Respiratory System Flashcards
what are the functions of the respiratory system (respiration)?
- ventilation
- external respiration: exchange of oxygen and co2 between the air in the lungs and the blood
- transports oxygen and co2 in the blood
- internal respiration: exchange of o2 and co2 between the blood and tissues
what are the functions of the respiratory system (not respiration)?
regulation of blood pH
voice production
olfaction
innate immunity
voice production?
air movement past the vocal cords
olfaction?
airborne molecules are drawn into the nasal cavity
innate immunity?
protects against certain micrroganisms and other pathogens- preventing them from enetering the body and by removing them from respiratory surfaces
what are the structures in the upper respiratory tract?
nose and nasal cavity
pharynx (throat)
larynx
what are the structures of the lower respiratory tract?
trachea
bronchi
lungs
what are the characteristics of the lungs?
Within the thoracic cavity
2 lungs
* separated by the mediastinum in which the
heart is situated
Each lung is divided into lobes
* Left lung – 2 lobes (upper and lower)
* Right lung – 3 lobes (upper, middle and lower)
Heart sits within the ‘cardiac notch’
* so the left lung slightly narrower
Each lung: Surrounded by
a pleural cavity
* formed by 2 pleural
membranes
* the visceral and parietal
pleurae
Passages branch
* Decrease in size
* Increase in number
what is the seperation of the bronchial tree?
- Left and right bronchi (one bronchus) or primary bronchi divide
- Secondary bronchi (in lobes of lung) - divide
- Tertiary bronchi - divide
- Bronchioles – divide (several times)
- Terminal bronchioles
what are the characteristics of the bronchial tree?
Top of tree
* Lots of cartilage some smooth muscle
* Keep airways open
Bottom of tree
* Lots of smooth muscle less cartilage
* Change diameter of airways
where is the respiratory zone?
alveoli
* Air filled sacs
* Membrane v elastic* Expand / contract
* Surrounded by a capillary network to provide efficient gas exchange
* The respiratory membrane
* where gas exchange between the air and
blood takes place
* Very very thin
what are the roles of type 1 alveolar cells?
Type I alveolar cells (95%) form
the alveolar wall,
* permit gas exchange
what are the roles of type 2 alveolar cells?
Type II alveolar cells secrete
surfactant
* Defence
* Role in breathing and stabilises
alveoli (surface tension)
* Recoil of lungs
what are the roles of alveolar macrophages?
defence against foreign particles/infectious
microorganisms that reach the alveoli
what are the two phases of ventillation?
- Inhalation (inspiration)
- Exhalation (expiration)
how is ventillation regulated?
- Changes in thoracic volume (drives)
- pressure changes
- Air flow is driven by
- the pressure difference between
- the atmosphere (barometric pressure)
- inside the lungs (intrapulmonary pressure)
what way does ai flow?
from an area of high pressure to low pressure
what are the respiratory muscles?
- Diaphragm
- Intercostal muscles
- External
- Internal
- Scalene muscles
- Sternocleidomastoid muscles
- Pectoral muscles
- Abdominal muscles
what are the characteristics of the diaphragm?
- 70 % ventilation
- Dome shaped
- Contracts
- Downwards and flattens
- (increasing thoracis cavity)
- Relaxes
- Recoils upwards
- (reducing thoracic cavity)
- Only respiratory muscle working when lying flat and sleeping
what are the charcateritics of intercoastal muscles?
- Between ribs
- Two planes of muscular and tendinous fibres occupying each intercostal space
* Internal beneath external - The external intercostal muscles
* slope downwards and forward
* Contract: ribs upwards and outward
* Elevates ribs and sternum - The internal intercostal muscles
* Opposite direction
* Contract: lower ribs - Stability
what is happening to the muscles while inspiration is happening?
- Quiet breathing
- Diaphragm contracts
- External intercostals
* Contract
- Forced breathing
- Contract more forcefully
- Others contract
- Scalene muscles
- Sternocleidomastoid
- Pectoral muscles
what is the active process of inspiration?
signals from the respuratory cavity in the medulla oblongta (brain stem) –>
contraction of the diaphram and intercostal muscles leading to the diaphram moving downward –>
transverse expansion of thoracic cavity+ vertical expansion of thiracic cavity –>
lung volume increases and the intra-alveolar pressure decreases –> air-sucked in
what is happening to the muscles while expirating?
- Quiet breathing
- Relatively passive
- Elastic tissue (lungs thorax)
- Lung recoils
- When…..
- Diaphragm relaxes
- Domes (decreases volume)
- External intercostals relax
- Downwards and inwards (decreases
volume)
- Downwards and inwards (decreases
- Relatively passive
- Laboured exhalation
- Internal intercostals contract
*Abdominal muscles contract
- Internal intercostals contract
what are the air flow and pressure changes in inspiration?
- Increased thoracic volume
- Increased alveolar volume
- Decreased alveolar pressure
- Atmospheric pressure > alveolar pressure
- Air moves into lungs
what are the air flow and pressure changes in expiration?
