Respiratory and Cardiology Path and Phys Flashcards
What does a high VQ mean?
More ventilation and less blood flow and the arterial blood PO2 will approach that of inspired air
Increase tidal volume and increase minute ventilation
What does low VQ mean for arterial PO2?
PO2 will approach that of mixed venous blood
increase PAO2 decrease PACO2
less O2 delivered and less Co2 expired
what is the alveolar gas equation and why is it useful?
PaO2 = PIO2 - (PACO2 / R )
it can be used to calculate alveolar-arterial (Aa) gradient and the amount of right to left shunt
What is Ficks law
Determines the rate of transfer of a gas across the blood-gas barrier
the magnitude of diffusion tendency is proportional to both the concentration gradient and cross sectional area
inversely proportional to the thickness of the membrane
CO2 vs O2 diffusion
CO2 diffuses 20x more readily than O2
it has a smaller MW and higher solubility
how fast does blood traverse the pulmonary capillaries
0.75s
Describe diffusion/perfusion of N2O, CO, O2
N2O - perfusion limited, not taken up by Hb so is limited by blood flowing through capillaries, equilibrium about 0.1s
CO - Diffusion limited, taken up by Hb at a high rate
O2 - perfusion limited, taken up by Jb, equilibrium at 0.3s. (can be a mixture of perfusion and diffusion)
Where is ventilation the most in the lung?
the lower zones ventilate more due to gravity
Where has the greatest compliance in the lung
Lower zones have greater compliance than the apex.
(the bottom of the lung expands more than the apex during inspiration)
Where has the greatest the perfusion in the lungs?
the lower zones perfuse more
due to gravity and the resultant hydrostatic pressure gradient
Describe the 4 zones of perfusion?
Zone 1 PA >Pa >PV
pulmonary arterial pressure is less than alveolar pressure, capillaries are squashed = no flow = physiological dead space
Zone 2 Pa >PA >PV
Arterial pressure exceeds alveolar pressure but alveolar pressure exceeds venous pressure, capillaries are partially squashed
Zone 3 Pa >PV > PA
venous pressure exceeds alveolar pressure, capillaries are distended as blood falls into them
Zone 4 - extra alveolar vessels become important , increased resistance and reduced flow
VQ measurements
Ventilation (V) = 4.2L/min
Perfusion (Q) = 5.5L/min
VQ ratio 0.8
VQ high at the apex and low at the base
what is the amount of anatomical dead space?
2ml/kg (150ml)
what is physiological dead space?
volume of gas that does not eliminate CO2
What happens to amount of physiological dead space during increased RR?
Increase
Explain how high RR increases volume of dead space.
Normal pulmonary ventilation =
PV = TV x RR
Dead space is sum of anatomical dead space and alveolar dead space
Alveolar volume (AV) = (TV-Dead space) x RR
but as you increase RR your tidal volume decreases due to shallow breaths
What happens to airway resistance while breathing through the nose?
Increases
halving the size of the tube increases the resistance 16 fold
What happens to compliance during inspiration and expiration
slightly greater when measured during deflation
Describe RQ
Respiratory Quotient is the steady state ratio of CO2 to O2 production in metabolism
average is 0.8
Fat - 0.7
Cabrohydrates 1.00
Brain 0.97-0.99
what is PAO2 at sea level?
PAO2 = [( atmospheric pressure - partial pressure of water) FiO2] - (partial pressure of CO2 / respiratory quotient)
PAO2 = [(Patm − PH2O) FiO2] − (PaCO2/RQ)
PAO2 = [(760 − 47) 0.21] − (40/0.8) = 99.7mmHg
what is Patm
atmospheric pressure - is 760mmHg at sea level
what is PH2O?
partial pressure of water = 45mmHg
in the alveolar gas equation what is PaCO2
between 40-45mmHg in normal physiology
What is the oxygen pressure in the bronchi at an altitude where barometric pressure is 500 mmHg, breathing 30% O2?
135 mmHg
NOTE IT SAYS BRONCHI SO CO2 PART OF CALCULATION NOT NEEDED
What is the calculation for compliance?
