Skeletal Muscle And Nerve Tissue Histo Flashcards
Skeletal muscle
Striated Multinucleated Fatigable Voluntary Quick Strong
Myofiber
A group of myofibrils surrounded by endomysium
Muscle Cell
Myocyte
Myofibrils
Groups of sarcomeres
Sarcomeres
Contractile group made of actin and myosin myofilaments
Actin
Thin filaments
Made of f-actin monomers
Monomers come together to form actin filaments (in double stranded rings)
Uses nebulin to determine length of filament
Tropomyosin is intertwined in actin filament
Troponin is bound to tropomyosin blocking the myosin binding site
Myosin
Thick filaments
Has 2 heavy chains and 2 light chains
Heavy chains contain ATPase domain, actin binding sites, and myosin heads
Connected to Z disk via titin
Fascicle
Group of myofibers
Surrounded by perimysium
Muscle
Group of fascicles
Surrounded by epimysium
Sequence of what makes a muscle
Myosin and actin myofilaments Sarcomere Myofibril Myofiber Fascicle Muscle cell
Z disk
Sarcomere is Z disk to Z disk
Contains actin and myosin
M line
Where myosin attaches
H zone
Contains no thin filaments
Changes size during contraction
I band
Contains no myosin
Changes size during contraction
A band
From the end of one myosin head to the end of an adjacent myosin head
Does not change size during contraction
Muscle Contracttion
Ca2+ is released by the sarcolemma and binds to troponin
Causes conformational change
Troponin lets go of tropomyosin
Myosin binds to actin and crawls across actin
Myosin and actin do NOT change size
H zone and I band shorten
Z disk to Z disk becomes closer
all myofibrils in a muscle contract at the same time making the entire muscle shorten
Skeletal muscle fiber types
Type I
Type IIa
Type IIb
Type I muscle fiber
Slow, not very powerful Many mitochondria Great deal of myoglobin Aerobic respiration Slow fatiguability
Type IIA muscle fiber
Intermediate speed and power Many mitochondria Many myoglobin Intermediate fatiguability Aerobic respiration (less O2 necessary than type I)
Type IIb muscle fiber
Quick, very powerful Few mitochondria Few myoglobin Quick fatiguability Anaerobic respiration
Sarcolemma
Membrane surrounding muscle cell
Transverse (T) tubule
Perforated muscle cells so electrical transmission can go from sarcolemma to muscle cell
Sarcoplasmic Reticulum (SR)
Acts as a smooth ER for muscle cells
Has terminal cisternae
Holds Ca2+
Terminal cisternae
Flattened sac of SR on either side of a T tubule
Triad
T tubule and 2 terminal cisternae (one on each side)
End feet
Connect T tubules with SR to allow Ca2+ release
Neuromuscular junction
Skeletal muscle innervated by alpha motor neurons from anterior horn of spinal cord
1 nerve per muscle cell
1 nerve can supply many muscle cells
Extrafusal fibers
Part of neuromuscular spindle apparatus
Contract muscles
Neuromuscular spindle appparatus
Reflexive response preventing overstretching of muscle
Intrafusal fibers
Sense length change in muscle fibers
Inside extrafusal fibers
Type Ia sensory muscle fibers
Afferent innervation in intrafusal fibers
Send signals to extrafusal and intrafusal muscle fibers
Alpha motor neurons
Efferent fibers from anterior horn of spinal cord causing contraction of extrafusal muscle fibers
Gamma motor neurons
Efferent neurons from anterior horn causing contraction of intrafusal muscle fibers
Soma/body of neuron
Contains all neuron organelles
Nissle substance
Abundant ribosomal ER in cytoplasm of soma/body of neurons
Dendrites
Receive signals from other neurons
Axon hillock
Connect soma/body with axon
Accumulates all electrical signals from dendrites to send them down the axon
Axon
Sends electrical signals from neuron to synapse
Synapse
Transfers electrical impulse from the neuron to the target tissue
Neuron types
Multipolar
Bipolar
Psueodunipolar
Multipolar
Multiple dendrites and one axon
Bipolar
1 dendrite (multiple extensions) and 1 axon
Pseudounipolar
1 dendrite and 1 axon, but cell body is separated from both
Myelination
Schwann cells-PNS
Oligodendrocytes-CNS
Transmits electrical signal faster
