Ch 19- Cardiac Muscle Fiber Anatomy+Contraction

autorhythmic cells

"pacemaker cells" show spontaneous depolarization w/o a stimulus

action potential

A neural impulse; a brief electrical charge that travels down an axon.

single unit (functional syncytium)

Gap junctions allow an action potential to move continuously along the sarcolemma of cardiac muscle cells, resulting in synchronous contraction of that chamber. Thus, cardiac muscle fibers can contract as a _________ _________,.

intercalated discs

Rings that provide a strong connection between cardiac muscle cells, to prevent tears and leaks in the heart.

Skeletal Muscle Cardiac Muscle

The difference with sarcomeres in cardiac muscle from those in skeletal muscle: In _________ _________, maximum overlap of thin and thick filaments within the sarcomeres does occur when at rest In _________ _________, maximum overlap of thin and thick filaments within the sarcomeres does not occur when at rest

energy

The heart muscle requires more _________ and mitochondria than skeletal muscle because it constantly contracts.

aerobic cellular respiration

The process by which cells use oxygen to obtain usable energy from an energy source. Cardiac muscle relies almost exclusively on this for energy.

sarcomere

The smallest functional unit of muscle tissue shorten and contract within cardiac muscle cells arrangement of myofibrils

cardiac muscle fiber

_________ _________ _________anatomy: form the myocardium. (a) Individual cells are relatively short, branched, and striated. (b) They are connected to adjacent cells by intercalated discs composed of both desmosomes and gap junctions. (c) T-tubules are invaginations of the sarcolemma that extend internally to the sarcoplasmic reticulum.

cardiac muscle

_________ _________ contraction.

desmosomes gap junctions

_________ are Cell junctions where intermediate filaments attach to in order to join cells together.) _____ _____ are Points that provide cytoplasmic channels from one cell to another with special membrane proteins. Also called communicating junctions.

electrocardiogram

a record of the electrical activity of the heart that, if abnormal, may indicate heart disease

Cardiac muscle

has a large number of mitochondria (comprising approximately 25% of its volume compared to about 2% of the volume in skeletal muscle)

absolute refractory period

in heart muscle contraction, this period is the time during which another action potential is impossible; limits maximal firing rate

cardiac muscle

maximum overlap of thin and thick filaments within the sarcomeres does not occur when_________ is at rest

action potential

spreads across the sarcolemma of the cardiac muscle cells, causing sarcomeres within cardiac muscle cells to contract.

functional syncytium

the heart is a _____ ______, or a mass of merging cells that act as a unit

mitochondria

there is a lot more ___________ in the heart than there is in skeletal muscles because the heart is constantly contracting and requires more energy