involuntary process that is controlled by the respiratory center in the brainstem and can be influenced by factors such as
-emotions,
-stress, and
-physical activity.

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73
Q

what is forced breathing?

A

Forced breathing, also known as hyperpnea, is the process of breathing that occurs when the body’s demand for oxygen increases, such as during exercise or in response to respiratory distress.
During forced breathing, the respiratory muscles work harder and contract more forcefully to move a larger volume of air in and out of the lungs. This increased effort requires more energy and can be achieved through the use of additional muscles (accessory muscles of respiration). Forced breathing can also involve an increase in respiratory rate (breaths per minute) to meet the increased demand for oxygen. Forced breathing is an active process that requires conscious effort and can feel more uncomfortable or difficult than normal quiet breathing.
It is necessary for maintaining adequate levels of oxygen in the body during periods of increased demand (such as in exercise) or respiratory compromise.

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74
Q

what are the primary muscles of inspiration

A

-Diaphragm
-External intercostal

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75
Q

describe the diaphragm

A

-A dome-shaped muscle supplied by 2 phrenic nerves
-Its contraction causes an increase in the superior-inferior diameter of the thoracic cavity (contraction of the diaphragm involves its lowering to a more flattened shape; this increases the thoracic volume and thus increases lung volume and thus reduces lung pressure)
-Contraction of the diaphragm accounts for 2/3rd of the air that flows into the lungs in quiet inspiration and 75% of the change in intrathoracic volume during quiet inspiration.

-Contraction of the diaphragm is limited by
-advanced pregnancy,
-obesity, and
-tight abdominal clothing

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76
Q

contraction of the diaphragm is limited by

A

-advanced pregnancy
-obesity
-overeating
-tight abdominal clothing

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77
Q

describe the external intercostals

A

This muscle runs obliquely downward and forward from rib to rib
On contraction, it elevates the lower ribs, thus pushing the sternum outward and thus increase the anterior-posterior diameter of the chest
The transverse diameter also increases, but to a lesser degree
This elevating the ribs and expansion of the rib cage also increases the thoracic volume
Contraction of the external intercostal muscle accounts for the remaining 1/3rd of air that fills the lungs during normal quiet breathin

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78
Q

what are the muscles of normal quiet inspiration

A

-diaphragm
-external intercostal

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79
Q

what are the accessory muscles of respiration

A

These group of muscles are usually called to play in forced inspiration.
They include;
-Scalene
-Sternocleidomastoid
-Alae Nasi
-Small muscles of the head and neck
-Elevators of the scapula and pectoralis major

-In forced/deep inspiration, these muscles on contraction elevate the ribs in an anteroposterior direction (thus increasing thoracic volume)
-At the same time, their contraction stabilizes the upper rib cage so that the external intercostal muscle becomes more effective

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80
Q

describe the actions of the accessory muscles of inspiration

A

-In forced/deep inspiration, these muscles on contraction elevate the ribs in an anteroposterior direction (thus increasing thoracic volume).

-At the same time, their contraction stabilizes the upper rib cage so that the external intercostal muscle becomes more effective

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81
Q

why is expiration in normal quiet breathing passive

A

No muscle which causes reduced intrathoracic volume contract
Normal expiration results from muscle relaxation and elastic recoil of lungs and thoracic cage
In expiration, the reduction in lung volume that results raises the pressure within the alveoli above the atmospheric pressure, this pushes air out of the lungs into the atmosphere

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82
Q

what is expiration sef

A

expiration also called exhalation is the removal of air, containing the by-products of respiration from the lungs, through the respiratory tract, out of the nose/mouth

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83
Q

what are the muscles of forced expiration

A

Rectus abdominis muscle
Transversus abdominis muscle
Internal oblique muscle
External oblique muscle
Internal Intercostal Muscle (on contraction, it depresses the rib cage)

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84
Q

explain the action of the muscles of forced expiration

A

-During forced expiration, these anterior abdominal wall muscles by their contraction force abdominal organs up against the diaphragm thus further reducing the volume in the thorax
-This way, alveolar pressure within the pleural cavities can raise to 20mmHg or 30mmHg above atmospheric pressure

85
Q

state Boyles law…

A

The pressure of a given mass of gas is inversely proportional to its volume

86
Q

state boyles law…

A

The pressure of a given mass of gas is inversely proportional to its volume

87
Q

explain the pressure changes in inspiration

A

-During inspiration, the diaphragm and the external intercostal muscles contract. The diaphragm increases the superior-inferior volume of the thoracic cavity, when it contracts and the external intercostals increases the anterior-posterior volume of the thorax (and also the transverse).

