Heart Physiology

Front 1

Cardiac muscle cells:

lenth = short or long

Back 1

SHORT

Front 2

Cardiac muscle cells:

side by side or branched interconnected?

Back 2

branched interconnected

Hint 2

tree like

Front 3

Cardiac muscle cells:

shape?

Back 3

semi-spindle

Hint 3

---- truck

Front 4

Cardiac muscle cells:

connected by?

Back 4

intercalated discs

Front 5

Cardiac muscle cells:

electrical link = ?

Back 5

gap junction

Front 6

Cardiac muscle cells:

syncytium = ?

Back 6

common contraction

in sync w each other

Hint 6

music group

Front 7

Cardiac muscle cells:

how many and what type of nuclei

Back 7

1 or2 centrally located

Front 8

Cardiac muscle cells:

endomysium is dense or light?

Back 8

dense

Front 9

Cardiac muscle cells:

vasculature is low medium or high?

Back 9

high vasculature

Front 10

Cardiac muscle cells:

mitochondria ? % of space

Back 10

25% space (many)

Front 11

Cardiac muscle cells:

aerobic or anaerobic?

Back 11

almost all AEROBIC (oxygen)

Front 12

Cardiac muscle cells:

fused at ends

Back 12

myofibers

Front 13

Cardiac muscle cells:

wider and fewer than skeletal muscle cells

Back 13

T tubules

Front 14

Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

1. membrane potential

Back 14

1. quickly depolarizes (-90 to +30 mV)

Front 15

Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

1. --- influx from extracellular space, causes positive feedback opening of

Back 15

1. Na+
voltage-gated Na+ channels

Front 16

Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

1. Na+ channels close within ? ms of opening

Back 16

1. Na+ channels close within 3 ms of opening

Front 17

Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

2. Depolarization causes release of ---- from ------------ ------- (as in skeletal muscle)

Back 17

2. Ca++
sarcoplasmic reticulum

Front 18

Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

3. Depolarization ALSO causes opening of ---- ---- -------- on the -------- (special to cardiac muscle),

Back 18

3. slow Ca++ channels
membrane

Front 19

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 ?.

Back 19

3. Ca++ influx and activation of filaments

Front 20

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).

Back 20

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).

Front 21

Differences Between Skeletal & Cardiac MUSCLE Contraction:

2. Automicity (Autorhythmicity) -

Back 21

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.

Front 22

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.

Back 22

250 ms vs. 2-3 ms
wave summation
tetanic

Front 23

Mechanism of Contraction of Contractile Cardiac Muscle Fibers:

2. Depolarization causes release of Ca++ from sarcoplasmic reticulum (as in skeletal muscle), allowing ------- ----- --- ------ to proceed.

Back 23

2. sliding actin and myosin

Front 24

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.

Back 24

1. linked electrochemically
wave throughout the entire heart

synchronistic