Compliance = Volume change L /Pressure change cmH2O
Given that the intrathoracic pressure changes from 5 cmH2O to 10 cmH2O with inspiration and a tidal volume (TV) of 500 mls, what is the compliance of the lung?
0.1L/cmH2O
ENSURE VOLUME CHANGE IS IN L
Lung volume amounts
TV = 500mls
IRV = 2000 - 3000mls
ERV = 1000mls
RV = 1300mls
VC = 3500 mls
IC = 2500mls
FRC = 2500mls
TLC = 5000mls
What is the most important acclimatisation mechanism for high altitude
Increased HCO3
produced by kidneys to compensate the alkalosis caused by hyperventilation
pH normalises after 2-3 days due to HCO3
what happens living at high altitude ?
lower alveolar PO2
Hyperventilation
Increased 2,3 diphosphoglycerate
low arterial HCO3
What is the PO2 of alveolar air with a CO2 of 64, breathing room air at sea level and a respiratory exchange ratio of 0.8?
Alveolar gas equation PAO2= (atmospheric pressure – vapour pressure) X inspired oxygen percentage - PaCO2/0.8
Therefore;
PAO2= (760-47) X 0.21 – 64/0.8 which equals 69 mmHg
medullary chemoreceptors respond to changes in what?
H+ concentration
When the blood PCO2 rises, CO2 diffuses into the CSF from the cerebral blood vessels liberating H+ ions that STIMULATE the chemoreceptors.
Explain Laplace’s law
P=2T/r
P - pressure
T - tension of the wall of a cylinder
r - radius
the smaller the radius of the alveoli the lower the tension is needed to balance the pressure
explains the tendency of small alveoli to collapse
What is the Haldane effect
a property of haemoglobin
Deoxygenation of the blood increase its ability to carry CO2 and H+.
What is Henry’s law
Refers to the amount of dissolved O2 which proportional to the pressure of O2.
At a constant temperature, the amount of given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium.
what is the Hamburger effect?
the chloride shift, this maintains electrical neutrality in plasma.
Cl- shifts into the RBC as HCO3 shifts out
describe anatomic dead space
is a volume f the conducting airways
normally 150mls
increases with large inspirations because of the pull exerted on the bronchi by lung parenchyma
changes with the size and posture
measured by Fowler’s method
what substance is synthesised and used in the lungs?
Surfactant
What substances are synthesised or stored in the lungs and released into the blood?
PG, histamine, kalilrein
what substances are partially removed from the blood in the lungs?
PG, bradykinin, adenine, nucleotides, serotonin, noradrenaline, ACH
what substances are activated in the lungs
angiotensin I to angiotensin II
Describe surfactant in the lungs
produced by type II alveolar epithelial cells
composed of phospholipids
increases lung compliance
helps keep alveoli dry
How does the lung respond to low alveolar PO2?
Hypoxic pulmonary vasoconstriction occurs
when alveolar PO2 is < 70mmHG, marked vasoconstriction, at very low PO2 almost abolished local blood flow
what moves the oxygen dissociation curve to the right?
rise in temperature
rise in H+ (low pH)
rise in 2,3 DOG
rise CO2
what happens to the PAO2 calculation if you double the ventilation?
alveolar PCO2 decreases
in this case it will half
PAO2= 0.21 (760-47) – 20/0.8 (20 as alveolar ventilation doubled)
PAO2=125mmhG
Describe Zone 1 of the lung
PA >Pa >PV
not observed in healthy human lung
only seen when a person is ventilated with positive pressure of haemorrhage
blood vessels can become collapsed by alveolar pressure, become alveolar dead space
sometimes not perfused
Describe Zone 2 of the lung
Pa >PA >PV
about 3cms above the heart
blood flows in pulses/cycles
Describe Zone 3 of the lung
Pa >PV > PA
majority of a healthy lung
blood flow is continuous throughout the cardiac cycle
Describe Zone 4 of the lung
seen at the lung bases at low lung volumes or in pulmonary oedema
What happens initially to pCO2 and pO2 with ventilation/perfusion (V/Q) mismatch?
pCO2 unchanged, pO2 decreases
What is the principle mechanism by which carbon monoxide exposure induces hypoxia?
