Cardiac Muscle Tissue - Downing Flashcards Preview

Skin and Musculoskeletal - Week 4 > Cardiac Muscle Tissue - Downing > Flashcards

Flashcards in Cardiac Muscle Tissue - Downing Deck (8)
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General Features of Cardiac Muscle:

Striated (involuntary)
T-tubule system (at z lines, not AI junctions)
Sarcoplasmic reticulum less well developed than in skeletal muscle
Single nucleus/cell; centrally located
Intercalated disks are diagnostic features of cardiac muscle tissue

If things look messy.... its cardiac muscle!


What is the comparison in number of mitochondria between cardiac and normal skeletal muscle?

Cardiac has TON of mitochondria!


Where do you normally find intercalated discs?

They can be located in spots where you would normally see the Z-disc


What parts of the intercalated discs do you see the macula adherens(desmosomes), zonula adherens, and gap junctions????

In the vertical portion:
Zonula adherens
Macula adherens

Horizontal portion:
gap junctions


What is microscopic feature unique to atrial cadriac muscle cells?

Atrial granules

Contain atrial natriuretic peptide
Lowers blood pressure by decreasing renal tubules ability to resorb (conserve) sodium and water


What are the modified cardiac muscle cells in the conduction system of the heart called?

Purkinje fibers!

Myofibrils reduced in number
Much larger
Contain more sarcoplasm
Nuclei more rounded
Large diameter
Lack T-tubules
More glycogen


Referring to their development, why do cardiac muscles have a single nucleus rather than many like in skeletal muscle?

Myoblasts DO NOT fuse in cardiac muscle


What is a diad?

Occurs in cardiac muscle

Made up of t-tubule and terminal portion of adjacent sarco reticulum