Download Chapters 13b and 15: General and Special Senses I. General Terms

Chapters 13b and 15: General and Special Senses
I. General Terms
A. sensation - awareness of external/internal conditions
B. perception - conscious registration of conditions
C. stimulus - change that can initiate nerve impulse
D. receptor (sense organ) - converts stimulus to impulse
E. transduction - changing stimulus signal into nerve signal
F. generator potential - electrical impulse in receptor
G. receptor potential - receptor releases neurotransmitter
H. adaptation - decreased sensitivity with repeat stimuli
a. rapidly adapting - pressure, touch, smell
b. slowly adapting - pain, position, blood chemicals
I. afterimage - sensation even after stimulus is gone
J. modality - distinct property of each sensation
II. General Classification of Receptors
A. Location
1. exteroreceptors - respond to external environment
2. enteroreceptors - respond to internal environment
3. proprioreceptors - respond to body position/motion
B. Type of Stimulus Detected
1. mechanoreceptors - any mechanical deviation
a. touch, pressure, vibration, proprioception etc.
2. thermoreceptors - changes in temperature
3. nocireceptors - pain; physical or chemical damage
4. photoreceptors - light; rods & cones of the eye
5. chemoreceptors - shapes of different molecules
a. taste, smell, chemicals of blood
C. Simplicity or Complexity of the Receptor Structure
1. simple receptors - associated with general senses
a. touch, pressure, temperature, vibration, pain
2. complex receptors - associated with SPECIAL senses
a. smell, taste, sight, hearing, equilibrium
III. Classification of General Senses
A. Cutaneous (Skin) Senses
1. tactile (touch)
a. light touch - location not perceived
b. discriminative touch - location perceived
c. Merkel's discs - discriminative touch
d. Meissner's corpuscle - discriminative touch
e. organs of Ruffini - deep, continuous touch
2. pressure
a. felt over a large area than touch, deeper
b. Pacinian corpuscle - lower layer of dermis
3. vibration - detect high and low frequency vibrations
4. thermosensation - respond to hot/cold; may be free nerve endings
5. pain (nociception)
a. acute pain - very quick, not felt in deep areas
b. chronic pain - longer lasting, gradual increase
c. somatic pain - skin, muscles, joints
i. superficial -skin
ii. deep - muscle, joint, tendon, fascia
d. visceral pain - from receptors in organs
e. referred pain - projected to skin above organ
B. Proprioceptive (kinesthetic) Sense
1. function - position of limbs/body and equilibrium
2. muscle spindles
a. intrafusal fibers - inner muscle fibers
i. type Ia sensory fiber - in center
ii. type II sensory fiber - at ends
iii. gamma motor neurons - from ventral horn
b. extrafusal fibers - outer muscle fibers
i. alpha motor neurons - form ventral horn
3. Golgi (tendon) organs
a. at junction of tendon and muscle
4. Joint Kinesthetic receptors
a. within/around synovial joints
IV. Classification of Special Senses
A. Olfaction (smell)
1. olfactory cells - bipolar neurons in epithelium
2. olfactory glands - secrete mucus to clean epithelium
3. olfactory nerve (I) - axons of olfactory cells
4. olfactory bulbs - brain region where (I) synapses
5. olfactory tract - axons from bulbs to cortex
B. Gustation (taste)
1. gustatory cells - neuron with hairlike extension
2. taste buds - location of gustatory cells
3. facial nerve (VII) - anterior 2/3 of tongue
4. glossopharyngeal nerve (IX) - posterior 1/3
5. vagus nerve (X) - throat and epiglottis
6. -> medulla -> thalamus -> cortex
C. Vision
1. Accessory Structures of the Eye
a. eyebrows
b. eyelids (palpebrae)
i. levator palpebrae superioris muscle
ii. palpebral fissure
iii. lateral commissure
iv. medial commissure
v. lacrimal caruncle (lacrimal gland) crying
c. tarsal plate - inner wall of eyelid
d. tarsal glands - secrete oil
e. conjunctiva - mucous membrane of eyelid
f. eyelashes
g. lacrimal gland - for tear secretion
i. lacrimal ducts
ii. lacrimal puncta
iii. lacrimal sac
iv. nasolacrimal duct
2. The Structure of the Eyeball
a. fibrous tunic - outer coat of the eyeball
i. sclera - posterior portion
ii. cornea - anterior portion
b. vascular tunic (uvea) - middle layer
i. choroid - posterior, pigment/vasculature
ii. ciliary body - muscle shapes lens
iii. iris - colored part, with pupil (hole)
c. nervous tunic (retina) - posterior surface
i. photoreceptors (rods & cones)
ii. bipolar cells
iii. ganglion cells
d. lens - just behind pupil and iris
3. Structure and Cells of the Retina
3. Pathway of Light to the Brain
a. photoreceptors pick up the light
b. ganglion cells converge signals -> optic nerve
c. optic nerve -> lateral geniculate of thalamus
d. lateral geniculate -> occipital cortex
4. Muscles of the Eye
D. Hearing & Equilibrium
1. external ear
a. pinna (auricle) - Ross Perot
b. helix - rim of the pinna
c. lobule - your mate's favorite part
d. external auditory canal
e. ceruminous glands - love that earwax!
f. tympanic membrane (eardrum)
2. middle ear
a. tympanic antrum - chamber to air cells
b. auditory (Eustachian) tube - to nasopharynx
c. auditory ossicles - bones of middle ear
i. malleus - attached to tympanic membrane
ii. incus - intermediate bone
iii. stapes - last bone
d. tensor tympani muscles - to malleus (protect)
e. stapedius muscle - to stapes (protect)
f. oval and round windows - to inner ear
3. inner ear (labyrinth)
a. bony labyrinth - has fluid called perilymph
i. vestibule
ii. cochlea
iii. semicircular canals
b. membranous labyrinth - has endolymph
c. vestibule - oval central portion body labyr.
i. utricle & saccule - two sacs
d. cochlea - sound organ, sounds are sensed here
e. semicircular canals - equilibrium in 3-D
4. Neural Pathway for Sound/Equilibrium Sensation
cochlea/vestibular -> vestibulocochlear (VIII) >>>>
spiral ganglion of cochlear nerve >>>>
cochelar nuclei of medulla >>>>
superior olivary nucleus of medulla >>>>
inferior colliculus of midbrain >>>>
medial geniculate nucleus of thalamus >>>>
primary auditory cortex of temporal lobe