Reduces oxygen carrying capacity of Hb
affinity of Hb for CO is 210 times affinity for O2
causes cherry red skin
What happens to compliance and the pressure-volume curve of the lung at high lung volumes?
Decreased compliance, flatter curve
Compliance decreased at higher lung volume as the lung reaches its limits of elasticity and stretch
reduced volume exchange and flatter curve
What is dead space in a lung?
dead space is an area with ventilation but without perfusion
What is the right ventricular pressure required for opening of the pulmonary valve?
12mmHg
In an upright individual, which area of the lung is most susceptible to capillary collapse due to gravity?
apex of the lung
what are the four morphological phases of pneumonia?
congestion
red hepatisation
grey hepatisation
resolution
what is the most common organism to cause lobar pneumoniae
streptococcus pneumoniae
what is non atopic (intrinsic ) asthma
aka non reaginic asthma
frequently caused by viral respiratory infections
FH uncommon
serum igE levels are normal
no other associated allergies
which type of emphysema is most commonly associated with smoking and chronic bronchitis
centriacinar or centrilobular
what type of emphysema is associated with alpha 1 antitrypsin deficiency
panacinar or panlobular
what type of emphysema is associated with fibrosis
irregular or airspace enlargement
what type of emphysema is associated with spontaneous pneumothorax
paraseptal or ductal
what are the characteristic changes in chronic bronchitis
major increase in size of mucus glands
increase goblet cel number
squamous metaplasia and dysplasia
The pathogenicity of Mycobacterium tuberculosis is caused by which mechanisms?
cell mediated (type IV) hypersensitivity response
The T cells are responsible for killing the macrophages that have the bacilli.
Lysis of macrophages results in the formation of caseating granulomas.
Mycobacterium cannot grow in this acidic, extracellular environment which is lacking in oxygen, and so the infection is controlled.
what are the 3 types of atelectasis?
Resorption/obstruction
Compressive
Patchy
what is Resoprtion/Obstruction atelectasis?
the consequence of complete airway obstruction leads to reabsorption of the oxygen trapped in the dependent alveoli, without impairment of the blood flow through the affected alveolar
what is compressive atelectasis?
the pleural cavity is partially or completely filled by fluid/tumour/blood/air
occurs in CCF, effusion, pneumothorax
What are Bronchogenic cysts
occur anywhere in the lungs
rarely in communication with the tracheobronchial tree
lined by bronchiolar type epithelium and usually filled with mucinous secretions
complications include infection, haemorrhage, pneumothorax, emphysema, malignancy deterioration
where do lung cancers most often occur?
most arise around the hilum of the lung
How is CO2 transported in the blood?
Dissolved (20x compared to O2)
Bicarbonate - CO2 is slowly hydrated to carbonic acid, that then dissociates to bicarb. CO2 + H2O = H2CO3 = H+ + HCO3
Carbamino compounds
What is the most common type of lung cancer
adenocarcinoma
typically presents as a peripheral mass
What are Langhans cells in TB?
fused macrophages oriented around tuberculosis antigen with the multiple nuclei in a peripheral position
occur in coalescent granulomata
What is a Gohn focus and Gohn complex?
Gohn focus - parenchymal subpleural lesion found just above or below the interlobular fissure between the upper and lower lungs
with nodal involvement becomes a Gohn complex
Characteristic in TB
where does primary and secondary TB typically occur in the lung
Primary tuberculosis (TB) implants in the lower part of the upper lobe or the upper part of the lower lobe.
Secondary TB occurs near the apical pleura
In bacterial pnuemonia, alveolar clearance is achieved by
macrophages
what is bronchiectasis
A disorder in which there is destruction of smooth muscle and elastic tissue by chronic necrotizing infections
leading to permanent dilation of bronchi and bronchioles
obstruction and infection are the major conditions associated
indications for a lung transplant
end stage emphysema
idiopathic pulmonary fiborsis
cystic fibrosis
idiopathic/familia pulmonary arterila hypertension
Features of malignant mesothelioma
90% asbestos related
lifetime risk of devloping mesothelioma in heavily exposed individuals is 7-10%
latent period of 25-45 years
mesothelioma arise from in the thorax
no increased risk in smokers
epitheloid is the most common morphological type
what is the mechanism of oedema in pleural effusion secondary to pneumonia
leukocyte mediated inflammation
serous in nature due to transudates from lymphocyte rich fluid
What is underlying pathological mechanism behind Acute Respiratory Distress Syndrome?