-As the thoracic volume increases, the intrapleural pressure reduces

-Inspiration begins when the alveolar reduces below atmospheric pressure, by 2.5mmHg. This is because the reduction of intrapleural pressure, increases alveolar volume and thus reduces alveolar pressure

-Thus air flows into the lungs, because the alveolar pressure is lower than the atmospheric pressure

88
Q

explain the pressure changes in inspiration

A

-During inspiration, the diaphragm and the external intercostal muscles contract. The diaphragm increases the superior-inferior volume of the thoracic cavity, when it contracts and the external intercostals increases the anterior-posterior volume of the thorax (and also the transverse).

-As the thoracic volume increases, the intrapleural pressure reduces

-Inspiration begins when the alveolar reduces below atmospheric pressure, by 2.5mmHg. This is because the reduction of intrapleural pressure, increases alveolar volume and thus reduces alveolar pressure

-Thus air flows into the lungs, because the alveolar pressure is lower than the atmospheric pressure

89
Q

explain the pressure changes during expiration

A

-During expiration, the diaphragm and any other muscles involved relax, and the thoracic volume reduces

-The reduction of intrathoracic volume, increases the intrapleural pressure

-As expiration begins, the alveolar pressure is higher than the atmospheric pressure, by 3mmHg. Thus is because the increased intrapleural pressure, reduces the alveolar volume, and thus increases the alveolar pressure.

-Thus air flows out of the lungs because the alveolar pressure is greater than the atmospheric pressure.

90
Q

what are the differences between normal quiet breathing and forced breathing

A
  1. Volume of air: During normal quiet breathing, only a small amount of air is moved in and out of the lungs with each breath, while during forced breathing, a larger volume of air is moved in and out of the lungs.
  2. Frequency of breaths: During normal quiet breathing, the frequency of breaths is relatively low (typically around 12-20 breaths per minute), while during forced breathing, the frequency of breaths may increase.
  3. Muscles used: In normal quiet breathing, accessory muscles are not involved. In forced breathing the accessory muscles are involved
  4. Energy expenditure: Forced breathing requires more energy than normal quiet breathing due to the increased use of muscles.
  5. Purpose: Normal quiet breathing is sufficient for maintaining normal levels of oxygen and carbon dioxide in the blood during rest or light activity, while forced breathing is necessary during periods of increased demand such as exercise or when respiratory function is compromised due to illness or injury.
  6. Lung capacity: Forced breathing can utilize a larger portion of lung capacity than normal quiet breathing, which typically only uses about 10% of total lung capacity.
  7. Airflow: During forced breathing, airflow through the airways increases due to the increased volume of air being moved in and out of the lungs.
  8. Gas exchange: Forced breathing may result in greater gas exchange due to the increased airflow and volume of air being moved in and out of the lungs.
  9. Respiratory rate: During forced breathing, respiratory rate may increase to meet the increased demand for oxygen.
  10. Sensation: Forced breathing can feel more uncomfortable or difficult than normal quiet breathing due to the increased effort required to move air in and out of the lungs.
  11. In normal quiet breathing, the expiration is passive. In forced breathing, expiration is active
91
Q

what is work of breathing

A

The work of breathing refers to the amount of energy required to move air in and out of the lungs during respiration

92
Q

why is there no work of breathing for expiration

A

This is because expiration is a passive process that requires no energy (except in forced expiration)

93
Q

the work on inspiration is divided into:

A

3 parts:
-compliance
-tissue resistance
-airway resistance

94
Q

what is compliance?

