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Acem Primary > Respiratory and Cardiology Path and Phys > Flashcards

Respiratory and Cardiology Path and Phys Flashcards

1
Q

What does a high VQ mean?

A

More ventilation and less blood flow and the arterial blood PO2 will approach that of inspired air
Increase tidal volume and increase minute ventilation

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2
Q

What does low VQ mean for arterial PO2?

A

PO2 will approach that of mixed venous blood
increase PAO2 decrease PACO2
less O2 delivered and less Co2 expired

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3
Q

what is the alveolar gas equation and why is it useful?

A

PaO2 = PIO2 - (PACO2 / R )
it can be used to calculate alveolar-arterial (Aa) gradient and the amount of right to left shunt

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4
Q

What is Ficks law

A

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

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5
Q

CO2 vs O2 diffusion

A

CO2 diffuses 20x more readily than O2
it has a smaller MW and higher solubility

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6
Q

how fast does blood traverse the pulmonary capillaries

A

0.75s

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7
Q

Describe diffusion/perfusion of N2O, CO, O2

A

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)

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8
Q

Where is ventilation the most in the lung?

A

the lower zones ventilate more due to gravity

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9
Q

Where has the greatest compliance in the lung

A

Lower zones have greater compliance than the apex.
(the bottom of the lung expands more than the apex during inspiration)

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10
Q

Where has the greatest the perfusion in the lungs?

A

the lower zones perfuse more
due to gravity and the resultant hydrostatic pressure gradient

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11
Q

Describe the 4 zones of perfusion?

A

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

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12
Q

VQ measurements

A

Ventilation (V) = 4.2L/min
Perfusion (Q) = 5.5L/min
VQ ratio 0.8
VQ high at the apex and low at the base

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13
Q

what is the amount of anatomical dead space?

A

2ml/kg (150ml)

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14
Q

what is physiological dead space?

A

volume of gas that does not eliminate CO2

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15
Q

What happens to amount of physiological dead space during increased RR?

A

Increase

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16
Q

Explain how high RR increases volume of dead space.

A

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

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17
Q

What happens to airway resistance while breathing through the nose?

A

Increases
halving the size of the tube increases the resistance 16 fold

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18
Q

What happens to compliance during inspiration and expiration

A

slightly greater when measured during deflation

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19
Q

Describe RQ

A

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

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20
Q

what is PAO2 at sea level?

A

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

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21
Q

what is Patm

A

atmospheric pressure - is 760mmHg at sea level

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22
Q

what is PH2O?

A

partial pressure of water = 45mmHg

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23
Q

in the alveolar gas equation what is PaCO2

A

between 40-45mmHg in normal physiology

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24
Q

What is the oxygen pressure in the bronchi at an altitude where barometric pressure is 500 mmHg, breathing 30% O2?

A

135 mmHg
NOTE IT SAYS BRONCHI SO CO2 PART OF CALCULATION NOT NEEDED

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25
Q

What is the calculation for compliance?

A

Compliance = Volume change L /Pressure change cmH2O

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26
Q

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?

A

0.1L/cmH2O
ENSURE VOLUME CHANGE IS IN L

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27
Q

Lung volume amounts

A

TV = 500mls
IRV = 2000 - 3000mls
ERV = 1000mls
RV = 1300mls
VC = 3500 mls
IC = 2500mls
FRC = 2500mls
TLC = 5000mls

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28
Q

What is the most important acclimatisation mechanism for high altitude

A

Increased HCO3
produced by kidneys to compensate the alkalosis caused by hyperventilation
pH normalises after 2-3 days due to HCO3

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29
Q

what happens living at high altitude ?

A

lower alveolar PO2
Hyperventilation
Increased 2,3 diphosphoglycerate
low arterial HCO3

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30
Q

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?

A

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

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31
Q

medullary chemoreceptors respond to changes in what?

A

H+ concentration
When the blood PCO2 rises, CO2 diffuses into the CSF from the cerebral blood vessels liberating H+ ions that STIMULATE the chemoreceptors.

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32
Q

Explain Laplace’s law

A

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

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33
Q

What is the Haldane effect

A

a property of haemoglobin
Deoxygenation of the blood increase its ability to carry CO2 and H+.

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34
Q

What is Henry’s law

A

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.

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35
Q

what is the Hamburger effect?

A

the chloride shift, this maintains electrical neutrality in plasma.
Cl- shifts into the RBC as HCO3 shifts out

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36
Q

describe anatomic dead space

A

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

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37
Q

what substance is synthesised and used in the lungs?

