Skeletal Muscle and Nerve Tissue Flashcards
What is a myofiber/muscle cell/ muscle fiber made of?
What surrounds these structures?
Myofibrils
Endomysium
What makes up a fasicle?
What surrounds these structures?
Groups of myofibrils
Perimysium
What makes up a muscle?
What surrounds this?
Groups of fasicles
Epimysium
What are some of the primary histological characteristics of skeletal muscle?
Striated; Large and multinucleated
What is the relationship between myofibrils and sarcomeres?
Myofibrils are groups of sarcomeres (which are single contractile units)`
Components of myosin?
2 heavy chains with globular heads (2 chainsss) w/ actin binding site for ATPase domain
2 light chains
Held in place by titin proteins connected to Z disc
THICCC
Components of actin
Made of F actin monomers
Tropomyosin wraps between strands
Troponin sits on tropomyosin and covers myosin binding sites on actin filament
What protein is a ruler for determining the length of an actin filament ?
Nebulin
What binds to troponin? What happens after this molecule binds to troponin?
Ca2+
Causes a conformational change so actin is now available to bind to the myosin heads
Describe the sliding filament mechanism
Myosin heads crawl across actin filaments
Z discs are brought closer together
Myosin and actin filaments overlap
THERE IS NO CHANGE IN LENGTH OF THE FILAMENTS THEMSELVES
What are the characteristics of Type I skeletal muscle fibers?
Lots of mitochondria + myoglobin
Slow, less powerful contraction
Slow to fatigue
Important in aerobic respiration (EX: Long distance running)
What are the characteristics of type II A skeletal muscle fibers?
Many mitochondria and myoglobin
Fast/int power contraction
Int. fatigue
Aerobic respiration ( w/less oxygen delivery than type I)
What are the characteristics of type IIB skeletal muscle fibers?
Few mitochondria and myoglobin
Fast, powerful contraction
Fast fatigue
Anerobic respiration (EX: Quick bursts of sprinting, powerlifting)
List the primary components of a typical neuron
Dendrites
Soma
Nissle substance ( lots of rER in the cytoplasm of the soma)
Axon hillock (Summates electrical signals from dendrites to transmit down axon)
Synapse (Transfers electrical impulses from neuron to target tissue)
What are the characteristics of a multipolar neuron?
Multiple dendrites
One axon
What are the characteristics of a bipolar neuron?
Single dendrite w/ multiple extensions
One axon
What are the characteristics of a pseudounipolar neuron?
One cell process
Single dendrite branch and axon branch
EX: Dorsal root/sensory ganglia of spinal nerves
What are myelinated axons in the CNS called?
Oligodendrocytes
What are myelinated axons in the PNS called?
Schwann cells
Describe the structure of the NMJ (be able to identify on histological slides)
1 nerve per muscle fiber
1 nerve fiber can innervate more than one muscle
What are the components of the neuromuscular spindle
Extrafusal muscle fibers Intrafusal muscle fibers Type I A sensory nerve fibers A motor nerve fibers G motor nerve fibers
What do extrafusal muscle fibers do?
Contract muscle to prevent overstretchin
What do intrafusal muscle fibers do?
Sense changes in length/ rate of that length change in the muscle
What do type I a sensory nerve fibers do?
Afferent (sensory) innervation of intrafusal fibers
What do a motor nerve fibers do?
Efferent (motor) innervation of extrafusal muscle fibers
What do g motor nerve fibers do
Efferent innervation to intrafusal muscle fibers