A

it is the ability of the lungs to expand against the lungs and chest elastic forces. It is simply the ability of the lungs to expand, according to changes in pressure. In easier terms, compliance shows how easily the lungs expand to accommodate a given volume of air
-Also called elastic work
-It accounts for about 65% of the work of breathing
-Compliance work can be calculated from:
∆V x ∆P/2
{∆V (increase in volume), ∆P (decrease in pressure)}

95
Q

what are the types of compliance

A

-static compliance
-dynamic compliance

96
Q

what is static compliance

A

Static compliance is the compliance measured under
static conditions, i.e. by measuring pressure and
volume when breathing does not take place. Static compliance is the pressure required to overcome the elastic resistance of respiratory system for a given tidal volume under zero flow (static) condition.

97
Q

what is dynamic compliance

A

Dynamic compliance is the compliance measured during
dynamic conditions, i.e. during breathing.

98
Q

what does dynamic compliance reduction mean

A

stiff lungs

99
Q

what is tissue resistance

A

It is the work required to overcome the viscosity (resistance to a change in form or shape) of the lungs and chest wall structures
Also called viscous resistance, it accounts for about 7% the work of breathing

100
Q

what is airway resistance

A

It is the work required to overcome airway resistance during the movement of air into the lungs
It accounts for about 25% of the work of breathing

101
Q

what is the 4th type of work of breathing

A

additional work. It is the work required to expand and contract the thoracic cage

102
Q

what is additional work

A

It is the work required to expand and contract the thoracic cage

103
Q

what differentiates compliance, tissue resistance, airway resistance from additional work

A

The 3 (compliance, tissue resistance, airway resistance) only concern the lungs and NOT the thoracic cage, while the additional work concerns the thoracic cage

104
Q

energy needed for compliance of the lungs is how many times that of the lung-thorax system

A

2X.

-The compliance of the total lung-thorax system is only slightly more than half that of the lungs alone

-Thus, almost two times as much energy is required for normal expansion and contraction of the total lung-thorax system as for expansion of the lungs alone

105
Q

so why is more energy needed for the compliance of the lung-thorax system than the lungs alone

A

this is because not only do the lungs expand and contract, but the chest wall and other muscles involved in respiration also move to allow air to enter and exit the lungs.

106
Q

during heavy breathing, the work of breathing is mainly concentrated on what

A

During heavy breathing when air must flow through the respiratory passage at high velocity, the greater proportion of the work of breathing is used to overcome AIRWAY RESISTANCE

107
Q

diseases that cause fibrosis concern what work of breathing

A

compliance and tissue resistance

108
Q

diseases that obstruct the airways greatly increase which which work of breathing

A

airway resistance

109
Q

comment on the work of breathing in expiration

A

No work is done in expiration (normal quiet breathing), however in deep breathing, or when airway resistance and tissue resistance are great, expiratory work does occur and could even become greater than inspiratory work
-In asthma, airway resistance is increased many fold during expiration but much less so during inspiration

110
Q

comment on the energy required for work of breathing in both normal quiet breath and forced/heavy breathing

A

-During normal quiet breathing, only 3 - 4% of total energy expended by the body is required to energize the pulmonary ventilatory process

-But during exercise (esp heavy exercise), the amount of energy required can increase by as much as 50-fold (esp in persons with any degree of increased airway resistance or reduced pulmonary compliance)

111
Q

what is a major limitation to the exercise a person can perform

A

the person’s ability to provide enough muscle energy for the respiratory process alone

112
Q

define compliance in terms of transpulmonary pressure

A

Compliance can also be defined as the change in lung volume as a function of change in the transpulmonary pressure (difference between Palv and the Pip)
This means, a given Ptp will cause greater or lesser expansion depending on the compliance of the lungs

113
Q

what is the normal total compliance of both lungs in an adult human

A

200ml/cmH2O (ie 0.2L/cmH2O)’

This means every time the Transpulmonary pressure increases by 1cm of H2O, the lungs expand by 200ml

114
Q

what does 200ml/cmH2O (ie 0.2L/cmH2O) mean

A

This means every time the Ptp increases by 1cm of H2O, the lungs expand by 200ml

115
Q

how can you measure compliance

A

Compliance can be determined by using the Oesophageal balloon (clinical method for measuring pleural pressure) which will give the Intrapleural pressure

116
Q

The oesophageal ballon gives what value of compliance

A

Intrapleural pressure

117
Q

draw a compliance graph

A

check the book man.

