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

Comprehensive vocabulary flashcards covering the structure and function of the nervous system, neuron anatomy, brain divisions, spinal cord, meninges, neurological disorders, and neurotransmitters.

Nervous System

Coordinates all the activities of the body and enables the body to respond and adapt to changes that occur both inside and outside the body.

Neuron

The basic structural unit of the nervous system, also known as a nerve cell.

Neuron Anatomy Activity

Anatomical components of a nerve cell: 1. Terminal buttons (transmits signals to other neurons), 2. Myelin sheath (protective coating that wraps around the axons), 3. Axon (moves signals), 4. Soma (the control center of the cell), 5. Nucleus (controls the neuron), and 6. Dendrites (receivers).

Cell Body (Soma)

Part of the neuron containing a nucleus that acts as the control center of the cell.

Dendrites

Nerve fibers that act as receivers, carrying impulses (action potentials) towards the cell body.

Axon

A nerve fiber that moves signals and sends messages by carrying impulses (action potentials) away from the cell body.

Myelin Sheath

A lipid protective coating covering much of the axon that insulates and maintains the axon while increasing the rate of impulse transmission ($\sim 268\,\text{mph}$).

Terminal Buttons

Axon terminals located at the end of the axon that transmit signals to other neurons.

Synapse

The junction and space located between the axon of one neuron and the dendrites of another neuron across which impulses pass.

Neurotransmitters

Special chemicals located at the end of each axon that allow impulses to pass across the synapse from one neuron to another; no transmission takes place without them.

Excitatory Neurotransmitters

Chemicals that help a neuron to propagate a nerve impulse.

Inhibitory Neurotransmitters

Chemicals that reduce the likelihood of a neuron propagating a nerve impulse.

Nerves

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

Sensory Nerves

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

Motor Nerves

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

Associative Nerves

Nerves that carry both sensory and motor messages.

Central Nervous System (CNS)

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

Peripheral Nervous System (PNS)

The division of the nervous system consisting of the nerves.

Autonomic Nervous System

A branch of the nervous system that controls involuntary body functions.

Sympathetic Nervous System

A division of the autonomic nervous system that prepares the body to act (fight or flight) by increasing heart rate, respirations, and blood pressure, while decreasing digestive tract activity.

Parasympathetic Nervous System

A division of the autonomic nervous system that returns the body to homeostasis by decreasing heart rate and respirations, lowering blood pressure, and increasing activity in the digestive tract.

Homeostasis

A balanced state achieved by the sympathetic and parasympathetic systems working together to maintain involuntary body functions at proper rates.

Brain

A mass of nerve tissue, well protected by membranes and the cranium.

Cerebrum

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

Frontal Lobe

Cerebral lobe responsible for memory formation, emotions, personality, decision-making, and logic.

Broca's Area

An area located in the left frontal lobe that controls facial neurons, speech, and language comprehension.

Broca's Aphasia

A condition characterized by the ability to comprehend speech accompanied by a decreased motor ability to speak or form words.

Parietal Lobe

Cerebral lobe responsible for senses and integration of sensation(s), spatial awareness, and perception.

Temporal Lobe

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

Wernicke's Area

An area located in the left temporal lobe that controls language comprehension.

Wernicke's Aphasia

A condition in which language comprehension is inhibited, words and sentences are not clearly understood, and sentence formation may be inhibited or nonsensical.

Occipital Lobe

Cerebral lobe responsible for the processing, integration, and interpretation of visual stimuli.

Cerebellum

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

Corpus Callosum

A broad band of fibers that connects the two hemispheres of the brain and allows communication between them.

Pons

Part of the brainstem that conducts messages to other parts of the brain and participates in reflex actions such as chewing, tasting, and saliva production.

Medulla Oblongata

The lowest part of the brainstem that connects with the spinal cord; regulates heartbeat, respiration, swallowing, coughing, and blood pressure.

Hypothalamus

Brain region that regulates and controls the autonomic nervous system, temperature, appetite, sleep, water balance, blood vessel constriction/dilation, and emotions such as anger, fear, pleasure, pain, and affection.

