Nervous System Lecture Review

Vocabulary flashcards covering neurons, brain structures, spinal cord components, neurotransmitters, and nervous system diseases based on lecture notes.

Sensory (afferent) neurons

Neurons that carry impulses from receptors to the Central Nervous System (CNS).

Motor (efferent) neurons

Neurons that carry impulses from the CNS to effectors like muscles and glands.

Interneurons

Neurons located only within the CNS that conduct impulses between sensory (afferent) and motor (efferent) neurons.

Reflex arc

A pathway of impulse conduction to and from the CNS consisting of a receptor, sensory neuron, CNS (interneuron), motor neuron, and effector organ.

Cranial nerves

12 pairs of nerves attached to the underside of the brain that conduct impulses between the brain and structures of the head, neck, and chest.

Spinal nerves

31 pairs of nerves originating in the spinal cord that connect the medulla with peripheral structures like the skin and skeletal muscles.

Dermatome

A cutaneous segment or section of skin that is innervated by a single spinal nerve.

Myotome

A muscle or group of skeletal muscles innervated by one or more spinal nerves.

Alzheimer's disease

A type of dementia involving progressive degeneration of the brain, leading to rapid memory loss, hallucinations, and language disorders.

Parkinson's disease

A neurodegenerative disorder characterized by abnormally low levels of dopamine in the basal ganglia, causing tremors, stiffness, and difficulty walking.

Multiple sclerosis (MS)

An autoimmune disease where the immune system attacks the protective myelin sheath of nerve fibers, causing communication problems and deterioration.

Meningitis

Inflammation of the meninges (brain and spinal cord membranes) typically caused by a viral, bacterial, or fungal infection.

Myasthenia gravis

An autoimmune disease characterized by muscle weakness due to antibody attacks on neuromuscular junction receptors, preventing acetylcholine messages.

White matter

Tissues in the CNS made up of myelinated axons and dendrites; it covers the gray matter in the medulla and forms inner parts of the brain.

Gray matter

Unmyelinated nervous tissue made of cell bodies, motor neurons, and interneurons; it forms the external cerebral cortex and an H-shape in the center of the spinal cord.

Meninges

The inner protective membranes of the CNS consisting of three layers: dura mater (outer), arachnoid mater (middle), and pia mater (inner).

Cerebrospinal fluid (CSF)

A clear, colorless fluid that flows through the ventricles and subarachnoid space to cushion the brain and spinal cord and maintain pH balance.

Neuron

The basic unit of the nervous system characterized by excitability and conductivity.

Dendrites

Branching projections of a neuron that carry signals toward the cell body.

Axon

A single elongated projection from a neuron that transmits impulses away from the cell body.

Schwann cells

Peripheral nervous system cells that produce the myelin sheath around neuronal axons.

Oligodendrocyte

A type of neuroglia in the CNS that functions to produce myelin.

Astrocytes

Neuroglia that help shape the developing brain and form the blood-brain barrier in adulthood.

Nodes of Ranvier

Periodic gaps in the myelin sheath that facilitate saltatory (rapid) conduction of nerve impulses.

Neuroglia

Specialized connective tissue cells that support, protect, and hold neurons together but do not transmit impulses themselves.

Synapse

The communication point between neurons where neurotransmitters are released across a small space called the synaptic cleft.

Neuromuscular junction

The specific contact point between a nerve ending and muscle fibers.

Acetylcholine

A neurotransmitter that excites skeletal muscle contraction, slows heart rate (PANS), and accelerates digestion.

Histamine

An inflammatory and stimulating chemical released by mast cells during allergic reactions, injury, or massage that causes vasodilation.

Dopamine

A neurotransmitter involved in motor control, focus, and pleasure; deficiencies are linked to Parkinson's disease.

Serotonin

A CNS inhibitor that improves mood, induces calm, regulates the sleep/wake cycle, and reduces irritability.

Adrenaline (epinephrine)

A sympathetic hormone secreted by the adrenal gland during stressful situations; massage reduces its levels.

Cortisol

A sympathetic stress hormone that causes immune suppression; massage reduces its levels in the body.

Polarization

The resting state of a neuron where there are more $Na^+$ ions outside and more $K^+$ ions inside, creating a positive charge outside.

Depolarization

The first part of a nerve impulse where $Na^+$ ions rush into the cell, making the inside charge positive.

Repolarization

The phase where $K^+$ ions move out of the cell to restore the positive charge to the outside.

Cerebrum

The largest part of the brain responsible for sensory input, memory, thought, and motor output.

Corpus callosum

The structure that connects the two hemispheres of the cerebrum.

Cerebellum

The part of the brain responsible for balance, posture, coordination, and involuntary movements.

Brainstem

Consists of the midbrain, pons, and medulla oblongata; it regulates vital reflexes like heart rate and breathing.

Thalamus

The sensory relay station of the diencephalon for all senses except smell.

Hypothalamus

The brain's homeostasis regulator that controls the Autonomic Nervous System (ANS) and the mind-body link.

Limbic system

The brain area involved in emotions, memory, and the release of endorphins.

Somatic Nervous System (SNS)

A subdivision of the PNS that governs voluntary control of skeletal muscles, skin, and joints.

Autonomic Nervous System (ANS)

A subdivision of the PNS that governs involuntary actions of smooth muscle, cardiac muscle, and glands.

Sympathetic Nervous System (SANS)

The 'fight or flight' division of the ANS, also known as the thoracolumbar division.

Parasympathetic Nervous System (PANS)

The 'rest and digest' division of the ANS, also known as the craniosacral division.

Hilton's law

The principle that the nerve supplying a muscle also innervates the joint that muscle acts upon and the overlying skin.

Ventral root (anterior)

The bundle of nerve fibers exiting the spinal cord that contains mostly motor (efferent) fibers.

Dorsal root (posterior)

The bundle of nerve fibers entering the spinal cord that contains mostly sensory (afferent) fibers.