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SOM 202 > WEEK1: REGULATION OF BREATHING AND COUGHING > Flashcards

WEEK1: REGULATION OF BREATHING AND COUGHING Flashcards

1
Q

Outline the functions of the respiratory system.

A

Delivery of O2 to the lungs and the expulsion of CO2 and H2O out of the lungs.​

Diffusion of O2 into the bloodstream and the diffusion of CO2 out of the bloodstream. ​

Regulation of the acid-base levels of blood. ​

Filters, warms, and humidifying inspired air. ​

Speech and melody created by the vibration of the vocal folds. ​

The process of detecting smell via olfactory receptors. ​

Protects the respiratory surfaces from dehydration and temperature change.​

Defends the body against inhaled pathogens.

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2
Q

What is Breathing or ventilation?

A

Ventilation, or breathing, is the movement of air through the conducting passages between the atmosphere and the lungs.

It is the provision of fresh air to the lungs

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3
Q

What is respiration?

A

respiration is the gas exchange between the body and the external environment

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4
Q

Define the following terms:
*Pulmonary ventilation
*External ventilation (alveolar respiration)
*Internal ventilation (Tissue respiration)

A

*Pulmonary ventilation: this includes the inhalation and exhalation of air between the atmosphere and the alveoli​

*External respiration (Alveolar respiration) : exchange of gases between the alveoli of the lungs and the blood in pulmonary capillaries. In this process the blood gains O2 and loses CO2.​

*Internal respiration(tissue) is the exchange of gases in the systemic capillaries and tissue cells. In this process the blood loses O2 and gains CO2.​

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5
Q

Define the following terms of pulmonary ventilation:

*Residual volume
*Expiratory reserve volume
*Resting tidal volume
*Inspiratory reserve volume
*Inspiratory capacity
*Functional residual capacity
*Vital capacity
*Total lung capacity

A

*RESIDUAL VOLUME: It is air remaining in the lungs after maximal exhalation

*EXPIRATORY RESERVE VOLUME: the maximal amount of extra air that can be forcefully exhaled after a normal exhalation

*RESTING TIDAL VOLUME: The volume of air inspired and expired during normal breathing.

*INSPIRATORY RESERVE VOLUME: the maximal amount of additional air that can be forcefully drawn into the lungs after a normal inspiration.

*INSPIRATORY CAPACITY: measures how much air you can breathe into your lungs after you breathe out normally.

*FUNCTIONAL RESIDUAL CAPACITY: the volume remaining in the lungs after a normal, passive exhalation.

*VITAL CAPACITY: the greatest volume of air that can be EXHALED after DEEP INSPIRATION.

*TOTAL LUNG CAPACITY: the maximum volume of air the lungs can hold.

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6
Q

What are the standard volumes for the following:

*Total lung capacity:
*Expiratory reserve volume:
*Residual volume:
* Inspiratory reserve volume:
*Resting tidal volume:

A

*Total lung capacity: 6000ml (6l)
*Expiratory reserve volume: 1300ml
*Residual volume: 1200ml
* Inspiratory reserve volume: 3000ml
*Resting tidal volume: 500ml

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7
Q

State the formulas for calculating the following:
*Inspiratory capacity
*Functional residual capacity
*Vital capacity

A

IC= TV+ IRV
FRC= RV+ ERV
VC= IRV+ERV +TV

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8
Q

NOTE: lung capacities are the sum of two or more lung volumes.

LUND VOLUMES are the 4 distinct components of the TOTAL LUNG CAPACITY.

A
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9
Q

What is minute ventilation?

A

Minute ventilation is the volume of gas inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a person’s lungs per minute.

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10
Q

What is alveolar ventilation?

A

Alveolar ventilation is the exchange of gas between the alveoli and the external environment.

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11
Q

State the formula for calculating minute ventilation.

A

Respiratory rate (breath/ min) x Tidal volume (ml/breath)

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12
Q

What is tidal volume and respiratory rate?

A

Tidal volume is the amount of air that moves in and out of the lungs during normal breathing.

Respiratory rate is the number of breaths per minute.

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13
Q

What is anatomical dead space? State its volume.
What is alveolar dead space?
What is physiologic dead space?

