Respiratory Flashcards
what are the functions of the respiratory system
gas exchange –> oxygen into body, CO2 out
acid base balance –> Ph. 7.35 - 7.45
Thermoregulation
sound production
anatomical substrate for sense of smell
respiratory surface protection from dehydration, temp changes, invading pathogens
what affects acid base balance
Co2 increase = blood is more acidic, can lead to acidosis
what is the goal of breathing regarding compliance
minimise resistance, maximise compliance
what affects the work of breathing
- resistance to airflow through respiratory tract
- compliance of lungs (how easy it is to inflate)
what is pulmonary fibrosis
damage, thickening & scarring of alveoli, that causes stiffening of the lungs and makes breathing more difficult
what is bmr
basal metabolic rate, measures oxygen consumption under mental and physical conditions. can be used to evaluate thyroid function
what are the muscles of inspiration
external intercostals, diaphragm,
what is the path of air when breathing in
air from nose or mouth
pharynx –> splits into esophagus & trachea
larynx –> above trachea
2 primary bronchi
23 bronchial subdivisions
bronchioles (div. 12-23)
alveolar ducts
alveoli
diff between bronchi and bronchioles
bronchus has cartilage, bronchiole has muscle for diameter adjustment (resistance)
what is the anatomical dead space
oxygen in conducting portion of airways that can’t be used e.g. diffusion only occurs in alveoli & respiratory bronchioles
example of increasing anatomical dead space
going snorkelling, you naturally start breathing deeper
function of nose
clean warm & humidify air
what happens when air enters the nose
external nares provide particle filtration
what is on the lateral surfaces of the nasal cavity
3 pairs of bony ridges on either side called conchae
what is the function of conchae
slow down air flow & incr. turbulence so the air has time to warm up and humidify because they have mucosa and are highly vascularised e.g. compare nose breathing to throat breathing
what forms the medial wall of the nose
nasal septum
what forms the floor of the nose
maxilla (hard pal.) & palatine bone
what forms the roof of the nose
nasal, frontal, ethmoid & sphenoid bones
what forms the inferior part of the nasal septum
vomer bone
where are the meatus
spaces under the conchae
difference between ethmoidal sinuses and others
they are like lots of small air pockets below the frontal sinuses & between the eyes
where do sinuses drain
meatus - superior, middle, inferior
function of paranasal sinuses
don’t really know
lighten the skull
resonate voice
mucus secretions
pathology of sinuses
sinusitis, more common in maxillary because drainage requires movement upwards
what is the pharynx
wide muscular tube to conduct air, food, drink from base to CV6
what are the parts of the pharynx
nasopharynx - chonanae (co-annie) to soft palate
oropharynx - soft palate to epiglottis
laryngopharynx - epiglottis - larynx/oesophagus
what is larynx
guardian of air passage (air comes from laryngopharynx) and passes air to trachea
important in vocalisation
how is the larynx protected
3 large unpaired cartilage:
- epiglottis, moves prevents food from going to larynx and sends it to oesophagus
- thyroid cartilage - adam’s apple
- cricoid cartilage - ring at bottom superior to trachea
3 small paired cartilage:
- positioning vocal folds
- arytenoid cartilage, corniculate, cuneiform
what is the trachea
long tube that provides air from larynx to bronchi. it has C shaped hyaline cartilage rings
why are the hyaline cartilage in the trachea shaped the way they are
allows oesophagus to expand to transport large boluses of food e.g. it encroaches when there are big lumps
name of secondary bronchi
lobar
location of primary bronchi
outside lung
how many bronchopulmonary segments in each lung?
