Cardiac Histology Flashcards

1
Q

Hallmarks of smooth muscle

A

no visible striations
elongated nuclei w/ rounded edges
diffuse staining
typically not wavy

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2
Q

Smooth muscle cells & # of nuclei

A

elongated fusiform cells with 1 nucleus

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3
Q

What connects smooth muscle cells?

A

gap junctions

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4
Q

Innervation of smooth muscle

A

inherent rhythmic contraction that is also responsive to ANS to increase or decrease contractile force

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5
Q

How is dense regular CT different from smooth muscle?

A

more wavy bundles of collagen that align in direction of stress (cells follow waves of collagen bundles)

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6
Q

Describe smooth muscle contraction

A

thin & thick filaments that anchor to dense bodies which connect to cell membrane

caveolae receive tension from dense bodies & allow for Ca2+ in to initiate contraction

**cells contract as 1 unit & assume globular shape

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7
Q

What are dense bodies composed of?

A

desmin & vimentin intermediate filaments

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8
Q

Hallmarks of cardiac muscle

A

striations, intercalated discs
cells w/ varying diameter & centrally located nuclei
lipofuscin granules
LOTS of capillaries

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9
Q

Cardiac muscle cells & # of nuclei

A

short, branched, Y-shaped w/ 1-2 nuclei

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10
Q

Intercalated discs

A

transverse junctions @ ends of cardiocytes that allow passage of electrical current (parallel to length of cell)

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11
Q

Purkinje cells

A

modified cardiac muscle cells that act as “pacemaker” for heart

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12
Q

What composes the pericardium?

A

Fibrous pericardium (dense CT)

Serous pericardium (parietal & visceral layers)

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13
Q

What is the visceral layer of the pericardium also called?

A

epicardium (outer layer of heart wall)

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14
Q

Anatomy of the heart wall

A

epicardium (mesothelium + CT)
myocardium (cardiac muscle)
endocardium (CT + mesothelium)

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15
Q

Epicardium histo features

A

dense fibrocollagenous CT w/ elastic fibers (lined by mesothelium)
branches of coronary arteries in fat/adipose tissue

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16
Q

Myocardium histo features

A

striations/intercalated discs/lipofuscin granules

diad T tubule system

Atrial granules

LOTS of mitochondria

17
Q

Cells of myocardium

A
cardiocytes (contractile)
nodal cardiocytes (SA & AV node)
myoendocrine cardiocytes (hormonal peptide)
18
Q

What are the roles of intercalated discs & where do you find them?

A

bind cells, transmit forces of contraction & allow spread of excitation

found where cells meet end to end (align w/ Z lines)

19
Q

3 types of IC discs (memb to memb contact)

A
Fascia Adherens (actin @ end of sarcomeres)
Desmosomes (anchor for intermed filaments)
Gap jxns
20
Q

What is purpose of gap junctions?

A

parallel membrane connections that allow excitation to pass b/w cells

sites of LOW electrical resistance

21
Q

What is purpose of fascia adherens?

A

transverse membrane connections that transmit contractile forces b/w cells

22
Q

Role of diad T-tubules

A

permits uniform contraction of myofibrils w/ in 1 cardiocyte (found @ Z lines)

1 tutubule & 1 SR cisterna

23
Q

Describe the conducting system of the heart

A

SA node –> AV node –> AV bundle –> R/L bundle branches (down intervent septum) –> Purinje fibers

24
Q

Role of parasympathetic & sympathetic fibers in nodes

A

MODIFY rate of intrinsic cardiac muscle contraciton

25
Q

Nodal cardiocytes

A

modified cells in SA/AV nodes that start & relay electrical signals

26
Q

Purkinje fibers

A

specialized cardiac muscle cells that conduct electrical impulse for coordinated contraction

@ periphery of myocardium w/ fewer myofibrils and striations

27
Q

Major features of myocardium

A

Cardiocytes
Intercalated discs
Diad (T-tubule system)
Granules

28
Q

Myoendocrine cardiocytes (atrial cells)

A

have membrane-bound granules that secrete atrial natriuertic factor (ANF targets kidneys to decrease H20 retention)

29
Q

Endocardium in ventricles

A

has subendocardial layer (CT w/ smooth muscle)

branches of Purkinje fibers

merges w/ myocardium

30
Q

Endocardium in atria

A

NO subendocardial layer

Purkinje fibers closer to endothelium

intermixed w/ myocardium

31
Q

Describe the cardiac skeleton

A

dense irregular CT in endocardium

32
Q

Roles of cardiac skeleton

A

anchors valves & surrounds AV canals for shape

contributes to interventricular & interatrial septa

insertion point for cardiac muscle

electrical insulator between atria & ventricles (to maintain proper pattern of contraction)

33
Q

What are the heart valves made of?

A

core of fibroelastic CT covered by endothelium (continuous w/ cardiac skeleton)

34
Q

What creates the valve ring?

A

central portion of valve from condensed fibroelastic layer of endocardium