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54 Cards in this Set
- Front
- Back
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What are the components of a triad and what are their functions?
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T-tubule: an invagination of the sarcolemma which is used to signal to the terminal cisternae
Terminal cisternae: tubes of sarcoplasmic reticulum which release Ca2+ for muscle contraction when signaled by the t-tubule |
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What is the plasma membrane called in muscle cells?
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Sarcolemma
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In which embryonic tissue layer does skeletal muscle originate?
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Somatic mesoderm
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What are the three layers of connective tissue at different levels of muscle organization and what structure do they surround?
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Endomysium: surrounds individual muscle fiber
Perimysium: surrounds muscle fascicle Epimysium: surrounds entire muscle |
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What is the difference between red fibers and white fibers?
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Red fibers are small and rich in myoglobin and mitochondria. They are slow twitch and built for endurance. They use aerobic metabolism.
White fibers are large and do not have as much myoglobin and mitochondria. They are fast twitch and easily fatigued. They use anaerobic metabolism. |
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What are the components of a sarcomere and what are they made of?
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Z-discs: site of actin anchoring
M-line: site of myosin filament attachment A-line: overlapping actin and myosin I-band: actin from adjacent sarcomeres H-zone: myosin |
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What neurotransmitter is released into the neuromuscular junction?
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Acetylcholine
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What does a neuromuscular junction look like on an EM image?
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A smiley face
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Name 5 distinguishing factors of cardiac muscle.
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Intercalated discs
Striations Branching Mononuclear cells Central nucleus |
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Does cardiac muscle have a diad or triad?
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Diad with a t-tubule and one terminal cisterna
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What are the three components of an intercalated disc?
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Fascia adherens
Desmosomes (look like oreos by EM) Gap junctions (important to synchronize contractions) |
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Define intrinsic rhythmicity.
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Intrinsic rhythmicity means that the heart rate can be regulated by autonomics but contractions are not initiated by nervous input.
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State whether each of the three types of muscle uses intra- or extracellular Ca2+.
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Skeletal muscle: intra
Cardiac muscle: both Smooth muscle: extra |
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Describe how the actin/myosin arrangement is different in smooth muscle than in skeletal or cardiac.
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The actin and myosin are in more of a fish net-like arrangement, rather than organized into sarcomeres.
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Which type of muscle is capable of mitosis?
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Only smooth!
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What are muscle spindles and what do they do?
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Proprioceptors sensing length of the muscle. Quickly stimulate contraction when the muscle is over-extended. (Knee reflex)
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What are Golgi tendon organs and what do they do?
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Proprioceptors near musculotendonal junction. Activate with twisting or compression and send an inhibitory signal to the motor neuron to terminate contraction.
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What is a Pacinian corpuscle? Is it encapsulated or unencapsulated?
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A Pacinian corpuscle is an encapsulated mechanoreceptor terminating in the skin that senses pain and pressure.
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What is a Meissner's corpuscle? Is it encapsulated or unencapsulated?
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A Meissner's corpuscle is a mechanoreceptor in the skin that sense light touch. It is encapsulated in unmyelinated nerve endings.
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Which embryonic tissue layer is neural tissue derived from?
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Neuroectoderm
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What does the neural tube become in the adult?
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Brain and spinal cord
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What does the neural crest become in the adult?
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Cranial and spinal nerves, ganglia, motor and sensory nerve endings
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What does the ectomesenchyme become in adults?
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Meninges, calvaria, nasal bones, maxilla, palette
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What are the three different structural arrangements of neurons?
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Bipolar: one dendrite, one axon
Multipolar: multiple dendrites, one axon Unipolar/pseudopolar: one axonal process, no dendrites, soma projects off of axon somewhere in the middle |
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Which direction do afferent and efferent nerves flow with respect to the CNS?
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Afferent: towards (sensory)
Efferent: away (motor) |
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What are Nissl bodies and what do they look like in an image?
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Aggregated RER
Look like little black spots in neuronal soma |
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What is the axon hillock and what does it look like in an image?
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Where the axon leaves the soma.
Clear space in periphery of soma, leading out to axon. |
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Can the same neurotransmitter have both stimulatory and inhibitory effects?
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Yes, the response can be varied based on the receptors present in the synapse.
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What is the perikaryon?
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The soma
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Which motor protein is used for rapid anterograde traffic in the axon? Is it ATP-dependent?
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Kinesin
Yes |
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Which motor protein is used for rapid retrograde traffic in the axon? Is it ATP-dependent?
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Dynein
Yes |
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What do oligodendrocytes do?
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Produce myelin
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What do astrocytes do?
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Form glia limitans (blood-brain barrier)
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What do microglia do?
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Phagocytosis
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Describe Wallerian degeneration.
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Wallerian degeneration occurs when there is injury to an axon. Chromatolysis (lysis of Nissl bodies) occurs from 1 day-2 weeks after injury. The side of the axon distal to the soma degenerates, but the Schwann cells maintain their tube formation. The axon slowly regenerates using slow axonal transport and looks for the tube of Schwann cells, which it will re-enter. Axon regrowth may result in mismatch of axons and soma.
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What are myofilaments?
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Filaments of actin and myosin fibers which aggregate to form myofibrils
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Describe the development of myofibers.
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Precursor myoblasts line up and fuse to form multinucleate myotubes with central nuclei. The myotubes mature to myofibrs when the nuclei migrate to a peripheral position.
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Are myofibers terminally differentiated?
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Yes
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Do A-bands and I-bands both shorten during muscle contraction?
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No, only I-bands do.
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How many muscle fibers does one motor neuron innervate?
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It depends on the tissue. Only a few in the eye, versus up to 1700 in the torso.
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How is the force of muscle contraction transferred to bone?
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The actin filament of the last sarcomere is anchored in the sarcolemma, which is connected to the tendon through reticular and collagen fibers of the endo-, peri-, and epimysium.
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What protein anchors actin filaments in smooth muscle?
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a-actinin
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What structures do smooth muscles have instead of t-tubules?
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Caveoli, which are invaginations of the sarcolemma that regulate Ca2+ entry
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How does skeletal muscle regenerate?
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It has very limited regenerative capacity with its few myoblasts, but most damaged tissue is replaced by hypertrophy of other cells.
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How does cardiac muscle repair injury?
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With connective tissue
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How much of the body's energy does the brain use? How much of the body's mass does it constitute?
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20%
2% |
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What is an interneuron, and what percent of the body's neurons does it constitute?
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A neuron which connects other neurons.
99.9% |
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What is lipofuscin?
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A pigment inclusion in neuronal cells, increasing with aging.
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What are neuroendocrine endings?
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Sites at which neurohormones are released into capillaries and interstitial spaces by neurons.
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Name four organelles and structural components that are found in axons and two that are not.
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Neurofilaments, neurotubules, vesicles, and mitochondria.
RER, Golgi. |
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What fluid creates a unique microenvironment in the PNS?
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CSF-like fluid
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What is a node of Ranvier?
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A structural gap between Schwann cells on an axon.
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What kind of cells surround cell bodies in the ganglion?
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Satellite cells
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What seven components will all PNS ganglia contain?
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neuron cell bodies
satellite cells Schwann cells myelinated axons unmyelinated axons capillaries LCT |