10 in right, 8-10 in left
which lung is smaller
left
what is unique about bronchopulmonary segments during surgery
they are self-contained, so can be completely removed because they have their own blood supply e.g. to remove a tumor
what are the pleurae
lining of connective tissue that covers & protects the lung, reduces friction, as well as ventilates it
parietal = stuck to chest wall
visceral = stuck to the lungs
extends from clavicle & 1st rib & 7th, 10th, 12tth ribs
where is the apex of the lung
root of neck above the 1st rib
what are the 4 types of pneumothorax
primary: absence of underlying condition
traumatic: gunshot, stab, biopsy - rips parietal pleura
secondary: underlying lung disease
tension: flap of tissue
what happens when a tension pneumothorax occurs
cardiac output decreases due to compression of the inferior vena cava. this will decrease venous return and can lead to edema & even cardiac arrest
additionally arterial bp drops, tachycardia can be auscultated & neck veins are distended
what is pneumothorax
pleural effusion/collapsed lung
negative pleural pressure is lost as a result of the seal of the pleural space being punctured
what are the 3 surfaces of the lungs
diaphragmatic surface (base) that sits on diaphragm
costal surface, largest surface, adjacent to ribs
mediastinal surface is in contact with midline/mediastinum
what separates the lung lobes
fissures - oblique & horizontal (only in right lung)
what is the parietal pleura
thin membrane lining chest wall
what is the visceral pleura
thin membrane lining lung. space between parietal & visceral pleura is called the pleural cavity containing intrapleural fluid
what is the purpose of pleural fluid
- reduces friction as lung moves relative to chest wall because friction can cause tissue damage & inflammation
- creates surface tension e.g. pleural fluid bond –> pleural linkage because the lung is trying to collapse and the chest wall is trying to expand
what is pleural effusion
build-up of fluid when lungs secrete too much and don’t re-absorb. can accumulate due to poor heart pumping &/ inflammation and may cause pneumothorax
what is pneumothorax
air in the thorax, pierces parietal visceral membrane, air gets in, breaks surface tension, lung collapses
what does pneumothorax look like on an xray
what does tension pneumothorax look like on a xray & what does it do
pushes heart to the right lung due to presence of air & can cause acute failure of heart. happens when the hole that allowed air into the pleural cavity has a flap that seals it during expiration (so air only gets in during inspiration) and increases the pressure that pushes the heart to the other side
what is atelectasis
loss of lung volume secondary to alveolar collapse. not caused by leakage of air into space but rather:
- obstruction of bronchi = obstructive
- compressive = compression on lungs e.g. PE, tension pneumothorax
- contraction = scarring of lungs
- adhesive = lack of surfactant decreases surface tension
what is traumatic/spontaneous pneumothorax
air comes from outside through chest wall or from lungs, both leading to collapse
mainly caused by COPD - chronic obstructive pulmonary disease
what are the main types of COPD
Pulmonary emphysema & chronic bronchitis
treatment for pneumothorax
chest drain
what is the purpose of bronchiole constriction
to slow down air to either filter out particles (bushfire), or warm up air (cold weather)
what pathology is hyperconstriction of bronchioles
asthma
what is unique about the blood travelling to the alveoli
it is low in oxygen and gets oxygenated as it passes the alveoli via the pulmonary capillaries
what factors determine the effectiveness of gas exchange/diffusion
- driving force/partial pressure gradient. oxygen will move from highly concentrated area to low concentrated area
- surface area (large area is provided by capillaries)
- a small distance for the gas to travel –> provided by thin respiratory membrane
what is the purpose of pulmonary surfactant
secreted by type ii alveolar cells to facilititate compliance & expansion
Reduces the surface tension on the alveoli
what are the types of alveolar cells
type I = respiratory membrane, together with capillary endothelium
type II = pulmonary surfactant
what is the main cause of respiratory issues in premature babies and what is IRDS
lungs haven’t started making pulmonary surfactant yet so atelectasis is likely
IRDS = infant respiratory distress syndrome
how is oxygen transported in the blood
- physically disolved in blood plasma
- bound to heme in haemoglobin molecules with red blood cells
haemoglobin transports more than plasma
what is normal PO2
100mHg
how much O2 can dissolve in 1L of blood at normal PO2
3mL = 15mL/min
what type of O2 contributes to PO2
the O2 dissolved in blood plasma, not the O2 bound to heme in haemoglobin
what are the pathologies of too much or too little haemoglobin
too little = anaemia
too much = polycythemia
how do you determine saturation of oxygen in haemoglobin
amount of heme that are bound. 4 per molecule
what is the main factor that determines the binding capacity of haemoglobin
PO2
how much oxygen is consumed at rest and during exercise
at rest 250mL
exercising = more (the remainder of oxygen that has not been diffused to muscles like a reserve)
what are the binding properties of haemoglobin
- the curve is asymptotically shaped
- at low PO2 levels it is hard for binding to occur
- in the middle binding is easier
- as PO2 gets really high, it is harder to bind again
- look at graph
how is PO2 measured
mm Hg
what happens when PO2 falls
haemoglobin will release oxygen. when it’s bound it’s unavailable, but when released, it’ll move into blood plasma and be available to cells
what are the implications of a 70-100 mmHg PO2
- dissociation curve is flat here
- O2 content of arterial blood is hardly affected
- breathing pure oxygen
- mild respiratory functions won’t affect..?
