Case 1 Flashcards
how does air flow?
region of high pressure to a region of low pressure
what kind of process is inhalation
an active process
what muscles are used in quiet inhalation
diaphragm, external intercostal muscles and potentially scalene muscles
how much of the air movement does diaphragmatic movement count for in quiet inhalation
75%
accessory muscles in forced inhalation
sternocleidomastoid, scalene, serratus anterior and pectoralis minor
why is air drawn into the bronchial tree during inhalation
due to positive atmospheric pressure exerted through upper respiratory tract and the negative pressure on the outer surface of the lungs, brought about by increase capacity of thoracic cavity
is quiet exhalation active or passive
largely passive - due to elastic recoilq
how does surface tension affect quiet expiration
fluid that lines the alveoli. as water molecules pull together they also pull on the alveolar walls, causing the alveoli to recoil and become smaller
what two factors prevent the lungs from collapsing
surfactant (reduces surface tension) and inter pleural pressure
is forced expiration passive or active
active
what are the muscles of forced expiration
external and internal oblique. transverses abdominis, rectus abdominis, transverses thoracis
what muscle pulls down the twelfth rib during forced expiration
quadratus lumborum
what are the respiratory centres
medulla oblongata and pons
what are the respiratory centres in the medulla oblongata
DRG and VRG
what does the DRG control
controls mostly inspiratory movements and their timing
what nerve innervates the diaphragm
phrenic nerve
what does VRG cause
forced expiration
what does VRG inspiratory centre do during forced inspiration
aids the DRG
how do the signals in the RAMP pathway occur
in action potential bursts
what do the 3 seconds of no signals in the RAMP pathway do
allow elastic recoil of the lungs and the chest wall to cause expiration (passive exhalation)
what is the advantage of the RAMP pathway
causes a steady increase in the volume of the chest during inspiration, rather than inspiratory gaps
what are the respiratory centres in the pons
apneustic and pneumotaxic centres
what are the stimuli for the respiratory centres in the pons
the vagus nerve and the glossopharyngeal nerves to the respiratory centres
where is the apneustic centres located
lower pons
what does the apneustic centre do
provides continuous stimulation to the DRG, resulting in long deep inhalation
what happens after 2 seconds of inhalation to the apneustic centres
they are inhibited by the pneumotaxic centres
where are the pneumotaxic centres located
in the upper pons
what does the pneumotaxic centre control
the ‘switch off’ point of the ramp signal, thus limiting inspiration
chemoreceptors:
P(CO2), P(02), pH of the blood
baroreceptors
changes in blood pressure
stretch receptors:
respons to changes in volume of the lungs (Hering-Breuer Reflex)
where do excess carbon dioxide and hydrogen ions in the blood act on
act directly on the respiratory centre itself
where does oxygen act on
on peripheral chemoreceptors in the carotid and aortic bodies
where is the chemosensitive area located
located bilaterally, lying beneath the ventral surface of the medulla
why can cross the blood-brain barrier
carbon dioxide
which has an effect in stimulation the neurone in the chemosensitive area
hydrogen ions have a direct effect unlike carbon dioxide
how does carbon dioxide effect the chemosensitive area
it cross the brain-blood barrier, reacts with water of the tissues to form carbonic acid, then dissociates into hydrogen and bicarbonate ions; the hydrogen ions then have a direct stimulatory effect on the chemosenstive area in the brain
do the Pco2, pH and Po2 values change during strenuous exercise
no they remain normal
what happens at the onset of exercise to the arterial Pco2
there is no increase, as alveolar ventilation increases instantaneously without an initial increase in arterial Pco2
which nerve is the carotid body associated with
glossopharyngeal nerve and then to the DRG
which nerve is the aortic body associated with
the vagus nerve which goes to the DRG
where are stretch receptors located
located in the muscular portions of the walls of the bronchi and bronchioles throughout the lungs
where do stretch receptors transmit signals to
the vagus nerve into the DRG when the lungs become over stretched
what happens where the lungs become overly inflated
the stretch receptors activate an appropriate feedback response that ‘switches off’ the inspiratory ramp and thus stops further inspiration
what happens in normal tissues if it becomes more active
Po2 falls and Pco2 rises
what do rising Pco2 levels do
they relax smooth muscle in walls of arteries and capillaries, causing vasodilation and increasing blood flow
what is hypoxia
lack of oxygen
what are the effects of hypoxia on the body
drowsiness, lack of energy, mental and muscle fatigue, headache and nausea
what is cyanosis
blueness of the skin
how is cyanosis caused
result of excessive amounts of deoxygenated haemoglobin in the skin blood vessels
what is pleural pressure
the pressure of the fluid in the pleural cavity which is the space between the visceral and parietal pleura
is pleural pressure usually slightly negative or positive
usually slightly negative (-5)
what happens to the pleural pressure during inspiration
expansion of the chest cage pulls outward on the lungs with greater force and therefore creates more negative pressure (7.5)
