chap 17 notes (needs to be finished)

what is a receptor?

any structure specialized to detect stimuli in the body and external environment

what is a transduction?

stimulus is converted into a neural signal that the brain can interpret

what is the passage of stimuli?

stimulus!→ sensory receptor→ sensory nuclei→ thalamus and primary cortex areas (awareness and identification)→ association cortex (interpretation and integration)

what are chemoreceptors?

chemicals, orders, taste

what are thermoreceptors?

heat, cold

what are nociceptors?

pain, tissue damage

what are photoreceptors?

light

what are mechanoreceptors?

• physical deformation

-baroreceptors?

what are general senses?

• distributed throughout the body

• free nerve endings

• encapsulated nerve endings

what are special senses?

accessory sensory receptor cells in complex structures of the head

what are exteroceptors?

*origin of stimulus

• detect stimuli external to body

what are interorecptors?

detect stimuli in viscera

*origin

what are proprioceptors?

• sense body movement and position

• skeletal muscles, tendon, joint capsules

*origin

what are the specifics of general senses?

• simple structure

• skin, skeletal muscles, internal organs, tendons, joint capsules

• touch, pressure, stretch, pain temp, chemicals, proprioception

what are the specifics of special senses?

• complex; specialized sensory organs

• head; cranial nerves

• vision, hearing, taste, smell, balance/equilibrium

what are encapsulated nerve endings?

1. free nerve endings: warm, cold + pain

2. tactile disc: light touch/pressure on skin

3. hair receptor: hair movement

what are encapsulated nerve endings?

*dendrites wrapped in glial cells or CT

• touch, pressure, stretch

• enhance receptor sensitivity or specificity

what are tactile corpuscle?

light touch + texture

what is a end bulb/krause bulb?

light touch + texture in certain mucous membranes

what is a bulbous corpuscle/Ruffini corpuscle?

heavy continuous touch/ pressure in skin + joint movements

what are lamellar corpuscle?

vibration, stretching + deep pressure of skin

what are muscle spindles + tendon organ?

stretch

what is a pseudounipolar/unipolar neuron?

location: cell body→ in posterior root ganglion or cranial nerve ganglia

what happens to the unipolar in the peripheral process?

splits into nerve endings connected to a sensory receptor (dendrites)

what happens to a unipolar neuron in a central process?

travels through posterior root and enters into the posterior horn of spinal cord

what is receptive field?

area supplied by a single neuron

• large vs. small

• two-point touch discrimination

basically:

• larger neuron in areas like the shoulder → no distinction

• smaller neurons in areas like the finger tips→ distinction

what is the somatosensory projection?

• transmission of info from a receptor/receptive field to a specific location in cerebral cortex

• brain is able to identify origin

what is the somatosensory projection pathways?

1. primary/first order neuron:

cell body in posterior root ganglion or cranial nerve sensory ganglia

2. secondary/second order neuron

cell body in posterior horn or brainstem nuclei

3. tertiary/third order neuron:

cell body in thalamus

4. primary somatosensory cortex

what is the outer ear?

conducts vibrations to tympanic membrane (eardrum)

• tympanic membrane: CT (fibrocartilage) lined w/ epithelial tissue

• guard hairs & ceruminous glands

what is the tympanic membrane?

seperates external ear & inner ear

what is the middle ear?

conducts sounds to inner ear

• tympanic membrane; CN V & CN X, high pain sensitivity

• auditory/eustachian tube: equalizes pressure

• auditory ossicles: malleus, incus, & stapes

• muscles: stapedius + tensor tympani → tympanic reflex

what is the function of the malleus?

connected to tympanic membrane

what is the function of the incus?

connection to malleus

what is the function of the stapes?

middle ear to cochlea

what is the inner ear?

vibrations are converted to nerve signals

cochlea: for hearing duct; aids in hearing discrimination

what is the vestibule?

• sense acceleration/movement

• chamber with organs for balance

what is are the semicircular ducts?

detect head rotation

what is the cochlear duct?

• organ for hearing

• inside the cochlea

• structures that convert sounds waves to nerve signals

• winds around “modiolus” spongy bone