W4 - Respiratory System Flashcards
Importance of the respiratory system
Gas exchange
Acid-base balance reg
Vocalisation
Homeostatic reg of body pH
Protection from inhaled pathogens + irritating substances
What are the types of respiration?
Pulmonary
Cellular
What comes under pulmonary respiration?
Process of ventilation
O2 + CO2 exchange in lungs
What comes under cellular respiration?
O2 utilisation
CO2 production
Site of carina
Ridge at the base of the trachea
What does the site of carina separate?
Openings or right + left bronchi
What leads off from the trachea?
Right + left primary bronchus
What leads off the right + left primary bronchus?
Secondary (lobar) bronchi
What leads off the secondary (lobar) bronchi?
Segmental tertiary bronchi
Where do the bronchioles branch off from?
Segmental tertiary bronchi
What are the types of bronchioles?
Lobular
Respiratory
Terminal
How many alveoli are there? What coverage??
480 million alveoli covering 75 square meters
What are the different zones in respiration?
Conducting
Respiratory
Purpose of the conducting zone
Moves air to respiratory zone
Humidifies, warms + filters air
What components are found in the conducting zone
Trachea
Bronchial tree
Terminal bronchioles
Purpose of the respiratory zones
Gas exchange
What components are found in the respiratory zone
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
No. of tubes in trachea
1
No. of tubes in bronchi
2, 4, 8
No. of tubes in bronchioles
16
Type II alveolar cell (septal cell)
Major functions
Synthesis + secretion of surfactant
Xenobiotic metabolism
Transepithelial movement of H20
Regeneration of alveolar epithelium after lung injury.
What is Xenobiotic metabolism ?
Typically:
Lipophilic compounds –> more readily excreted hydrophilic metabolites.
Definition for lipophilic
Tend to combine w. or dissolve in lipids or fats
Describe Type I alveolar cells
Squamous
Very thin
Function of Type I alveolar cells
Involved in GE between alveoli + blood
What are alveolar macrophages?
Primary phagocytes of innate immune system
What do Alveolar macrophages do?
Clear air spaces of infectious, toxic or allergic particles that have evaded the mechanical defences of the respiratory tract, i.e nasal passages.
What comes under pulmonary ventilation / breathing?
Inhalation
Exhalation
(Exchange of air between atmosphere + alveoli)
What comes under external pulmonary respiration?
GE between alveoli + blood
What comes under internal cellular respiration
Systemic capillaries transport to tissue cells
Supplies cellular respiration
What law is inhalation based on?
Boyle’s law
What does Boyle’s law state?
Pressure of a gas in a closed container is inversely proportional to the vol of the container at a CONSTANT temp
What happens to the diaphragm, ribs and chest cavity during inhalation/inspiration?
D = Contracts, flattens + descends
R = Rise
CC = Elongates + enlarges
== ⬆️ air into lungs as intrapulmonic pressure is below atmospheric pressure
How does inspiration during physical activity differ from resting inspiration?
Diaphragm, rib cage + abdominal muscles synchronise to contribute.
Scaleni + external intercostal muscles between ribs contract = ribs rotate + move up + away from body.
What are the 2 factors from which expiration results from?
Natural recoil of stretched lung tissue
Relaxation of inspiratory muscles.
How are the thoracic dimensions reduced during strenuous activity?
Internal intercostal + abdominal muscles act powerfully on ribs + abdominal cavity
Intrapulmonary and intrapleural pressure relationships
Alveolar pressure changes during different phases of the cycle.
Equalizes at 760 mm Hg but doesn’t stay there.
What is Intrapleural pressure
Air pressure in pleural cavity between visceral + parietal pleurae
Which is always less than the other?
Intrapulmonary or intra pleural pressures?
Intrapleural is always less than intrapulmonary
What is the intrapulmonary pressure during inspiration + expiration?
Inspiration = Subatmospheric
Expiration = Greater than atmospheric pressure
What are the effects to COPD?
Chronic inflammation of airways
Structural changes + collapse of small airways
Impaired exhalation
Lung hyperinflation
Altered diaphragm
Reduced motion
What 3 components are measured in the diaphragm release technique (DRT)
Diaphragm mobility
Respiratory pressures
Chest wall + abdominal kinematics
What does the diaphragm release technique (DRT) improve?
