Sensation And The Chemical Senses

Question 1

Sensory receptor overview

Answer 1

Stimulus->transduction(graded potential)-> action potential->Propagation (via Labled line)-> sensation->perception.

Question 2

Sensory cell types

Answer 2

Free nerve ending
Receptor cell-> Nerotransmitter-> neuron
Transduce different stimuli

Question 3

Receptor potential

Answer 3

Graded depolarization or hyperpolarization by stimulus may change rate of action potentials

Question 4

Receptor properties: modality

Answer 4

Labeled line:
Neural pathway
Sensory receptor-> cerebral cortex
Depends on the brain region stimulated

Question 5

Receptor properties: location

Answer 5

Receptive field
Sensory projection
Location perceived based on brain region
Two point discrimination
Based on relative number of reception fields in skin area. Moorefield equal greater ability to localize stimulus

Question 6

Receptor properties: intensity, how strong

Answer 6

1. Higher rate of action potentials
2. Multiple neurons
3. Various sensitivity

Question 7

Receptor properties: duration

Answer 7

Sensory adaptation
Physic (fast-adapting) receptors
Provide information on onset and or intensity of stimulation, followed by adaptation
Examples: Thermo receptors, tactile receptors, taste, and smell
Tonic (slow adapting) receptors
Little or no adaptation
Examples: pain, muscle spindles, joint proprioceptors

Question 8

Receptor types

Answer 8

Modality
Stimulus origin
Receptor distribution

Question 9

Receptor types: modality

Answer 9

Thermoreceptors
Photoreceptors
Nociceptor
Chemoreceptors
Mechanoreceptors
Osmoreceptors

Question 10

Stimulus origin

Answer 10

Exteroceptors
Interoceptors
Proprioceptors

Question 11

Receptor distribution

Answer 11

General (somatosensory) senses

Special senses

Question 12

Receptor types

Answer 12

Free nerve endings (general)
Root hair plexuses (light touch)
Tactile(merkels’s) discs ( light touch)
Tactile (meissner’s) corpuscles (light touch)
Lammellated(pacinian) corpuscles(deep pressure)
Bulbous (ruffini) corpuscles (skin distortion)

Question 13

Somatosensory pathways: first order neuron

Answer 13

Sensory location-> spinal cord (gray horns)

Question 14

SomatoSensory pathways: second order neuron

Answer 14

Gray horn-> thalamus (after crossing over)

Question 15

Somatosensory pathways: third order neuron

Answer 15

Thalamus-> sensory cortex
CNS interneuron->CNS interneuron
Crossover, left sensory to right hemisphere

Question 16

Gustation, taste

Answer 16

Taste buds(epithelium plus taste receptors)
Fungiform papillae
Circumvallate papillae

Question 17

Taste receptors

Answer 17

Sweet, salty, sour, bitter, umami

Question 18

Taste physiology

Answer 18

Sour (H+) and salt (Na+) pass through leak ion channels

Others utilize G protein receptors (gusts ins) and cAMP

Question 19

Olfaction, smell

Answer 19

Olfactory epithelium
Olfactory receptors
Modified neurons
10-20 million
2-4k

Question 20

Smell physiology

Answer 20

Odorant binding two specific G protein.
Adenylate Cyclades activation
ATP->cAMP
CAMP open Na and Ca channels
Depolarization->action potential

Question 21

Smell integration

Answer 21

Olfactory nerve-> olfactory bulb
Calamus, hypothalamus, and limbic system
Olfactory cortex
Rapid, central adaptation