Muscle Tissue Flashcards
What are the 3 types of muscle tissue and are they striated/un-striated?
- Skeletal - striated
- Cardiac - striated
- Smooth - unstriated
Describe the transverse cross section of skeletal muscle.
- Myocytes, myofibres, or muscle fibres
- Peripheral nuclei
- Sacrolemma & basement membrane
- Sarcoplasm & myofibrils
- Endomysium, satellite (myoblasts) and fibrocytes
Describe the longitudinal cross section of skeletal muscle.
- Parallel arrangment non branching muscle fibres
- Syncytium
- Multiple nuclei at boundary
- Visible striations
What is the muscle wrapped in?
Dense connective tissue called the epimysium.
What is a fascicle?
A bundle of skeletal muscle fibers running parallel to each other, enveloped by a collagenous sheath called the perimysium.
What coats muscle fibres?
Loose connective tissue called endomysium.
What is the sarcolemma?
The cell membrane of a muscle fibre.
Describe the nuclei of a muscle fibre.
Multinucleated - positioned at the periphery.
What other units do muscle fibres contain and what are they?
Myofibrils - bundles of actin and myosin filaments organised into a chain of repeating units called sarcomeres.
What are the striations?
Visible sarcomeres
What is contained within a sarcomere?
- 1 = z-line to z-line
- z-line anchors actin
Describe the transverse cross section of cardiac muscle.
- Cross sections of comparable size
- Centrally placed nucleus in majority
- Endomysium is more abundant
- Sacrolemma and basement membrane
- Sarcoplasm, myofibrils
Describe the longitudinal cross section of cardiac muscle.
- Looser arrangement of fibres
- Consists of individual cells - may branch
- Central nucleus
- Visible striations
- Lots of blood vessels associated with endomysium
- Intercalated discs = specialised junctional complexes —> adhesion and communication
Describe what smooth muscle looks like under microscope.
- Single cells
- Fusiform or spindle shaped
- Variable diameter in TS
- Centrally placed nucleus
- Tapered ends in LS
- Nos striations
- Reticular fibres - endomysium
- Close apposition - communicate via gap junctions
- Often arranged circumferentially