what is alveolar pressure
pressure inside the alveoli
what happens to the alveolar pressure when there is no air flow
it is equal to the atmospheric pressure which is considered to zero
what has to happen to pressure in alveoli during inspiration
the pressure must fall to a value slightly below atmospheric pressure (below 0)
what happens to alveolar pressure during expiration
the alveolar pressure rises to about +1 and this forced 0.5 litres of inspirited air out of the lungs during the 2 or 3 seconds of expiration
what is transpulmonary pressure
this is the difference between the alveolar pressure and the pleural pressure
what is recoil pressure
measure of the elastic forces in the lungs that tend to collapse the lungs at each instant of respiration
what does the work of breathing depend on
the tidal volume - increased = more work done by lungs
respiratory frequency
what is airflow
partial pressure / airways resistance
what is partial pressure
alveolar pressure - atmospheric pressure
what happens in the airway is long
greater airway resistance
what happens in airway is short and narrow
the greater the airway resistance
What is compliance
indication of the lung’s expandability or how easily the lungs expand and contract
what happens when the compliance is low
the greater the force required to fill and empty the lungs
what happens when the compliance is great
the easier to fill and empty the lungs
what is surfactant
surface active agent in water, which means it greatly reduced the surface tension of water
what cells secrete surfactant
type II alveolar epithelial cells
what confirms a pneumothorax
chest X-ray
what does a collapsed lung look like on an X-ray
extra black space indicates the presence of air
what are the steps to do a chest X-ray
A - airways
B - breathing and bones
what Is the order for chest X-ray
A - airways B - breathing and bones C - cardiac D - diaphragm E - everything else
what films are used for pneumothorax
standard erect posterior anterior are usually adequate although if too injured to stand used anterior posterior
what treatment is used for a complete primary
aspirate / chest drain
what treatment is used for a moderate primary
aspirate
what treatment is used for a small primary
observe
what treatment is used for a complete secondary
chest drain
what treatment is used for a moderate secondary
chest drain
what treatment is used for a small secondary
chest drain
what treatment is used fro a complete traumatic
chest drain
what treatment is used for a moderate traumatic
chest drain
what treatment is used for a small traumatic
observe / chest drain
what else is given during immediate manage of a pneumothorax
supplemental oxygen
where does aspiration take place
second intercostal space, mid-clavicular line
where is a chest drain inserted
inter pleural space between two ribs
what does a chest drain do
it allows air to escape from the inter pleural space so that the underlying lung can re-inflate
how is pneumothorax drained via a chest tube
as pressure in the inter pleural space becomes positive, due to coughing, air passes along the chest drain and out into the atmosphere through an underwater seal and the pneumothorax is drained
what is ATLS
advanced trauma life support
what is the principle of ATLS
treat the greatest threat to life first
is a definitive diagnosis necessary to treat patient initially under ATLS protocol
no
what is the primary survey of ATLS protocol
A - airway maintenance with cervical spine protection
what does ABCDE stand for in ATLS protocol
A - airway maintenance and cervical spine protection
B - breathing and ventilation
C - circulation with haemorrhage control
D - disability and neurologic status
E - exposure and environment
what Is the secondary survey of ATLS protocol
a head to toe evaluation of the trauma patient, including a complete history and physical examination including the reassessment of all the vital signs
what happens if at any point during secondary survey of ATLS protocol the patient deteriorates
another primary survey is carried out as a potential threat to life may be present
what type of fibres are acetylcholine
cholinergic
what type of fibres are norepinephrine
adrenergic
what fibre are all preganglionic neurons
cholinergic
what type of fibres are in postganglionic of sympathetic
adrenergic
what receptors do acetylcholine activate
nicotinic receptors and muscarinic resceptors
where are nicotinic receptors found
found in the autonomic ganglia at the synapses between the pre and post ganglionic neurones of both para and sympathetic systems
where are muscarinc receptors found
found on all effector cells that are stimulated by the postganglionic cholinergic neurones of the parasympathetic nervous system
where are alpha 1 receptors found
in walls of blood vessels and cause smooth muscle contraction
what do alpha 2 receptors do
inhibit adenylate cyclase - decreasing cAMP formation
negative feedback for release of norepinephrine from presynaptic neurone
what do all beta receptors stimulate
adenylate cyclase
where are beta 1 receptors found
located in the heart, increase cardiac output
where are beta 2 receptors found
in the lungs - bronchodilator
where are beta 3 receptors found
in fat cells - lypolisis in adipose tissue
what type of receptors are alpha and betas
they are G protein coupled receptors (intracellular messengers)
how does noradrenaline stimulate receptors
