Ch. 8.1 Sensory Receptor Organs Detect Energy or Substances

Question 1

What is a sensory receptor organ?

Answer 1

An organ (such as the eye or ear) specialized to detect particular stimuli - this means they detect and respond to some events but not others.

Question 2

What is an event that affects the sensory organ called?

Answer 2

Stimulus (plural = stimuli)

Question 3

What is an example of a stimulus?

Answer 3

examples:
A sound wave
light reaching the eye
food touching the tongue

Question 4

What are the cells within the organs that detect particular kinds of stimuli called?

Answer 4

Receptor cells

Question 5

What do receptor cells do?

Answer 5

Located in organs, they detect particular kinds of stimuli and convert them into the language of the nervous system (which is electrical signals)

Question 6

Name the 6 types of sensory systems.

Answer 6

1. Mechanical
2. Visual
3. Thermal
4. Chemical
5. Electrical
6. Magnetic
   (hint: My Cat Molly went to the VET)

Question 7

What are the 6 modalities of the mechanical sensory system and their adequate stimuli?

Answer 7

1. Touch (contact with or deformation of body surface_
2. pain (tissue damage)
3. Hearing (sound vibrations in air or water)
4. Vestibular (head movement and orientation)
5. Joint (position and movement)
6. Muscle (tension)

Question 8

What is the modality of the visual sensory system and its adequate stimulus?

Answer 8

Seeing (visible radiant energy)

Question 9

What are modalities of the thermal sensory system and their adequate stimuli?

Answer 9

1. cold (decrease in skin temperature)
2. warmth (increase in skin temperature)

Question 10

What are the 4 modalities of the chemical sensory system and their adequate stimuli?

Answer 10

1. smell (odorous substances dissolved in the air or water)
2. Taste (substances in contact with the tongue or palate)
3. Common chemical (changes in CO2, pH, osmotic pressure)
4. Vomeronasal (pheromones in air or water)

Question 11

What is the modalities of the electrical sensory system and its adequate stimulus?

Answer 11

Electroreception (differences in density of electrical currents)

Question 12

What is the modalities of the magnetic sensory system and its adequate stimulus?

Answer 12

Magnetoreception (orientation of Earth’s magnetic field)

Question 13

What is adequate stimuli mean?

Answer 13

It is the type of stimulus for which a given sensory organ is particularly adapted.

Question 14

Give an example of a restricted range of responsiveness of a sensory system.

Answer 14

1. Humans do not hear some sounds that other animals can hear.

Question 15

What is the doctrine of specific nerve energies?

Answer 15

The receptors and neural channels for the different senses are independent and operate in their own special ways and can produce only one particular sensation each. (Johannes Müller)

Question 16

What is a sensory modality?

Answer 16

An aspect of a stimulus or what is perceived after a stimulus. The term sensory modality is often used interchangeably with ‘senses’.

Question 17

What is labeled lines?

Answer 17

Each nerve to the brain only reports a particular type of information.
ex: one nerve signals sound, another, smell, another, light touch etc.

Question 18

What type of energy do neurons use?

Answer 18

Action potential

Question 19

Why does a dark blob appear in your field of view when you apply pressure to your eye?

Answer 19

The energy you applied, pressure, affected action potentials coming from your eye. Because your brain labels that line as always carrying visual information, what you experienced was a change in vision.

Question 20

What is sensory transduction?

Answer 20

The process in which a receptor cell converts the energy (from a stimulus) into another type of energy by a change in the electrical potential across its membrane. (Remember a resting neuron is about -68mV)

Question 21

What do you know about receptor cells?

Answer 21

A. some have axons to transmit information, others do not.
B. If they do not have axons, they can stimulate associated nerve endings either mechanically or chemically.
C. the place where energy is converted from one form to another.

Question 22

What is the initial stage of sensory processing?

Answer 22

The change in electrical potential in receptor cells due to stimulus.

Question 23

What determines the form of energy received by the cell

Answer 23

The structure of the cell.

Question 24

What is the Pacinian corpuscle (also called lamellated corpuscle)?

Answer 24

A skin receptor cell type that detects vibration.

Question 24

What is the difference between action potential and receptor potential?

Answer 24

Action potential triggers the release of neurotransmitters in the neurons (which help in transmitting electrical impulses throughout the body). In contrast, receptor potential only facilitates signal transduction or stimulates inward current flow (call if needed)

Question 25

What is action potential?

Answer 25

An action potential is a rapid sequence of changes in the voltage across a membrane which triggers the release of neurotransmitters in neurons.

Question 26

What is another name for potential?