A

Surfactant

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38
Q

What substances are synthesised or stored in the lungs and released into the blood?

A

PG, histamine, kalilrein

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39
Q

what substances are partially removed from the blood in the lungs?

A

PG, bradykinin, adenine, nucleotides, serotonin, noradrenaline, ACH

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40
Q

what substances are activated in the lungs

A

angiotensin I to angiotensin II

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41
Q

Describe surfactant in the lungs

A

produced by type II alveolar epithelial cells
composed of phospholipids
increases lung compliance
helps keep alveoli dry

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42
Q

How does the lung respond to low alveolar PO2?

A

Hypoxic pulmonary vasoconstriction occurs
when alveolar PO2 is < 70mmHG, marked vasoconstriction, at very low PO2 almost abolished local blood flow

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43
Q

what moves the oxygen dissociation curve to the right?

A

rise in temperature
rise in H+ (low pH)
rise in 2,3 DOG
rise CO2

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44
Q

what happens to the PAO2 calculation if you double the ventilation?

A

alveolar PCO2 decreases
in this case it will half
PAO2= 0.21 (760-47) – 20/0.8 (20 as alveolar ventilation doubled)
PAO2=125mmhG

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45
Q

Describe Zone 1 of the lung

A

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

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46
Q

Describe Zone 2 of the lung

A

Pa >PA >PV
about 3cms above the heart
blood flows in pulses/cycles

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47
Q

Describe Zone 3 of the lung

A

Pa >PV > PA
majority of a healthy lung
blood flow is continuous throughout the cardiac cycle

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48
Q

Describe Zone 4 of the lung

A

seen at the lung bases at low lung volumes or in pulmonary oedema

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49
Q

What happens initially to pCO2 and pO2 with ventilation/perfusion (V/Q) mismatch?

A

pCO2 unchanged, pO2 decreases

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50
Q

What is the principle mechanism by which carbon monoxide exposure induces hypoxia?

A

Reduces oxygen carrying capacity of Hb
affinity of Hb for CO is 210 times affinity for O2
causes cherry red skin

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51
Q

What happens to compliance and the pressure-volume curve of the lung at high lung volumes?

A

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

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52
Q

What is dead space in a lung?

A

dead space is an area with ventilation but without perfusion

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53
Q

What is the right ventricular pressure required for opening of the pulmonary valve?

A

12mmHg

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54
Q

In an upright individual, which area of the lung is most susceptible to capillary collapse due to gravity?

A

apex of the lung

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55
Q

what are the four morphological phases of pneumonia?

A

congestion
red hepatisation
grey hepatisation
resolution

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56
Q

what is the most common organism to cause lobar pneumoniae

A

streptococcus pneumoniae

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57
Q

what is non atopic (intrinsic ) asthma

A

aka non reaginic asthma
frequently caused by viral respiratory infections
FH uncommon
serum igE levels are normal
no other associated allergies

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58
Q

which type of emphysema is most commonly associated with smoking and chronic bronchitis

A

centriacinar or centrilobular

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59
Q

what type of emphysema is associated with alpha 1 antitrypsin deficiency

A

panacinar or panlobular

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60
Q

what type of emphysema is associated with fibrosis

A

irregular or airspace enlargement

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61
Q

what type of emphysema is associated with spontaneous pneumothorax

A

paraseptal or ductal

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62
Q

what are the characteristic changes in chronic bronchitis

A

major increase in size of mucus glands
increase goblet cel number
squamous metaplasia and dysplasia

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63
Q

The pathogenicity of Mycobacterium tuberculosis is caused by which mechanisms?

A

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.

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64
Q

what are the 3 types of atelectasis?

A

Resorption/obstruction
Compressive
Patchy

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65
Q

what is Resoprtion/Obstruction atelectasis?

A

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

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66
Q

what is compressive atelectasis?

A

the pleural cavity is partially or completely filled by fluid/tumour/blood/air
occurs in CCF, effusion, pneumothorax

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67
Q

What are Bronchogenic cysts

A

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

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68
Q

where do lung cancers most often occur?

A

most arise around the hilum of the lung

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69
Q

How is CO2 transported in the blood?

A

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

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69
Q

What is the most common type of lung cancer

A

adenocarcinoma
typically presents as a peripheral mass

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70
Q

What are Langhans cells in TB?

A

fused macrophages oriented around tuberculosis antigen with the multiple nuclei in a peripheral position
occur in coalescent granulomata

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71
Q

What is a Gohn focus and Gohn complex?