118
Q

what is the volume of functional residual capacities

A

2.3L or 2300mL

119
Q

What factors affect compliance

A

👉Lung Volume; FRC (functional residual capacity, about 2.3L or 2300ml) = ERV + RV is the amount of air that remains in the lungs at the end of normal expiration, FRC affects volume of distribution. Compliance reduces with less lung filling

👉Posture; lung volumes are usually reduced in supine position due to increase in intrathoracic blood volume. Compliance reduces in the supine position due to this reduction in lung volumes

👉Lung diseases; Compliance increases in emphysema (excess air in the lungs, its both obstructive and destructive, and mostly a consequence of long-term smoking) and reduces in fibrosis (which cause loss of elasticity of lung tissue)

👉Thoracic cage disease like Kyphoscoliosis (a musculoskeletal disorder in which there is an abnormal curvature of the spine in both the coronal and sagittal plane, results in under-ventilation of the lungs, and pulmonary hypertension) reduces compliance

👉Alveolar Surface Tension; a very important factor which affects (i.e. it resists distension) the compliance of the lungs is alveolar surface tension

120
Q

what is functional residual volume

A

FRC (functional residual capacity, about 2.3L or 2300ml) = ERV + RV is the amount of air that remains in the lungs at the end of normal expiration, FRC affects volume of distribution

121
Q

state the law of laplace

A

The law of LaPlace describes this; the pressure created is directly promotional to the surface tension and inversely promotional to the radius of the alveolus
P = 2 x T / R

P (pressure, also known as collapse pressure)
T (surface tension)
r (radius of alveolus)

122
Q

what is the implication of the law of laplace

A

the pressure in a smaller alveolus would be greater than that in a larger alveolus if the surface tension is the same in both

123
Q

comment on surface tension in the lungs

A

-A very important factor affecting (i.e. it resists distension) the compliance of the lungs is surface tension that is exerted by fluid in the alveoli

-Although the alveoli is relatively dry, it contains a very thin film of fluid

-Surface tension is created because H2O molecules at the surface are attracted more to other H2O molecules than to air

-Because whenever water forms a surface with air, the water molecules on the surface of the water have an extra strong attraction for one another

-As a result, the surface water molecules are pulled tightly together by attractive forces from underneath.

-The surface tension of an alveolus produces a force that is directed inwards, and as a result creates pressure within the alveolus

124
Q

why is surface tension created in the lungs

A

H2O molecules at the surface are attracted more to other H2O molecules than to air. Because whenever water forms a surface with air, the water molecules on the surface of the water have an extra strong attraction for one another

125
Q

another name for the respiratory zone

A

acinus

126
Q

functions of surfactant

A

-Reduction of surface tension; thus increasing the compliance of the lungs and reducing work of breathing

-Increases the alveolar radius by filling irregularities in the alveolar surface thus reducing the transpulmonary pressure.
This effect increases compliance and reduces the work of breathing

-Surfactant enhances alveoli stability

127
Q

what is surfactant

A

Surfactant is a surface active agent (in that when it spreads over the surface of a fluid, it greatly reduces surface tension), produced by the type II pneumocytes. It is a complex mixture of
-phospholipids (dipalmitoylphosphatidylcholine [DPPC], also called dipalmitoyl lecithin),
-protein (surfactant apoprotein)
-ions (calcium ions, e.t.c)

128
Q

what is the action of surfactant

A

-They don’t dissolve in the fluid, instead, they spread over its surface because one portion of each phospholipid molecule is hydrophilic and dissolves in the water lining the alveoli

-Whereas the lipid portion of the molecule is hydrophobic and oriented towards the air, forming a lipid hydrophobic surface exposed to the air

-The surface thus formed has between 1/12 to 1/2 the surface tension of a pure water surface

129
Q

what is the function of surfactant apoprotein and calcium ion in the surfactant

A

in their absence, the DPPC spreads so slowly over the fluid surface that it cannot function effectively

130
Q

what is the surface tension unit

A

dynes/cm

131
Q

what is the surface tension of water

A

72

132
Q

what is the surface tension of normal fluid lining the alveoli (without surfactant)

A

50

133
Q

what is the surface tension of the fluid lining the alveoli (with surfactant)

A

5-30 (increasing as surface increases)

134
Q

what is the %composition of phosphatidylcholine in surfactant

A

65

135
Q

what is mechanics of breathing

A

It is the sum total of processes that must occur for air to enter the lungs from the atmosphere, and for air to leave the lungs into the atmosphere, as a result of pressure change in lung volume.

