Nervous System and Special Senses Review

Comprehensive vocabulary flashcards covering nervous system organization, neuron structure, action potential physiology, sensory organs (eye and ear), cerebral lobes, brain anatomy, and tissue organization.

Central nervous system (CNS)

Nervous system subdivision composed of the brain and spinal cord that interprets incoming information and issues orders.

Peripheral nervous system (PNS)

Nervous system subdivision composed of cranial nerves, spinal nerves, and ganglia outside the brain and spinal cord; serves as communication lines linking all parts of the body to the CNS.

Somatic nervous system

Subdivision of the PNS that controls voluntary activities, such as the activities of skeletal muscles.

Autonomic nervous system

Subdivision of the PNS that regulates the activity of smooth muscle, heart, and glands; also called the involuntary nervous system, it can alter heart rate, respiration rate, blood pressure, and salivation.

Axon

Neuron process that generally conducts nerve impulses away from the cell body.

Axon terminal

Structure at the end of an axon that releases neurotransmitters.

Dendrite

Neuron process that receives incoming signals and conducts electrical currents toward the cell body.

Myelin sheath

Insulating layer around nerve fibers that increases the speed of impulse transmission.

Cell body

The metabolic center of the neuron containing the nucleus.

Schwann cells

Specialized supporting cells that myelinate fibers of PNS neurons.

Synapse

The junction or point of close contact between two neurons across which chemical signals are transmitted.

Interneuron

Neuron found within the CNS that serves as part of the conduction pathway between sensory and motor neurons, processing and transmitting signals.

Nodes of Ranvier

Gaps occurring at regular intervals in a myelin sheath along an axon.

Efferent (motor) neuron

Neuron in the PNS that conducts impulses away from the CNS to effector organs like muscles and glands to produce responses.

Afferent (sensory) neuron

Neuron in the PNS that detects stimuli and conducts impulses toward the CNS from the body periphery.

Neurotransmitter

Chemical signals released by neurons that diffuse across a synapse to stimulate other neurons, muscles, or glands.

Action potential

An all-or-none, self-propagating electrical impulse involving a brief reversal in membrane potential caused by positively charged ions diffusing into the neuron; it does not decay with distance.

Retina

Sensory tunic layer of the eye containing photoreceptor cells known as rods and cones.

Lens

Clear, adjustable disk that focuses light onto the retina, provides fine focus, and helps bend incoming light.

Cornea

Most anterior, transparent part of the sclera referred to as the 'window on the world'; helps bend light entering the eye.

Sclera

The opaque 'white' protective outer layer of the eye made mostly of collagen and some elastic fiber.

Pupil

The central opening in the iris through which light enters the interior of the eye.

Optic disk

The site where the optic nerve exits the eyeball; lacks photoreceptors and constitutes the blind spot.

Choroid layer

Vascular layer of the eye that absorbs light once it has passed through the retina.

Fovea

Specific region of the retina that contains the highest concentration of cones and provides the sharpest visual acuity.

Iris

The pigmented, diaphragm-like muscular structure of the eye that regulates the amount of light entering through the pupil.

Auditory nerve

Cranial nerve that carries auditory sensory impulses from the cochlea to the brain.

Ear drum (tympanic membrane)

Membrane that vibrates as sound waves hit it, transferring sound wave vibrations into the ossicles.

Hammer (malleus)

One of the three small auditory ossicles in the middle ear that conducts vibrations to the inner ear.

Eustachian tube

Auditory tube that connects the middle ear to the throat to equalize air pressure on both sides of the eardrum.

Cochlea

Snail-shaped structure of the inner ear containing hair cells that convert wave energy into electrical nerve impulses.

Outer ear

External portion of the ear that funnels sound from the environment into the auditory canal.

Frontal lobe

Cerebral lobe that controls reasoning, judgment, emotions, and some voluntary body movements.

Occipital lobe

Posterior lobe of the cerebrum where the sense of vision is located and processed.

Temporal lobe

Lateral lobe of the cerebrum where the sense of hearing is interpreted.

Parietal lobe

Cerebral lobe that interprets somatic sensory input such as pain, pressure, touch, hot, and cold.

Brainstem

Region of the brain consisting of the midbrain, pons, and medulla oblongata.

Gray matter

Neural tissue containing neuron cell bodies that processes information; found in the outer cortex of the cerebrum and the inner region of the spinal cord.

White matter

Neural tissue containing mostly myelinated axons that carries signals across the nervous system; located in the inner region of the cerebrum and the outer region of the spinal cord.

Cerebellum

Brain structure responsible for controlling balance and muscular coordination.

Medulla oblongata

Inferior part of the brainstem that controls vital autonomic functions, including breathing and heart rate.

Thalamus

Brain structure that acts as a relay station for incoming sensory information.

Hypothalamus

Subcortical brain structure that regulates body temperature, hunger, and thirst.

Corpus callosum

Large band of neural fibers that connects the left and right cerebral hemispheres, facilitating communication between them.

Pons

Brainstem structure that plays a critical role in controlling breathing and sleeping.

Cerebrum

Largest part of the brain, associated with higher mental functions including thinking, memory, and conscious sensory processing.

Pituitary gland

Endocrine gland connected to the base of the brain that secretes regulatory hormones.

Meningitis

An inflammation of the protective meninges covering the brain and spinal cord.