Mastering A&P 10-9 Cardiac Muscle Tissue

Each cardiac muscle cell is bound to its neighboring cells at sites called

intercalated discs

How many nuclei does a cardiac muscle cell have?

one (centrally located)

Cardiac cells are relatively ______ in size

Small

What are the functions of intercalated discs? (3)

1) Stabilize the position of adjacent cardiac cells 2) Maintain the 3-dimensional structure of the tissue 3) Allow ions to move from one cell to another

Cardiac cells contracting without neural stimulation is a property known as ______

Automaticity

The movement of ions from one cardiac cell to another via gap junctions at intercalated discs allows cardiac muscle cells to ______ together

Beat in rhythm

The sarcoplasmic reticulum of cardiac cells lack ______, which is why they store less calcium ions compared to muscle fibers

Terminal cisternae

What similarities do cardiac muscles share with skeletal muscle fibers? (3)

Excitable membranes Organized myofibrils Sacromeres (which give them straiations like skeletal muscles)

Regions where adjacent cardiac muscle cells interlock and when gap junctions permit electrical coupling between cells are called ______

Intercalated discs

Refractory periods are _______ in cardiac cells compared to muscle fibers

Longer

The sarcoplasm of a cardiac cell contains large numbers of _______ as well as abundant reserves of _____

Mitochondria Myoglobin

Cardiac muscle contracts without ______

Neural stimulation

Automaticity of cardiac cells are controlled by ________, which normally determine the timing of contractions

Pacemaker cells

What can alter the pace/rate set by pacemaker cells and adjust the amazing of tension being produced during a contraction?

The nervous system

How do T tubules of cardiac cells differ from t tubules of skeletal muscle cells?

They are short & broad with no triads They encircle the sacromeres at the z lines (instead of at the zone of overlap)

Cardiac muscle cell contractions are _______ compared to contractions of skeletal muscle cells

10x longer

Cardiac muscle cells are almost completely dependent on _______ for the energy they need to continue contracting

Aerobic metabolism

How does the overall shape of a cardiac muscle cell differ from a skeletal muscle cell structurally?

Cardiac cells are branched

Because cardiac muscle cells are physically, chemically, and electrically connected to one another, resembling a single enormous muscle cell, cardiac muscle has been called a __________ (a fused mass of cells)

Functional syncytium

Action potentials can move quickly from one cardiac cell to another thanks to their ________ connections with one another

Gap junction

At an intercalated disc, the sarcolemmas of 2 adjacent cardiac muscle cells are extensively intertwined and bound together by ______ and ______

Gap junctions Desmosomes

Cardiac muscle cells have energy reserves in the form of _____ and ______

Glycogen reserves Lipid inclusions

Cardiac muscle cells are found only in the _____

Heart

tubules of sarcoplasmic reticulum in cardiac cells contact the _____ as well as the ______

Plasma membrane T tubules

What do cardiac muscle cells contain an abundance of that contains the oxygen they need to break down energy reserves during times of peak activity?

Reserves of myoglobin

What do the special properties of sarcolemma in cardiac muscles prevent? (2)

Wave summation Tetanic contractions (tetanus)