The Nervous System: Anatomy, Divisions, Neurotransmitters, and Disorders

Comprehensive vocabulary flashcards covering the anatomy of neurons, divisions of the nervous system, brain structures, neurotransmitters, and nervous system pathologies from the lecture notes.

Nervous System

The organ system that coordinates all body activities and enables the body to respond and adapt to changes occurring both inside and outside the body.

Neuron

The basic structural unit of the nervous system (also known as a nerve cell) consisting of a cell body, dendrites, and an axon.

Cell Body (Soma)

The central region of a neuron that contains the nucleus and functions as the control center of the cell.

Dendrites

Nerve fibers that receive messages and carry impulses (action potentials) toward the cell body of a neuron.

Axon

A single nerve fiber that carries impulses (action potentials) away from the cell body to send messages to other neurons.

Myelin Sheath

A lipid covering wrapped around much of an axon that insulates and maintains the fiber while increasing the rate of impulse transmission to approximately $\sim 268\,\text{mph}$.

Axon Terminal Buttons

Specialized structures located at the ends of axon branches that transmit nerve impulses to adjacent neurons.

Synapse

The microscopic space between the axon of one neuron and the dendrites of an adjacent neuron.

Neurotransmitters

Special chemical messengers located at the terminal ends of axons that allow impulses to bridge the synapse from one neuron to another; no impulse transmission occurs without them.

Excitatory Neurotransmitters

Chemical messengers that help a neuron propagate and fire a nerve impulse.

Inhibitory Neurotransmitters

Chemical messengers that reduce the likelihood that a receiving neuron will propagate a nerve impulse.

Nerves

Combinations of many nerve fibers bundled together located outside the brain and spinal cord.

Sensory Nerves

Nerves that transmit messages from all parts of the body to the brain and spinal cord.

Motor Nerves

Nerves that transmit messages from the brain and spinal cord to muscles and glands.

Associative Nerves

Nerves that carry both sensory and motor messages within the nervous system.

Central Nervous System (CNS)

The major division of the nervous system consisting exclusively of the brain and spinal cord.

Peripheral Nervous System (PNS)

The division of the nervous system composed of all the nerves extending outside the central nervous system.

Autonomic Nervous System

A functional subdivision of the peripheral nervous system that controls involuntary body functions.

Sympathetic Nervous System

The division of the autonomic nervous system that prepares the body for 'fight or flight' by increasing heart rate, respirations, and blood pressure while decreasing digestive tract activity.

Parasympathetic Nervous System

The division of the autonomic nervous system responsible for 'rest and digest' that lowers heart rate, respirations, and blood pressure while increasing digestive activity to restore homeostasis.

Homeostasis

A balanced physiological state maintained by the coordinated, opposing actions of the sympathetic and parasympathetic nervous systems controlling involuntary functions at proper rates.

Brain

A mass of nerve tissue well protected by protective membranes (meninges) and the cranium.

Cerebrum

The largest and highest section of the brain, separated into distinct lobes; functions as the center for reasoning, thought, memory, speech, sensation, sight, smell, hearing, and voluntary body movement.

Frontal Lobe

The lobe of the cerebrum involved in memory formation, emotions, personality, decision-making, and logic.

Broca's Area

A region located in the left frontal lobe that controls facial neurons, speech production, and language comprehension.

Broca's Aphasia

A language impairment characterized by retained speech comprehension alongside a decreased motor ability to speak and formulate words.

Parietal Lobe

The cerebral lobe responsible for processing senses, integrating sensations, and managing spatial awareness and perception.

Temporal Lobe

The cerebral lobe responsible for hearing, organization and comprehension of language, and information retrieval (memory and memory formation).

Wernicke's Area

A specific cortical area located in the left temporal lobe that controls language comprehension.

Wernicke's Aphasia

A condition in which language comprehension is inhibited, leading to difficulty understanding words and producing speech that is impaired or nonsensical.

Occipital Lobe

The posterior lobe of the cerebrum dedicated to the processing, integration, and interpretation of visual stimuli.

Cerebellum

The brain structure located below the back of the cerebrum responsible for muscle coordination, balance, posture, and muscle tone.

Corpus Callosum

A broad band of nerve fibers that connects the left and right cerebral hemispheres, facilitating communication between them.

Brainstem

The stalk of neural tissue comprising the pons and medulla oblongata that connects the cerebrum to the spinal cord.

Pons

The upper part of the brainstem that conducts messages to other brain regions and coordinates reflex actions like chewing, tasting, and saliva production.

