intro and electrophysiology Flashcards
What are the two basic cell types in the heart
- myocardial cells
- conducting cells
the branching network of myocardial cells is called a
syncytium
what are the types of conducting cells
- pacemaker cells
- electrical conducting cells
- bundle branches
- purkinje fibers
myocardial cells are surrounded by a membrane called
a sarcolemma
special contact points where the myocardial cells connect are called
intercalated disks
- house gap junctions
what structure hold myocardial cells together during contraction
desmosomes
electrical impulses in the atria must travel through to get to the ventricles
specific conduction pathways
what provides a support structure for the AV and semilunar valves and seperates the upper pumping chambers from the lower chambers
plate of fibrous connective tissue that lies between the atria and ventricles
where are the two main baroreceptors found
- aorta
- carotid arteries
information from baroreceptors and chemoreceptors is transmitted to the cardioregulatory center in the
medulla oblongata
4 functions of sympathetic stimulation on heart
- increased pacemaker firing
- increased impulse conduction through heart
- increased force of contraction
- coronary vasodilation
2 functions of parasympathetic stimulation on heart
- decreased rate of SA node pacemaker firing
- decreased rate of impulse conduction through AV node
what are the 4 key properties of myocardial cells
- automaticity
- excitability
- conductivity
- contractility
the ability of certain cells to produce an electrical impulse without outside nerve stimulation
automaticity
the ability to respond to an electrical stimulus
excitability
the ability to transmit an electrical stimulus from cell to cell
conductivity
the ability to contract when electrically stimulated
contractility
function of pacemaker cells
have the ability to spontaneously generate an impulse at a certain rate
function of electrical conducting cells
- carry the electrical impulses to the appropriate regions of the heart
List the 3 pacemaker cells and their intrinsic rate
- SA node: 60-100 bpm
- AV node: 40-60 bpm
- purkinje fibers: 20-40 bpm
where are the SA node and AV node located in the heart
- SA node: posterior right atrium
- AV node: low right atrium
list conduction pathway through heart
- SA -> AV- > bundle of HIS -> right and left bundle branches (left -> anterior and posterior fascicles) -> purkinje fibers: spread throughout myocardium
what are primary charges inside and outside of myocardial cell in polarized state
- resting state
- negatively charged ions INSIDE cell
- Positively charged ions OUTISDE cell
depolarization occurs when what ions enter the cell
- positive ions
- Na+
- Ca2+
what happens during repolarization
- after depolarization
- positive ions (Na+, Ca2+, K+) leave the cells and interior cells returns to its negatively charged state
list two types of refractory periods
- absolute refractory period: following depolarization, cells is resistant to further depolarization
- relative refractory period: in the late phase of repolarization, a very strong electrical stimulate will cause depolarization
bipolar leads have what electrodes
- positive and negative electrodes
unipolar leads have what electrodes
only a positive electrode
list the bipolar leads
- the limb leads
what are the limb leads
- I, II, III
list the unipolar leads
- chest/precordial leads
- augmented limb leads
list the chest/precordial leads
V1-V6
list the augmented limb leads
- aVR: right arm
- aVL: left arm
- aVF: foot
lead I goes from
- right arm (-) to left arm (+)
lead II goes from
- right arm (-) to left leg (+)
lead III goes from
- Left arm (-) to left leg (+)
movement toward a positive electrode appears as what on the ECG tracing
upright, above the baseline
movement away from a positive (toward a negative) electrode appears as what on the ECG tracing
below the baseline
ECG records the sum of all the small directional electrical currents, these are called ? and their sum is called ?
- vectors
- electrical axis
P wave represents
atrial depolarization
QRS complex represents
ventricular depolarization
T wave represents
ventricular repolarization
atrial repolarization is hidden in the
QRS wave
