Muscle lecture notes Flashcards
What does muscle mean?
Little mouse
Functions of muscle
- Movement of bones
- Movement of fluids
- Constriction/dilation of tubes
- Heat generators
Muscles can only…
Contract, shorten in length, and pull
Muscles can NOT…
Push
Name the 3 body movements
1) Prime movers (action)
2) Antagonists (opposite of prime movers)
3) Synergists (work with prime movers)
Examples of the 3 body movements when we flex the forearm
1) Prime mover- biceps brachii
2) Antagonists- triceps brachii
3) Synergists- brachialis
How do we “push” if muscles only pull?
By levers for example olecranon process
What kind of tissue are tendons?
Dense regular connective tissue, they attach muscle to bone or another muscle
Aponeurosis are
Tendons that form thin, tough flattened sheets
Origin is an
Attachment that is more proximal or more stationary
Insertion is an
Attachment that is more distal or more mobile
Belly is
Body, main region that shortens & thickens when it contracts. Creates the action
What are the different muscle shapes
1) Circular muscles
2) Parallel muscles
3) Convergent muscles
4) Pennate muscles
The fascicles in a parallel muscle
Run parallel to its long axis. They run side by side
The fibers in a pennate muscle
Are arranged at an oblique angle to the tendon. The fibers come off the sides of the tendon.
What are the different types of pennate muscles
1) Unipennate: All muscle fibers on the same side of the tendon
2) Bipennate: Muscle fibers on both sides of the tendon
3) Multipennate: Tendon branches within the muscle
Name example for Unipennate, bipennate, & multipennate muscles
1) Unipennate: Extensor digitorum
2) Bipennate: Rectus femoris
3) Multipennate: Deltoid
Convergent fibers are
Over a wide area but come together in a common tendon (pectoralis major)
Circular muscle fibers are
The sphincter fibers are concentric around a body opening (orbicularis oris)
Name the types of muscle
1) Skeletal
2) Cardiac
3) Smooth
Smooth muscles are
Muscles of the organs and blood vessels. Unicleate, tapered ends, non-striated, involuntary
Cardia muscle is
The heart muscle. 1-2 nuclei, branched, intercalated discs, striated, involuntary
Skeletal muscle is
Muscles attached to the bones, multinucleate, peripheral nuclei, striated, voluntary
Myology=
Study of muslces
Muscle comes from
Mesoderm
Some mesoderm differentiate into
Somites which in turn differentiate into myotomes
How does a muscle come about?
Mesoderm>Somite>Myotome>Muscle
Myotomes form
Skeletal muscles
Epimysium surrounds
The entire muscle
Perimysium surrounds
Bundles (fascicles)
Endomysium surrounds
Muscle fiber. Satellite cells are scattered here & there
Satellite cells help repair
Tissue damage
Sarcomere is a
Contractile unit
Sarco means
Flesh
Sarcophage is a
Flesh eater
Sarcophagidae flies eat
Flesh, or at least their maggots do
The plasma membrane in a muscle cell is
Sarcolemma
The transverse (T) tubules are
Deep, tubular extensions of the sarcolemma
The ER endoplasmic reticulum in a muscle cell is
Sarcoplasmic reticulum (SR)
The “canal” ends of SR are
Terminal cisternae
One T tubule plus 2 lateral terminal cisternae=
Triad
What are important for the conduction of impulse to stimulate muscle contraction?
- Sarcolemma
- Transverse (T) tubules
- Sarcoplasmic reticulum (SR)
- Terminal cisternae
- Triad
T-tubules carry
Nerve impulses from the surface sarcolemma deep into the sarcoplasm.
Terminal cisternae are
Smooth ER: Stores Ca++ until released when a nerve impulse arrives
Neuron impulse travels to the muscle cell membrane=
Neuromuscular junction (motor end plate or synaptic knob)
Synaptic vesicles contain
Acetylcholine (ACh)
When a nerve impulse reaches the motor end plate what happens?
It releases Ach which crosses the synaptic cleft & binds to Ach receptors on the sarcolemma
The action potential (nerve impulse) continues (now on the muscle cell) across the entire sarcolemma and…
Down the triads
What releases stored Ca++ onto the muscle proteins?
Sarcoplasmic reticulum
Muscle proteins are called?
Myofilaments
What are the two types of muscle proteins myofilaments?
Thick and thin.
1) Myosin- thick filaments. A swivel headed protein chain.
2) Actin tropomyosin troponin (proteins)- thin filaments. Double strands of actin plus strands of tropomyosin that cover the active binding sites on each actin
Troponin protein holds what in place?
Tropomyosin
What are the different banding patterns?
A bands
I bands
Z line
H zone
A bands are
(dark) includes H zone, M
line & zone of (thin & thick filament) overlap
I bands are
(light); the region between the A band
& Z line containing primarily thin filaments
Z line functions as
The connecting framework for the thin filaments and defines the borders of the sarcomere (from Z line to Z line)
The H zone
or H band, is also lighter since it has thick filaments only & the M line running down the center
Banding: “dark” has an “A” in the word, Thus “A” band is….
Dark
Banding: “light” has an “I” in the word, Thus “I” band is
Light
Banding: “Z” is at the end of the alphabet
Thus “Z” marks the…
End of the sacromere
Banding: “H” and “M” are in the middle of the alphabet, thus
They are in the middle of the sacromere
The current model for muscle contraction is called?
Sliding filament theory
In relaxed muscle tropomyosin blocks the…
actin binding sites, preventing myosin cross-bridges
When Ca++ is released, it binds to troponin causing it to…
Shift the position of tropomyosin, opening actin binding sites for myosin heads to form cross-bridges
Cross bridge results in a power stroke due to potential energy stored in the myosin head. ATP energy is required to…
Detach the cross-bridge and reload the head
Acetylcholinesterase (AChE) In the synaptic cleft breaks down…
ACh. The action potential ceases
The sarcoplasmic reticulum reabsorbs

Ca++ via active transport
