Muscle Histology Flashcards
3 main points of muscle
- Body movement
- Aggrates of special long cells for contrsction
- Actin and myosin
Thin myofilament, formed from globular ____ proteins
Actin filament
thick myofilament consisting of 200-300 ____ molecules
Myosin filament
cells do not have cross-striations
Smooth musle cells
cells have cross-striations
Striated Muscle cell
Striated Muscle cell
attached to bone, responsible for movement
Skeletal
Striated Muscle cell
restricted to soft tissues (tongue, pharynx, upper esophagus, lumbar part of diaphragm) no bones.
Visceral Striated
Striated Muscle cell
wall of heart and base of large veins that empty into the heart
cardiac
Skeletal muscles cells are ____
rich blood supply
Multinucleated(formed from fusion of myoblasts)
Lenght of skeletal muscle cell depeneds on what?
On muscle it makes up
Skeletal muscle cells are surroudned by what that aids in force transduction from muscle to tendon
Connective tissue
How are skeletal muscle connected to bone?
Via tendon
(inner most)
* CT surrounding individual muscle cells
* composed of reticular fibers, external lamina (basal lamina), and thin areolar tissue
* allows room for capillaries and nerve fibers essential for initiat muscle contraction.
Endomysium
thicker CT, surrounds and defines fascicles (functional bundles of muscle fibers)
Perimysium
(outer most) sheet of dense connective tissue which surrounds a collection of fascicles. surrounds entire muscle
Epimysium
Types of Skeletal Muscle Fibers
- Fatigue resistant motor units
- Large numbers of mitochondria and amounts of myoglobin
- Endurance athletes
long term
Type I- Slow oxidative
Types of Skeletal Muscle Fibers
- Fast-twitch, fatigue-resistant motor units
- Generate high-peak muscle tension
- Hockey players, mid distance 400-800m sprinters higher concentration.
Type IIa- fast oxidative
Types of Skeletal Muscle Fibers
- Fast-twitch, fatigue-prone motor (fast) units
- Fastest of all fiber types
- Short-distance sprinters, weightlifters; higher levels of fast glycolytic fibers.
Type IIb fast glycolytic
sprinters
dark bands (myosin)
A band
light bands (actin)
I band
anchor for actin
Z line
only myosin, no actin
H band
middle of sarcomere
M line
Each sarcomere in contraction myosin filament stay stable in center, thick filament slide over thin filament and bring ____ closer together.
Z line
molecule that polymerizes to form double-stranded to form F-actin
G actin
filament in the groove of F-actin 2 in double helix.
Tropomyosin
What doe tropomyosin do ?
Masks myosin binding site at rest, doesnt allow actin ot bind, prevents muscle contraction
3 parts of troponin complex
- TnC; bind Ca+
- TnT; bind tropomyosin
- Tn; bind actin
What does the **binding of calcium on TnC **of the troponin complex do?
Moves the tropomyosin out of way allowing myosin and actin to ineract and contract. Calcium is very important for muscle contraction
actin capping protein sit at end of actin filament and acts as a cap.
Tropomodulin
* maintains + regulate actin filiment lenfh preventing unwinding & degredation
Acts as a molecular ruler and adds stability to thin filaments (actin)
Nebulin
lack of would resilt in diff size actin
3 parts of myosin thick filament
- Tail
- Lever arm
- Head
intertwin to form thick myosin filament
Tail
important in movment of thick filament andallow actin to slide over myosin
Lever arm
important in grabbing onto acitn, hydrolyzing atp, and forming connection btwn myosin and actin for muscle contraction. Contain actin binding site and ATP binding site.
Head
zone in the M-line that has no myosin heads
bare Zone
____ shape allow consistent smooth contraction smooth sliding of actin filment onto myosin filament
Spiral
Acessory protien
- prevents excessive stretching of the sarcomere
- One of larget portien in body
Titin
Acessoru {protems
attach titin to Z-line
A-actin
Acessory protiens
forms stabilizing cross-links between myofibrils
Desmin
Acessory protiens
attach titin to M-line
* Titin stretch from M line to Z line, prevent over stretching.
M-line protiens
Acessory protiens
links laminin to actin filaments.
* Important for transfer of contraction form indv sarcomere out into connective tissue for muscle contraction
Lack of linkage will result in no mvmt in muscle.
Dystrophin