Special sense-1

Question 1

Perception

Answer 1

is the conscious interpretation of the external world created by patterns of activity in the brain

Question 2

Perception is Limited by

Answer 2

1. Our receptor types
   example: humans do not sense magnetic fields or UV light
2. Our level of sensitivity
   example: we only hear certain frequencies of sound
3. Central processing and filtering
   example: what grabs your attention in a crowded room is based on your sensitivity, past experience, etc

Question 3

What is responsible for perception and sensation

Answer 3

The outer region of the brain, the cerebral cortex

Question 4

the awareness of the stimuli

Answer 4

Sensation

Question 5

the interpretation of the stimuli

Answer 5

Perception

Question 6

Question 7

Sensory Receptor Action

Answer 7

Sensory Receptors convert (transduce) information from the environment into electrical signals.

Question 8

Stimulus:

Answer 8

change detectable by the body

Question 9

Receptor:

Answer 9

structure within an afferent neuron that responds to stimuli by producing depolarizing graded potentials (receptor potentials)

Question 10

Sensory Transduction:

Answer 10

conversion of stimulus energy (ex: light, heat, sound) into electrical energy

Question 11

The _______ consists of nerve fibers that carry information between the CNS and other parts of the body.

Answer 11

peripheral nervous system

Question 12

The _________ of the PNS sends information about the external and the internal environment to the CNS.

Answer 12

afferent division

Question 13

Stimuli exist in various energy forms, or modalities, such as

Answer 13

heat, light, sound, pressure, and chemical changes.

Question 14

Afferent neurons have sensory receptors at their _________ that respond to stimuli in both the external world and the internal environment.

Answer 14

peripheral endings

Question 15

Receptors must convert these other forms of energy into

Answer 15

electrical signals

Question 16

Stimuli bring about graded potentials known as _______ in the receptor.

Answer 16

receptor potentials

Question 17

sensory transduction.

Answer 17

The conversion of stimulus energy into a receptor potential

Question 18

Receptor potentials in turn trigger ________ in the afferent fibres

Answer 18

action potentials

Question 19

Sensory Receptors are activated by a specific stimulus with different sensitivities, this is called the

Answer 19

adequate stimulus

Question 20

Some receptors can respond weakly to stimuli other than their adequate stimulus, but even when activated by a different stimulus, a receptor still gives rise to the sensation usually detected by that receptor type
True or false?

Answer 20

True

Question 21

Photoreceptors

Answer 21

responsive to visible light

Question 22

Mechanoreceptors

Answer 22

sensitive to mechanical energy

Question 23

Thermoreceptors

Answer 23

sensitive to heat and cold.

Question 24

Osmoreceptors

Answer 24

detect changes in the concentration of solutes in the extracellular fluid (ECF) and the resultant changes in osmotic activity

Question 25

Chemoreceptors

Answer 25

sensitive to specific chemicals

Question 26

Nociceptors, or pain receptors

Answer 26

sensitive to tissue damage

Question 27

What causes changes in electrical activity in a sensory neuron

Answer 27

An adequate stimulus at a receptor

Question 28

Some receptors can respond weakly to other stimuli in addition to their adequate stimulus. Give an example

Answer 28

photoreceptors respond to light, but also weakly to mechanical touch, a mechanical compression of the eye will result in “perception” of light.

Question 29

What increases stimulus intensity

Answer 29

Number of receptors stimulated – stronger stimuli usually affect larger areas Frequency of action potentials – stronger stimuli generate a larger receptor potential, therefore a greater frequency of action potentials

Question 30

T/F | The body is able to adjust to stimulus as more information is brought in.

