Histology of Cardiac Muscle Flashcards
Describe the location of the muscle cells
Sk - Attached to bone or skin.
C - walls of the heart
Sm - Walls of hollow organs or intrinsic eye muscles
Describe the cell shape and appearance of each muscle type
Sk - Single, long, cylindrical multinucleated cells with obvious striations.
C - Branching cells with 1/2 nucli, soft striations.
Sm - Single, spindle shaped, uninucleated cells, no striations
Describe the connective tissue components
Sk - epimysium, perimysium and endomysium.
C -Endomysium attached to fribrous skeleton og heart.
Sm - endomysium
Presence of myofibrils composed of sarcomeres?
Sk - yes
C - Yes but myofibrils are irregular thickness.
Sm - No but actin and myosin are present.
Presence of T tubules?
Sk - Yes, two at the A-I junction
C - Yes at larger and at each Z disc
Sm - No, instead have caveoli
Is there an elaborate sarcoplasmic reticulum?
Sk - yes.
C - yes but to lesser degree than Sk
Sm - Yes to same extent as C muscle.
Presence of gap junctions?
Sk - no,
C - yes at intercalated discs
Sm - yes in single unit muscle.
Do cells have individual neuromusclar junctions?
Sk - yes
C - no
Sm- not in single unit muscle but yes in multiunit muscle.
Describe the regulation of contractions for each muscle type
Sk - voluntary via somatic nervous system.
C - involuntary vi ANS, hormones, stretch.
Sm - involuntary via ANS, hormones, local chemicals and stretch.
Describe the source of calcium for each muscle type
Sk - sarcoplasmic reticulum.
C - SR and extracellular fluid.
Sm - SR and extraceullar fluid
Site of calcium regulation
Sk- Troponin on actin filaments.
C - Troponin on actin filaments.
Sm - Calmodulin on the sarcoplasm
Presence of pacemakers
Sk - no.
C - yes.
Sm - Only in single unit muscle.
Effects on the nervous system
Sk - Excitation.
C - Exitation or inhibition.
Sm - Excitation or inhibition
What is the speed of contraction
Sk - slow to fast.
C - Slow.
Sm - Very slow.
Is their rhythmic contraction?
Sk - no.
C - yes.
Sm - only in single unit muscle.
