Unit 3 feb 2

a nerve cell that is specialized to send and receive electrical impulses

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

The endpoint of a neuron where neurotransmitters are stored

a neuron's bushy, branching extensions that receive messages and conduct impulses toward the cell body.

A part of the cell containing DNA and RNA and responsible for growth and reproduction

contains the cell nucleus and much of the chemical machinery common to most cells

covers the axon of some neurons and helps speed neural impulses by providing electrical insulation

Gaps in the myelin sheath

provide physical support, insulation, and nutrients for neurons

allow a very small amount of sodium to leak into the cell

open when a local region is depolarized and have an inactivation gate- this limits the flux of sodium ions by blocking the channel shortly after depolarization opens it: when there is repolarization the inactivation gate is released back out of the pore and the channel can return to the closed state

allow a small amount of potassium to leak out of the cell

open when a local region is depolarized and have an inactivation gate- this limits the flux of potassium ions by blocking the channel shortly after depolarization opens it: when there is repolarization the inactivation gate is released back out of the pore and the channel can return to the closed state the closing of these channels returns the membrane back to its resting value and initiates a negative feedback loop

a neural impulse; a brief electrical charge that travels down an axon

consists of the brain and spinal cord (no extensions)

the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

carries nerve signals from the body to the brain and back Except for reflex arcs

contains only sensory and motor neurons Signals don't get carried to the brain

Simplest- sensory and motor neurons only

sensory, interneurons, motor neurons

detect and respond to touch, pressure, vibration, and stretch Mainly involved in touch

detect respond to changes in temperature Mainly involved in touch

Detect and respond to tissue damage Mainly involved in touch

detect and respond to chemicals or chemical changes mainly involved in tasted and smell

detect and respond to light Mainly involved in vision

Temperature, touch, pressure and pain Not equally distributed higher quantities in the finger pads the sense of touch

Sensory organ of touch largest organ of the body

includes the pinna and the auditory canal

the visible part of the outer ear

short tunnel that runs from the pinna to the eardrum

the chamber between the eardrum and cochlea containing 3 tiny bones (malleus, incus, and stapes) that concentrate the vibrations of the eardrum on the cochlea's oval window

piece of skin that's stretched tight vibrates the ossicles (bones) in the tympanic cavity

3 tiny bones of the middle ear: the malleus, incus, and stapes

A narrow tube between the middle ear and the throat that serves to equalize pressure on both sides of the eardrum

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibule

a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid stimulate the Corti

Sensory organ of hearing found within the cochlea After being stimulated sends AP through the cochlear nerve to the auditory cortex in the brain

The portion of the inner ear that senses the position of the head. Its sensory epithelium that uses hair cells to detect movement Aids in maintaining balance

three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement Aids in maintaining balance

sense of taste

Bumps on the tongue that contain taste buds, the sensory receptors for taste.

Receptor cells for taste send the AP that signal to the gustatory cortex of the brain to release digestive enzymes to break down food for energy

stem cells that make new gustatory epithelial cells

Sense of smell

When olfactory receptors contact a substance continually, they become insensitive to the smell

molecules bind to its receptors sending AP down the olfactory nerve into the ethmoid bone and eventually to the olfactory bulb in the brain From here it travels down to the olfactory cortex and gets sent to the frontal lobe to be identified and to the emotional pathway in our limbic system

dominant sense of human beings

sensory organs of vision use photoreceptors to convert light energy into AP that travel to the visual cortex in brain

electromagnetic waves

Located superior to the eye, they partially shade the eyes, and protect them from sweat.

trigger reflexive blinking to keep eyes moist

consists of the lacrimal gland and a number of ducts that secrete and drain tears

Six muscles attach to the outer surface of the eye and produce eye movements

consists of sclera and cornea

white of the eye anchoring site for the extrinsic eye muscles

The clear tissue that covers the front of the eye and allows light through

Includes the choroid, the pupil, and the intrinsic eye muscles: the ciliary body and the iris

middle, vascular layer of the eye that supplies all layers with blood and nutrients

ring of muscle tissue around the lens

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

Black in the center of the eye The opening through which light enters the eye Low light- wide open High light- nearly closed

retina and optic nerve

two types of photoreceptors in the retina that convert light energy into AP that travel through the optic nerve to the thalamus and then the visual cortex of the brain

Light sensitive inner most layer of the eye; contains rods and cones

retinal receptors that detect black, white, and gray

retinal receptor cells that detect fine detail and color

eyeball is too short

eyeball is too long

fluid in the eye, found between the cornea and the pupil

the transparent jellylike tissue filling the eyeball behind the lens.

Consists of glands that control many of the body's activities by producing hormones.