Answer 30

True

Question 31

Response to a stimulus can be altered in 3 ways

Answer 31

Receptor Adaptation Neuron Habituation Neuron Sensitivity

Question 32

Sensory Receptor Adaptation

Answer 32

Receptors can “adapt” to stimuli by decreasing the extent of depolarization to sustained or repeated stimuli. If a stimulus is repeated enough times, then the frequency of action potentials generated to the SAME stimulus will decrease, and the receptor no longer responds to the same degree as it did before

Question 33

Tonic Receptors:

Answer 33

[do not adapt, or adapt very slowly] - Constant firing rate - For situations where continuous information about a stimulus is valuable Examples: proprioceptors pain, muscle stretch continue to generate action potentials, even with multiple repeated stimuli used for maintenance functions, example balance and posture information always relayed to CNS via stretch receptors

Question 34

Phasic Receptors:

Answer 34

``` [rapidly adapting] - Report changes in the environment - Burst of firing at the beginning and end of stimulus Examples: temperature, smell, touch ``` stop responding quickly when stimulus is repeated used for signalling stimulus changes and intensity, example touch receptors on skin adapt to items frequently worn such as a ring or a watch.

Question 35

Habituation:

Answer 35

Neurons will reduce their response to repeated stimuli by depressing synaptic activity

Question 36

Neuron Habituation example mechansim

Answer 36

repeated stimulus reduces activity through changes in the voltage-gated Ca2+ channels in the presynaptic terminal

Question 37

Sensitization:

Answer 37

Neurons will increase their responsiveness to stimuli following strong or noxious stimulus

Question 38

Neuron Sensitization example mechanism

Answer 38

painful or strong stimulus leads to serotonin release, acting via a 2nd messenger cAMP cascade, which blocks K+ channels, prolonging action potentials in the pre-synaptic neuron

Question 39

receptive fields

Answer 39

Sensory neurons respond to stimulus information within small regions of input

Question 40

The sensitivity of an area is determined by

Answer 40

the amount of receptors per area, where the most receptors in a small space leads to the highest sensitivity.

Question 41

fingertip touch receptors

Answer 41

Small, dense receptive fields correspond to the most sensitive areas

Question 42

lower leg touch receptors

Answer 42

Large, diffuse receptive fields correspond to the least sensitive areas

Question 43

Lateral Inhibition

Answer 43

> helps to increase sensory discrimination and localization when receptive fields are very dense > The receptive field closest to the stimulus will be most active, and the receptive fields nearby will be only weakly activated > This occurs at the level of the receptors and the CNS via inhibitory neuron activation and increases the contrast of stimuli perception

Question 44

Answer 44

Question 45

Major Sensory Pathways

Answer 45

``` Somatic Sensation Pain Sensation Special Senses - Vision - Hearing - Equilibrium - Taste Visceral Sensation (unconscious) ```

Question 46

Somatic Sensation

Answer 46

the sensation of body surfaces, including skin, muscle and joint sensation.

Question 47

Somatic Sensation

Answer 47

the sensation of body surfaces, including skin, muscle and joint sensation.

Question 48

Somatic Sensory Receptors

Answer 48

Skin Sensation Muscle Sensation Joint Sensation

Question 49

Somatic Sensory Processing:

Answer 49

Spinal cord and Brain

Question 50

Somatic Sensory Receptors: | Tactile (touch) receptors

Answer 50

hair receptors: hair movement, rapidly adapting Merkel’s disc; soft touch, slowly adapting Pacinian corpuscle; vibration and deep pressure, rapidly adapting Ruffini endings; deep pressure, slowly adapting Meissner’s corpuscles; soft touch, tickle, rapidly adapting

Question 51

Question 52

more than a direct response to a stimulus.

Answer 52

Pain

Question 53

The sensation of pain is accompanied by

Answer 53

motivated behavioral responses and emotional reactions.

Question 54

The subjective perception of pain can be influenced by

Answer 54

other past or present experiences.

Question 55

Categories of Pain Receptors

Answer 55

1. Mechanical nociceptors 2. Thermal nociceptors 3. Polymodal nociceptors

Question 56

Mechanical nociceptors

Answer 56

respond to mechanical damage such as cutting, crushing, or pinching

Question 57

Thermal nociceptors

Answer 57

respond to temperature extremes, especially heat

Question 58

Polymodal nociceptors

Answer 58

respond equally to all kinds of damaging stimuli, including irritating chemicals released from injured tissues.

Question 59