Diaphragm mobility
Inspiratory capacity
⬆️ Vital capacity
What has inspiratory muscle training (IMT) been observed to do for people with cervical spinal cord injuries?
⬆️ inspiratory muscle strength
Reduce dyspnea
⬆️ diaphragm thickness by 22%
What is dyspnea
Inordinate shortness of breath
Sense of breathing incapacity during PA
Tidal volume (TV)
Vol of air breathed in or out per breath
Inspiratory reserve volume (IRV)
Max inspiration after TV inspiration
Expiratory reserve volume (ERV)
Max expiration after TV expired
Total lung capacity (TLC)
Vol. in lungs after max inspiration
Residual lung vol (RLV)
Vol in lungs after max expiration
Forced Vital Capacity (FVC)
Max vol of air expired after Max inspiration
How is minute ventilation calculated?
TV x breathing freq
What % of the tidal volume reaches the respiratory zone?
70%
What % of the tidal volume reaches the conducting zone?
30%
What is airway resistance?
Amount of resistance to the flow of air through the respiratory tract during inspiration + expiration
What does the degree of airway resistance depend on in particular?
Diameter of airway
Whether flow is laminar or turbulent
Airway resistance represents 80% of the resistance to the flow of air, what causes the other 20% resistance?
Friction of pulmonary + thoracic tissues
What does P(little ATM) stand for?
Atmospheric pressure
What does P(little A) stand for?
Alveolar pressure
What does V stand for?
Volumetric airflow
Equation for measuring airway resistance
R(little AW) = P(little ATM) - P(little A) / V
Functional residual capacity (FRC)
Vol or air in lungs at end of passive expiration
What is the total lung capacity ?
~6L
How is vital capacity calculated?
TV + IRV + ERV
How is inspiratory capacity calculated?
TV + IRV
How is the functional residual capacity calculated? (FRC)
ERV + RV
How is total lung capacity calculated?
TV + ERV + IRV + RV
Where is the respiratory centre located?
Medulla oblongata + pons in the brainstem
What are the 3 major respiratory groups of the respiratory centre?
Dorsal respiratory group
Ventral respiratory group
Pontine respiratory group
Which of the 3 major respiratory groups of the respiratory centre are found in the medulla?
Dorsal respiratory group
Ventral respiratory group
Which of the 3 major respiratory groups of the respiratory centre are found in the pons?
Pontine respiratory group
What are the 2 centres of the pontine respiratory group?
Pneumotaxic centre
Apneustic centre
In order to regulate the RATE + DEPTH of breathing, where does the respiratory centre receive input from?
Chemoreceptors
Mechanoreceptors
Cerebral cortex
Hypothalamus
What is the main function of the medulla oblongata?
Sends signals to the muscles that initiate inspiration + expiration
Pneumotaxic centre/area of the pontine respiratory group.
Where?
Superior portion of pons
Pneumotaxic centre/area of the pontine respiratory group.
What does it do?
Works w/ the medulla rhythmicity area to set the rhythm of breathing.
Has inhibitory impulses.
Prevents lungs from becoming too full w. air.
Limits duration of inspiration.
Pneumotaxic centre/area of the pontine respiratory group.
Active or inactive?
Active
Pneumotaxic centre/area of the pontine respiratory group.
Quicker or slower than the apneustic centre/area?
Quicker
Apneustic centre/area of the pontine respiratory group.
Where?
Inferior portion of pons
Apneustic centre/area of the pontine respiratory group.
What does it do?
Coordinates transition between inspiration + expiration.
stimulate inspiratory area to prolong inspiration + slow rate of breathing
Apneustic centre/area of the pontine respiratory group.
When does it occur?
Only when pneumotaxic area is inactive.
Which is overridden by which?
Apneustic vs Pneumotaxic
Apneustic is overriden by pneumotaxic
Apneustic centre/area of the pontine respiratory group.
Active or inactive?
Active
Apneustic centre/area of the pontine respiratory group.
Quicker or slower than the Pneumotaxic centre/area?
