EX 2; The Heart Flashcards
This is a rapid assessment of blood composition; the percent of the blood volume that is composed of RBCs
hematocrit; should be roughly 45%
Estimate the hematocrit of a person with a plasma volume of 3L and a total blood volume of 4.5L
- 5-3 = 1.5L
1. 5/4.5 = 33% hematocrit
The exchange of oxygen, carbon dioxide, nutrients, and metabolic end products occurs at the level of what
capillaries
Which portions of the body receive the most blood flow at rest
muscle
kidneys
abdominal organs
This is the volume per unit time
flow
What is the equation for determining flow
change in pressure/resistance
This is how difficult it is for blood to flow between 2 points
resistance
What can affect resistance
change in radius
What is the equation for resistance
8(length)(fluid viscosity(ή))
divided by
Ħ (radius)^4
This can alter the resistance and thereby flow
blood viscosity
What causes the heart valves to open and close
pressure differences
How does the electrical conduction flow through the heart
via gap junctions; allowing it to be very rapid
What is the flow of the electrical current through the heart
SA - atria - AV - bundle of His - bundle fibers - ventricles
This is the hearts pacemaker because it initiates each wave of excitation with atrial contraction
SA node
What is the role of the bundle of His and other parts of the conduction system
deliver the excitation to the apex of the heart so that ventricular contraction occurs in an upward sweep
What is the P
atrial depolarization
What is the QRS
ventricle depolarization
What is the T
ventricle repolarization
What happens to the atrial repolarization
it is “lost” in the QRS series
The rapid opening of what is responsible for the rapid depolarization phase
voltage gated sodium channels
The prolonged “plateau” of depolarization is due to what
the slow but prolonged opening of voltage gated calcium channels plus the closures of the potassium channels
This results in the repolarization phase
opening of the potassium channels
These two things cause a threshold graded depolarization in the action potential of an auto rhythmic cardiac cell
sodium ions “leaking” in through the F-type (funny) channels plus Ca ions moving through the T channels
in the action potential of an auto rhythmic cardiac cell, the rapid opening of this is responsible for the rapid depolarization phase
voltage gated calcium channels
in the action potential of an auto rhythmic cardiac cell, these two things are responsible for the repolarization plhase
reopening of the potassium channels
closing of the calcium channels
A myocyte cannot beat outside of the heart, why
because it needs the SA node to be active
A SA nodal cell will beat outside of the heart, why
due to the automaticity of the funny channel; it does not have a resting membrane potential
How does the electrical signal transfer to a contractile force
excitation-contraction coupling
Excitation-contraction coupling links the cardiac muscle cell action potentials to contraction via what
control of calcium within the myocardium
calcium induced calcium release
The prolonged refractory period of cardiac muscle prevents what two things
tetanus
and allows time for the ventricles to fill with blood prior to pumping
Cardic activity can be expressed as what
cardiac output; in reference to the amount of blood moved per unit of time
What is the first heart sound
closure of the AV valves
What is the second heart sound
closure of the aortic and pulmonary valves
What are three defects of the heart causing murmurs
stenosis = narrowing
regurgitation = insufficiency
septal defects
Which portion of the blood flow is in a series; where the components are connected end-to-end
pulmonary circuit
Which portion of the blood flow is in parallel; where components are connected between the same two sets of electrically common points, creating multiple paths
systemic circulation
What does the parallel blood flow of the systemic system allow for
organs to get 100% of oxygenated blood
This is the volume of blood each ventricle pumps per minute or the volume of blood flowing through either the pulmonary or systemic circuit per minute
cardiac output
What is the equation for cardiac output
CO = HR x SV
The parasympathetic system acts upon which receptors on the heart
muscarinic
Does the parasympathetic act on the atria or ventricles
atria
muscarininc receptors on the atria
What neurotransmitter does the PS release
ACh
The sympathetic system acts upon which receptors on the heat
beta
Does the sympathetic act on the atria or ventricles
both!
What neurotransmitters does the S system release
NE and E
What two things can be used to speed up heart rate
increase sympathetic control; NE and E
decrease parasympathetics control; reduce ACh
What are the three factors influencing stroke volume
pre-load; the volume of blood in the ventricles just before contraction (end-daistolic volume)
magnitude of sympathetic input to the ventricles
afterload; the pressure against which the ventricles pump
What is the Frank-Starling mechanism
increasing the stroke volume
In which two ways can you increase the stroke volume via Frank-Starling Mechanism
fill it more with blood
deliver sympathetic signals
What does sympathetic signals do to the contractile force
they cause a stronger and more rapid contraction and more rapid relaxation
Sympathetic effects cause an increase in this, which increases contraction
calcium
True or False
It is possible to affect stroke volume without affecting heart rate
False; it is not possible, under normal circumstances, to increase SV or HR without influencing the other
What are five ways in which to measure cardiac function
thermodultion cardiac output angiography echocardiogram MRI ejection franction
This occurs is 1:500 people, characterized by increased heart all thickening particularly in the inter ventricular septum interfering with blood ejection
hypertropic cardiomypathy
What are three symptoms of hypertrophic cardiacmyopathy
angina
arrhythmyas
sudden cardiac death