A

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

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72
Q

where does primary and secondary TB typically occur

A

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

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72
Q

In bacterial pnuemonia, alveolar clearance is achieved by

A

macrophages

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73
Q

what is bronchiectasis

A

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

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74
Q

indications for a lung transplant

A

end stage emphysema
idiopathic pulmonary fiborsis
cystic fibrosis
idiopathic/familia pulmonary arterila hypertension

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75
Q

Features of malignant mesothelioma

A

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

76
Q

what is the mechanism of oedema in pleural effusion secondary to pneumonia

A

leukocyte mediated inflammation
serous in nature due to transudates from lymphocyte rich fluid

77
Q

What is underlying pathological mechanism behind Acute Respiratory Distress Syndrome?

A

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.

78
Q

what are late changes seen in an acute asthma attack?

A

epithelial cell damage
persisting bronchospasm, oedema, leukocyte infiltration, eosinophil mediated epithelia damage and loss

79
Q

Lung abscesses are commonly associated with which pathogen?

A

Strep pneumococcus

80
Q

What is the most common bacterial trigger of COPD

A

H. influenzae

81
Q

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?

A

primary ciliary dyskinesia

82
Q

What is Boyle’s law?

A

at a constant temperatures Pressure and Volume are inversely proportional

83
Q

what are the conducting zones of the lung?

A

trachea, bronchi, bronchioles
not involved in gas exchange

84
Q

Type I and Type II Alveoli cells

A

Type I - flat cells that line the alveoli covering 95% of its surface
Type II - secrete surfactant

85
Q

what is the autonomic innervation in the bronchi and bronchioles?

A

Beta2 receptors - SNS, mediate bronchodilation and increase secretion
Alpha1 receptors - SNS, reduce secretion
M receptors - PNS induce bronchoconstriction
noncholinergic and nonadrengergic - induce bronchodilation

86
Q

where is the primary centre for control of ventilation?

A

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

87
Q

Describe role of carotid bodies in ventilation

A

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

88
Q

Role of Aortic bodies in ventilation

A

Two or more located near the aortic arch
Afferents to the vagus nerve

89
Q

What are the 4 lung receptors that control ventilation

A

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

90
Q

Treatment of altitude related illnesses

A

Descent
Azetazolamide (diuretic)
Glucocorticoids

91
Q

Fastest pacemaker in the heart?

A

SA node

92
Q

slowest conduction rate in the heart

A

AV node
allows the atrial muscle to contract before ventricular contraction

93
Q

what has the longest action potential in the heart?

A

ventricular muscle

94
Q

what is the fastest conduction in the heart?

A

purkinje system
can conduct the impulse about 4m/secs

95
Q

What is the oxygen consumption of the heart?

A

Basal consumption is 2ml/100g/min
O2 consumption by a beating heart at rest is 90ml/kg/min

96
Q

difference between stroke work of the left ventricle and right ventricle

A

seven times greater

97
Q

what cation is the main cause of action potential in SA and AV node

A

Ca2+

no contribution from sodium

98
Q

What does the Poiselle-Hagen formula explain

A

the relation between the flow in a long narrow tube, the viscosity of the fluid and the radius of the tube

99
Q

with regards to Poiseulle - hagen formula how does flow change with change in diameter

A

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

100
Q

PR interval duration

A

0.18 (0.12-0.2)
atrial depolarisation and conduction through the AV node

101
Q

QRS duration

A

0.08 -0.10
Ventricular depolarisation and atiral repolarisation

102
Q

QT interval is

A

0.40 -0.43
ventricular depolarisation and ventricular repolarisation

103
Q

ST interval is

A

0.32
ventricular repolarisation

104
Q

what is Laplaces law and what does it predict

A

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

105
Q

the greatest percentage of the circulating blood is contained where

A

venules and veins

106
Q

what is the c wave in the JVP due to ?

A

Transmitted pressure due to tricuspid bulging in isovolumetric contraction

107
Q

what is the a wave in the JVP ?

A

due to atrial systole

108
Q

what is the first x descent in the JVP?

A

atrial contraction

109
Q

what is the X’ (second x ) descent in the JVP

A

downward movement of tricuspid valve with ventricular contraction

110
Q

what is the V wave in JVP?

