Transcript SSN MUSCLE - Columbia University Medical Center

MUSCLE
Histology SSN
October 25, 2004
Presented By:
Nadia Goodwin & Rebecca Nardi
Muscle Types
Which is Which?
Cardiac?
Skeletal
•Striated
•Voluntary
Skeletal?
Smooth?
Smooth
•Smooth
•Involuntary
Cardiac
•Striated
•Involuntary
What other places can “skeletal” muscle be found?
Skeletal Muscle Cross section
• Endomysium
• Perimysium
• Epimysium
Skeletal Muscle Organization
Ross Fig 10-3 (p.250, 4th ed.)
How do Muscles get their Stripes?
• Light band is the I
band = actin only
– Actin anchored at the Z
disc at center of I band
• Dark band is the A
band = myosin +
overlapping actin
– Contains H band =
myosin only
– Myosin anchored at the
M line
When Muscles Contract…
• The A band does NOT
change length
• H and I bands shrink
• Z discs are drawn closer
together
• Actin & myosin filaments
do not actually shorten,
they just slide past each
other
The Triad
• Triad = 1 T tubule + 2 terminal
cisternae of the sarcoplasmic
reticulum
• There are 2 triads per sarcomere
(in skeletal muscle) located at
the ends of the A band (A-I
junctions)
• Function- Depolarization of
sarcolemma (T tubule) triggers
Ca2+ release from sarcoplasmic
reticulum to initiate contraction
Motor End Plates
Motor unit = motor nerve + muscle cells it innervates
Other Things to Know
Muscle-tendon Junction
Cardiac Muscle
Like skeletal muscle, cardiac
muscle has:
• Sarcomeres (striations)
• T-tubules
• Calcium regulation at
level of thin filaments
So what’s different?
Lab 7 Slide 13
Cardiac Muscle –
Defining Characteristics
Branching myofibrils
Large, central, ovoid
nuclei
Intercalated Disks
Lab 7 Slide 14
Intercalated Disks
Lab 7 Slide 16
Also, T Tubules and SR
arranged in a diad, not triad
Which is which?
Cardiac
Skeletal
Which is which?
Lab 7. Slide 15.
Cardiac
Lab 17. Slide 10.
Skeletal
Smooth Muscle
Located in
blood vessels,
ducts, and here,
in the GI tract.
(This is the
colon.)
Lab 7 Slide 17
Smooth Muscle
Longitudinal section
?
Myenteric Ganglion
Cross Section
A Closer Look
Elongated nuclei
Indistinct boundaries
(w/ H&E)
Wrinkled nuclei
Centrally located
nuclei
Lab 7 Slide19
Smooth Muscle
Cardiac Muscle
Smooth Muscle vs. CT
Smooth Muscle
•Darker Staining
•Nuclei within fibers
•Wrinkled nuclei
DIACT
•Lighter Staining
•Fewer nuclei, outside
fibers
Lab 4. Slide 16.
Smooth Muscle v. CT
Smooth Muscle
DRACT
Silver Stain
Clear
Basal
Lamina
Lab 7 Slide 23
A Closer Look –
Why the “Dotted Lines”?
Interrupted
basal lamina
due to GAP
JUNCTIONS
•Ensure
coordination
during contraction
Lab 7 Slide 24
What Muscle??
Smooth
Nerve
Skeletal
Lab 17. Slide 14
Esophagus – Where Smooth
and Skeletal Muscle
Combine
1.
A
B
2.
3.
A
B
C
D
4.
5.