Heart Physiology Flashcards by T W

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

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max heart rate

200 btm (could vary slightly via genetic diversity)

60 secs per minute / .3 beats per second

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heat cells can spontaneously depolarize, what word can describe this?

automaticity

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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

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what starts Action Potential in the heart?

the sino-atrial node

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what node fires stronger and for longer?

the atrio-ventricular node

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role of chordinae tendinae?

prevent atrioventricular valves from inversion, NOT used to open the valves

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what does the interventricular septum do during contraction?

pulls the heart up from the bottom towards the middle, further decreasing space in the ventricles

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what causes the sound of a heart beat?

the valves in the heart closing

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what does the P wave measure?

atrial contraction/depolarization

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what does the QRS complex measure?

ventricular contraction/depolarization

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what does the T wave measure?

ventricular relaxation/repolarization

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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

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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

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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

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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

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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

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what is Arrhythmia?

irregular heart rate (beat/rhythm)

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what is Bradycardia?

slower than normal heart rate

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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?

1 systole + 2 diastole ----------------------------- 3