Somatic Nervous System and Central Nervous System Vocabulary

Vocabulary flashcards generated from the lecture covering the somatic nervous system, neuromuscular junction components, neuromuscular toxins, neurogenesis, astrocyte functions, and cerebral lateralization.

Somatic nervous system

A division of the nervous system responsible mostly for voluntary actions, characterized by a single type of efferent neuron originating in the ventral horn of the spinal cord or brainstem to innervate skeletal muscles.

Neuromuscular junction

The specialized junction or synapse between a somatic motor neuron and a muscle fiber.

Motor unit

A functional unit comprising a single motor neuron, the neuromuscular junction, and all the individual muscle fibers that the neuron innervates.

Synaptic knob

An expanded region at the terminal end of an axon branch (teledendria) containing synaptic vesicles filled with acetylcholine.

Motor end plate

The specialized, highly folded region of the sarcolemma (muscle cell membrane) containing acetylcholine receptors at the neuromuscular junction.

Synaptic cleft

The fluid-filled space between the synaptic knob of a motor neuron and the motor end plate of a muscle cell across which acetylcholine diffuses.

End plate potential

A graded voltage change produced at the motor end plate when acetylcholine binds to nicotinic cholinergic receptors, typically depolarizing the muscle fiber to threshold.

Excitatory postsynaptic potential (EPSP)

A temporary depolarization of a postsynaptic membrane that brings the membrane potential closer to threshold.

Myasthenia gravis

A condition typically affecting women ages 20 to 50, characterized by rapid onset and severe fatigue of specific muscle groups (such as facial, limb, or respiratory muscles) after use.

Letroxin

A active compound in black widow spider venom that stimulates excessive release of acetylcholine, leading to muscle spasms, rigidity, and potential respiratory failure.

Crotoxin

A toxin present in South American rattlesnake venom that inhibits the release of acetylcholine, causing flaccid paralysis of muscles.

Curare

A plant-derived toxin from sources such as Chondrodendron tomentosum or Strychnos toxifera that acts as a competitive acetylcholine antagonist, blocking neuromuscular transmission and causing paralysis.

Neurogenesis

The process by which new functional neurons are formed from neural stem cells in specific areas of the adult brain.

Subventricular zone

A neurogenic region adjacent to the lateral ventricles where neural stem cells produce new interneurons that migrate to the striatum in humans.

Subgranular zone

A region within the hippocampus where adult neurogenesis occurs to generate new interneurons that assist in learning and memory.

Astrocytes

Star-shaped glial cells in the central nervous system that maintain ionic homeostasis, convert glutamate to glutamine, supply lactate for energy, direct neurogenesis, and support the blood-brain barrier.

Glial derived neurotrophic factor

A signaling substance secreted by astrocytes necessary for the survival and maintenance of spinal motor neurons and dopamine-releasing neurons.

Cerebral lateralization

The specialization of specific cognitive, motor, or sensory functions within either the left or right cerebral hemisphere, mediated by crossed pathways.

Hemispatial neglect

A condition (such as left side neglect) following brain injury or dementia in which an individual fails to perceive or respond to stimuli presented on the side opposite the brain damage.