Chapter 17 - cardiac muscle tissue anatomy and electrophysiology

flow of ions or electrons with a chemical or electrical gradient

current

Cardiac muscle cells, like skeletal muscle fibers have what?

striations

concentration of sodium and calcium ions in extracellular fluid is ___________ than that in cytosol; while concentration of potassium ions in ECF is ________ than that in cytosol

higher; lower

Cardiac muscle cells contain unique structures called _____ that join adjacent cardiac muscle cells, pacemaker cells to contractile cells, and contractile cells to one another

intercalated discs

K ions follow their concentration gradient and _________ cell when their channels open

leave

voltage difference that exists across membranes of all cells, including excitable cells

membrane potential

cardiac muscle sets its own rhythm without a need for input from nervous system known as what?

autorhythmicity

Cardiac muscle cells contain an abundant amount of a protein that carries oxygen called?

myoglobin

________ and _______ action of these ion channels is responsible for both pacemaker and contractile cardiac action potentials

opening and closing

cardiac electrical activity is coordinated by a very small, unique population of cardiac muscle cells called what?

pacemaker cells

all types of cardiac muscle cells have one or more types of ____________; some are _______-gated or _______-gated

potassium ion channels; ligand or voltage

return of a cell to its negative resting membrane potential; occurs when positive charges (K ions) leave cell

repolarization

Like skeletal muscle fibers and other excitable cells, a cardiac muscle cell contains _____________ in its sarcolemma

selective gated ion channels

calcium ion gradient is maintain by a _________ active transport pump

separate

Both skeletal and cardiac muscle tissues have same general functions, what are they?

to generate tension and generate tension through sliding-filament mechanism of contraction

sodium and potassium ion gradient are maintained by what?

Na/K pump

Cardiac muscle cells are __________ cells with a single nucleus; ________ and ___________ than skeletal muscle fibers

branched; shorter and wider

Pacemaker cells rhythmically and spontaneously generate action potentials that spread to other type of cardiac muscle cells called what?

Contractile cells

membrane potential of an excitable cell at rest; difference in concentration of ions across a plasma membrane; average between -60 and -90 mV

Resting membrane potential

Cardiac muscle cells contract in response to electrical excitation in the form of what?

action potentials

What are striations?

alternating dark and light bands

demonstrate voltage-gated opening but time-gate closing, meaning that they close after a certain period regardless of voltage

calcium ion channels

change in resting membrane potential to a value less negative that when it is at rest; occurs when positive charges rush into cell

depolarization

Intercalated discs contain ___________ that hold cardiac muscle cells together and __________ ________ that allow ions to rapidly pass from one cell to another, permitting communication among cardiac muscle cells

desmosomes; gap junctions

Unlike skeletal muscle and smooth muscle cells, cardiac muscle cells __________ require stimulation from nervous system to generate action potention

do not

Nearly half of cardiac muscle cytoplasmic volume is composed of mitochondria due to high ______

energy demands

Na and Ca ions tend to follow their concentration gradients to ________ a cell when their channels open

enter

A difference in electrical potential between two points

voltage

Open in response to voltage changes across membrane; found in all cardiac muscle cells except certain pacemaker cells

voltage-gated sodium ion channels