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24 Cards in this Set

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Cardiac muscle cells:

lenth = short or long
SHORT
Cardiac muscle cells:

side by side or branched interconnected?
branched interconnected
tree like
Cardiac muscle cells:

shape?
semi-spindle
---- truck
Cardiac muscle cells:

connected by?
intercalated discs
Cardiac muscle cells:

electrical link = ?
gap junction
Cardiac muscle cells:

syncytium = ?
common contraction

in sync w each other
music group
Cardiac muscle cells:

how many and what type of nuclei
1 or2 centrally located
Cardiac muscle cells:

endomysium is dense or light?
dense
Cardiac muscle cells:

vasculature is low medium or high?
high vasculature
Cardiac muscle cells:

mitochondria ? % of space
25% space (many)
Cardiac muscle cells:

aerobic or anaerobic?
almost all AEROBIC (oxygen)
Cardiac muscle cells:

fused at ends
myofibers
Cardiac muscle cells:

wider and fewer than skeletal muscle cells
T tubules
Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

1. membrane potential
1. quickly depolarizes (-90 to +30 mV)
Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

1. --- influx from extracellular space, causes positive feedback opening of
1. Na+
voltage-gated Na+ channels
Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

1. Na+ channels close within ? ms of opening
1. Na+ channels close within 3 ms of opening
Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

2. Depolarization causes release of ---- from ------------ ------- (as in skeletal muscle)
2. Ca++
sarcoplasmic reticulum
Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

3. Depolarization ALSO causes opening of ---- ---- -------- on the -------- (special to cardiac muscle),
3. slow Ca++ channels
membrane
Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

3. Depolarization ALSO causes opening of slow Ca++ channels on the membrane (special to cardiac muscle), further increasing ?.
3. Ca++ influx and activation of filaments
Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

3. This causes more prolonged -------------- than in -------- ------, resulting in a ------- action potential, rather than a "spiked" action potential (as in skeletal muscle cells).
3. This causes more prolonged depolarization than in skeletal muscle, resulting in a plateau action potential, rather than a "spiked" action potential (as in skeletal muscle cells).
Differences Between Skeletal & Cardiac MUSCLE Contraction:

2. Automicity (Autorhythmicity) -
2. some cardiac muscle cells are "self-excitable" allowing for rhythmic waves of contraction to adjacent cells throughout the heart.
Skeletal muscle cells must be stimulated by independent motor neurons as part of a motor unit.
Differences Between Skeletal & Cardiac MUSCLE Contraction:

3. Length of Absolute Refractory Period - The absolute refractory period of cardiac muscle cells is much longer than skeletal muscle cells (--- ms vs. --- ms), preventing ---- --------- and ------- contractions which would cause the heart to stop pumping rhythmically.
250 ms vs. 2-3 ms
wave summation
tetanic
Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

2. Depolarization causes release of Ca++ from sarcoplasmic reticulum (as in skeletal muscle), allowing ------- ----- --- ------ to proceed.
2. sliding actin and myosin
Differences Between Skeletal & Cardiac MUSCLE Contraction:

1. All-or-None Law -
Gap junctions allow all cardiac muscle cells to be ------ -----------------, so that activation of a small group of cells spreads like a ---- ---------- --- ------ -----. This is essential for "------------" contraction of the heart as opposed to skeletal muscle.
1. linked electrochemically
wave throughout the entire heart

synchronistic