4. Skeletal Muscle and Nerve Tissue Flashcards
Where is calcium stored within a muscle?
In the Sarcoplasmic Reticulum
How many dendrites and axons for a bipolar neuron?
Single dendrite (with multiple extensions) and one axon
What is the function of gamma motor nerve fibers?
Contraction of the intrafusal muscle fibers in response to the Neuromuscular Spindle Apparatus detecting an excessive stretch
What two chains does Myosin have?
Heavy chain with a globular head
Light chain
From smallest unit to largest, what are the divisions of a muscle?
Sarcomere -> Myofibrils -> Myocyte (Myofiber) -> Fascicle -> Muscle
What does Tropomyosin do?
Wraps between actin strands and holds troponin
What is this type of neuron?
Multipolar
What is marked here as 2?
A Band
What connects the Transverse Tubule to the Terminal Cisternae?
What do they do?
“End Feet”
Allow for calcium release
What is actin made of?
G-Actin Monomers
(globular protiens)
What features can be used to identify Skeletal Muscle?
Peripheral nucleii
Striations
Multiple nucleii
What is this type of neuron?
Pseudounipolar
What is this type of neuron?
Bipolar
What two regions of a Myofibril shorten during muscle contraction?
The H Zone and the I Band
Where do Oligodendrocytes operate?
CNS
What makes up the “thick filament” of a muscle fiber?
Myosin
What is Sarcoplasmic Reticulum?
Tubular system which acts like smooth ER.
Do Schwann cells wrap around parts of single axons or many axons together?
Parts of a single axon
What keeps the muscles from contracting all the time?
Tropomyosin blocks the myosin binding sites
Where are myosin going one direction attached to the myosin going the other direction?
M line / M disc
What is the function of the Axon Hillock?
Sums up all of the action potentials from the dendrites, and sends a signal down the axon if it is sufficient.
What is an intrafusal muscle fiber?
Muscle fiber that senses length and rate of change of a muscle
Do Oligodendrocytes wrap around parts of single axons or many axons together?
Many axons together
What is the connective tissue layer surrounding the outside of the entire spinal nerve?
Epineurium
What makes up the “thin filament” of a muscle fiber?
Actin
How many dendrites and axons for a multipolar neuron?
Multiple dendrites, one axon
What is a Type 1A sensory nerve fiber?
Afferent innervation to an intrafusal muscle fiber (sends strech sensory information to the spine)
What are the basic characteristics of type 2 muscle fibers?
Less mitochondria than type 1
More explosive contractions
Fatigues quickly
Less myoglobin
What determines the length of an Actin filament?
Nebulin
What is an extrafusal muscle fiber?
Muscle fiber under voluntary control, in charge of contracting the muscle fibers.
What is marked here as 4?
M Line
What are the basic characteristics of Type 1 muscle fibers?
Low fatigability
Slow Contraction
Abundant Myoglobin for O2
Very Aerobic
Many Mitochondria
What fascial covering covers the fascicles?
Perimysium
What are Transverse (T) Tubules?
Bits of Sarcolemma (membrane) that penetrate the cell.
What are the characteristics of a pseudounipolar neuron?
A cell body connected to a cell process with a dendrite branch and an axon branch.
What serves as the defined border of a sarcomere?
Z disks
What is the Sarcoplasm?
Cytoplasm of a muscle cell
Does the A Band shorten during contraction?
No. Only the H Zone and the I band shorten
What does Calcium do to incite muscle contraction?
It binds to Troponin, which then causes Tropomyosin to change conformation, and no longer block the Myosin binding sites on the Actin Filament
What connective tissue layer wraps a single myelinated or unmyelinated axon?
Endoneurium
What is marked here as 1?
I Band
What is the Sarcolemma?
The membrane around myocytes that penetrates the muscle cell as T tubules
What all is contained within the H Zone?
Myosin fibers and the M line
Why is it important to have electrical impulses shuttled into the cell?
So that the myocyte can contract all at once, instead of from the outside in.
What is the function of Alpha-Motor nerve fibers?
Sends the signal to contract to a muscle
What attaches to the Z disk?
Actin and Titin (which in turn holds myosin)
What is marked here as 5?
Z Disk
What is contained within the I band?
Actin
The Z Disk
(straddles sarcomeres)
What is defined as the A band?
Distance from end to end of myosin within one sarcomere.
What fascial covering covers the myofibers?
Endomysium
What fascial covering surrounds the muscle itself?
The epimysium
What is marked here as 3?
H Zone
What holds the Myosin to the Z disk, thus holding Myosin in place?
Titin protiens
What connective tissue layer wraps a fascicle of nerve fibers together?
Perineurium
What are Terminal Cisternae?
Flattened sacs of sarcoplasmic reticulum laying alongside the T tubules.
Where do Schwann cells operate?
Peripheral Nervous System
How many nerves innervate one myofiber?
How many fibers might one nerve innervate?
1
More than one
