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PMP-101 > Respiratory system 2 + 3 > Flashcards

Respiratory system 2 + 3 Flashcards

1
Q

Air flow and pressure changes

A

respiratory pressure cycle

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1
Q

End of Expiration

A

Alveolar/ intra pulmonary pressure = atmospheric pressure
No air movement

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2
Q

Inspiration

A

Increased thoracic volume >
Increased alveolar volume
Decreased alveolar pressure
Atmospheric pressure > alveolar pressure
Air moves into lungs

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3
Q

End of Inspiration

A

Alveolar pressure = atmospheric pressure
No air movement

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4
Q

Expiration

A

Decreased thoracic volume
Decreased alveolar volume
Increased alveolar / intrapulmonary pressure
Alveolar pressure > atmospheric pressure
Air moves out of lungs

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5
Q

What is pleural pressure?

A

the pressure in the pleural cavity

Normally lower than alveolar pressure.
Suction effect - fluid removal by the lymphatic system

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6
Q

Negative pressure difference (lower pleural pressure than alveolar pressure) - role?

A

keeps the alveoli expanded

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7
Q

-ive pressure significance

A

Pulls the pleura away from the outside of the alveoli

Pressure on the alveoli is lower

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8
Q

Expansion is opposed by the tendency of the lungs to _____

A

recoil

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9
Q

Pneumothorax

A

Pleura pierced

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10
Q

Pneumothorax : Pleura pierced

A

Air introduced
Pleural pressure is not low enough to overcome lung recoil
Alveoli collapse

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11
Q

volume larger

A

more air sucked in

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12
Q

Inspiration
Active process(needs energy)

A

Signals from the respiratory centre in the medulla oblongata (brain stem) >

Contraction of the diaphragm and intercostal muscles leading to the diaphragm moving downward >

Transverse expansion of thoracic cavity
+
Vertical expansion of thoracic cavity
>

Lung volume increases and the intra-alveolar pressure decreases >

Air is sucked in (inhalation)

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13
Q

ExhalationPassive process - what kind of energy needed?

A

elastic potential energy

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14
Q

The process of exhalation:

A

A passive event due to elastic recoil of the lungs
Relaxation of diaphragm and external intercostal muscles
During forced expiration, ONLY there is contraction of abdominal, internal intercostal (accessory muscles)

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15
Q

Characteristics of

A

No inherent rhythm

Generate tension due to rhythmic pattern of neuron-induced action potentials activating them

Muscles attempt to overcome the resistance to airflow within the airways

When at rest, the thorax assumes the FRC (Functional Residual capacity) position

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16
Q

Respiratory Function: measurement

A

Spirometry is the process of measuring volumes of air that move into and out of the respiratory system

measure respiratory volumes: peak flow (info on health of lungs)

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17
Q

Volumes and Capacities

A

Respiratory volumes:
measures of the amount of air movement during different portions of ventilation,
Respiratory capacities
Sums of two or more respiratory volumes

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18
Q

How many litres does the total of volume of air contain in the respiratory system?

A

4-6L

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19
Q

Tidal Volume (VT)

A

The volume of gas expired/inspired in one breathing cycle

Also known as ‘resting’ or ‘quiet’ breathing

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20
Q

Inspiratory reserve volume

A

Inspiratory reserve volume is the amount of air that can be inspired forcefully beyond the resting tidal volume

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21
Q

Expiratory reserve volume

A

Expiratory reserve volume is the amount of air that can be expired forcefully beyond the resting tidal volume

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22
Q

Residual volume

A

Residual volume is the volume of air still remaining in the respiratory passages and lungs after maximum expiration

Without a residual volume, the lungs would completely collapse and the pressure required to generate inflation would be high

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23
Q

Total lung capacity (TLC)

A

The volume of gas in the lungs and airways at a position of full inspiration – therefore we are measuring how much air the lungs can actually hold

Lung expansion is limited at a point which defines TLC

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24
Q

Breathing out maximally does not mean you breathe ____ air out of lungs

A

ALL

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25
Q

Vital Capacity (VC)

A

The total volume of gas that can be expired from the lungs from a position of full inspiration/ the total volume of gas that can be inspired from a position of residual volume

This is similar to an FVC manoeuver except it is not forced

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26
Q

Inspiratory capacity

A

The tidal volume plus the inspiratory reserve volume

The amount of air a person can inspire maximally after a normal expiration

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27
Q

Functional Residual Capacity fluctuates between

A

lung recoil and chest wall

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28
Q

Limits of Spirometry

A

Cannot measure TLC, FRC, RV

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29
Q

Dynamic Lung Volumes

A

Rate at which air moved

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30
Q

Peak expiratory flow (PEF):

A

ameasure of how quickly youcan blow air out of yourlungs

31
Q

What are capacity?

