Nervous System - Lecture 10 (BScN 114)

Vocabulary flashcards covering key terms and definitions from the Nervous System lecture notes.

Brain

Enclosed by the skull; contains neurons; major processing center of the CNS.

Spinal cord

Links brain to body; protected by vertebral column; site of information processing and transmission.

Nerve fiber

A single extension from a neuron; includes dendrites and axons.

Nerve

Bundle of nerve fibers in the PNS with a defined pathway.

Tract

Band or bundle of axons in the CNS.

Cranial nerves

12 pairs emerging from the brain base; have defined paths for head/neck innervation.

Spinal nerves

Nerves exiting the spinal cord; combine dorsal and ventral roots.

Ganglia

Small clusters of neuron cell bodies outside the CNS.

Enteric plexuses

Networks of neurons in the digestive system.

Sensory receptors

Dendrites or specialized cells that monitor internal/external changes.

Neuron

Nerve cell; excitable cell that transmits electrical impulses.

Neuroglia (glial cells)

Support cells that surround neurons.

Ependymal cells

Line brain ventricles and spinal canal; produce/circulate CSF.

Astrocytes

Glial cells that maintain the blood-brain barrier and support neurons.

Oligodendrocytes

Glial cells that myelinate CNS axons.

Microglia

Phagocytic glial cells that remove debris and pathogens.

Satellite cells

Glial cells surrounding neuron cell bodies in ganglia.

Schwann cells

Glial cells that myelinate PNS axons and aid repair.

Myelin sheath

Lipid-protein wrapping that speeds conduction; produced by oligodendrocytes (CNS) or Schwann cells (PNS).

Demyelination

Loss or destruction of myelin; impairs nerve conduction.

Action potential

All-or-none electrical impulse triggered when threshold is reached.

Threshold

Membrane potential (~-55 mV) needed to trigger an action potential.

Saltatory conduction

Rapid impulse conduction in myelinated fibers jumping at nodes of Ranvier.

Axon diameter

Larger diameter speeds signal conduction.

Temperature

Higher temperature speeds conduction; cooling slows it.

Synapse

Junction where neurons communicate; presynaptic and postsynaptic cells.

Presynaptic neuron

Neuron sending the signal across the synapse.

Postsynaptic neuron

Neuron receiving the signal at the synapse.

Axodendritic synapse

Synapse between axon terminal and a dendrite.

Axosomatic synapse

Synapse between an axon terminal and a neuron’s soma.

Electrical synapse

Direct current flow via gap junctions between neurons.

Chemical synapse

Neurotransmitter-mediated communication across the synaptic cleft.

Neurotransmitters

Chemical messengers; examples include ACh, glutamate, GABA, glycine, NE, dopamine, serotonin.

Blood-brain barrier (BBB)

Tight junctions that protect the CNS from many substances; glucose via transporters; lipid-soluble substances pass freely.

CSF (Cerebrospinal Fluid)

Fluid protecting CNS; provides nutrients and pH balance; circulates in ventricles and subarachnoid space.

Choroid plexus

CSF-producing tissue in the ventricles.

Ventricular system

Four ventricles (two lateral, third, fourth) containing CSF.

Meninges

Three protective membranes: dura mater, arachnoid mater, pia mater.

Broca’s area

Frontal lobe region for speech production; damage causes aphasia.

Wernicke’s area

Left temporal/parietal region for language comprehension; damage causes aphasia.

Reticular activating system (RAS)

Brainstem network controlling wakefulness and cortical arousal.

REM sleep

Dream-rich sleep stage; rapid eye movements; distinct EEG patterns.

NREM sleep

Non-REM sleep stages; dream less frequent; different brain activity.

Cranial nerves (I-XII)

Nerves with sensory, motor, or both roles; numbered I–XII.

Olfactory (I)

Sensory nerve; sense of smell.

Optic (II)

Sensory nerve; vision.

Oculomotor (III)

Motor nerve; eye movements and pupil constriction.

Trochlear (IV)

Motor nerve; eye movement.

Trigeminal (V)

Mixed nerve; facial sensation and mastication muscles.

Abducens (VI)

Motor nerve; eye movement.

Facial (VII)

Mixed nerve; facial expression; taste (anterior 2/3).

Vestibulocochlear (VIII)

Sensory nerve; hearing and balance.

Glossopharyngeal (IX)

Mixed nerve; taste (posterior 1/3); swallowing.

Vagus (X)

Mixed nerve; autonomic regulation of thorax/abdomen; wide innervation.

Spinal accessory (XI)

Motor nerve; moves sternocleidomastoid and trapezius.

Hypoglossal (XII)

Motor nerve; tongue movement.

Cervical enlargement

Spinal cord region supplying upper limbs.

Lumbar enlargement

Spinal cord region supplying lower limbs.

Conus medullaris

Conical end of the spinal cord.

Filum terminale

Fibrous extension anchoring the spinal cord within the vertebral canal.

Cauda equina

Bundle of dorsal/ventral roots at the spinal canal’s end.

31 pairs of spinal nerves

31 spinal nerves named by exit level: 8C, 12T, 5L, 5S, 1Co.

Nerve plexuses

Networks of intersecting nerves: cervical, brachial, lumbar, sacral.

Lumbar puncture (spinal tap)

Needle sampling of CSF from subarachnoid space; usually between L3-L4.

Dura mater

Outer protective meningeal layer.

Arachnoid mater

Middle meningeal layer; web-like trabeculae.

Pia mater

Innermost meningeal layer; adheres to brain/spinal cord.

Alzheimer’s disease

Neurodegenerative dementia; amyloid plaques and tau tangles; hippocampus/cortex affected.

Parkinson’s disease

Neurodegenerative movement disorder; loss of dopaminergic neurons in substantia nigra; Lewy bodies (alpha-synuclein).

Multiple sclerosis

Autoimmune demyelinating disease of CNS; fatigue, vision issues, weakness.

Epilepsy

Chronic tendency for recurrent seizures due to abnormal brain activity.

Syncope

Fainting; temporary loss of consciousness due to reduced brain perfusion.

Spinal cord trauma

Injury causing paralysis or sensory loss; may cause paraplegia/quadriplegia.

Reflex

Rapid, automatic response to a stimulus; can be inborn or learned.

Reflex arc

Neural pathway of a reflex: receptor → sensory neuron → integration center → motor neuron → effector.

Monosynaptic reflex

Single synapse between sensory and motor neurons (e.g., stretch reflex).

Polysynaptic reflex

Involves one or more interneurons; multiple synapses.

Somatic nervous system

Voluntary control; skeletal muscles; one-neuron motor pathway; all motor neurons release ACh.

Autonomic nervous system

Involuntary control; two-neuron pathway (preganglionic and postganglionic); regulates smooth/cardiac muscles and glands.

Parasympathetic divison

Rest-and-digest effects; promotes conservation of energy.

Sympathetic division

Fight-or-flight effects; prepares body for stress.

Major autonomic effects (Parasympathetic vs Sympathetic)

Parasympathetic: pupil constriction, increased digestion, slowed heart; Sympathetic: pupil dilation, reduced digestion, increased heart rate.