A

*Anatomical Dead space is 150 mL (air in the conducting airways)

*Alveolar dead space; Air reaches these alveoli, but they are not perfused as such the oxygen is not extracted​

-the volume of gas in the lungs that does not participate in gas exchange (alveolar ventilation) and is represented by the space in alveoli occupied by air that does not participate in oxygen-carbon dioxide exchange.

*Physiologic dead space-Alveolar dead space and anatomical dead space

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14
Q

What is the formula for calculating alveolar ventilation?

A

(Tidal volume - Dead space) x respiratory rate

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15
Q

Describe the steps of external respiration.

A

1.Ventilation: exchange of gas between the alveoli sacs and the external environment.

2.Alveolar respiration: exchange of oxygen and Carbon dioxide down partial pressure gradient between alveoli and blood in pulmonary capillaries

3.Gas transport: between the lungs to body tissues

4.Tissue respiration: exchange of oxygen and Carbon dioxide between systemic capillaries and the body tissues.

5.Tissue respiration: The use of oxygen to release energy via aerobic respiration.

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16
Q

State factors influencing the rate of air flow and the amount of effort needed for breathing.

A

*Alveolar surface tension ​:

*Compliance of the lungs​: The lung’s ability to stretch and expand (distensibility of elastic tissue)

-This refers to how much effort is required to stretch the lungs and chest wall. High compliance means that the lungs and chest wall expand easily; low compliance means that they resist expansion.​

*Surfactant

*Air way resistance

-The rate of air flow through the airways, depends on both the pressure difference and the resistance.

-This is determined by the diameter of the bronchioles and signals from the sympathetic system.​
*Elastance

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17
Q

What is elasticity?
Describe factors that influence lung elasticity.

A

The ability of an object or material to resume its normal shape after being stretched or compressed.

The tendency of a material to try and maintain its shape and offer resistance to stretching forces.

Because of the presence of elastic and collagen fibers in their parenchyma.

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18
Q

Name and describe the law that illustrates elasticity.
What is the formula for elastance?

A

Hooke’s law states that the amount of force applied to an elastic object is proportional to how far it stretches.

Elastance= Change in pressure/ Change in volume

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19
Q

Distinguish between elasticity and compliance.

A

Elasticity is the ability of the lungs to return to original shape after stretching while compliance is the ability of the lungs to stretch.

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20
Q

State two components which are found in surfactant.

A

Surfactant consists of the phospholipids dipalmitoyl lecithin and sphingomyelin​

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21
Q

Describe the law of Laplace for surfactant.

A

tension is proportional to the product of the pressure and the radius, and inversely proportional to the wall thickness.

Pressure=2xTension/ Radius

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22
Q

State and describe the law that explains airway resistance in respiration.

A

Ohm’s law states that the current through a conductor between two points is directly proportional to the voltage across the two points.

Flow= air pressure in mouth - air pressure in the alveoli/ resistance to flow of air in airways

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23
Q

Describe factors affecting pulmonary ventilation-Airway resistance​.
Poiseuille’s LAW.

A

Resistance= 8viscoucity in inspired air x length of the airway/ pie x radius to the fourth power

Radius reduction​ CAN BE DUE TO:

-Bronchoconstriction​
-Pulmonary edema​
-Loss of surfactant​
-Loss of elastic fibers​

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24
Q

State the factors that could increase the work of breathing​.

A

*Decreased compliance e.g., pulmonary fibrosis​

*Increased airway resistance e.g., COPD (Chronic pulmonary obstructive disease)​

*Decreased elastic recoil e.g., Emphysema​

*The need for increased ventilation e.g., exercise​

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25
Q

When does air move into and out of the lungs in respect to the pressure?

A

Air move into the lungs when air pressure inside the lung is lesser than the atmosphere and air moves out when the pressure inside the lung is greater than the atmosphere.

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26
Q

Describe Boyle’s law.

A

The pressure (p) of a gas in a closed container is inversely proportional to the volume (V) of the container: ​

*If the size (volume) of the closed container is decreased, the pressure of the gas inside the container increases​

*if the size of the container increases, the pressure of the gas inside the container decreases.

27
Q

State the formula for Boyle’s law.

A

P1V1=P2V2=P3V3= constant

28
Q

Gas exchange involves simple diffusion of O2 and CO2 down their partial pressure gradients at both the pulmonary and tissue capillaries. ​

This occurs in alveolar respiration and Tissue respiration​.

A
29
Q

What is partial pressure?