stimulates alpha receptors more than beta receptors
how does adrenaline stimulate receptors
stimulates alpha and beta receptors equally
what are the three phases of the stress response
- Alarm phase
- resistance phase
- exhaustion phase
what happens during alarm phase of the stress response
response is directed by the sympathetic nervous system and causes increased secretion of adrenaline
what happens in alarm phase pt.2
energy reserves are mobilised, mainly in the form of glucose
what happens in the resistance phase of the stress response
the dominant hormone is cortisol which is a glucocorticoid
what happens during exhaustion phase of stress response
homeostatic regulation breaks down and the exhaustion phase begins
the failure of one or more organ systems will prove fatal
what happens with mineral balance in the exhaustion phase of the stress response
the production of aldosterone throughout the resistance phase results in the conservation of Na at the expense of K, as body’s K content declines, neurones and muscle fibres begin to malfunction
when does stress occur
when the perceived demands of a situation are appraised as exceeding a person’s perceived resources and ability to cope
what is the role of appraisal
Lazarus argued that stress involved in a transaction between the individual and their external world, and that a stress response was elicited if the individual appraised a potentially stressful event as actually being stressful
what is primary appraisal
when the individual initially appraises the event itself
how can an event be appraised
- irrelevant
- benign and positive
- harmful and a threat
- harmful and a challenge
what is the secondary appraisal of stress
the individual evaluating the pros and cons of their different coping strategies
what happens during acute stress response according the Cannon
- increased sympathetic activation
- increased cognitive performance
- increased muscular priming
- increased immune functioning
what happens during chronic stress response according to Cannon
- decreased immune functioning
- decreased cognitive functioning
- this eventually leads to exhaustion
what are the three distinct functional states of sodium channels
resting, open, refractory
what class of drug is lidocaine
class Ib
what is PTSD
ir is a condition where exposure to an intense and frightening emotional experience leads to lasting changes in behaviour, mood and cognition
major symptoms of PTSD:
feeling numb to the world, reliving trauma repeatedly, sleep disturbances, over alertness
what is category A of PTSD
exposure to an event involving actual/threatened death or serious injury
what is category b of PTSD
1+ symptoms of reliving the trauma repeatedly
what is class C of PTSD
3+ symptoms of persistent avoidance of trauma stimuli or numbing of general responsiveness
what is category D of PTSD
2+ symptoms of persistent increased arousal
how is PTSD diagnosed
had symptoms for one or more months
how is prevention of PTSD better achieved
through the support offered by others who were also involved
what is the primary goal of CBT for PTSD
undergo some sustained emotional processing of the traumatic experiences
what is CBT
A structured therapy that focuses on clearly identified and achievable treatment goals
what is the aim of CBT for PTSD patients
to desensitise the patient to the traumatic event
other aim of CBT
to modify unhelpful and maladaptive beliefs and to generate more flexible rational and adaptive beliefs
what is the bystander effect
psychosocial phenomenon in which someone is less likely to help and intervene in an emergency situation when other people are present
what is pluralistic ignorance
everybody in the group misleads everybody else by defining the situation as a non-emergency
what causes a person to not react to a clear cut emergency
diffusion of responsibility
what is catamenial pneumothorax
pneumothorax caused by endometriosis of a woman at the time of menstruation
what does monoaimine oxidase do
breaks down norepinephrine molecules after they have been released in the sympathetic synapse
do you get a decrease of blood pressure as a result of PTSD
no
what is the alveolar pressure required to draw in 0.5L of air in normal inspiration
-1mmHg
how does adrenaline lower cAMP levels
acts on the alpha 2 adrenergic membrane receptors
what pulse rate suggests a tension pneumothorax
pulse over 135bpm
what is first line treatment for PTSD
eye movement desensitisation and reprocessing
the activation of what receptor leads to peripheral vasoconstriction
alpha receptors
where are chest drains placed
best paced between the 5th and 6th ribs, anterior axillary line
what channels does lidocaine block
sodium channels
what is the brand name for lidocaine
Xylocaine
mode of action of lidocaine
- stabilises the neuronal membrane by inhibiting the ionic fluxed required for the initiation and conduction of pulses, thereby effecting local anaesthetic action
mode of action of lidocaine pt2
at sodium channels, neutral uncharged lidocaine molecules diffuse through neural sheaths into the axoplasm where they are subsequently ionised by joining with hydrogen ions. the resultant lidocaine cations are then capable of reversibly binding the sodium channels from the inside and keeping them locked in an open state that prevents nerve depolarisation. as a result, the membrane of neurone will ultimately not depolarise and thus fail to transmit an action potential.