136
Q

%composition of Phosphatidylglycine in surfactant

A

5

137
Q

%composition of Other Phospholipids in surfactant

A

10

138
Q

%composition of neutral lipids in surfactant

A

13

139
Q

%composition of CHO in surfactant

A

2

140
Q

%composition of PROTEINS in surfactant

A

8

141
Q

What is RDS

A

-Surfactant does not normally begin to be secreted into the alveoli until between the 6th and 7th month of gestation and in some babies even later than that

-Thus, many premature babies have little or no surfactant in their alveoli, and so the lungs of this babies have extreme collapse tendencies, and this causes their alveoli to collapse

-This condition is called respiratory distress syndrome (RDS)

-It does not occur in all premature babies because the rate of development of the lungs depends on hormonal conditions (esp. thyroxine and hydrocortisone) and genetic factors

-RDS is fatal if not treated immediately with strong measures (properly applied continuous positive pressure breathing)

-Infants with RDS have inadequate gas exchange

142
Q

what is the treatment for RDS

A

properly applied continuous positive pressure breathing

143
Q

why does RDS not occur in all premature infants

A

It does not occur in all premature babies because the rate of development of the lungs depends on
-hormonal conditions (esp. thyroxine and hydrocortisone) and
-genetic factors

144
Q

what diseases are related to surfactant

A

Respiratory distress syndrome
Atelectasis

145
Q

what is atelectasis

A

Atelectasis refers to partial or complete collapse of
lungs, (in an entire lobe, or in an entire lung
). When a large portion of lung is collapsed, the
partial pressure of oxygen is reduced in blood, leading
to decreased partial pressure of oxygen, leading to dyspnea (shortness of breath).

146
Q

causes of atelectasis

A
  1. Deficiency or inactivation of surfactant. It causes collapse of lungs due to increased surface tension, which leads to respiratory distress syndrome.
  2. Obstruction of a bronchus or a bronchiole. In this
    condition, the alveoli attached to the bronchus or
    bronchiole are collapsed.
  3. Presence of air (pneumothorax), fluid (hydrothorax),
    blood (hemothorax) or pus (pyothorax) in the pleural
    space.
147
Q

what is asthma

A

asthma is the respiratory disease characterized
by difficult breathing with wheezing. Wheezing refers
to whistling type of respiration. It is due to bronchiolar
constriction, caused by contraction of smooth
muscles in bronchioles, leading to obstruction of air
passage. Obstruction is further exaggerated by the
edema of mucus membrane and accumulation of
mucus in the lumen of bronchioles. Carbon dioxide accumulates, resulting in acidosis, dyspnea and cyanosis.

148
Q

what are the causes of asthma

A
  1. Inflammation of air passage: Leukotrienes released
    from eosinophils and mast cells during inflammation
    cause bronchospasm.
  2. Hypersensitivity of afferent glossopharyngeal
    and vagal ending in larynx and afferent trigeminal
    endings in nose: Hypersensitivity of these nerve
    endings is produced by some allergic substances
    like foreign proteins.
  3. Pulmonary edema and congestion of lungs caused
    by left ventricular failure: Asthma developed due to
    this condition is called cardiac asthma.
149
Q

in asthma there is a reduction of what

A

i. Tidal volume
ii. Vital capacity
iii. Forced expiratory volume in 1 second (FEV1)
iv. Alveolar ventilation
v. Partial pressure of oxygen in blood.

150
Q

what is emphysema

A

Emphysema is a type of chronic obstructive pulmonary disease (COPD) that affects the lungs. It is characterized by damage to the air sacs (alveoli) in the lungs, which causes them to lose their elasticity and become enlarged. This reduces the surface area available for gas exchange and makes it difficult to breathe.

-Emphysema is most commonly caused by long-term exposure to cigarette smoke or other irritants, and is often associated with chronic bronchitis.

