Chapter 10 - Sensory Physiology

Question 1

proprioception

Answer 1

awareness of body position and movement in space

Question 2

stimulus processing that is usually conscious

Answer 2

somatic senses (touch, temperature, pain, itch, proprioception) and special senses (vision, hearing, taste, smell, equilibrium)

Question 3

stimulus processing that is usually subconscious

Answer 3

somatic stimuli (muscle length and tension, proprioception) and visceral stimuli (BP, distension of GI tract, blood glucose concentration, internal body temp, osmolarity of body fluids, lung inflation, pH of CSF, pH and O2 content of blood)

Question 4

special senses of sensory stimuli

Answer 4

vision, hearing, taste, smell, equilibrium

Question 5

somatic senses of sensory stimuli

Answer 5

touch, temperature, nociception (pain, itch), and proprioception

Question 6

stimulus is converted by a receptor into:

Answer 6

an intracellular signal (usually a change in membrane potential)

Question 7

signal transduction

Answer 7

the transmission of information from one side of a membrane to the other using membrane proteins. Able to turn physical energy into a signal that CNS can interpret. Usually voltage gated channel opening or secondary messenger to cause action potential

Question 8

if the stimulus is above threshold,

Answer 8

action potentials pass along a sensory neuron to the CNS. we become aware of some stimuli but are never conscious of others.

Question 9

signals acted on subconsciously are integrated in CNS at:

Answer 9

cerebral cortex

Question 10

simple sensory system

Answer 10

single sensory neuron w/ branched dendrites that function as receptors (pain, itch)

Question 11

complex sensory system

Answer 11

include multicellular sense organs (eye, ear, touch)

Question 12

complex sensory receptors

Answer 12

have nerve endings enclosed in connective tissue capsules that increase surface area that sensations can be received from

Question 13

chemoreceptors

Answer 13

respond to chemical ligands that bind to the receptor. examples: oxygen, pH, various organic molecules such as glucose, taste, smell

Question 14

mechanoreceptors

Answer 14

respond to various forms of mechanical energy, including pressure, vibration, gravity, acceleration, and sound/hearing

Question 15

photoreceptors

Answer 15

respond to photons of light

Question 16

thermoreceptors

Answer 16

respond to temperature; free nerve endings, terminate in subcutaneous layers

Question 17

adequate stimulus

Answer 17

a particular form of energy to which a receptor is most responsive

Question 18

receptor potential

Answer 18

the change in sensory receptor membrane potential

Question 19

graded potential

Answer 19

variable strength signal that travels over short distances and loses strength as it travels through the cell

Question 20

receptive field

Answer 20

the region within which a sensory neuron can sense a stimulus. multiple sensory neurons may converge on one secondary neuron and create a single large receptive field. fields can overlap w/ neighboring fields

Question 21

convergence

Answer 21

multiple presynaptic neurons providing input to a smaller number of postsynaptic neurons; sensory neurons of neighboring receptive fields may exhibit convergence

Question 22

proust phenomenon

Answer 22

the ability of odors to spontaneously cue autobiographical memories which are highly vivid, affectively toned and very old

Question 23

perceptual threshold

Answer 23

level of stimulus intensity necessary for you to be aware of a particular sensation. brain can filter many stimuli bombarding sensory receptors (“tune out”)

Question 24

habituation

Answer 24

decreased perception of a stimulus via inhibitory modulation

Question 25

inhibitory modulation

Answer 25

diminishes a suprathreshold stimulus until it is below the perceptual threshold. occurs in habituation

Question 26

4 properties of a stimulus

Answer 26

1. nature/modality, 2. location, 3. intensity, 4. duration

Question 27

modality/nature of a stimulus

Answer 27

indicated by which sensory neurons are activated and where the neurons terminate in the brain

Question 28

labeled line coding

Answer 28

the association of a receptor with a specific sensation. ex. cold perceived as cold

Question 29

location of a stimulus

Answer 29

coded according to which receptive fields are activated (auditory info is an exception - depends on the timing of receptor activation in each ear)

Question 30

lateral inhibition

Answer 30

increases contrast between activated receptive fields and inactive neighbors to determine location of a stimulus

Question 31

population coding

Answer 31

multiple receptors functioning together to calculate location and timing of a stimulus

Question 32

intensity of a stimulus

Answer 32

coded by number of receptors activated and frequency of action potentials. as a stimulus increases in intensity, additional receptors are activated. the CNS then translates the number of active receptors into a measure of stimulus intensity

Question 33

duration of a stimulus

Answer 33

coded by duration of action potentials. some receptors can adapt, or cease to respond

Question 34

tonic receptors

Answer 34

slowly adapt to sustained stimulus. the sensory neuron fires action potentials as long as the receptor potential is above threshold. ex. pressure, irritant, tactile, proprioceptors

Question 35

phasic receptors

Answer 35

rapidly adapt to sustained stimulus; cease firing if the stimulus remains constant. allows body to ignore info that has been evaluated and found not to threaten homeostasis; lets us focus on what is new, different, or essential. ex. smell

Question 36

somatosensory pathway

Answer 36

1. pain, temp, and coarse touch cross the midline in the spinal cord. 2. fine touch, vibration, and proprioception pathways cross the midline in the medulla. 3. sensory pathways synapse in the thalamus. 4. sensations are perceived in the primary somatic sensory cortex.

Question 37

nociceptors

Answer 37

respond to strong noxious stimulus that may damage tissue. free nerve endings. modulated by local chemicals. has reflexive protective response.

Question 38

nociceptors: itch

Answer 38

histamine activates C fibers, causing itch

Question 39

nociceptors” pain

Answer 39

subjective perception. fast (sharp and localized) or slow (dull, more diffuse)

Question 40

fast pain

Answer 40

sharp, localized. transmitted rapidly by small, myelinated fibers

Question 41

slow pain

Answer 41

dull, diffuse. carried by small, unmyelinated fibers