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PMP-101 > Respiratory system 2 + 3 > Flashcards

Respiratory system 2 + 3 Flashcards

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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
Breathing out maximally does not mean you breathe ____ air out of lungs
ALL
25
Vital Capacity (VC)
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
26
Inspiratory capacity
The tidal volume plus the inspiratory reserve volume The amount of air a person can inspire maximally after a normal expiration
27
Functional Residual Capacity fluctuates between
lung recoil and chest wall
28
Limits of Spirometry
Cannot measure TLC, FRC, RV
29
Dynamic Lung Volumes
Rate at which air moved
30
Peak expiratory flow (PEF):
a measure of how quickly you can blow air out of your lungs
31
What are capacity?
amount of air the lungs can hold IN TOTAL
32
peak flow properties?
Measured in litres/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
Forced (Expiratory) Vital Capacity
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
FORCED vital capacity
individual inspires maximally and then exhales maximally as rapidly as possible into a spirometer: records volume of air expired per s
35
What conditions can be identified where vital capacity might not be affected but the expiratory flow rate is reduced?
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
FEV1 – Forced Exhaled Volume in 1 Second = Key Parameters
Amount of air exhaled in 1 second Affected by airway diameter Predict ‘healthy’ values by age, gender and height
37
FVC – Forced Vital Capacity Definition Key parameters
Total amount of air that can be exhaled FVC + Residual Volume = Lung Capacity Predict ‘healthy’ values by age, gender and height
38
FEV1 / FVC ratio = key parameters
Does not require tables, FEV1 values adjusted to FVC Ratio <0.7 indicates airway obstruction
39
Basic gas exchange
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
Gas Exchange
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
What effects gas exchange?
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
1. Blood from tissues
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
2. Venous ends of the capillaries:
Pressures equal because of diffusion The blood carries O2 away by bulk flow to the tissues where O2 is required
44
3. Mixing with deoxygenated blood = PO2 levels?
lower PO2 than in capillaries
45
4. Oxygen diffuses out of the blood and into the interstitial fluid then into cells
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
5. Equilibrium
equal pressure
47
Transport of Oxygen
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
Haemoglobin - structure:
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
Gases can dissolve & diffuse between the ___ and the ________ system
lungs circulatory
50
oxygen diffuses into
red blood cells
51
carbon dioxide diffuses into
alveolus
52
Haemoglobin – Structure
- 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
Oxyhaemoglobin Dissociation Curve
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
Oxyhaemoglobin Dissociation Curve
Amount of O2 released from oxyhemoglobin (reduced affinity) is increased by low Po2, high Pco2 low pH high temperature Physical Exercise
55
Transport of Carbon Dioxide
Carbon dioxide diffuses from cells into the blood. Transported by: 1. 7% is transported as CO2 dissolved in the plasma 2. 23% is transported bound to blood proteins, primarily haemoglobin 3. 70% as bicarbonate ions
56
Gas exchange in Tissues
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
Gas Exchange in Lungs
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
What does CO2 and water form?
carbonic acid H2CO3
59
How is pH regulated?
Chemical acid-base buffer system of bodies fluids - (seconds) The respiratory centre – minutes The kidneys - hours-days
60
Control of Respiration
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
Rhythmic Breathing
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
1. Starting inspiration.
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
2. Increasing inspiration
Once inspiration begins, more and more neurons are activated Progressively stronger stimulation of the respiratory muscles, lasts for approximately 2 seconds
64
3. Stopping inspiration
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
Control of Respiration
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
Respiratory control system
Central control system > output > effectors > sensors [chemoreceptors, lungs and other rreceptors] > input back to CCS
67
Respiratory control centres Major groups of neurones in respiratory centre which control respiration:
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
Nervous Control of Breathing
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
Chemical control of Breathing
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
the system has three control pathways – to control of breathing
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
Central chemoreceptors
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
Chemoreceptors
Centrally; Medulla oblongata Peripherally Carotid bodies Aortic bodies
73
Chemical control
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
Global Innervation
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
Autonomic Nervous System Physiology
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
Sympathetic nervous system - types of receptors
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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