Diffus alveolar damage
a disruption to the alveolar-capillary interface in the lung causes an acute neutrophilic inflammatory response and flooding of alveoli, with subsequent damage to type II pneumocytes and hyaline membrane formation.
what are late changes seen in an acute asthma attack?
epithelial cell damage
persisting bronchospasm, oedema, leukocyte infiltration, eosinophil mediated epithelia damage and loss
Lung abscesses are commonly associated with which pathogen?
Strep pneumococcus
What is the most common bacterial trigger of COPD
H. influenzae
A young non-smoking woman presents with a 3 month history of cough with occasional blood-stained sputum. Her older brothers are married but without children. What is the most likely diagnosis?
primary ciliary dyskinesia
What is Boyle’s law?
at a constant temperatures Pressure and Volume are inversely proportional
what are the conducting zones of the lung?
trachea, bronchi, bronchioles
not involved in gas exchange
Type I and Type II Alveoli cells
Type I - flat cells that line the alveoli covering 95% of its surface
Type II - secrete surfactant
what is the autonomic innervation in the bronchi and bronchioles?
Beta2 receptors - SNS, mediate bronchodilation and increase secretion
Alpha1 receptors - SNS, reduce secretion
M receptors - PNS induce bronchoconstriction
noncholinergic and nonadrengergic - induce bronchodilation
where is the primary centre for control of ventilation?
Medullary respiratory centre
in the reticular formation of the medulla below the fourth ventricle
Pacemaker cells in pre-Botzinger complexes either side of the medulla
Describe role of carotid bodies in ventilation
Located near the carotid bifurcation
have afferents to the glossopharyngeal nerve
Primary function is O2 sensing
contain 2 types of glomus cells;
- Type I contain granules that release catecholamines during hypoxia
- Type II Glia like cells
Role of Aortic bodies in ventilation
Two or more located near the aortic arch
Afferents to the vagus nerve
What are the 4 lung receptors that control ventilation
Stretch receptors - within smooth muscle, respond to distention and reduce the RR
Irritant receptors - cause bronchoconstriction and hyperpnoea
J receptors - play a role in rapid, shallow breathing
Bronchial C fibres - rapid shallow breathing
Treatment of altitude related illnesses
Descent
Azetazolamide (diuretic)
Glucocorticoids
Fastest pacemaker in the heart?
SA node
slowest conduction rate in the heart
AV node
allows the atrial muscle to contract before ventricular contraction
what has the longest action potential in the heart?
ventricular muscle
what is the fastest conduction in the heart?
purkinje system
can conduct the impulse about 4m/secs
What is the oxygen consumption of the heart?
Basal consumption is 2ml/100g/min
O2 consumption by a beating heart at rest is 90ml/kg/min
difference between stroke work of the left ventricle and right ventricle
seven times greater
what cation is the main cause of action potential in SA and AV node
Ca2+
no contribution from sodium
What does the Poiselle-Hagen formula explain
the relation between the flow in a long narrow tube, the viscosity of the fluid and the radius of the tube
with regards to Poiseulle - hagen formula how does flow change with change in diameter
Flow varies directly and resistance inversely with the fourth power of the radius.
eg flow is doubled by increase of 19% of radius
resistance is reduced to 6% if radius is doubled
PR interval duration
0.18 (0.12-0.2)
atrial depolarisation and conduction through the AV node
QRS duration
0.08 -0.10
Ventricular depolarisation and atiral repolarisation
QT interval is
0.40 -0.43
ventricular depolarisation and ventricular repolarisation
ST interval is
0.32
ventricular repolarisation
what is Laplaces law and what does it predict
The law states that tension in the wall of a cylinder is equal to the product of the transmural pressure and the radius, divided by the wall thickness
It predicts;
increased myocardial work in dilated cardiomyopathy, protection of capillaries against rupture, pattern of intravesical pressure/volume curve
the greatest percentage of the circulating blood is contained where
venules and veins
what is the c wave in the JVP due to ?