A

passive atrial filling

111
Q

what is y descent in JVP

A

atrial emptying with opening of the tricuspid valve

112
Q

describe the JVP wave

A

a wave
x descent
c wave
X’ descent
V wave
y descent

113
Q

major criteria of Rheumatic fever

A

migratory polyarthritis of large joints
pancarditis
endocarditic subcutaneous nodules
erythema marginatum
Sydenham chorea (involuntary rapid purposelss movements )

114
Q

cause of rheumatic fever

A

occurs 10 days to 6 weeks after episode of pharyngitis
Group A strep in 3% of infected patients

115
Q

minor criteria for rheumatic fever

A

infective endocaridits, arthralgia, raised CPR/ESR, leukocytosis, prolonged PR interval

116
Q

Heart failure increases levels of what substances?

A

Renin
Aldosterone
ADH and ANP

117
Q

in chest pain caused by vasoconstriction what causes this pain?

A

cetecholamines acting on alpha 1 receptors

118
Q

What are U waves

A

represent repolarisation of the papillary muscles or Purkinje fibres

119
Q

what do the limb leads record?

A

the standard BIPOLAR limb leads I II III record the difference in potential between two limbs

120
Q

what type of vessel is the major source of peripheral resistance?

A

arterioles

121
Q

what type of vessels are important in temperature regularion

A

ateria-venous anastomoses

122
Q

what type of vessels have the greatest wall thickness to lumen ratio in blood vessels

A

arterioles
this muscle is controlled by vasoactive substances and vasomotor nerves to regulate local blood flow

123
Q

in a healthy man who is running what happens to the BP

A

Systolic BP rises
Diastolic BP either falls or stays the same

124
Q

what happens to cardiac output and O2 extraction in a healthy male who is running

A

Cardiac output can increase by 700%
O2 extraction can increase by 100%

125
Q

compensatory reactions activated by haeomorrhage?

A

vasoconstriction, tachycardia, venoconstriction, tachypnoea, restlessness
Increased secretion of norepinephrine, epinephrine, vasopressin, glucocorticoids, renin, aldosterone, erythropoietin, plasma protein synthesis

125
Q
A
126
Q

How does Noradrenaline increase HR

A

increases Na and Ca permeability
increases HR by decreasing the negativity of the resting membrane potential and by increasing the slope of phase 4

127
Q

In MI when does irreversible cell injury occur?

A

20-40 mins

128
Q

In MI when does fibrotic scarring complete

A

2 months

129
Q

In MI when does gross necrotic change occur

A

4-12 hours

130
Q

What is phase 1 of the cardiac cycle?

A

atrial systole

131
Q

what is phase 2 of the cardiac cycle?

A

isovolumetric ventricular contraction
aortic valve opens at the end of phase II

132
Q

what is phase 3 of the cardiac cycle

A

ventricular ejection
T wave

133
Q

what is phase 4 of the cardiac cycle

A

isovolumetric ventricular relaxation

134
Q

what is phase 5 of the cardiac cycle

A

ventricular filling

135
Q

first phase of the valsalva manouvre

A

blood pressure increases slightly due to increased intrathoracic pressure
as forced expiration is continued, mean arterial pressure and pulse pressure decrease

136
Q

phase 2 of the valsalva manoouvre

A

heart rate begins to increase

137
Q

phase 3 of valsalva manoeuvre

A

begins with the release of the forced expiration
further drop in BP due to sudden drop in intrathoracic pressure, HR increase

138
Q

the fourth phase of the valsalva manoeuvre

A

increased cardiac output
overshoot HTN
reflex bradycardia

139
Q

Commonest site of Berry aneurysm

A

Junction of anterior cerebral and anterior communicating artery

140
Q

how does carotid sinus massage stop SVT

A

increases X nerve discharge to the conducting tissue between atria and ventricles and to SA and AV nodes

141
Q

which substance is vasodilatory on cardiac muscle but not in skeletal muscle?

A

Adenosine

142
Q

Compensated cardiac hypertrophy results in

A

diffuse fibrosis
decreases in the capillary to myocte ratio
increase in number and mutations of sarcomeres
dysfunctional proteins
extreme hypertrophy

143
Q

what and where are baroreceptors

A

are stretch receptors
in the tunica adventitia in the walls of the heart and blood vessels

144
Q

what stimulates the baroreceptors

A

distension of the structures
they discharge at an increased rate when the pressure in these structures rises

145
Q

what happens when baroreceptors are stimulated

A

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

146
Q

what happens to baroreceptors in chronic hypertension

A

the reflex mechanism is reset

147
Q

approximate times of onset of events in ischaemia

A

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

148
Q

Describe the action potential graph/diagram of a pacemaker cell

A

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

149
Q

Sympathetic effect on pacemaker potentials

A

increases HR
increase cAMP facilitates increase Ca channels, faster depolarising

150
Q

Vagal effect on pacemaker potentials

A

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

151
Q

which vasoactive mediator causes angiooedema

A

Kinins

152
Q

what vasoactive mediator inhibits platelet activation and is an effective vasodilator

A

prostacyclin

153
Q

what is phase IV of the cardiac cycle

A

isovolumetric relaxation

154
Q

In compensated heart failure what happens to CO, right atrial pressure, Renin, fluid retention

A

CO is unchanged
Right atrial pressure increases
Renin level increases
Fluid retention plays an important role

155
Q

the work performed by the left ventricle is greater than that performed by the right is because ?