what neurone does not depolarise when lidocaine is used
postsynaptic
Hypothalamic Pituatary-Adrenal System
- the stressor activates the HPA
- the hypothalamus stimulates the pituitary gland
- the pituitary gland secretes adrenocorticotropic hormone (acth)
- ACTH stimulates the adrenal glands to produce the hormone corticosteroid
- cortisol enables the body to maintain steady supplies of blood sugar
- adequate and steady blood sugar levels help a person cope with a stressor
functions of cortisol
releases stored glucose from the liver, controls swelling after an injury and also surpasses the immune system
true or false: chronic stress is maladaptive
true
oxygen needs of the body
250ml/min at rest
carbon dioxide production:
200ml/min at rest
what is the functional residual capacity
when respiratory muscles are relaxed the lung volume at this point is the FRC
why does a lung collapse?
when the pleural pressure is equal to the atmospheric pressure there is no force to counter the elastic recoil force
what is airway resistance proportional to:
length/radius
what cells are in the trachea
ciliated epithelium
what cells are in the primary bronchus
basal cells
secondary and tertiary bronchus have what cells
goblet cells and club cells
what cells do smaller bronchi, bronchioles and terminal bronchioles have
serous cells, brush cells and club cell
what cells do respiratory bronchioles and alveolar sacs have
alveolar type I and II cells
how many alveolar sacs are there on average
150 million
lining cells:
ciliated, intermediate, brush, basal epithelium
contractile cells:
smooth muscle
secretory cells:
goblet, mucous, serious (glands)
connective tissue:
fibroblast, interstitial cell produce elastin, collagen, proteoglycans, cartilage
neuroendocrine:
nerves, ganglia, neuroepithelial cells
vascular cells:
endothelial, smooth muscle, pericyte
immune cells:
mast cell, dendritic cells, lymphocyte, eosinophil, macrophage, neutrophil
functions of airway macrophages
- induction of inflammation: pathogens
- inhibition of inflammation: clearance of self cells and extracellular matrix turnover products
type I alveolar cells
simple squamous epithelium, non-ciliated and main site of gas exchange - covers 90% of alveolus
type II alveolar cells
produce surfactant to reduce surface tension preventing alveoli collapse and renew of type I cells
what are the four types of clinical studies
randomized controlled trials (RCTs), cohort studies, case-control studies and qualitative studies
what is a randomised control study
A randomized controlled trial is a form of scientific experiment used to control factors not under direct experimental control.
what is a cohort study
A cohort study is a particular form of longitudinal study that samples a cohort, performing a cross-section at intervals through time. It is a type of panel study where the individuals in the panel share a common
what is a case control study
case–control study is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribut
what is a qualitative study
Qualitative research investigates the why and how of decision making, not just what, where, and when. Therefore, the need is for smaller but focused samples rather than large random samples. Qualitative analysis involves categorizing data into patterns as the primary basis for organizing and reporting results.
what does the carotid body detect that the aortic body does not
pH
what valves does thematic fever effect
mitral and aortic valves
what us cause of rheumatic fever
group A beta-haemolytic streoptocci
what immunoglobulin is most likely to cause rheumatic feeer
IgM
