9/11 SkM and Nerve Histology Flashcards
Function of Muscle
- Generate force for movement
- Energy from ATP is converted to mechanical energy
- ______– voluntary movements and postural stability
- _______– contract the heart to pump blood throughout body
- _______– involuntary movements for respiration, digestion, blood vessel control
Skeletal muscle
Cardiac muscle
Smooth muscle
Skeletal muscle
• Striated
- Strong
- Quick
- Voluntary
- Fatigable
• Multinucleated (peripheral)
• Large cells
Cardiac Muscle
- Striated • Strong • Quick • Involuntary • Must NEVER fatigue • Uninucleated (central) • Branched cells
- Separated by______
intercalated discs
Smooth Muscle
• Not striated • WeakER • Slow and rhythmic • Involuntary • Uninucleated (central)
Muscle Terminology/Arrangement
- Muscle cell = Myofiber/Myocyte/Muscle fiber – Made up of _____
- Chains of _____ linked together – Sarcomere = contractile unit of muscle made of ____ and ____ myofilaments – Surrounded by endomysium (fascial covering)
- _____= group of myofibers – Surrounded by perimysium (fascial covering)
- Muscle = group of _____– Surrounded by epimysium (fascial covering)
myofibrils
sarcomeres/actin/myosin
Fascicle
fascicles
group of sarcomeres =?
group of myofibrils =?
group of muscle fibers =?
group of fascicles=?
myofibrils
muscle fiber
fascicle
muscle
endomysium wraps?
perimysium wraps?
epimysium wraps?
muscle fibers
fascicles
muscle
endomysium
myosin (thick filament)
- 2 heavy chains with globular heads – Have _____ site with ATPase domains
- ___ light chains
- Held in place by _____ proteins connected to Z-disk
actin binding
2
Titin
Actin (Thin Filaments)
- Made of ____ monomers (globules)
- Monomers bind together forming double stranded chains
- _____ = “ruler” for determining length of actin filament
- ______ strands wrap between the actin strands
- _____ sits on tropomyosin strands and covers myosin binding sites on actin filament
F-actin
Nebulin
Tropomyosin
Troponin
Sarcomere Components
- _____: attachment site for myosin
- _____: separates sarcomeres; attachment site for actin and titin
- _____: space on either side of M-line where there is no actin
- ______: distance from the end of one myosin head to the head of the opposite myosin (overlap of actin + myosin and H band)
- ____: space on either side of the Z-disk where there is no myosin
M-line
Z-disk
H band
A band
I band
Muscle Contraction
- For contraction to occur, ____must bind to actin
- _____blocks the myosin binding sites on actin filaments
- _____released from the SR binds to troponin causing a conformational change – This makes the actin binding sites accessible to myosin heads
myosin
Troponin
Calcium
*Troponin-Ca complex pulls tropomyosin alway, exposing the myosin binding site on the actin
Sliding Filament Mechanism
- Thin filaments slide past thick filaments – Myosin heads “crawl” across actin filaments
- This brings ____ -disk’s closer together
- All _____ in a muscle contract at the same time making the entire muscle shorten
- *Actin and myosin DO NOT change in length, they simply overlap each other
z-disk
myofibrils
*a-band doesn’t shorten
*H-band shortens
What are the three subtypes of muscle fibers?
type I and Type IIA/B
Electrical Impulse Transmission
- ______: membrane around each muscle cell
- ______: membrane system penetrating the muscle cell to convey electrical impulses from sarcolemma into cell
- _____: cytoplasm of muscle cell
- ______: tubular system acting like the smooth-ER – Terminal Cisternae = flattened sac of SR on either side of a Transverse T Tubule
- _____= T tubule + 2 Terminal cisternae (1 on either side)
- _____: connect T tubules with SR to allow Ca release
Sarcolemma
Transverse (T) tubules
Sarcoplasm
Sarcoplasmic Reticulum
Triad
End Feet
Neuromuscular Junction (NMJ)
- Skeletal muscle innervated by peripheral a-motor neurons from the _____ of the spinal cord
- _____ nerve per muscle fiber
- _____muscle fiber per nerve
anterior horn
1
>1
Neuromuscular Junction
Neuromuscular Junction Histology
Neuromuscular Junction Histology
- Action: reflexive response to prevent overstretching of a muscle
- Components:
– Extrafusal muscle fibers: contract the muscle
– Intrafusal muscle fibers: sense length and rate of change of the muscle
– Type Ia sensory nerve fibers: afferent innervation of intrafusal fibers
– a-motor nerve fibers: efferent innervation of extrafusal muscle fibers
– g-motor nerve fibers: efferent innervation of intrafusal muscle fibers
Neuromuscular Spindle Apparatus
- ____ fibers: sense stretch and rate of change of intrafusal fibers
- _____neurons: receive signal from type Ia fibers and cause extrafusal muscle fibers to contract (shorten)
- _____neurons: receive signal from type Ia fibers and cause intrafusal muscle fibers to contract (shorten)
- Continuously receiving signal from higher brain centers to stay taught to be able to detect that changes
Type Ia
A-motor
G-motor
Neuron Terminology
- Soma/Body: contains all the organelles of the neuron
- Nissle Substance: abundant rER w/in the cytoplasm of the soma • Dendrite: receives signals from other neurons
- Axon Hillock: connection b/w soma and axon (summates electrical signals received by all dendrites to transmit down axon) • Axon: conveys electrical impulse to synapse
- Synapse: transfers electrical impulse from the neuron to the target tissue
Nerve Terminology/Arrangement
Neuron Types
- _____: multiple dendrites and one axon
- ______: single dendrite (multiple extensions) and one axon
- ______: one cell process with a single dendrite branch and axon branch
Multipolar
Bipolar
Pseudounipolar
Myelination
- _____: surround axon and create myelin sheath in PNS – Wrap around one part of one axon
- ______: surround axon and create myelin sheath in CNS – Wrap around a part of many axons
- _____: circumferential layers of myelin allowing for faster signal conduction velocity
Schwann cell
Oligodendrocyte
Myelin Sheath
a sarcomere is between which two landmarks?
z disc to z disc
when muscle contracts, which zone and band shorten?
H and I