A

the afterload is greater

156
Q

what is the cause of oedema in heart failure

A

raised venous pressure

157
Q

calculation for cardiac output of left ventricle

A

O2 consumption ml/min divided by (arterial O2 - venous O2)

158
Q

what substance can cause peripheral fluid retention in CCF

A

Aldosterone
decrease renal blood flow activates RAS which increases aldosterone which causes sodium and water retention

159
Q

Describe the murmur of mitral regurgitation

A

a high pitched blowing holosystolic murmur
best heard at the apex, usually radiates to axilla

160
Q

what does increased baroreceptors do

A

Inhibit the tonic discharge of sympathetic (vasoconstrictor) nerves and excites the vagal innervation

161
Q

when does isovolumetric relaxation in the cardiac cycle end

A

it ends when ventricular pressure falls below atrial pressure
then AV valves open and blood fills the ventricles

162
Q

what does the R wave in the ECG represent

A

initial depolarisation of cardiac muscle
sudden influx of Na through rapidly opening Na channels

163
Q

in cardiac action potential of a ventricular cell how much longer is the plateau phase than depolarisation

A

100x

164
Q

Difference between Absolute refractory period and relative refractory period

A

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

165
Q

what does phase 1 represent in the cardiac cycle

A

atrial systole

166
Q

what is considered normal degree range for normal axis in ECG

A

-30 to +110

167
Q

describe phase 2 of the cardiac cycle

A

start of ventricular systole
AV valves close
intraventricular pressure rises sharply
isovolumetric ventricular contraction

168
Q

what is myocardial oxygen consumption in a beating and a non beating heart

A

90ml/kg/min (9ml/100g/min)

non beating = 2ml/100g/min

169
Q

how does the stroke volume in the left ventricle compare to the right ventricle

A

left ventricle is 7x greater

170
Q

amount of blood ejected by each ventricle per stroke

A

70-90ml

171
Q

what is the end diastolic ventricular volume of the heart

A

130ml
(~50mls in each ventricle)

172
Q

what does the third heart sound corresponds to ?

A

In rushing of blood with the period of rapid ventricular filling
can be heard in normal young individuals

173
Q

time of a normal PR interval

A

150ms

174
Q

histological changes seen in 24 hours of MI

A

early coagulation necrosis
pallor
oedema
haemorrhage

175
Q

histological changes seen form day 3-7 of MI

A

Disintegration of myofibres

176
Q

histological changes seen at 2 to 8 weeks of MI

A

collagen deposition

177
Q

what changes occur in compensated pressure loaded cardiac hypertrophy?

A

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

178
Q

what change in seen in VOLUME loaded cardiac hypertrophy

A

dilation of the ventricle

179
Q

Causes of high output failure

A

anaemia
sickle cell disease
renal failure
pregnancy
beri beri (thiamine deficiency)
Pagets disease
ateriovenous fistula
morbid obesity
cor pulmonale

180
Q

what is the most common cause of endocarditis in prosthetic valves

A

staph epidermidis

181
Q

four features of tetralogy

A

VSD
obstruction of right ventricular outflow tract
aorta overrides VSD
right ventricular hypertrophy

182
Q

what is the most important independent risk factor in the development of atherosclerosis

A

Genetics

183
Q

risk of rupture of a 5.5% AAA

A

5-15%

184
Q

describe phase 3 of cardiac cycle

A

Aortic and pulmonary valves open
ventricular ejection

185
Q

describe phase 5 of cardiac cycle

A

late diastole
ventricles fill 70%

186
Q

The most important ion for cardiac resting membrane potential (CRMP) is?

A

Potassium

187
Q

what does Calmodulin do for smooth muscle

A

causes smooth muscle contraction
it binds to Ca activating myosin light chain kinases
this with ATP activates myosin to bind to Actin for contraction

188
Q

what does hyperkalaemia do to the resting membrane potential

A

decreases the resting membrane potential

(ignore the negative numbers)

189
Q
A

Acem Primary (5 decks)

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