Answer 26

Voltage

Question 27

What is receptor potential?

Answer 27

A local change in the resting potential of a receptor cell because of a stimulus. This consists of a change in voltage across the receptor membrane proportional to the stimulus strength. The intensity of the receptor potential determines the frequency of action potentials traveling to the nervous system.

Question 28

What are the stages from mechanical stimulus to action potential?

Answer 28

1. Mechanical stimulation deforms the corpuscle
2. Deformation of the corpuscle stretches the tip of the axon
3. Stretching the axon opens stretch-sensitive ion channels (made up of a protein called Piezo) in the membrane allowing positively charged ions to enter
4. When the receptor potential reaches threshold amplitude, the axon produces one or more action potentials.

Question 29

What is coding?

Answer 29

The rules by which action potentials in a sensory system reflect a physical stimulus.
(because action potentials are limited to size and duration, coding is use - number, frequency, and patterns (volleys) of action potentials

Question 30

What is range fractionation?

Answer 30

Intensity values are encoded differently in cells. Each cell specialized to detect a particular rang of intensities. ie: low threshold neurons, medium threshold neurons and high threshold neurons.

Question 31

What is somatosensory system?

Answer 31

Refers to body sensation - particularly touch and pain

Question 32

What is the process called adaptation?

Answer 32

The progressive loss of receptor sensitivity as stimulation is maintained

Question 33

In terms of adaptation, what are the two kinds of receptors?

Answer 33

1. Tonic receptors (the frequency of action potentials declines slowly or not at all as stimulus is maintained)
2. Phasic receptors (the frequency of action potentials drops rapidly as stimulus is maintained)

Question 34

What is top-down process?

Answer 34

A process in which higher-order cognitive processes control lower-order systems. ie: the brain can inhibit incoming pain signals

Question 35

What is a sensory pathway

Answer 35

The chain of neural connections from sensory receptor cells to the cortex. Each sensory modality - such as touch, vision or hearing- has a distinct hierarchy of tracts and stations in the brain.

Question 36

What do the stations in the sensory pathway do?

Answer 36

Each station in the pathway accomplishes a basic aspect of information processing. For example, painful stimulation of the finger leads to reflex withdrawal of the hand, at a different level, the head can turn towards the source of the pain.

Question 37

What is the thalamus?

Answer 37

The brain regions that surround the third ventricle and trades info with the cortex.
For most senses, info about each sensory modality is sent to a separate division of the thalamus. The thalamus can emphasize or suppress info from a stimulus.

Question 38

How does sensory information enter the CNS?

Answer 38

Question 39

What is the receptive field of a sensory neuron?

Answer 39

It consists of a region of space in which a stimulus will alter that neuron’s firing rate.
They have either an excitatory center and an inhibitory surround, or an inhibitory center and an excitatory surround.
They differ in size and shape and in the quality of stimulation that activates them (ex: some neurons respond preferentially to light touch and others respond to cooling or pain).

Question 40

The primary sensory cortex

Answer 40

For a given sensory modality, the region of cortex that receives most of the information about that modality from the thalamus, or in the case of olfaction, directly from the secondary sensory neurons.

Question 41

Secondary sensory cortex (also named nonprimary sensory cortex)

Answer 41

For a given sensory modality, the cortical regions receiving direct projections from primary sensory cortex for that modality.

Question 42

How is information sent between the primary and nonprimary sensory cortex?

Answer 42

Through subcortical loops

Question 43

What do you know about the primary somatosensory cortex (somatosensory 1, or S1)

Answer 43

1. It lies in the postcentral gyrus of the parietal cortex, just behind the central sulcus.
2. Each S1 receives touch info from the opposite side of the body.
3. Each region is a map of the body in which the relative areas devoted to body regions reflect the density of body innervation. Thus, parts of the body where we are especially sensitive (like the hands) send info to a larger area of S1.

Question 44

What do you know about the secondary somatosensory cortex (somatosensory 2, or S2)

Answer 44

1. It maps both sides of the body in registered overlay; that is , the left arm and right arm representations occupy the same part of the map.

Question 45

What is attention?

Answer 45

1. The process by which we select or focus on one or more specific stimuli for enhanced processing and analysis.
2. The posterior parietal lobe plays a special role in attention.
3. The cingulate cortex is involved in attention.

Question 46

What is synesthesia?

Answer 46

A condition where a there is a tiny gap between neurons where information is passed from one to the other and stimuli from one modality evoke the involuntary experience of an additional sensation in another modality. For example: Tuesday is a yellow word or a certain musical tone triggers a particular taste.