Transmitted pressure due to tricuspid bulging in isovolumetric contraction
what is the a wave in the JVP ?
due to atrial systole
what is the first x descent in the JVP?
Ventricle contraction
Atrium relaxing
what is the X’ (second x ) descent in the JVP
downward movement of tricuspid valve with ventricular contraction
what is the V wave in JVP?
passive atrial filling
what is y descent in JVP
atrial emptying with opening of the tricuspid valve
describe the JVP wave
a wave
x descent
c wave
X’ descent
V wave
y descent
major criteria of Rheumatic fever
migratory polyarthritis of large joints
pancarditis
endocarditic subcutaneous nodules
erythema marginatum
Sydenham chorea (involuntary rapid purposelss movements )
cause of rheumatic fever
occurs 10 days to 6 weeks after episode of pharyngitis
Group A strep in 3% of infected patients
minor criteria for rheumatic fever
infective endocaridits, arthralgia, raised CPR/ESR, leukocytosis, prolonged PR interval
Heart failure increases levels of what substances?
Renin
Aldosterone
ADH and ANP
in chest pain caused by vasoconstriction what causes this pain?
cetecholamines acting on alpha 1 receptors
What are U waves
represent repolarisation of the papillary muscles or Purkinje fibres
what do the limb leads record?
the standard BIPOLAR limb leads I II III record the difference in potential between two limbs
what type of vessel is the major source of peripheral resistance?
arterioles
what type of vessels are important in temperature regularion
ateria-venous anastomoses
what type of vessels have the greatest wall thickness to lumen ratio in blood vessels
arterioles
this muscle is controlled by vasoactive substances and vasomotor nerves to regulate local blood flow
in a healthy man who is running what happens to the BP
Systolic BP rises
Diastolic BP either falls or stays the same
what happens to cardiac output and O2 extraction in a healthy male who is running
Cardiac output can increase by 700%
O2 extraction can increase by 100%
compensatory reactions activated by haeomorrhage?
vasoconstriction, tachycardia, venoconstriction, tachypnoea, restlessness
Increased secretion of norepinephrine, epinephrine, vasopressin, glucocorticoids, renin, aldosterone, erythropoietin, plasma protein synthesis
How does Noradrenaline increase HR
increases Na and Ca permeability
increases HR by decreasing the negativity of the resting membrane potential and by increasing the slope of phase 4
In MI when does irreversible cell injury occur?
20-40 mins
In MI when does fibrotic scarring complete
2 months
In MI when does gross necrotic change occur
4-12 hours
What is phase 1 of the cardiac cycle?
atrial systole
what is phase 2 of the cardiac cycle?
isovolumetric ventricular contraction
aortic valve opens at the end of phase II
what is phase 3 of the cardiac cycle
ventricular ejection
T wave
what is phase 4 of the cardiac cycle
isovolumetric ventricular relaxation
what is phase 5 of the cardiac cycle
ventricular filling
first phase of the valsalva manouvre
blood pressure increases slightly due to increased intrathoracic pressure
as forced expiration is continued, mean arterial pressure and pulse pressure decrease
phase 2 of the valsalva manoouvre
heart rate begins to increase
phase 3 of valsalva manoeuvre
begins with the release of the forced expiration
further drop in BP due to sudden drop in intrathoracic pressure, HR increase
the fourth phase of the valsalva manoeuvre
increased cardiac output
overshoot HTN
reflex bradycardia
Commonest site of Berry aneurysm
Junction of anterior cerebral and anterior communicating artery
how does carotid sinus massage stop SVT
increases X nerve discharge to the conducting tissue between atria and ventricles and to SA and AV nodes
which substance is vasodilatory on cardiac muscle but not in skeletal muscle?