A

if a container filled with more than one gas, each gas exerts pressure. The pressure of anyone gas within the container is called its partial pressure​

30
Q

State the formula for calculating partial pressure.

A

Partial pressure exerted by each gas in a mixture

total pressure X the fractional composition of this gas in the mixture​

31
Q

Describe Dalton’s law

A

*Dalton’s law of partial pressure states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

*Pressure exerted by each gas is independent of the other gases.

32
Q

State the amount of atmospheric pressure.

A

760mmHg

33
Q

What is the percentage of components in air?

A

Oxygen: 21%
Carbon dioxide: 0.04%
Nitrogen: 78%
Inert gases :0.9%
Remaining other gases

34
Q

Describe Henry’s law

A

When a liquid is exposed to air containing a particular gas, molecules of the gas will enter the liquid and dissolve in it. ​

Henry’s law states that the amount of gas dissolved will be directly proportional to the partial pressure of the gas with which the liquid is in equilibrium. ​

OR​

at equilibrium, the partial pressures of the gas molecules in the liquid and gaseous phases must be identical.​

35
Q

Describe inspiration process.

A

Expansion of the chest creates a “Space” for the expanding lungs =Transthoracic pressure gradient increases) ​

The pressure in the pleural cavity decreases (Transpulmonary Pressure gradient widens)​

Alveolar pressure decreases (Trans respiratory pressure widens) = Air into the lungs

36
Q

Describes expiration process

A

EXHALATION: ​

Inspiratory muscle tension decreases​

Chest shrinks​

The pressure in the pleural cavity rises​

Alveolar pressure rises above atmospheric pressure ​

Air expelled from the lungs​

37
Q

Describe a graph showing Intra-pulmonary pressure, intra- pleural and volume of air moved into the lungs.

A

For intra- pulmonary and pleural, the graph goes down during inspiration and goes up during expiration.

The volume of air moved into the lungs goes up during inspiration and goes down during expiration.

38
Q

State the 2 parts of brainstem responsible for regulating breathing.

A

*Medulla
*Pons

39
Q

What term is used to refer to the center in medulla that control breathing?

A

The medullary rhythmicity area is located in the medulla oblongata of the brainstem.​
​

40
Q

Which part of the medullary rhythmicity is inspiratory, and which one is expiratory?

A

It can be further divided into the inspiratory area, also known as the dorsal respiratory group or DRG, and expiratory area, also known as the ventral respiratory group or VRG.

41
Q

Describe the functions of the DRG and VRG in controlling breathing.

A

The inspiratory area stimulates spontaneous ventilation and is responsible for the resting breathing rate. It responds to afferent signals from chemoreceptors and mechanoreceptors present in the body and sends impulses via the intercostal and phrenic nerves to the muscles of respiration.

The expiratory area responds to stimulation beyond that of normal breathing; during normal quiet breathing this area is usually dormant.

  • It is particularly sensitive to the body’s changing needs for oxygen and responds by altering breathing pattern, sending impulses to the muscles of expiration. ​
42
Q

Describe the function of the Pneumotaxic center

A

Pneumotaxic center : transmits inhibitory nerve impulses to the inspiratory area of the medullary rhythmicity area, DRG switching it off before the lungs become too full of air.

When active, it also overrides signals sent from the apneustic area.​
​
An increase in the firing rate of the pneumotaxic area will increase the breathing rate, so the pneumotaxic area can be said to indirectly influence breathing rhythm

Controls rate & depth of breathing

43
Q

Describe the function of the Apneustic center.

A

Apneustic center- opposes the pneumotaxic center

The apneustic area constantly transmits stimulatory nerve impulses to the inspiratory area of the medullary rhythmicity area DRG, which if left alone, would cause prolonged, deep inhalations. ​

​However, when active, the pneumotaxic area overrides the action of the apneustic area and prevents over-inflation of the lungs. ​

44
Q

What stimulates the peripheral chemoreceptors in regulation of breathing?

A

They are sensitive to decreased levels of PO2 and increase in pH (hydrogen concentration)

*Sensitive to oxygen, only if PO2 is less than 60mmHg.​
*H+ and CO2 less sensitive

45
Q

Where are central chemoreceptors located and what stimulates them?

A

Located in the medulla and respond to changes in the brain extracellular fluid

Stimulated by increased CO2 and changes in hydrogen concentration.

46
Q

State the two peripheral chemoreceptors.