Slower
Medullary rhythmicity area at REST
What happens during active inspiration?
w/in 2 secs:
Diaphragm + external intercostals actively contract
Medullary rhythmicity area at REST
What happens during active expiration?
W/in 3 secs:
Diaphragm + external intercostals relax
Elastic recoil or chest wall + lungs
Medullary rhythmicity area - FORCED BREATHING
What happens as soon as forced inspiratory happens?
Expiratory area is activated:
Internal intercostals + abdominal muscles contract
= forced expiration
What dictates how we breathe?
Voluntary Control
Involuntary Control
Where are central chemoreceptors located?
Medulla oblongata of brainstem
What do central chemoreceptors do?
Detect changes in arterial pCO2.
What happens once changes in arterial pCO2 are detected by the central chemoreceptors?
Send impulses to respiratory centres in brainstem to:
initiate changes in ventilation to restore normal pCO2.
= hyperventilation.
What happens to CO2 once it enters the Cerebrospinal fluid (CSF) after diffusing across the blood brain barrier from the arterial blood?
Carbonic anhydrase converts it to HCO3- + H+.
H+ = ⬇️ CSF pH
Both elevated pCO2 + red pH stimulate the chemoreceptors.
Where are the peripheral chemoreceptors primarily located?
Carotid body
…then the aortic body
Function of the peripheral carotid chemoreceptors
Stimulate breathing in response to hypoxia.
What is the carotid sinus nerve?
A branch of the glossopharyngeal nerve (a.k.a cranial nerve 9 (CN9))
What does the carotid sinus nerve do with the branch of the glossopharyngeal nerve?
Provides sensory innervation to the carotid body.
What is the sensory nerve fibre in the glossopharyngeal nerve sensitive to?
⬇️ in p02
What do the aortic body peripheral chemoreceptors do?
Measure changes in bp
Where do signals from the aortic body chemoreceptors travel down to the medulla?
Vagus nerve (CN X)
What are the respiratory stretch receptors activated by?
Over inflation of the lungs
What happens when the respiratory stretch receptors are activated?
Inhibitory discharge is sent to the inspiratory area…
Expiration begins + lungs deflate
Where can irritant receptors be found?
Between airway epithelial cells
What are irritant receptors stimulated by?
Noxious gases
Cold + inhaled dusts
What happens once the irritant receptors have been activated?
Send APs down vagus nerve to cause:
Bronchoconstriction + ⬆️ resp rate
Where are proprioreceptors located?
In NM spindles + Golgi tendon organs
What are the 3 basic types of proprioreceptors?
Muscle spindles
Golgi tendon organs
Joint receptors (low-threshold mechanoreceptors)
What are afferent impulses?
Neural impulses travelling from sensory organs/receptors to the CNS
What are efferent impulses?
Neural impulses travelling from CNS to the organs/glands.
In a study inhibiting muscle afferent fb, what did they use to partially block sensory responses?
Lumbar intrathecal fentanyl
What was measured in the study inhibiting muscle afferent fb
Minute ventilation (V little E)
Breathing frq. (f)
Tidal vol
What is the most commonly used pulmonary function test?
Spirometry test
Overview of procedure for spirometry test
Patient breathes in to full inspiration
Hold their breath long enough to seal their lips around mouthpiece.
Patient forcibly expires until nothing left to expel.
For how long can the forced expiration for the spirometer test last for those who suffer from severe COPD?
up to 15 secs
How many spirometer readings should be taken?
3
Best 2 should be w/in 100ml or 5% of each other
What does spirometry measure?
Records vol vs time.
What after a spirometry test is used to determine where there’s any evidence of restrictive or obstructive lung disease?
Ratio of FEV1 to FVC
What needs to be corrected for when looking at the individuals measurements of FEV1 and FVC?
FEV1 = Forced expiratory volume in 1 second
Sex
Ethnicity
Height
Age
How is FEV1 + FVC expressed after a spirometry test?
As a % of predicted for matched, healthy ind w/ no lung disease.
What happens to FEV1 with obstructive spirometry?
Decreases
w/ less than 70% of the total amount in the 1st second.