Adenosine
Compensated cardiac hypertrophy results in
diffuse fibrosis
decreases in the capillary to myocte ratio
increase in number and mutations of sarcomeres
dysfunctional proteins
extreme hypertrophy
what and where are baroreceptors
are stretch receptors
in the tunica adventitia in the walls of the heart and blood vessels
what stimulates the baroreceptors
distension of the structures
they discharge at an increased rate when the pressure in these structures rises
what happens when baroreceptors are stimulated
their afferent fibres pass via CNIX and X to the medulla
increased baroreceptor discharge inhibits tonic discharge of the vasoconstrictor nerves and excites vagal innervation
vasodilation, venodilation, drop in BP, bradycardia, decrease in CO
what happens to baroreceptors in chronic hypertension
the reflex mechanism is reset
approximate times of onset of events in ischaemia
ATP depletion occurs in seconds
ATP reduced 50% of normal in 10 min, 10% of normal in 40 min
Loss of contractility occurs within 60 seconds
Irreversible cell injury in 20-40mins
microvascular injury occurs >1 hour
Describe the action potential graph/diagram of a pacemaker cell
Prepotential phase (phase 4); at -60mV slow influx of Na, gentle increase of mV
Depolarisation starts between -40 to -30mV with the opening of Ca channels, fast influx of Ca. Steep increase in mV to +30mV (phase 0)
Repolarisation (Phase 3) potassium channels open and have outflux of K, repolarise to -60mV when the Na channels open again
Sympathetic effect on pacemaker potentials
increases HR
increase cAMP facilitates increase Ca channels, faster depolarising
Vagal effect on pacemaker potentials
Decreases heart rate
via M2 muscuranic receptors
G protein mediated opening of special K channels leads to hyperpolarisation
decrease cAMP slows opening of Ca channels
which vasoactive mediator causes angiooedema
Kinins
what vasoactive mediator inhibits platelet activation and is an effective vasodilator
prostacyclin
what is phase IV of the cardiac cycle
isovolumetric relaxation
In compensated heart failure what happens to CO, right atrial pressure, Renin, fluid retention
CO is unchanged
Right atrial pressure increases
Renin level increases
Fluid retention plays an important role
the work performed by the left ventricle is greater than that performed by the right is because ?
the afterload is greater
what is the cause of oedema in heart failure
raised venous pressure
calculation for cardiac output of left ventricle
O2 consumption ml/min divided by (arterial O2 - venous O2)
what substance can cause peripheral fluid retention in CCF
Aldosterone
decrease renal blood flow activates RAS which increases aldosterone which causes sodium and water retention
Describe the murmur of mitral regurgitation
a high pitched blowing holosystolic murmur
best heard at the apex, usually radiates to axilla
what does increased baroreceptors do
Inhibit the tonic discharge of sympathetic (vasoconstrictor) nerves and excites the vagal innervation
when does isovolumetric relaxation in the cardiac cycle end
it ends when ventricular pressure falls below atrial pressure
then AV valves open and blood fills the ventricles
what does the R wave in the ECG represent
initial depolarisation of cardiac muscle
sudden influx of Na through rapidly opening Na channels
in cardiac action potential of a ventricular cell how much longer is the plateau phase than depolarisation
100x
Difference between Absolute refractory period and relative refractory period
Absolute refractory period 0.20s- phase 0 to half way through phase 3, Na channels cannot be reopened - prevents tetanus
Relative refractory period 0.05s as some Na channels are closed they have the potential to be reopened but would need a greater stimuli
what does phase 1 represent in the cardiac cycle
atrial systole
what is considered normal degree range for normal axis in ECG
-30 to +110
describe phase 2 of the cardiac cycle
start of ventricular systole
AV valves close
intraventricular pressure rises sharply
isovolumetric ventricular contraction
what is myocardial oxygen consumption in a beating and a non beating heart
90ml/kg/min (9ml/100g/min)
non beating = 2ml/100g/min
how does the stroke volume in the left ventricle compare to the right ventricle
left ventricle is 7x greater
amount of blood ejected by each ventricle per stroke
70-90ml
what is the end diastolic ventricular volume of the heart
130ml
(~50mls in each ventricle)
what does the third heart sound corresponds to ?