-Symptoms of emphysema include shortness of breath, wheezing, coughing, and chest tightness.

-Treatment may include medications, oxygen therapy, and lifestyle changes such as quitting smoking.

151
Q

what are the causes of emphysema

A
  1. Cigarette smoking
  2. Exposure to oxidant gases
  3. Untreated bronchitis
152
Q

What are the symptoms of emphysema

A

shortness of breath,
wheezing,
coughing, and
chest tightness.

153
Q

What is the treatment for emphysema

A

medications,
oxygen therapy, and
lifestyle changes such as quitting smoking.

154
Q

What is spirometry

A

It’s one of the primary Pulmonary Function Tests (PFT) used to check the health of the lungs and respiratory passageways.

155
Q

What is a spirometer

A

When a spirometry test is performed, the subject breathes through a mechanical or electronic airflow sensor called a spirometer.

156
Q

What are the types of spirometer

A

Mechanical
Electrical

157
Q

Recording of a subjects airflow

A

Spirogram

158
Q

The readings of a spirogram are compared against

A

normal values for an
-individual’s height,
-weight,
-sex, and
-age.

159
Q

A reduced rate of airflow in a spirogram indicates

A

blockage in one or more of the airways (an obstructive disorder),

160
Q

Reduced volume in a spirogram indicates what

A

inability to fully expand the lungs (a restrictive disorder).

161
Q

The amount of air in the lungs is divided into _ and _

A

4 volumes and 4 capacities

162
Q

The 4 lung volumes added together gives what

A

it equals the maximum volume to which the lungs can be expanded

163
Q

What is tidal volume

A

the amount of air that can be inhaled and exhaled during one normal (quiet) breathing cycle (about 500 ml for men & women).

164
Q

What is the value of tidal volume

A

500mL in both male and female

165
Q

What lung volume is synonymous with forced inspiration

A

Inspiratory reserve volume

166
Q

What lung volume is synonymous with forced expiration

A

Expiratory reserve volume

167
Q

What is inspiratory reserve volume

A

the amount of air that can be forcibly inhaled beyond a tidal inhalation (about 3,000 ml for men & 2,000 ml for women).

168
Q

What is the value of inspiratory reserve volume

A

about 3,000 ml for men &
2,000 ml for women

169
Q

What is the value of expiratory reserve volume

A

the amount of air that can be forcibly exhaled beyond a tidal exhalation (about 1100 ml for men & 700 ml for women).

170
Q

What is the value of expiratory reserve volume

A

About 1100 ml for men &
700 ml for women

171
Q

Inspiratory reserve volume of males

A

3000mL

172
Q

Expiratory reserve volume of females

A

700mL

173
Q

Inspiratory reserve volume of females

A

2000mL

174
Q

Expiratory reserve volume of males

A

1100mL

175
Q

What is residual volume

A

theamount of air remaining in the lungs after an ERV (most forced expiration) (= about 1,200 ml in men & women).

176
Q

What is the value of residual volume in male and female

A

1200mL

177
Q

The older you get,…

A

the harder it is for your lungs to breathe in and hold air.

178
Q

What is the implication of breathing less oxygen

A

our body and cells also receive less oxygen, forcing our heart to work harder to pump oxygen throughout the body

179
Q

What forms a respiratory lung capacity

A

2 or more respiratory volumes added together

180
Q

What 2 lung volumes give inspiratory capacity

A

Tidal volume (Vt) + Inspiratory reserve volume (IRV)

181
Q

What is the value of inspiratory capacity

A

3500mL

182
Q

What is inspiratory capacity

A

About 3,500 mL, is the amount of air a person can breath in, beginning at the normal expiratory level and distending(outwardly expanding) the lungs to the maximum amount

183
Q

What 2 lung volumes form functional reserve capacity

A

Expiratory reserve volume (ERV) + Reserve volume (RV)

184
Q

What is the value of functional reserve capacity

A

2300mL

185
Q

What is functional reserve capacity

A

About 2,300 mL, is the amount of air remaining in the lungs after a normal expiration

186
Q

What lung volumes form vital capacity

A

Tidal volume(Vt) + Inspiratory reserve volume (IRV) + Expiratory reserve volume (ERV)

187
Q

What is the value of vital capacity

A

4600mL

188
Q

What is vital capacity

A

-About 4,600 mL, is the total amount of air a person can expel from the lungs after first filling the lungs to their maximum extent

-It is approximately 80 percent of TLC.