- Decreased thoracic volume
- Decreased alveolar volume
- Increased alveolar / intrapulmonary pressure
- Alveolar pressure > atmospheric pressure
- Air moves out of lungs
what is pleural pressure?
the pressure in the pleural pressure
-normally lower than alveolar pressure
-suction effect- fluid removal by the lymphatic system
why is exhalation a pasive process?
- 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)
what are the characteristics of the respiratory muscles?
- 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
what is the process of measuring volumes of air that move into and out of the respiratory system?
spirometry
what is respiratory volumes?
measures of the amount of air movemnet during different portions f ventillation
what are respiratory capacities?
sums of two or more respiratory volumes
what is the tidal volume?
the volume of gas expired/inspired in one breathing cycle
(resting or quiet breathing)
what is inspiratory reserve volume?
inspiratory reserve volume is the amount of air that can be inspired forcefully beyond the resting tidal volume
what is expiratory reserve olume?
expiratory reserve volume is the amount of air that can be expired forcefully beyond the resting tidal volume
what is residual volume?
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
what is total lung capacity?
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
what is vitl capacity?
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
what is inspiratory capacity?
- The tidal volume plus the inspiratory reserve volume
- The amount of air a person can inspire maximally after a normal
expiration
what is functional residual capacity?
The volume of gas in the lungs and airways at the end of a tidal
breath
* This is the point at which the inward pull of the lungs and the
outward pull of the chest wall are in equilibrium
what are the limits of spirometry?
cannot measure TLC, FRC, RV
what is dynamic lung volumes?
rate at which air moved
what is peak expiratory flow (PEF)?
a measure of hw quickly you can blow air out of your lungs
what is forced (expiratory) vital capacity?
rate at which lung volume changes during direct measurement of the capacity
what are the limits of gas exchange?
- thickness of the membrabe
- total surface area of the respiratory membrane
- partial pressure of gases across the membrane
what are the steps of gas exchange?
- blood from tissues has a lower Po2 and a higher Pco2 compared to alveolar air
2.venous ends of the capillaries - mixing with deoxygenated blood= lower Po2 than in capillaries
- oxygen diffuses out of the blood and into the interstitial fluid then into cells
- equilibrium
what are the four forms that oxygen is stored in the body?
as a gas in the lungs
dissolved in tissue fluids
as oxyhaemoglobin in blood
as oxymyoglobin in muscle
what is the structure of haemoglobin?
- 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
what is the amount of O2 released from oxyhaemoglobin increased by?
low Po2
high Pco2
low pH
high temperature
how is carbon dixide transported?
- 7% is transported as CO2 dissolved in the plasma
- 23% is transported bound to blood proteins, primarily haemoglobin
- 70% as bicarbonate ions
how does 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.
how does 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
what is the importance of carbon dioxide on pH?
- Carbon dioxide has an important effect on the pH of blood
- As CO2 levels increase, the blood pH decreases (becomes more acidic)
because CO2 reacts with H2O to form H2CO3 - The H+ that results from the dissociation of H2CO3 is responsible for
the decrease in pH. - Conversely, as blood levels of CO2 decline, the blood pH increases
(becomes less acidic, or more basic
what three functions must the system preform to control respiration?
- Maintain, through involuntary controls, a regular rhythmic breathing
pattern - 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 - Adjust the breathing pattern to be consistent with other activities using
the same muscles, such as speech
in the respiratory control system, what are the structures of the central control system?
pons
medulla
other parts of the brain
in the respiratory control system, what are the structures of the effectors?
respiratory muscules
in the respiratory control system, what are the structures of the sensors?
chemoreceptors
lungs
other receptors
what does the pons do?
pontine respiratory group
controls switches between inspiration and expiration
what is the medulla responsible for?
Dorsal respiratory group (DRG)
* Diaphragm (inspiratory)
Ventral respiratory group (VRG)
* Intercostals
* Abdominals
* Inspiratory and expiratory
what is the heuring-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
what is the principle pathway to controlling the rate and depth of breathing?
the PCO2 (level of CO2)
what are the steps when there is an increase of H+ ions?
PaCO2 rises causing a rapid increase in H+
ions
This causes pH to fall (increase acidity)
This causes the central chemoreceptors to
transmit a signal to increase ventilation
In doing so, PaCO2 and CO2 decrease and
when balance is restored, ventilation
will decrease
what are the central chemoreceptors?
medulla oblongata
what are the peripheral chemoreceptors?
carotid bodies
aortic bodies
what are the roles of the parasympathetic nervous system in the respiratory 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
what are the roles of the sympathetic nervous system in the respiratory system?
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
what is included in the conducting zone?
trachea, bronchi, terminal bronchi
strictly for ventilation
NOT respiratory bronchioles
what is reduced in asthma?
FEV1
what is tidal volume?
the volume of gas expired/ inspired in one breathing cycle
