Anatomy & Physiology: Neurons, Eye, Ear, Smell and Taste

Dendrites

Receives signals from other cells

Soma

Organizes and keep cells function

Cell membrane

Protects the cell

Axon hillock

generates impulse in the neuron

Node of Ranvier

Space between myelin sheath that allows for diffusion of ions

Schwann cells

Produce myelin sheaths in the PNS

Nucleus

Controls the entire neuron

Axon

Transfers signals to other cells and organs

Myelin sheath

Increases the speed of the signal

Axon terminal

Forms junctions with other cells

How nerve impulses travel through neurons

A neuron receives a stimulus, creating an action potential that travels down the axon. Schwann cells (PNS) or oligodendrocytes (CNS) produce myelin which wraps around the axon and insulates it which makes it travel faster and reaches the node of ranvier. The electrical impulse jump from 1 node to the next through salfactory conduction. The signal reaches the axon terminals and passes the message to another cell.

Cornea

Clear front covering of the eye

Sclera

white part of the eye

Iris

Colored part of the eye that controls pupil size

Pupil

Opening in the center of the iris that lets light enter the eye

lens

focuses light onto the retina

optic nerve

carries visual info from the retina to the brain

retina

carries visual info from the retina to the brain

optic disc

where optic nerve exits the eyes

vitreous humor

clear, jelly-like substance that fills the back of the eye and helps maintain its shape

Tapetum lucidum

Reflective layer that helps animals see better in low light

Pathway of light through the eye

Light enters the cornea and then passes through the pupil. The iris controls how much light enters and the lens focuses the light. Light travels through the vitreous humor and reaches the retina. The retina converts light into nerve signals and the optic nerve carries signals to the brain.

Auricle

Outer ear that collects sound waves

Helix

Helps funnel sound into the ears

Acoustic meatus

Ear canal that carries sound waves towards the ear drum

Tympanic membrane

eardrum that vibrates when soundwaves hit it

Malleus

Receives vibrations from the eardrum

Incus

Transfers vibrations to the inner ear

Stapes

Transfers vibrations to the inner ear

Eustachian tube

Equalizes pressure on both sides of the ear drum

Cochlea

Converts sound vibrations into electrical nerve signals for hearing

Semicircular canals

Detects head rotation and help maintain balance

Vestibulocochlear nerve

Carries hearing and balance information from the inner ear to the brain

Pathway of sound

Sound waves enter the auricle and travel through the acoustic meatus. It heats the tympanic membrane causing vibration that is received by the malleus, transferred the incus, and then to the stapes to be sent to the cochlea in the inner ear. The cochlea converts the waves to nerve signals that are carried to the brain by the vestibulocochlear nerve.

Nasal cavity

space inside the nose where air and odor molecules enter

superior nasal concha

Curved bone that directs air to the olfactory region

Superior portion of perpendicular plate

Supports upper nasal region

cribriform plate

allows olfactory fibers to pass through

Foramina

openings in cribriform plate that allows olfactory nerve fibers to travel through

Olfactory bulb

Receives and processes smell information from olfactory receptors

Tongue

Muscular organ containing taste receptors

Papillae

BUmps on tongue that contain taste buds

Taste buds

Contains sensory receptors cells that detect chemicals in food and drink

Pharynx

Throat region that moves food from the mouth towards the esophagus

Epiglottis

Covers airway during swallowing to prevent food from entering the trachea