A

amount of air the lungs can hold IN TOTAL

32
Q

peak flow properties?

A

Measured inlitres/minute(l/min)

“Normal” will depend on age, height and gender

Record in a peak flow diary and compare against “best”

Can be used for diagnosis of asthma or to predict oncoming asthma attack

33
Q

Forced (Expiratory) Vital Capacity

A

Rate at which lung volume changes during direct measurement of the vital capacity.
FEV1 forced expiratory volume amount of air you can force from your lungs in one second

Important pulmonary test

34
Q

FORCED vital capacity

A

individual inspires maximally and then exhales maximally as rapidly as possible into a spirometer:
records volume of air expired per s

35
Q

What conditions can be identified where vital capacity might not be affected but the expiratory flow rate is reduced?

A

Asthma - contraction of the smooth muscle in the bronchioles increases the resistance to airflow

Emphysema - changes in the lung tissue result in the destruction of the alveolar walls, collapse of the bronchioles, and decreased elasticity of the lung tissue.
increase the resistance to airflow

36
Q

FEV1 – Forced Exhaled Volume in 1 Second = Key Parameters

A

Amount of air exhaled in 1 second

Affected by airway diameter

Predict ‘healthy’ values by age, gender and height

37
Q

FVC – Forced Vital Capacity Definition
Key parameters

A

Total amount of air that can be exhaled

FVC + Residual Volume = Lung Capacity

Predict ‘healthy’ values by age, gender and height

38
Q

FEV1 / FVC ratio
= key parameters

A

Does not require tables, FEV1 values adjusted to FVC

Ratio <0.7 indicates airway obstruction

39
Q

Basic gas exchange

A
  1. Ventilation – we need to be able to get air to the alveoli for gases to exchange
  2. Perfusion – the circulatory system needs to ensure blood gets to the alveolar
40
Q

Gas Exchange

A

Between air and blood occurs at the respiratory membranes

Alveoli

Some in the respiratory bronchioles and
alveolar ducts

Not in conducting zone - the bronchioles, bronchi, and trachea.

The volume of these = anatomical dead space

Pathology such as emphysema can increase this

41
Q

What effects gas exchange?

A
  1. Thickness of the membrane
    - O2 diffuses through the respiratory membrane less easily than does CO2
    - O2 diffuses through the respiratory membrane less easily than does CO2
  2. Total surface area of the respiratory membrane
    - reducing reduces gas exchange
  3. Partial pressure of gases across the membrane
    - pressure excreted by a specific gas in a mixture of gases
    PO2, PCO2
    - gases in the air dissolve in liquid
    - until partial pressure in liquid pressure in air
    - gases in liquid and air diffuse from areas of higher partial pressure toward area of lower. partial pressure until equal
42
Q
  1. Blood from tissues
A

Blood from tissues has a lower Po2 and a higher Pco2 compared to alveolar air
O2 diffuses from the alveoli into the pulmonary capillaries
Po2 in the alveoli > in the pulmonary capillaries
CO2 diffuses from pulmonary capillaries into the alveoli
Pco2 pulmonary capillaries > alve

43
Q
  1. Venous ends of the capillaries:
A

Pressures equal because of diffusion

The blood carries O2 away by bulk flow to the
tissues where O2 is required

44
Q
  1. Mixing with deoxygenated blood = PO2 levels?
A

lower PO2 than in capillaries

45
Q
  1. Oxygen diffuses out of the blood and into the interstitial fluid then into cells
A

Po2 in interstitial fluid < capillary
Po2 in cells < than interstitial fluid

Carbon dioxide diffuses from cells into the interstitial fluid and from the interstitial fluid into the blood

46
Q
  1. Equilibrium
A

equal pressure

47
Q

Transport of Oxygen

A

Oxygen is stored in the body in four forms -
As a gas in the lungs
Dissolved in tissue fluids
As oxyhaemoglobin in blood
As oxymyoglobin in muscle

