Chapter 7 - Sensory Physiology

Question 1

Sensory receptor classes

Answer 1

Thermoreceptors 
Nocioreceptors 
mechanoreceptors
Photoreceptors
Chemoreceptors
Proprioreceptors
Special sense receptors

Question 2

Thermoreceptors

Answer 2

Temperature - cool and warm

Question 3

Nocioreceptors

Answer 3

Respond to pain stimuli and tissue damage due to heat

Question 4

Mechanoreceptors

Answer 4

Pressure and stretch

Question 5

Photoreceptors

Answer 5

Light - cons and rods

Question 6

Chemoreceptors

Answer 6

Smell and taste

Changes in pH and O2

Question 7

Proprioreceptors

Answer 7

Changes in body position or muscle contraction

Question 8

Special sense receptors

Answer 8

Hearing and equilibrium

Question 9

Coding

Answer 9

Convert stimulus energy into signal that carries the sensory information to the CNS

Question 10

Sensory unit

Answer 10

Single afferent neuron with all of its receptor endings

Less receptor endings = less tactile tough

Question 11

Information needed to code a response

Answer 11

Stimulus type
Stimulus intensity
Stimulus location
Stimulus duration

Question 12

Recruitment

Answer 12

Activation of one or more receptors

Stronger stimulus recruits more receptors

Question 13

Lateral inhibition

Answer 13

Sharpens the contrast of neighboring neurons

Helps to accurately locate stimulation source / location

Question 14

Somatosensory cortex

Answer 14

Parietal lobe

Receives receptors from the skin muscles and tendons

Question 15

Visual cortex

Answer 15

Occipital lobe

Receives eye receptors

Question 16

Auditory cortex

Answer 16

Temporal lobe

Receives hearing receptors

Question 17

Olfactory cortex

Answer 17

Receives sensations for smell

Question 18

Taste cortex

Answer 18

Parietal lobe

Receives receptors for taste

Question 19

Cold sensing receptors

Answer 19

0-35 degrees C

Cation channels release Na ions that depolarize afferent neurons in response to cold

Question 20

Hot sensing receptors

Answer 20

35-50 degrees C

Cation channels release Na ions that depolarize neurons in response to warn temps

Question 21

Pain stimulus pathway

Answer 21

Pain stimulus -> afferent neuron -> substance P is released in CNA -> thalamus -> somatosensory cortex -> pain felt

Positive feedback

Question 22

Analgesic system

Answer 22

Suppression of pain

Axo axonic synapses releases an opiate NT which binds to pain axon terminal and blocks the release of substance P

Question 23

Exogenous morphine

Answer 23

Produced by pituitary gland and will act on the axon terminal to prevent release of substance P

Question 24

Myopia

Answer 24

Nearsighted

Eye too long

Question 25

Hyperopia

Answer 25

Farsighted | Eye too short

Question 26

Rods

Answer 26

Black and white vision

Question 27

Cones

Answer 27

Color vision

Question 28

Unique characteristic of vision sensory cell

Answer 28

Rest (dark) cell is depolarized | Stimulus (light) cell is hyperpolarized

Question 29

Absence of light pathway

Answer 29

Guanylyl cyclase converts GTP into cGMP -> cGMP opens Na/Ca ion channels -> influx of Na and Ca causes depolarization

Question 30

Presence of light

Answer 30

Light reaches photopigment opsin -> travels through transducer which activates phosphodiesterase -> rapidly degrades cGMP -> Na and Ca ion channels close -> hyperpolarization

Question 31

Neural pathway vision

Answer 31

AP created by photoreceptor -> leave the eye via the optic nerve -> medial fibers cross at the optic chasm -> pass through lateral geniculate nucleus -> fibers travel to visual cortex

Question 32

Hearing pathway

Answer 32

Vibrations enter ear -> transmitted to the tympanic membrane -> mvmt of membrane caused mvmt of ossicles -> stapes moves against oval window -> ripples in cochlear fluid -> basal membranes moves in cochlea -> round window membrane moves -> tectorial membranes shift by moving direction of hair cells -> causes depolarization -> NT glutamate released -> AP to vestibulocochlear nerve

Question 33

Taste: salty

Answer 33

Triggered by Na+ ion | Depolarization inside gustatory cell -> opens Ca+ channels -> NT released

Question 34

Taste: sour

Answer 34

Triggered by H+ ions | Depolarization in gustatory cell -> Ca+ channel opens -> NT released

Question 35

Taste: sweet/savory

Answer 35

Gustaducin (g protein) activates a 2nd messenger -> depolarization of gustatory cell -> K+ ion channels close -> depolarization. -> NT released

Question 36

Taste: bitter

Answer 36

Gustaducin (g protein) activates 2nd messenger -> Ca released from endoplasmic reticulum -> Ca+ allows for NT release

Question 37

Smell pathway

Answer 37

Odorant binds to odorant receptor -> G proteins are activated -> ATP converts AMP in CAMP -> cAMP acts as a 2nd msgr to open Na and Ca ion channels -> depolarization occurs