In rushing of blood with the period of rapid ventricular filling
can be heard in normal young individuals
time of a normal PR interval
150ms
histological changes seen in 24 hours of MI
early coagulation necrosis
pallor
oedema
haemorrhage
histological changes seen form day 3-7 of MI
Disintegration of myofibres
histological changes seen at 2 to 8 weeks of MI
collagen deposition
what changes occur in compensated pressure loaded cardiac hypertrophy?
diffuse fibrosis
decrease on myocyte ratio
increase in number and mutations of the sarcomeres
synthesis of abnormal and dysfunctional proteins
extreme hypertrophy
concentric increase in ventricular wall
what change in seen in VOLUME loaded cardiac hypertrophy
dilation of the ventricle
Causes of high output failure
anaemia
sickle cell disease
renal failure
pregnancy
beri beri (thiamine deficiency)
Pagets disease
ateriovenous fistula
morbid obesity
cor pulmonale
what is the most common cause of endocarditis in prosthetic valves
staph epidermidis
four features of tetralogy
VSD
obstruction of right ventricular outflow tract
aorta overrides VSD
right ventricular hypertrophy
what is the most important independent risk factor in the development of atherosclerosis
Genetics
risk of rupture of a 5.5% AAA
5-15%
describe phase 3 of cardiac cycle
Aortic and pulmonary valves open
ventricular ejection
describe phase 5 of cardiac cycle
late diastole
ventricles fill 70%
The most important ion for cardiac resting membrane potential (CRMP) is?
Potassium
what does Calmodulin do for smooth muscle
causes smooth muscle contraction
it binds to Ca activating myosin light chain kinases
this with ATP activates myosin to bind to Actin for contraction
what does hyperkalaemia do to the resting membrane potential
decreases the resting membrane potential
(ignore the negative numbers)
what are the 3 components of atherosclerotic plaques
- cells - smooth muscle cells, macrophages, leucocytes
2.connective tissue extra cellular matrix - collagen, elastic fibrees, proteoglycans - intracellular extracellular deposits
In atherosclerosis, the cells at the centre of the plaque are?
foam cells
The atherosclerotic plaque consists of a superficial fibrous cap which is comprised of
smooth muscle cells
few leukocytes ad connective tissue
with regards with malignant hypertension what are the risk factors
younger individuals, men, black and those with a diastole of >130mmHg. It is associated with abnormally high levels of renin
what changes occur in compensated pressure loaded cardiac hypertrophy
Diffuse fibrosis
Decrease in the capillary myocyte ratio
Increase in number and mutations of sarcomeres
Synthesis of abnormal and dysfunctional proteins
Extreme hypertrophy
Concentric increase in ventricular wall
Causes of high output failure
anaemia
Renal failure (lack of erythropoietin).
pregnancy,
beriberi (vitamin B1/thiamine deficiency),
thyrotoxicosis,
Paget’s disease,
arteriovenous fistulae and arteriovenous malformations,
morbid obesity,
cor pulmonle,
carcinoid syndrome,
multiple myeloma,
beta-thalassemia intermedia
cirrhosis.
In endocarditis what is the most common cause on prosthetic valves
staphylococcus epidermis
In MI when does irreversible cell injury occur
20-40 minutes
In MI when does fibrotic scaring occur
in 2 months
In MI when does gross necrotic change occur
within 4-12 hours
what are the 4 morphological phases of strep pneumoniae
congestion, red hepatisation, grey hepatisation and resolution
in chronic bronchitis what happens to;
mucus glands
bronchial epithelium
Reid index
increase in size of mucus glands
squamous cell metaplasia and dysplasia
Ried index increased = ratio of thickness of mucus gland layer to the thickness of the wall between the epithelium and cartilage
particle sizes and where they get lodged in the respiratory tract
> 10 microns = upper airway.
5-10 microns = lower trachea or conducting airways.
0.5 - 5 microns = distal lung parenchyma (i.e. size of many bacteria) get phagocytosed
in asthma what do steroids do
inhibit cytokines
where in the lungs do bronchogenic cysts occur
adjacent to bronchioles
rarely communicate with tracheobronchial tree
complications of bronchogenic cysts
infection,
rupture causing haemorrhage,
pneumothorax
interstitial emphysema
small risk of malignant deterioration
where do lung cancers normally occur
around the hilum of the lung
what is the most common type of lung cancer
Adenocarcinoma
In TB what is the Ghon focus
a parenchymal subpleural lesion found just above or below the interlobar fissure between the upper and lower lungs
in TB what are the coalescent granulomata composed of
epitheliod cells surrounded by a zone of fibroblasts and lymphocytes that usually contain Langhans giant cells.