Spinal Cord

Structure protected by vertebrae that continues down from the medulla oblongata to the $1^{\text{st}}$ or $2^{\text{nd}}$ lumbar vertebrae; responsible for reflex actions and for carrying sensory messages up to the brain and motor messages down to muscles and glands.

Meninges

Membranes that cover and protect the brain and spinal cord, consisting of the dura mater, arachnoid membrane, and pia mater.

Dura Mater

The thick, tough outer layer of the meninges.

Arachnoid Membrane

The delicate, weblike middle layer of the meninges.

Pia Mater

The innermost layer of the meninges, closely attached to the brain and spinal cord, which contains blood vessels that nourish nerve tissue.

Ventricles

Hollow spaces within the brain that connect with each other and with the subarachnoid space; site where cerebrospinal fluid is produced.

Cerebrospinal Fluid (CSF)

Fluid produced and circulated in the ventricles of the brain that acts as a shock absorber for the brain and spinal cord, carries nutrients, and removes metabolic wastes.

Cerebral Palsy

A disturbance in voluntary muscle action caused by brain damage from a lack of $O_2$ to the brain; characterized by exaggerated reflexes, tense muscles, contractures, speech impairment, and mental retardation (incurable).

Cerebrovascular Accident (CVA)

Destruction of brain tissue caused by a lack of $O_2$ from impaired blood flow to the brain due to a hemorrhage or clot (thrombus); immediate care during the first $3\,\text{hours}$ can help minimize brain damage.

Encephalitis

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

Epilepsy

A brain disorder associated with abnormal electrical impulses in neurons; causes include birth injury/trauma, tumors, toxins (lead or $CO$), infections, or idiopathic origins; symptoms include loss of consciousness, violent convulsions, and hypersalivation.

Hydrocephalus

Excessive accumulation of CSF in the ventricles caused by a congenital defect, infection, or tumor that builds pressure leading to brain damage; presents with an abnormally enlarged head, prominent forehead, and bulging eyes; treated with a surgical shunt.

Meningitis

Inflammation of the meninges and/or spinal cord caused by bacteria, viruses, fungi, or toxins (lead, arsenic); manifests with high fever, headache, back and neck pain/stiffness, delirium, convulsions, coma, and death.

Multiple Sclerosis (MS)

A chronic, progressive, disabling condition caused by the degeneration of the myelin sheath in the CNS; usually occurs between ages $20\text{ to }40$ of unknown cause, presenting with tremors, weakness, numbness, visual disturbances, and incontinence.

Neuralgia

Nerve pain caused by inflammation, pressure, toxins, or other diseases; treated by eliminating the underlying cause.

Parkinson's Disease

A chronic, progressive degeneration of brain cells usually occurring in individuals $> 50\,\text{years old}$; characterized by tremors, muscular rigidity, forward-leaning position, shuffling gait, drooling, loss of facial expression, and depression.

Paralysis

Loss of function and sensation below the level of injury resulting from brain or spinal cord trauma that destroys neurons; currently has no cure.

Hemiplegia

Paralysis affecting one side of the body, caused by a tumor, injury, or CVA.

Paraplegia

Paralysis of the lower extremities or lower part of the body, caused by a spinal cord injury.

Quadriplegia

Paralysis affecting the arms, legs, and body below the level of a spinal cord injury.

Shingles

Acute inflammation of nerve cells caused by the herpes virus (chickenpox virus), usually localized to the thoracic region on one side along the nerve path; produces fluid-filled vesicles, severe pain, redness, and itching lasting $1\text{ to }4\,\text{weeks}$.

Acetylcholine

A neurotransmitter that is essential for muscle contraction.

Dopamine

A neurotransmitter that modulates mood and plays a central role in positive reinforcement and dependency.

Glutamate

An excitatory neurotransmitter associated with learning and memory.

Epinephrine

A neurotransmitter that regulates attention and mental focus; elevated levels correlate with sleep problems, anxiety, and ADHD, while decreased levels correlate with fatigue and inability to focus.

Serotonin

A neurotransmitter that helps regulate sleep and mood.