-The value varies according to age and body size.

189
Q

Vital capacity varies according to

A

-age
-body size

190
Q

Vital capacity is what % of total lung capacity

A

80%

191
Q

What lung volumes constitute total lung capacity

A

Residual volume (RV) + Vital capacity (VC).

OR

Tidal volume (Vt) + Inspiratory reserve volume (IRV) + Expiratory reserve volume (ERV) + Residual volume (RV)

192
Q

What is the value of total lung capacity

A

5800mL

193
Q

What is the physiological distribution of lung volumes and capacities

A

-All pulmonary volumes and capacities are usually about 20 to 25% less in women than in men, and
- they are greater in large and athletic people than in small and asthenic people

194
Q

Draw a graph to show the lung volumes and capacities

A

Check the book.

195
Q

What is structural dead space

A

Some air breathed doesn’t reach the gas exchange areas, but fills respiratory passages where gas exchange don’t occur (nose, pharynx, trachea)

196
Q

What is the functional dead space

A

On occasion, some of the alveoli are nonfunctional or only partially functional because of absent or poor blood flow (poor perfusion) through the adjacent pulmonary capillaries.

197
Q

What air is expired first in expiration

A

Dead space

198
Q

What is anatomical Dead space

A

-Anatomical dead space is the total volume of the conducting airways from the nose or mouth down to the terminal bronchioles, its about 150ml on the average.

-It can also be described as the portion of the tidal volume that does not take part in gas exchange

199
Q

What is the volume of anatomical Dead space

A

150mL

200
Q

What is physiological Dead space

A

-Physiological dead space is when alveolar dead space is included in the total measurement of dead space

-Physiological dead space includes the anatomical dead space and alveoli which are well ventilated but poorly perfused, and are thus less efficient at exchanging gas with the blood

201
Q

Comment on the dead space in normal people

A

Normally (in healthy individuals), anatomical and physiological dead spaces are nearly equal because all the alveoli are functional in the normal lung

202
Q

Comment on dead space as a disorder

A

But in a person with partially functional or nonfunctional alveoli in some parts of the lungs, the physiological dead space may be as much as 10 times the volume of the anatomical dead space (1L – 2L).

203
Q

Why is physiological Dead space more useful in a clinical setting

A

in a person with partially functional or nonfunctional alveoli in some parts of the lungs, the physiological dead space may be as much as 10 times the volume of the anatomical dead space (1L – 2L).

204
Q

What is the implication of high rates of air exchange in functional alveoli

A

High rates of air exchange in functioning alveoli –> that is higher alveolar ventilation, would bring in fresh oxygen-rich air and efflux carbon dioxide-laden air rapidly; –> consequently, the concentration of oxygen would be higher and the –> concentration of carbon dioxide would be lower within alveoli.

205
Q

What is the implication of low rates of gas exchange

A

low rates of air exchange in functioning alveoli, —> that is lower alveolar ventilation, would bring in fresh oxygen-rich air and efflux carbon-dioxide-laden air slowly; —> consequently, the concentration of oxygen would be lower and —> the concentration of carbon dioxide would be higher within the alveolus.

206
Q

What is alveolar ventilation per minute (Va)

A
  • The total volume of new air that enters the alveoli (tidal volume) and adjacent gas exchange areas each minute.

-It equals the respiratory rate times the amount of new air that enters these areas per minute

207
Q

What is the formula for alveolar ventilation per minute

A

VA = Freq x (VT – VD)

VA (volume of alveolar ventilation per minute)
VT (tidal volume)
VD (physiological dead space volume)
Freq (frequency of respiration per minute ie respiratory rate)

VA = 12 x (500 – 150)
= 4200ml/min

208
Q

What is the value of alveolar ventilation per minute

A

4200ml/min

209
Q

A major factor that determines the concentration of oxygen and carbon dioxide in the alveoli is…

A

alveolar ventilation

MB prep: Physiology (12 decks)

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