Unit 4 Senses Combined Terms

Peripheral nervous system

the sensory and motor neurons that connect the CNS to the rest of the body

Stimulus

change that is detectable by the body

Response

a reaction to a stimulus

Sensory Receptor

neuron that reacts to a specific stimulus by sending impulses to other neurons and eventually to the central nervous system

Photoreceptors

respond to light

Mechanoreceptors

respond to touch, pressure, vibration, and stretch

Thermoreceptors

detect changes in temperature

osmoreceptors

detect the osmotic pressure of body fluids

chemoreceptors

respond to chemicals

Nocireceptors

pain receptors, sense tissue damage or intense stimulation of any receptor

special senses

vision, hearing, taste, smell, equilibrium

general senses

Somatic and visceral- temperature, pain, touch, pressure, vibration, proprioception

somatic senses

touch, temperature, pain, proprioception

visceral senses

information about conditions within internal organs

perception

The act of becoming aware through the senses

adaptation

decreased receptor response during prolonged stimulation

free nerve endings

pain and temperature, itch

encapsulated nerve endings

dendrites enclosed in connective tissue capsule for pressure, vibration, and some touch sensations

separate specialized cells

hair cells in inner ear, photoreceptors in retina of eye

touch receptors (examples)

meissner corpuscles, hair root plexus, merkel disc or tactile discs, ruffini corpuscles

pressure receptors (examples)

Pacinian corpuscles

Vibration receptors (receptors)

Meissner and Pacinian

Gustation

sense of taste

5 primary tastes

sweet, salty, bitter, sour, umami

Location of taste buds (larger organs)

tongue, pharynx and epiglottis

Papillae

Structures on the tongue that contain taste buds

Vallate papillae

Posterior, arranged in the form of a V

Fungiform papilla

located allover tongue, rounded

filiform papillae

Only touch receptors

gustatory receptor cells

sensory cells in the taste bud that transduce the chemical stimuli of gustation

Gustatory hair

Microvilli, project through taste pore

Basal cells

stem cells that replace taste cells every 7 to 10 days

Saliva

digestive juice produced by salivary glands, dissolved tastant

Sequence of stimulation of taste receptors

Tastant dissolves in saliva →

Enters taste pore → contacts gustatory hair→

Electrical signal produced →

Causes gustatory cell to release neurotransmitter

That activates dendrites of first-order neurons

Gustatory pathway

Cranial nerves transmit impulses

Facial (CN VII) from anterior of tongue

Glossopharyngeal (CN IX) from posterior

Vagus (CN X) from pharynx, epiglottis

To medulla oblongata

→ Thalamus → primary gustatory area of cerebral cortex

→Limbic system or hypothalamus

Cranial Nerves involved in taste

facial, glossopharyngeal, vagus

Limbic system

neural system located below the cerebral hemispheres; associated with emotions and drives

Olfaction

sense of smell

Parts of the brain involved in olfaction

temporal lobe of the cerebral cortex, hypothalamus, limbic system

Olfactory receptors

nerve endings that act as the receptors for the sense of smell

Supporting cells

cells that insulate, support and protect neurons

Basal Cells

stem cells that produce new neurons (rare)

nasal mucosa

the lining of the nose, contains olfactory receptors

Olfactory bulb

a brain structure located above the nasal cavity beneath the frontal lobes

In order to be smell substances must be

Volatile

Water soluble

Lipid soluble

Volatile

able to evaporate easily

water soluble

able to be dissolved in water

lipid soluble

able to be dissolved in fats

odorant molecules

volatile chemicals that bind to receptor proteins in olfactory neurons to stimulate the sense of smell

Pathway of smell

Olfactory cells convey nerve impulses to the olfactory nerves, olfactory bulbs, olfactory tracts, cerebral cortex, limbic system, and the hypothalamus

Olfactory hairs

cilia that extend from the olfactory receptor cells into the nasal cavity

chemoreceptors

respond to chemicals

auricle (pinna)

outer ear

External auditory canal (meatus)

channel that leads from the pinna to the eardrum

tympanic membrane

The eardrum. separates the outer ear from the middle ear and vibrates in response to sound waves

Semicircular canals

three fluid-filled canals in the inner ear responsible for our sense of balance

Ossicles

malleus, incus, stapes; three tiny bones in the middle ear

malleus

hammer; first of the three auditory ossicles of the middle ear

incus

anvil; middle of the three auditory ossicles of the middle ear

Stapes

stirrup; last of the three auditory ossicles of the middle ear (Smallest bone in the body)

Cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

Vestibular cochlear nerve

transmits signals from the cochlea to the brain

Tympanic cavity

opening of middle ear

Round window

The membrane that relieves pressure from the vibrating waves in the cochlear fluid.

conjuctiva

Thin outer lining of the eye and eyelid

Extrinsic Eye Muscles

move the eyeball

Lacrimal Glands

glands that secrete tears, drain into nasal cavity

Outer Tunic of the Eye

cornea, sclera, optic nerve

Cornea

the transparent layer forming the front of the eye, focuses the light

sclera

white part of the eye

optic nerve

the nerve that carries neural impulses from the eye to the brain

Middle Tunic of eye

choroid, ciliary body, iris, and lens, pupil, aqueous humor

Choroid

middle, vascular (blood vessels) layer of the eye, between the retina and the sclera

Ciliary body

Composed of ciliary muscle and ciliary processes,

Lens

Focuses light onto retina

iris

Colored part of the eye

pupil

The opening through which light enters the eye

aqueous humor

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

inner tunic

retina, fovea centralis, optic disc, vitreous humor

retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

fovea centralis

area consisting of a small depression in the retina containing cones and where vision is most acute

optic disc

Blind Spot- Region at the back of the eye where the optic nerve meets the retina

vitreous humor

the transparent jellylike tissue filling the eyeball behind the lens.

Describe the different types of receptors.

-Thermoreceptors :Respond to heat energy

-Chemoreceptors: Respond to chemical energy

-Photoreceptors: Respond to light energy (i.e., rods and cones)

-Mechanoreceptors: Respond to mechanical energy (e.g., blood pressure)

Distinguish between the Meissner's corpuscles and the Pacinian corpuscles.

Describe the acute pain, chronic pain, viscerial pain and referred pain.

-acute pain: short lived

warning of injury

presents symptoms at the tissue level

resolves when healed

body emits a reflex response through the spinal cord

-Chronic Pain: pain lasting for more than 6 months of expected healing time

symptoms may be psychological and can interfere with daily activities

concern when treating: narcotic dependence

-Referred Pain: Pain is remote from site of injury

What is the difference between a somatic sense and special sense?

Somatic Senses: Receptors associated with the skin, muscles, joints, and viscera make up the somatic senses.

Special Senses: These include the senses of smell, taste, hearing, static equilibrium, dynamic equilibrium, and sight.

Define and give an example of sensory adaption.

The ability of the nervous system to become less responsive to a maintained stimulus

Ex: Getting used to the temperature of the ocean

What are olfactory receptors and where are they located?

Smell Receptors, in the Mucosa

List the four different types of taste sensations. What is umami?

Sweet, sour, salty, bitter, umami (Savory)

Describe the path sound waves take within the ear and are eventually processed by the brain.

Steps of Hearing:

1.Sound waves enter external auditory meatus eardrum vibrates

2.Auditory ossicles (malleus, incus, stapes) amplify vibrations

3.stapes it oval window and transmits vibrations to cochlea

4.coati contain receptor cells (hair cells) Thant deform from vibrations

5.impulses sent to the vestibule cochlear nerve

Compare static equilibrium; what part of the ear maintains your equilibrium?

-Static equilibrium: Sense the position of the head, maintain stability and posture

-Dynamic equilibrium (semicircle canals): Balance the head during sudden movement

What is the difference between rods and cones?

rods detect light; cones detect color

Describe how we see images and the part of the brain that interprets those images.

-Light refraction: The bending of light around an object images viewed by the eye are upside-down, our brains interpret in properly

Know what the blind spot is, where it's located and why it exists.

On the back of our eye, the retina is the stuff that detects the light. All the information that the retina picks up is sent to the brain through the optic nerve. The only problem is that the optic nerve needs a way to get out of the eye. The place where it leaves is where we have our blind spot.

Define refraction and discuss how it affects your vision. What is the fovea centralis?

Refraction is when light bends around object; we see everything upside down.

-Fovea Centralis: region of sharpest vision.

What is myopia, hyperopia and astigmatism? What is a cataract?

-Myopia (Nearsightedness): Eyes that're too long. Can see up close, but not far away.

-Hyperopia (far-sighted): Eyes are too short. Can see far away, but not up close.

-Cataracts: Clouding of the lens that leads

What are the muscles that move the eye called?

-superior rectus

-trochlea

-superior oblique

-medial rectus

-inferior rectus

-inferior oblique

-lateral rectus

Label the parts of the eye on a diagram and know the functions.

Eye Diagram

auricle

A