A

Aortic and Carotid bodies

47
Q

What initiates a cough reflex?

A

A reflex initiated by irritants or foreign matter lodging on the lower respiratory passages

48
Q

Describe the process of a cough reflex

A

*Rapid inspiration of large amount of air​

*Closure of the epiglottis and vocal cords, trapping the inspired air​

*Forceful contraction of abdominal and internal intercostals, pushing against the diaphragm, therefore raising the inter-alveolar pressure​

*The result is a rapid and forceful opening of the epiglottis and vocal cords, releasing the entrapped air to the outside; removal of foreign matter presently lodging in the trachea and bronchi​

49
Q

How are sensory signals from the trachea, bronchi, larynx and bronchioles are sent to the medulla?

A

Sensory signals from the trachea, bronchi, larynx and bronchioles are sent to the medulla via the vagus nerve

50
Q

State the following components of the cough reflex

*Cough receptor
*Afferent nerves
*Cough effector
*Efferent nerves
*Effector muscles

A

*Rapidly adapting receptors at pharynx, trachea, bronchi and bronchioles.
*Vagus and glossopharyngeal nerve
* Medulla (Nucleus Tractus solitarius)
* Vagus nerve, phrenic and spinal nerves
*Glottis, external intercostal, diaphragm, Major inspiratory and expiratory

51
Q

Describe the sneezing reflex

A

Similar to the cough reflex but:​

Initiated by irritants or foreign matter lodging on the nasal passages​

Sensory signals from the nasal passages are sent to the medulla via the CN ​

Uvula is depressed​

Release of the inspired air to the outside is mainly through the NOSE rather than the mouth.​

52
Q

Describe where the following efferent nerves of the coughing and sneezing reflex send impulses to:

A

*Vagus nerve: larynx, trachea, bronchi
*Phrenic nerve: Diaphragm
*Spinal nerves: expiratory muscles including pelvic sphincters

53
Q

Describe how humans produce sound

A

*Sound is produced by the voice box or the larynx in humans.
.
*Two vocal cords are stretched across the voice box leaving a narrow slit.

*When the lungs force air, the vocal cords vibrate to produce sound.

*When the vocal cords are tight and thin, the type or quality of voice is different from that when they are loose and thick.

54
Q

How does hoarseness of voice come about?

A

A hoarse voice is where the vocal cords become inflamed, causing a low, raspy voice. The inflammation can be due to several factors. Some causes are temporary, such as excessive shouting.

55
Q

What is the air flow of the blood through the lung determined by?

A

The flow of the blood through the lung is determined by the perfusion pressure and vascular resistance

56
Q

What is perfusion?

A

Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue.

57
Q

What is ventilation: perfusion ratio?

A

The V/Q ratio can therefore be defined as the ratio of the amount of air reaching the alveoli per minute to the amount of blood reaching the alveoli per minute

58
Q

What is the normal V/ Q ratio?

A

0.8

59
Q

Describe the ventilation perfusion ratio in relation to the base and apex of the lungs.

A

At the base of the lungs, there is great perfusion and not so great ventilation.

At the apex of the lungs, there is worst perfusion and not so bad ventilation.

As a result, the ventilation perfusion ratio is higher at the
apex of the lungs compared to the base.

60
Q

State the main thing that influence the ventilation and perfusion at the base and apex of the lungs.

A

Gravity

61
Q

What is absolute physiological shunt?

A

When ventilation is zero, so the V/Q ratio becomes zero.

Perfusion with no ventilation.

Can be due to atelectasis, Pulmonary edema, Pneumonia, Lung Cancer​

62
Q

What is absolute dead space? (Functional dead space​)
Which part of the respiratory system is dead space?

A

Ventilation with no perfusion.
The air is reaching the alveoli but no gaseous exchange as there is no perfusion of pulmonary blood.

Trachea

Can be due to Pulmonary embolism.

63
Q

Explain the cause of high and low V/Q ratio.

A

*Alveoli at apex are overall poorly ventilated and poorly perfused, but relatively better ventilated than perfused = high V/Q ratio.​

*Alveoli at base are well ventilated, perfused, but better perfused than ventilated = low V/Q ratio​

64
Q

State possible disorders of the respiratory system

A

*Disorder of Ventilation​

*Disorders of Perfusion​

*Ventilation-perfusion mismatch (Distribution) ​

*Diffusion disorders​

SOM 202 (15 decks)

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