Unit 3 feb 2

Neuron

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

Axon

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

axon terminal

The endpoint of a neuron where neurotransmitters are stored

Dendrites

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

Nucleus

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

Soma (Cell Body)

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

Myelin Sheath

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

Nodes of Ranvier

Gaps in the myelin sheath

neuroglial cells

provide physical support, insulation, and nutrients for neurons

Sodium Leak Channels

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

Sodium Gated Channels

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

Potassium Leak Channels

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

Potassium Gated Channels

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

action potential (AP)

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

Central Nervous System (CNS)

consists of the brain and spinal cord (no extensions)

Peripheral Nervous System (PNS)

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

Spinal Nerve Cord

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

simple reflex arc

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

2 neuron arc

Simplest- sensory and motor neurons only

3 neuron arc

sensory, interneurons, motor neurons

Mechanoreceptors

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

Thermoreceptors

detect respond to changes in temperature
Mainly involved in touch

Pain Receptors

Detect and respond to tissue damage
Mainly involved in touch

Chemoreceptors

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

Photoreceptors

detect and respond to light
Mainly involved in vision

cutaneous sensations

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

Skin

Sensory organ of touch
largest organ of the body

Outer ear

includes the pinna and the auditory canal

Pinna

the visible part of the outer ear

Auditory Canal (Ear Canal)

short tunnel that runs from the pinna to the eardrum

middle ear (tympanic cavity)

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

typanic membrane (eardrum)

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

auditory ossicles

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

Eustachian tube

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

inner ear

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

cochlea

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

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

vestibule of ear

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

semicircular canals

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

Gustration

sense of taste

papillae

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

gustatory epithelial cells

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

basal epithelial cells

stem cells that make new gustatory epithelial cells

Olfactory

Sense of smell

Accommodation

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

olfactory epithelium

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

Vision

dominant sense of human beings

eyes

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

Light Energy

electromagnetic waves

Eyebrows

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

eyelids and eyelashes

trigger reflexive blinking to keep eyes moist

lacrimal apparatus

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

extrinsic eye muscles

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

fibrous layer of eye

consists of sclera and cornea

Sclera

white of the eye
anchoring site for the extrinsic eye muscles

Cornea

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

vascular layer of eye

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

choroid

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

ciliary body

ring of muscle tissue around the lens

Iris

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

pupil

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

inner layer of eye

retina and optic nerve

rods and cones

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

Retina

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

Rods

retinal receptors that detect black, white, and gray

Cones

retinal receptor cells that detect fine detail and color

far-sightedness

eyeball is too short

near sightedness

eyeball is too long

Aqueous Humor

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

Vitreous Humor

the transparent jellylike tissue filling the eyeball behind the lens.

Endocrine System

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