48
Q

Haemoglobin - structure:

A

red blood cell

no nucleus so more haemoglobin can fit in

cytoplasm with large amount of haemoglobin

shape gives large surface area to pass oxygen through

49
Q

Gases can dissolve & diffuse between the ___ and the ________ system

A

lungs
circulatory

50
Q

oxygen diffuses into

A

red blood cells

51
Q

carbon dioxide diffuses into

A

alveolus

52
Q

Haemoglobin – Structure

A
  • Consists of 4 myoglobin units joined together
  • Each has one polypeptide chain and one heam group
  • Haem contains central Iron (Fe2+ )atom
    Iron atom binds to one oxygen as blood travels between lungs and tissues
  • one Hb molecule can bind 4 O2 molecules
53
Q

Oxyhaemoglobin Dissociation Curve

A

Ability of hemoglobin to bind to O2 depends on the Po2
- oxy-Hb dissociation curve

  • High Po2, haemoglobin binds to O2
  • Low Po2, hemoglobin releases O2
    lungs, Po2 normally high
  • hemoglobin holds as much O2 as it can
  • In the tissues, Po2 is lower
    hemoglobin releases O2
54
Q

Oxyhaemoglobin Dissociation Curve

A

Amount of O2 released from oxyhemoglobin (reduced affinity) is increased by
low Po2,
high Pco2
low pH
high temperature
Physical Exercise

55
Q

Transport of Carbon Dioxide

A

Carbon dioxide diffuses from cells into the blood.
Transported by:
1. 7% is transported as CO2 dissolved in the plasma

  1. 23% is transported bound to blood proteins, primarily haemoglobin
  2. 70% as bicarbonate ions
56
Q

Gas exchange in Tissues

A

CO2 diffuses into plasma and RBC

Forms carbonic acid catalysed by carbonic anhydrase found inside RBC and on capillary epithelium

Carbonic anhydrase increases the rate at which carbonic acid generated in tissue capillaries

promotes the uptake of CO2 by red blood cells.

57
Q

Gas Exchange in Lungs

A

Capillaries of the lungs
the process is reversed

CO2 diffuses from RBC to alveoli

HCO3−dissociates to produce H2CO3

Carbonic anhydrase catalyses formation of CO2 and H20 from H2CO3

The CO2 diffuses into the alveoli and is expired

58
Q

What does CO2 and water form?

A

carbonic acid
H2CO3

59
Q

How is pH regulated?

A

Chemical acid-base buffer system of bodies fluids - (seconds)

The respiratory centre – minutes

The kidneys - hours-days

60
Q

Control of Respiration

A

Normal rate of breathing in adults

Between 12 and 20 breaths per minute
rate of breathing determined by the number of times respiratory muscles are stimulated

Breathing is spontaneously initiated within the central nervous system (CNS)

Medulla oblongata (brainstem)

An increased depth of breathing results from

stronger contractions of the respiratory muscles caused by recruitment of muscle fibres

increased frequency of stimulation of muscle fibres

61
Q

Rhythmic Breathing

A

It takes more effort and time to fill the lungs than it takes to exhale, when the diaphragm simply relaxes to push out the air. Rhythmic breathing can make us more aware of the need for a longer time to inhale the oxygen needed for high-intensity exercise like running.

62
Q
  1. Starting inspiration.
A

Neurons in the medullary respiratory center that promote inspiration - continuously active
stimulation from
blood gas levels, movements of muscles and joints, voluntary respiratory movements
When the inputs reach a threshold level
somatic nervous system neurons stimulate respiratory muscles ( via action potentials)
inspiration starts

63
Q
  1. Increasing inspiration
A

Once inspiration begins, more and more neurons are activated
Progressively stronger stimulation of the respiratory muscles, lasts for approximately 2 seconds

64
Q
  1. Stopping inspiration
A

Neurons stimulating muscles of inspiratory muscles also stimulate medullary neurons that stop inspiration
- These also receive input from the pontine respiratory neurons
- Stretch receptors in the lungs

When the inputs to these neurons exceed a threshold level,
they cause the neurons stimulating respiratory muscles to be inhibited.
Relaxation of respiratory muscles leads to in expiration (3 s).
Next inspiration step 1