Medulla Oblongata

The lowest section of the brainstem connecting directly to the spinal cord; regulates heartbeat, respiration, swallowing, coughing, and blood pressure.

Hypothalamus

A regulatory center of the brain controlling the autonomic nervous system, temperature, appetite, sleep, water balance, blood vessel dilation/constriction, and emotions like anger, fear, pleasure, pain, and affection.

Spinal Cord

A neural structure continuing downward from the medulla oblongata to the $1^{\text{st}}$ or $2^{\text{nd}}$ lumbar vertebrae, protected by vertebrae; coordinates reflex actions and relays sensory and motor impulses.

Meninges

A set of three protective membranes covering and safeguarding the brain and spinal cord.

Dura Mater

The thick, tough outermost layer of the meninges.

Arachnoid Membrane

The delicate, web-like middle layer of the meninges.

Pia Mater

The innermost meningeal layer that closely adheres to the surface of the brain and spinal cord, containing blood vessels that nourish nerve tissue.

Ventricles

Interconnected hollow cavities within the brain that communicate with each other and the subarachnoid space.

Cerebrospinal Fluid (CSF)

A clear fluid produced and circulated within brain ventricles that acts as a shock absorber for the CNS, transports nutrients, and eliminates metabolic wastes.

Cerebral Palsy

A non-curable disturbance in voluntary muscle action caused by brain damage from lack of $\text{O}_2$ to the brain; marked by exaggerated reflexes, tense muscles, contractures, speech impairment, and mental retardation.

Cerebrovascular Accident (CVA)

Destruction of brain tissue resulting from impaired blood flow and oxygen deprivation caused by a clot (thrombus) or hemorrhage; prompt treatment within the first $3\,\text{hours}$ helps minimize brain damage.

Encephalitis

Inflammation of brain tissue caused by a virus, bacterium, or chemical agent; the viral form is frequently transmitted via mosquito bites (such as in St. Louis Encephalitis).

Epilepsy

A brain disorder marked by abnormal electrical impulses in cerebral neurons caused by trauma, tumors, toxins (such as lead or $\text{CO}$), or idiopathic causes; characterized by convulsions, loss of consciousness, and hypersalivation.

Hydrocephalus

An abnormal accumulation of cerebrospinal fluid ($\text{CSF}$) within the brain ventricles due to infection, congenital defects, or tumors; treated by surgically implanting a shunt into the abdominal cavity.

Meningitis

Inflammation of the protective meninges of the brain or spinal cord caused by bacteria, viruses, fungi, or toxins (such as lead or arsenic); presents with fever, stiff neck and back, delirium, and convulsions.

Multiple Sclerosis (MS)

A chronic, progressive, disabling condition of unknown etiology typically diagnosed between ages $20$ and $40$, characterized by the progressive degeneration of the myelin sheath in the CNS.

Neuralgia

Severe nerve pain resulting from localized inflammation, direct pressure, toxins, or secondary diseases; managed by eliminating the root cause.

Parkinson's Disease

A chronic, progressive degeneration of brain cells typically appearing in individuals over $> 50\,\text{years old}$; characterized by tremors, rigidity, shuffling gait, forward-leaning posture, and mask-like loss of facial expression.

Paralysis

Loss of voluntary motor function and sensation below the site of a brain or spinal cord injury due to neuron destruction.

Hemiplegia

Paralysis affecting only one side of the body, commonly caused by a brain tumor, localized trauma, or a cerebrovascular accident (CVA).

Paraplegia

Paralysis localized to the lower extremities or the lower half of the body resulting from spinal cord injury.

Quadriplegia

Paralysis involving both arms, both legs, and all body structures below the anatomical level of a spinal cord injury.

Shingles

An acute viral inflammation of nerve cells caused by the herpes virus (chicken pox) that erupts unilaterally along affected nerve pathways (usually thoracic) with painful fluid-filled vesicles lasting $1\text{--}4\,\text{weeks}$.

Acetylcholine

A neurotransmitter essential for triggering and maintaining skeletal muscle contraction.

Dopamine

A neurotransmitter responsible for modulating mood, facilitating positive reinforcement, and driving dependency pathways.

Glutamate

A primary neurotransmitter strongly associated with learning processes and long-term memory formation.

Epinephrine

A neurotransmitter that regulates attention and mental focus; excessive levels are linked to anxiety, insomnia, and ADHD, whereas low levels correlate with fatigue and poor focus.

Serotonin

A vital neurotransmitter that helps regulate circadian sleep cycles and mood stability.