Intro to cardio Flashcards
What is cardio electrophysiology
The study of the electrical activity of the heart
what is cardiovascular mechanics?
understanding how the contractile properties of the heart affect its function
what is cardiovascular hemodynamcs
the study of blood flow and the factors that control it
what type of tissue is blood
connective tissue with a fluid ECM
how many pumps does the heart have and where do they pump blood to?
2 pump - the right and left side
- the right side pumps blood to the lungs to be oxygenated and left to the systemic circulation
what are the chambers of the heart
4 chambers : right and left atrium and right and left ventricle
what are the ventricles separated by and why
they are separated by the interventricular septum to prevent the mixing of blood
what are the functions of the heart valves?
to prevent back flow
what is the function of the aortic and pulmonary semi lunar valve
to prevent back flow into the ventricles
what is the function of the mitral and tricuspid valves
to prevent back flow into the atrium
what connects the valves to the heart
papillary muscles and chordae tendinae
what percentage of blood is pumped from the right atrium to the left ventricle and aorta
100% of the blood from the right atrium returns to the left ventricle and out through the aorta
which organ systems receive the most blood
renal
GI
skeletal muscle
what is the normal cardiac output ? what does this mean for venous return
5L/min this means venous return is also 5L/min
heart function can be charecterized into which 2 events
electrical and mechanical
how is mechanical activity of the heart influenced by the electrical
the mechanical activity of the heart is triggered by the electrical stimulus that is triggered within the heart
what is automaticity?
what types of cells make it up automaticity?
- the ability of the heart to spontaneously fire action potentials
- pacemaker cells
are pacemaker cells neurons
NO they are modified cardiomyocytes
what is excitability/responsivness
the ability of the cardaic cells to respond to electrical activity
what does excitability of the heart depend on
depends on the refractory period which is the ability of the heart to relax before it contacts again
what is conductivity
the ability of the heart to conduct the action potential from its site of origin to all cardiac cells
what does conductivity of the hear depend on
depedns on the heart functioning as a functional syncytium in which it functions as a unit
how does the concentration of Na,K,Ca,Cl compare outside the cell than inside the cell
- Na is greater outside than inside
- K is greater inside than outside
- Ca is MUCH greater outside than inside
- Cl is greater outside than inside
what is the resting membrane potential of a cardiac cell and what is it determined by
- the restin mem potential is between -60 and -85 mv
- depends on the concentration differences of the ions across the cel membrane and the membrane conductance to reach ion
what are the 2 types of cardiac muscle cells that generate different action potentials
contractile cells and pacemaker cells(SA and AV node)
what is the restinf membrane potentail of contractile cells and pace maker cells
- contractile = -100mv
- pacemaker = -60mv
how many phases in a cardiac action potential? hoe is the pacemaker cell different
ther are 5 phases but pacemaker cell is different bc it has 4. ( NO plateu phase)
what are the phases of a contractile cell action potential
- phase 4: resting membrane potential- opening of inward rectifying K channels
- Phase 0: depol- opening of voltage gated Na channels
- Phase 1: transient repol: opening of transient outward K channels
- phase 2: plateu phase- balance between K and Ca channels (funny channels)
- Phase 3: repol: opening of delayed rectifier K channels
what are the phases of the pacemaker cell action potential
phase 4: pacemaker potential- opening of inward rectifying K channels and funny channels
phase 0: depol- opening of voltage gated Ca channels
phase 3: repol: opening of delayed rectifier K channels
what are funny channels what do they allow for?
- chanels that have little selecttivity and allow NA and Ca in and K out
- allow for automaticity
What are the phases of the functional refecactory period of contractile cells and what is included in each
- Effective refractory period
> absolute refractory period
> relative refractory period - supranormal phase
> also know as the vulnerable
phase
what is the absolute refectory period
- period in which a stronger than normal stimulus can trigger and AP
whar is the relative refractory period
- period in which a stronger than normal stiumuls can trigger an AP but it will have an abnormal shape
what is the supranormal phase?
why is it also known as the vulnerable phase
a normal stimulus can trigger a normal AP bc the channels are almost all recovered
- called vulnerable bc the RMP is slightly higher here than normal so can reach a threshold fast and trigger an AP
what does a long refecatory period allow for
allows for the heart to recover relax before contracting again
how do the phases of heart contraction have to occur for the heart to function properly
must occur in the same order each time
what structure allows for the the cardiomyocytes to function as a functional syncytium
- intercalted disks that contain gap junctions that allow electrical stimuli to travel from depolarized cell to neighboring cell that has not been stiumlated yet
what are the pacemmakers of the heart?
SA and AV node and purkinjee fibers
how are purkinjee fiber part of the pacemaker>?
if the AV node fails to transmit the signal from the atria to the ventricles the purinjee fibers will take over and transmit the signal
what is the normal pace maker of the heart and why
the SA node because it has the most AP’s per minute
what would happen if SA node function stops and AV node takes over as the pacmaker
the HR would decreases because the AV node has generates fewer APs per minute
what is overdrive surpression
allows the fastest pacemaker (SA node) contril the heart rate
what system modulates the rate of firing of cardiac action potentials
the autonimic NS
how how the sympathetic and Para sympathetic NS affect HR and by what mechanisms
- sympatheitic increases because epinephrinse opens Ca channels
- para sympathetic decreases because it induces hyperpolarization of the membrane potential
what is the cellular response of sympathetic stimulation of the heart
- NE /E released
- bind to B1/Gs receptors
- Camp increases = increase opening of Ca channels
- increases in Na and Ca influx
- increase depol
- increase HR
what is the cellular response of the Parasympathetic NS on the heart
- Ach relaeased
- bind to M2/Gi receptor
- Camp decreases
- increase in K efflux and decreasein Ca influx
- decrease rate of depol
- decrease HR
