Biology 110: Nervous, Sensory, and Endocrine Systems Study Guide

Vocabulary terms and definitions spanning the nervous system, general and special senses, and the endocrine system derived from Biology 110 study guide notes.

Central Nervous System (CNS)

The division of the nervous system made up of the brain and spinal cord.

Peripheral Nervous System (PNS)

The division of the nervous system consisting of the cranial and spinal nerves.

Afferent division

The sensory division of the peripheral nervous system that carries impulses toward the central nervous system.

Efferent division

The motor division of the peripheral nervous system that responds via muscles, glands, and organs.

Neuroglia

Non-neuronal cells in nervous tissue that function to support and nourish neurons.

Dendrites

The branched extensions of a neuron that receive impulses from sensory receptors and other neurons.

Axon

The elongated portion of a neuron that carries nerve impulses away from the cell body.

Schwann cells (neurolemmocytes)

Neuroglial cells that produce sheaths of myelin around larger axons in the peripheral nervous system.

Oligodendrocytes

The neuroglial cells in the central nervous system that produce myelin.

Nodes of Ranvier

Narrow gaps in the myelin sheath along an axon.

White matter

Nervous tissue containing myelinated nerve fibers that gives it a white appearance.

Gray matter

Nervous tissue that lacks myelin insulation and appears gray.

Multipolar neurons

Neurons having many dendrites and one axon, including motor neurons and interneurons.

Bipolar neurons

Neurons characterized by having exactly one dendrite and one axon.

Unipolar neurons

Neurons that have one nerve fiber that divides into one axon and one dendrite; mostly sensory neurons.

Saltatory conduction

The rapid conduction of nerve impulses jumping from one node of Ranvier to the next along myelinated fibers.

Synapse

The junction between two communicating neurons across which nerve impulses are transmitted.

Synaptic cleft

The narrow space between the presynaptic neuron and the postsynaptic neuron.

Meninges

The protective membranes that surround the brain and spinal cord.

Dura mater

The outermost meninx composed of tough, white dense connective tissue with many blood vessels.

Arachnoid mater

The thin middle layer of the meninges that lacks blood vessels and resembles a spider web.

Pia mater

The thin innermost meninx that contains many blood vessels and nerves.

Choroid plexus

The brain vascular structure that produces cerebrospinal fluid (CSF).

Subarachnoid space

The space located between the arachnoid mater and pia mater containing cerebrospinal fluid.

Corpus callosum

A deep ridge of nerve fibers that connects the two cerebral hemispheres.

Cerebral cortex

A thin layer of gray matter lying on the outside of the cerebrum containing most of the neuron cell bodies.

Primary somatosensory area

The cortical area posterior to the central sulcus in the parietal lobes where sensory input from the skin and skeletal muscles is received.

Primary taste area

The functional area of the cerebral cortex located within the insula and parietal lobes.

Primary visual area

The cortical area located in the occipital lobe that receives information from the eyes.

Primary auditory area

The cortical area located in the temporal lobe responsible for hearing.

Association areas

Cerebral regions where neural integration occurs and memories are stored.

Broca's area

The motor speech area located in the brain.

Mechanoreceptors

Sensory receptors stimulated by changes in pressure or body movement.

Thermoreceptors

Sensory receptors stimulated by changes in external or internal temperature.

Nociceptors

Pain receptors stimulated by tissue damage or oxygen deprivation.

Chemoreceptors

Sensory receptors stimulated by changes in the chemical concentrations of substances.

Photoreceptors

Sensory receptors stimulated by light energy.

Meissner corpuscles

Fine touch receptors located in the dermal papillae of hairless skin.

Markel disks

Receptors for fine touch located in the deepest layer of the epidermis.

Root hair plexus

Receptors for fine touch located around the hair follicle.

Pacino corpuscles

Receptors for pressure located deep in the dermis.

Ruffini endings

Receptors for pressure located in the dermis and hypodermis.

Krause end bulbs

Receptors for pressure located in the superficial dermis.

Referred pain

Pain that occurs because of common nerve pathways leading from both the skin and internal organs.

Taste buds

The organs of taste located within papillae on the surface of the tongue, pharynx, and epiglottis.

Cornea

The transparent front portion of the eye's outer fibrous tunic that refracts light.

Sclera

The tough, white exterior protective tissue of the outer tunic of the eye.

Choroid coat

A highly vascular, darkly pigmented layer of the middle tunic that nourishes tissues and keeps the inside of the eye dark.

Ciliary body

A ring around the front of the eye containing ciliary muscles and suspensory ligaments that controls the shape of the lens.

Fovea centralis

The central retinal area of acute vision containing densely packed cone cells.

Optic disc

The blind spot where the optic nerve exits the eye, lacking rod and cone photoreceptors.

Accommodation

The ability of the eye lens to change its shape in order to focus at different distances.

Cataract

An eye disorder caused by clouding of the lens.

Glaucoma

An eye disorder caused by increased intraocular pressure resulting from the buildup of aqueous humor.

Tympanic membrane

The eardrum, which converts sound air waves into mechanical vibrations.

Auditory ossicles

The three tiny middle ear bones—malleus, incus, and stapes—that amplify sound waves.

Eustachian tube

The auditory tube connecting the middle ear to the throat to maintain equal air pressure across the eardrum.

Organ of Corti

The spiral organ in the cochlea resting on the basilar membrane with hair cells that bend to generate hearing impulses.

Semicircular canals

Three fluid-filled inner ear canals that detect rotational movement of the head for dynamic equilibrium.

Otoliths

Tiny calcium stones embedded in a gelatinous membrane that shift with gravity to bend hair cells during static equilibrium.

Non-steroid hormones

Water-soluble peptide hormones that combine with receptors on the target cell membrane via a first and second messenger system.

Steroid hormones

Fat-soluble hormones that diffuse through the cell membrane to combine with receptors inside the nucleus.

Oxytocin

A posterior pituitary hormone that stimulates uterine contractions during labor and milk letdown when nursing.

Calcitonin

A thyroid hormone that lowers blood calcium levels when they rise.

Aldosterone

A mineralocorticoid produced by the adrenal cortex that regulates sodium ion conservation in the kidneys.

Cortisol

A glucocorticoid stress hormone that influences glucose, protein, and fat metabolism.

Glucagon

A pancreatic hormone secreted by alpha cells that increases blood glucose by stimulating glycogen breakdown in the liver.

Insulin

A pancreatic hormone that lowers blood glucose levels by promoting the liver to synthesize glycogen.

Melatonin

A hormone secreted by the pineal gland that regulates circadian rhythms.

Atrial natriuretic hormone (ANH)

A hormone secreted by the heart that functions to increase urine volume.

Erythropoietin

A hormone secreted by the kidneys that targets red bone marrow to increase red blood cell production.

Leptin

A hormone that signals satiety to the hypothalamus.

Ghrelin

A hormone that signals hunger.