Clinical Significance of Physiology Flashcards
Match the definitions to the key words below:
A cardiac function curve is shown below.
Draw in the lines to show how the curve changes:
a) during exercise?
b) during heart failure?
What is the definition of the law of LaPlace?
What is the equation of law LaPlace?
The Law of Laplace essentially states that the tension within the wall of a sphere filled to a particular pressure depends on the thickness of the sphere. Consequently, even at a constant pressure, the tension within a filled sphere can be decreased simply by increasing the thickness of the sphere’s wall
Pressure = (2 x Thickness x Tension)/Radius
Where:
Pressure = The pressure inside the sphere
Thickness = Thickness of the sphere’s wall
Tension = Tension within the sphere’s wall
What changes occur in:
a) The resistance vessels
b) the heart
after prolonged hypertension in relation to the law of LaPlace?
a) Resistance vessels will thicken (AKA the wall thickens) due to increase in pressure. The overall radius should remain the same but the lumen is likely to get smaller
b) Complex series of events but the increased afterload (pressure) will require increased force of systole, which leads to the thickening of the wall of the left ventricle
Match the images with the labels of the cardiac cycle:
What equation links together cardiac output, stroke volume and heart rate?
Using that equation, fill out the table below:
CO = HR x SV
Where:
CO = cardiac output (mL/min)
HR = heart rate (bpm)
SV = sttoke volume (mL/beat)
We can modify cardiac output by:
a) an increase heart rate
b) a decrease in heart rate
c) an increase in stroke volume
d) a decrease in stroke volume
How and why might these happen?
a) How = sympathetic NS activation i.e. fight or flight, circulating hormones e.g. adrenaline, exercise; Why = increase blood perfusion to organs during exertion, pathophysiology
b) How = parasympathetic NS activation i.e. rest and digest, baroreceptor reflex, beta blockers, sleeping; Why = reduce the exertion on the heart
c) How = increased contractility, increased preload; Why = healthier heart (in athletes), increased blood volume (during pregnancy), also during exercise (increase efficiency of exchange)
d) How = decreased contractility, increased afterload; Why = mycardial tissue damage, hypertension
What are two physiological factors that affect HR?
What are three factors that affect SV?
Hrmone e.g. adrenaline, body temperature
Preload, afterload, contractility
Match the airway terms with the appropriate definition:
On this diagram, draw in:
a) The heart (anterior view only)
b) The lungs (anterior and lateral views)
c) The pleural cavity (anterior and lateral views)
d) The diaphragm (anterior view only)
Label the lung volumes and capacities and indicated by the arrows in the diagram below:
What is the equation for alveolar ventilation?
Using that information, fill in the table below:
Alveolar ventilation (L/min) = Breathing frequency (breaths/min) x [Tidal volume (L) - Dead space (L)]
Table 2 shows: the mean values for ventilation at the end of intense exercise. VEmax = maximum voluntary ventilation; RRmax = maximum respiratory rate, VTmax = maximum tidal volume
Referring to this, work out:
a) how high can maximum voluntary ventilation go and how does this compare to normal values?
b) factors that impact maximum ventilation?
c) a limiting factor?
d) how does maximum voluntary ventilation compare with maximum cardiac output
a) Aroound 130-140 in younger males - a 20 times increase from normal values
b) Age and Sex
c) Respiratory muscle fatigue
d) 4-5 times increase in cardiac output, compared to a 20 times increase in ventilation - this is because the lungs are a larger chamber and so can adapt greater
What is a pressure-volume (PV) loop, also known as a flow-volume loop when applied to ventilation?
What is a restrictive disease?
What is an obstructive disease?
A plot of inspiratory and expiratory flow (on the Y-axis) against volume (on the X-axis) during the performance of maximally forced inspiratory and expiratory maneuvers
Restrictive = reduction in lung volume
Obstructive = reduction in air flow
The panels below show a normal P-V loop. On the diagrams A and B below, plot what would be seen in:
A - a restritive disease
B - an airway obstruction
