2. General Principles of Sensory Physiology Flashcards

1
Q

Interaction between sensory system and motor system

A

Sensory receptors in the PNS generate an impulse
The CNS interprets the impulse
The PNS stimulates a response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Sensory receptors

A

Some specialized structures activated by stimuli and convert a stimulus into neuronal activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Types of sensory receptors

A
  1. Endings of afferent neurons (somatosensory and olfactory systems)
  2. Specialized epithelial cells adjacent to an afferent neuron (visual, taste, and auditory systems)
  3. Specialized structure associated with nerve terminals (Pacinian corpuscles)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Simple receptors

A

Neurons with free nerve endings, work on somatosensory and olfactory systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Complex neural receptors

A

Nerve endings enclosed in connective tissue capsules, Pacinian corpuscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Special senses receptors

A

Cells that release neurotransmitter onto sensory neurons, initiating an action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

5 types sensory receptors

A

Mechanoreceptors, photoreceptors, chemoreceptors, thermoreceptors, nociceptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Mechanoreceptors

A

For touch, is a pacinian corpuscle and located on the skin
For audition, is a hair cell and located in the organ of corti
For vestibular, is a hair cell locating on macula, semicircular canal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Photoreceptors

A

For vision, rods and cones are the receptors and located on the retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Chemoreceptors

A

For olfaction: olfactory receptors on olfactory mucosa.
For arterial Po2 on carotid and aortic bodies.
Fo pH of CSF on ventrolateral medulla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Thermoreceptors

A

For temperture, receptors are cold receptors and warm receptors, on skin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Nociceptors

A

Detect stimuli causing tissue damage, can be thermal, mechanical or polymodal, located on skin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Receptor potential vs. action potential

A

Receptor potential = graded, non-propagated

Action potential = hyperpolarizing or depolarizing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Sensory transduction

A
  1. Stimulus -> ion channel opening
  2. Current –> receptor potential
  3. Depolarization -> voltage gated sodium channels, action potentials
  4. Propagation -> NT release
  5. Transmission to CNS through sensory afferent neurons (1st, 2nd, 3rd, and 4th order)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Sensory unit

A

primary sensory neuron with all sensory receptors (endings or associated sensory receptor cells).
The smallest unit of sensory response.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Receptive field

A

an area of the body surface that when stimulated results in a change in firing rate of a sensory neuron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What determinates the size of receptive field of a sensory neuron?

A

Terminal size and associated cells; Convergence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Receptive field variation in size

A

The smaller the receptive field, the more precisely the sensation can be localized or identified.
The higher the order of the CNS neuron, the more complex the receptive field.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Receptive field firing rate

A

Receptive field can be excitatory or inhibitory depending on the change in firing rate.

20
Q

Four aspects of a stimulus

A

Stimulus Modality: light, sound, temperature, taste, smell, pressure

Stimulus Intensity: strength of a stimulus

Stimulus Location: acuity, lateral inhibition

Stimulus Duration: adaptation

21
Q

Modality of mechanoreceptors

A

Stretch and pressure

22
Q

Modality of photoreceptors

A

Light

23
Q

Modality of chemoreceptors

A

Chemicals

24
Q

Modality of thermoreceptors

A

Cold, warm

25
Q

Modality of nociceptors

A

Stimuli causing tissue damage

26
Q

Adequate stimulus

A

Each sensory receptor is particularly sensitive to one stimulus type or modality

27
Q

Labeled line

A

the distinct anatomical pathways (including ascending pathways, specific neuronal circuits, from sensory receptors to a specific region of the CNS) associated with a particular stimulus modality.

28
Q

Do all receptors from same sensory unit respond to same modality?

A

Yes

29
Q

What encodes stimulus intensity?

A
  1. The number of receptors that are activated. A stronger stimulus affects a larger area and recruit a larger number of receptors.
  2. Differences in firing rates of sensory neurons in the pathway. An increased stimulus results in a higher frequency of action potential.
  3. Activating different types of receptors. A light touch of the skin may activate only mechanoreceptors, while an intense damaging stimulus to the skin may activate mechanoreceptors and nociceptors.
30
Q

Lateral inhibition

A

The capacity of an excited neuron to reduce the activity of its neighbors
Further enhance sensory acuity

31
Q

Acuitity

A

Precision of stimulus location
Positively correlated with the density of sensory units
Negatively correlated with the receptive field size

32
Q

Adaptation

A

sensory receptors decrease in sensitivity to stimulus of constant strength
⇒ action potential frequency decreases

33
Q

Phasic sensory receptors

A

Phasic (rapidly adapting): generate a receptor potential and action potential at the onset (and offset) of a stimulus but very quickly cease responding; detect changes in the stimulus

34
Q

Tonic sensory receptors

A

Tonic (slowly adapting): maintain a persistent or slowly decaying receptor potential and continue firing during a constant stimulus; encode duration and intensity of a stimulus

35
Q

Microneurography

A

an invasive method used by neuroscientists to visualize and record the normal traffic of nerve impulses.

36
Q

Relay nuclei

A

Integrate converging information
Prominent in thalamus.
Contain local interneurons and projection neurons

37
Q

Topographic organiztaion

A

Neural maps
Somatosensory system: somatotopic map (sensory homunculus)
Visual system: retinotopic map
Auditory system: tonotopic map

38
Q

Decussation

A

The crossings of sensory (and motor) pathways in the spinal cord or in the brain.
Commissure: e.g. corpus callosum
Optic chiasm

39
Q

Classification of nerve fibres

A

Many! Look at table haha

40
Q

Sensory (ascending) pathways

A

A series of sensory afferent neurons travel in bundles of parallel pathways to pass on certain sensory information to the brain.
First-order neuron is the primary sensory afferent neuron.
Second-order sensory afferent neurons is located in relay nuclei in the spinal cord or in the brain stem. They cross at the midline (decussation).
Third-order neurons typically reside in relay nuclei in the thalamus.
Fourth-order neurons reside in the appropriate sensory area of the cerebral cortex.

41
Q

Divergence of Ascending Pathways

A

One primary sensory neuron synapses onto many higher-order neurons.

42
Q

Convergence of Ascending Pathways

A

A higher-order sensory neuron may receive inputs from more than one primary sensory neuron (information processed rather than just relayed).

43
Q

Where do ascending pathways terminate

A
Terminate in specific primary sensory areas
Somatic receptors ⇒ Somatosensory cortex
Eyes ⇒ visual cortex
Ears ⇒ auditory cortex
Nose (nasal cavity) ⇒ olfactory cortex

Further processing in associational cortical areas for complex integration.

Leads to perception of sensations

44
Q

Perception vs Sensation

A

Perception is an active process and sensation is a passive process.

45
Q

Influence of Desending Pathways

A

Descending pathways can inhibit (directly or indirectly) the transduction of sensory information to the brain. Not all sensory information reaches conciousness.