Heart Physiology Flashcards
gap junction
where heart cells connect in their cell membranes, provides for easier communication via depolarization and repolarization, causing an Action Potential to travel in a rapid wave-like motion
max heart rate
200 btm (could vary slightly via genetic diversity)
60 secs per minute / .3 beats per second
heat cells can spontaneously depolarize, what word can describe this?
automaticity
what bundle of cells can fire off Action Potential at a faster rate than any other cell in the heart?
sino-atrial and antrio-ventricular nodes
what starts Action Potential in the heart?
the sino-atrial node
what node fires stronger and for longer?
the atrio-ventricular node
role of chordinae tendinae?
prevent atrioventricular valves from inversion, NOT used to open the valves
what does the interventricular septum do during contraction?
pulls the heart up from the bottom towards the middle, further decreasing space in the ventricles
what causes the sound of a heart beat?
the valves in the heart closing
what does the P wave measure?
atrial contraction/depolarization
what does the QRS complex measure?
ventricular contraction/depolarization
what does the T wave measure?
ventricular relaxation/repolarization
what does a hill mean in a EKG graph when using Lead II?
Action Potential moving from probe near the Right Arm to the probe near the Left Leg
what does a ditch mean in a EKG graph when using Lead II?
Action Potential moving from probe near the Left Leg to the probe near the Right Arm
atrial fibrillation sign(s) in an EKG and what it means is happening in the heart
P wave is a ditch as opposed to a hill, therefore the signal is coming from the AV node, and the SA node must be damaged/dead
first-degree atrioventricular block sign(s) in an EKG and what it means is happening in the heart
the PR interval is to long (exceeds ~200 milliseconds), meaning that the Av node is not intensifying the Action Potential
pulmonary embolism sign(s) in an EKG and what it means is happening in the heart
the T wave is a ditch, therefore there is an issue with polarization in the heart coming to rest
what is Arrhythmia?
irregular heart rate (beat/rhythm)
what is Bradycardia?
slower than normal heart rate
what is Tachcardia?
faster than normal heart rate
what is Fibrillation?
irregular heart beat caused by issue in atria
what is myocardial ischemia?
decreased blood flow casing poor oxygen delivery to cells, and could cause death
what causes plaque formation?
1) injury to the arterial wall
2) white blood cells attaching to the interior wall
examples of how the arterial wall can get damaged
-turbulent blood flow caused by hypertension
-inflammatory immune response
-infection
-chemical abnormalities in the blood such as diabetes or high cholesterol
how does the arterial walls get ‘healed’
cholesterol and other fatty materials used as a pseudo-band-aid, which can become a plaque deposit over time
systole =
contraction
diastole =
relaxation
auscultations =
sounds
stenosis =
stiffening and narrowing
atrial venous oxygen differentiation =
difference in oxygen concentrations in the artery and veins
EDV =
end diastolic volume, when the ventricle is full, ~120mL
ESV =
end systolic volume, when the ventricle is empty, ~50mL
stoke volume =
EDV minus ESV, amount of blood ejected in a heart beat
what happens when blood pressure in the vessels increase?
blood pressure in the ventricles MUST increase to be greater than that blood pressure in the blood vessels, or else the semi-lunar valves will not open
what does isovolumetric contraction correlate with?
dramatic INCREASE in ventricular pressure
why is there not alot of pressure in the atrium?
because the vena-cava/the pulmonary veins are always open, emptying into the atrium
what does isovolumetric relation correlate with?
dramatic DECREASE in ventricular pressure
what occurs when both atrial-ventricular and semi-lunar valves are closed?
isovolumetric contraction / relaxation
what is hypertrophic cardiomyopathy?
the muscles in the heart grows via cells creating alot of actin and myosin, creating an issue with stroke volume, with no effect on building pressure
what organ has the worst blood flow to it and is at the highest risk of ischemia?
the heart! ironic, huh?!
what are some characteristics specific to arteries?
-movement away from the heart
-branch away from heart
-more integrity because of the external/internal elastic membrane
-better contractile force bc of the tunica media
-has no valves bc gravity works with the blood flow, so no risk of back ups
what are some characteristics specific to veins?
-movement towards the heart
-branch towards the heart
-lacks internal and external elastic membrane
-presence of tuncia media, however, it is much thinner than the one found in the arteries
-has valves to prevent back flow of blood, bc has to work against gravity
how do bruises form?
capillaries are very thinly walled and semi-permeable, therefore when stretched blood is able to leak out from the capillary(ies)
what is a varicose vein?
swollen, twisted veins that lie just under the skin, common in the legs, often in the elderly
what is an aneurysm?
an air bubble in the blood system, causing a loss of integrity in the arterial wall, which can lead to the artery bursting
what is a thrombus (aka embolism)
a clot, specifically in the vein
what is the mean arterial pressure?
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