what are the implications of a 10-50 mmHg PO2
the curve is very steep, so a small change in PO2 will result in a drastic release of O2 from the haemoglobin, making it available to diffuse from the pulmonary capillaries to the systemic capillaries (tissue)
what is normal PO2 of venous blood
40 mmHg
what is the utilisation coefficient
the capacity to provide more O2 to tissues e.g. when exercising
what causes the PO2 dissociation curve to shift
- right = Hb binding is now lower in high temp, high acidity, high PCO2 e.g. in increased metabolic activity
- left = low PCO2, low temp, low acidity, Hb binds more O2
what causes the PO2 dissociation curve to shift
- right = Hb binding is now lower in high temp, high acidity, high PCO2 e.g. in increased metabolic activity
- left = low PCO2, low temp, low acidity, Hb binds more O2 –> occurs more in pulmonary capillaries
what is the most important muscle of inspiration
diaphragm, long thin large muscle to increase/dec thoracic volume
what muscles work with diaphragm to change thoracic volume
intercostal
what innervates the diaphragm
phrenic nerve
what innervates the intercostal muscles
intercostal nerves
what can further reduce intrapulmonary pressure
action of accessory muscles
what is boyles gas law
increase in thoracic volume causes a decrease in intrapulmonary pressure. intrapulmonary pressure falls to a level below atmospheric pressure during inspiration
what are the accessory muscles for inspiration
sternocleidomastoid and scalenus
what happens in between inspiration and expiration
relaxation of inspiratory muscles
what decreases the size of the chest cavity
- relaxation of diaphragm
- elastic recoil of alveoli
look at xrays of inspiration & expiration
which rib does the diaphragm sit at during inspiration & expiration
inspiration = border of 10th rib
expiration = 9th rib
why does the heart look bigger in expiration
the capacity of the lungs decreases
what is normal tidal breathing in mL
500 mL
what is total lung capacity
5 700 mL for a male, 4 500 mL for a female
what is the residual volume
1 200 mL
what is FRC
functional residual capacity, where the lungs sit at rest. Capacity is about 2 200 mL
what are the features of normal breathing
- rhythmic
- involuntary
- occurs without conscious thought
- can be controlled by hyper/hypoventilation but ultimately autonomic control takes over
what unconsciously increases breathing rate
exercise or arousal
what part of the brain initiates breathing
medullary respiratory centre
what part of the brain regulates breathing
dorsolateral pons / respiratory centres
where are the breathing centres of the brain
image
where are the peripheral chemoreceptors
in the carotid body, a vascular organ on the wall of the carotid artery
what receptors work when there is low PO2 and what do they do
peripheral chemoreceptors via IX cranial nerve
effects:
- increase rate & depth of ventilation
- increase sympathetic nerve activity to cardiovascular system = vasoconstriction
- blood flow to peripheral tissues decreases so it can be sent to brain & heart
what receptors sense CO2 & what are their response
central chemoreceptors in medulla oblongata
they increase the rate & depth of breathing
explain the physiology of CO2 stimulating chemoreceptors
increase in arterial blood CO2 = increased CO2 in medulla because high level of CO2 causes diffusion from capillaries to interstitial fluid. together they produce carbonic acid which stimulates the medullary chemoreceptors and increase rate and depth of breathing by activating dorsal & ventral respiratory groups
what is pleural effusion
excess fluid in the pleural space
what are the types of pleural effusion
transudative, exudative, lymphatic
what is a transudative PE
what is exudate PE
inflammation of pulmonary capillaries leading to fluid leaking into pleural space
caused by trauma, malignancy, infection, pneumonia
what is lymphatic PE or chylothorax
lymphatic fluid accumulates because thoracic duct is obstructed
what does PE look like on an xray
blurring as fluid settles into costophrenic angles
will look layered if patient is lying down
what is hemothorax
blood in pleural space
What is the characteristic of alveoli in pathologies like COPD and fibrosis
The elasticity
More elastic in copd
Less elastic in fibrosis