65
Q

Control of Respiration

A

The system must perform three key functions:

  1. Maintain, through involuntary controls, a regular rhythmic breathing pattern
  2. Adjust the tidal volume (VT) and breathing frequency (fb) such that alveolar ventilation is sufficient to meet the demands for gas exchange at cellular level
  3. Adjust the breathing pattern to be consistent with other activities using the same muscles, such as speech
    Some conscious control
66
Q

Respiratory control system

A

Central control system
> output > effectors > sensors [chemoreceptors, lungs and other rreceptors] > input back to CCS

67
Q

Respiratory control centres
Major groups of neurones in respiratory centre which control respiration:

A

Pons
Pontine respiratory group
Controls switches between inspiration and expiration
Medulla
Dorsal respiratory group (DRG)
Diaphragm (inspiratory)
Ventral respiratory group (VRG)
Intercostals
Abdominals
Inspiratory and expiratory

68
Q

Nervous Control of Breathing

A

Some voluntary control

Most autonomic

Several reflexes, such as sneeze and cough reflexes, can modify breathing

The Hering- Breuer reflex
- limits the extent of inspiration
- As the muscles of inspiration contract the lungs fill with air
- Sensory stretch receptors located in the lungs are stimulated
- Action potentials sent to the medulla oblongata

Here they inhibit the respiratory centre neurons and cause expiration
- In infants important role in regulating the basic rhythm of breathing and over inflation
- In adults when the tidal volume is large - during heavy exercise

69
Q

Chemical control of Breathing

A

Level of CO2 (not O2), in the blood is the major driving force
Even a small increase in the CO2 level (hypercapnia) results in a powerful urge to breathe
Breathing is controlled so finely that the PaO2 and PaCO2 are kept within normal limits

70
Q

the system has three control pathways – to control of breathing

A

The PCO2 is the principle pathway, controlling the rate and depth of breathing on a breath-by-breath basis
Under certain circumstances, such as acclimatization to altitude, the PO2 pathway (the second pathway) can override the PCO2 pathway.
3rd pathway is required to allow all other actions e.g. talking/swallowing/coughing to break through the normal pattern of breathing and try to match breathing to the expected voluntary or behavioural activity

71
Q

Central chemoreceptors

A

An increase in H+ ions increases ventilation and vice versa as follows:

PaCO2 rises causing a rapid increase in H+ ions > causes pH to fall (increase acidity) > central chemoreceptors to transmit a signal to increase ventilation > PaCO2 and CO2 decrease and when balance is restored, ventilation will decrease

72
Q

Chemoreceptors

A

Centrally;

Medulla oblongata
Peripherally
Carotid bodies
Aortic bodies

73
Q

Chemical control

A

pH that accompanies an increase in CO2 levels
Chemoreceptors
Medulla oblongata
chemoreceptors H+ concentration
pH CO2
If blood CO2 levels decrease, pH increase > medullary chemoreceptors signal a decreased breathing rate > retains CO2 in the blood
More CO2 in the blood causes H+ levels to increase, > blood pH to decrease to normal levels
Carotid and Aortic bodies:
pH, > Co2, > O2
Increased breathing

74
Q

Global Innervation

A

Airways
Innervated by the vagus nerve – Parasympathetic
Dominant
Bronchoconstriction
Innervated by the Sympathetic nerve chain

Respiratory Muscles
Innervated by the intercostal (motor) nerves
Phrenic nerve innervates the diaphragm

75
Q

Autonomic Nervous System Physiology

A

Parasympathetic nervous system
Neurotransmitter (effector) – Acetylcholine (Ach)
Receptors – muscarinic / cholinergic receptors
M1 to M5

Airways: M1 M2 M3 present. M3 most important

Muscarinic receptors
Stimulation causes the contraction of bronchial smooth muscle

Muscarinic receptors located in many glands help to stimulate secretion e.g. mucus and saliva

76
Q

Sympathetic nervous system - types of receptors

A

Neurotransmitter (effector) – Noradrenaline (NA)

Receptors – adrenergic receptors
alpha, beta1 and beta2

Beta1 receptors – heart
Stimulation increases rate and force e.g.
adrenaline/epinephrine

Beta2 receptors – smooth muscle of bronchioles
Stimulation (Agonist) causes relaxation e.g. salbutamol

PMP-101 (53 decks)

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