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PHY V > General Senses > Flashcards

General Senses Flashcards

1
Q

Sensory neuron

  1. Directs impulses towards?
  2. Type of neuron
A
  1. CNS

2. Unipolar

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2
Q

Describe the structure of a sensory unit.

A

It is a single neuron with its peripheral and central terminal.

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3
Q

Conscious processes which are the immediate results of the stimulation of the sense organs, by which means of which man becomes aware of existence and properties of particular objects which stimulate senses to actions.

A

Sensation

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4
Q

Somatic vs. Special senses?

A

Somatic senses

  • aka somesthetic senses
  • aka general senses
  • receptors are found all over the body
  • touch, temperature, vibration, nociception, itch, proprioception

Special senses

  • aka modalities - type of sensation elicited by the stimulus
  • receptors are located in a particular organ
  • e.g. vision, hearing, taste, smell, equilibrium; these are the “senses”
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5
Q 
Stimulus
1. What is it?
2. Location
3. Give the form of energy given the modality.
A. For vision
B. For touch, pressure
C. For static and dynamic position senses
D. For taste and smell
E. For pain
A
  1. A stimulus is anything that affect any of the body’s activities
  2. Location: Either external or internal (wrt body)
  3. A. Electromagnetic radiation or light: For vision
    B. Mechanical stimuli: For touch, pressure
    C. Proprioception: For static and dynamic position senses
    D. Chemical: For taste and smell
    E. Nociception: For pain
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6
Q

Effect of increasing stimulus intensity?

A

Inc stimulus intensity -> inc rate of discharge -> inc strength of sensation

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7
Q

Duration of stimulation with respect to sensation?

A

= duration of sensation

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8
Q

What is adequate stimulus?

A

Adequate stimulus is a form of energy w/ the least intensity which a receptor responds to.

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9
Q

Sensory receptors
Types:
1. Receptor will be activated by stimuli located outside the body
2. Receptor whose stimuli is located inside the body
3. Receptors for position senses, you have these in the skeletal ms, tendons, ligaments, joints

A
  1. Exteroceptors
  2. Interoceptors
  3. Proprioceptors
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10
Q

Give the 3 proprioceptors and their function.

A

JM G XD

Muscle spindle
-detect change in the length of the ms and rate of change in the length of the ms

Golgi tendon organ
-Detects change in the ms tension

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11
Q

Different modalities of the deep senses?

A

Pain, Pressure, Vibration

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12
Q

Functional Classification and Structural Classification of Receptors?

A 
Functional Classification (accdg to stimuli)
>Mechanical
>Thermal
>Chemical
>Electromagnetic

Structural Classification (accdg to dendritic portion)
>Free nerve ending
>Encapsulated

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13
Q 
What is the receptive field?
Types? Differentiate in terms of:
1. Area
2. Borders
3. Sensitivity
4. Example
A

Spatial distribution from which a stimulus evoke a response.

Type I Receptive Field

  • Smaller area
  • Well defined borders
  • Highly sensitive
  • E.g. Meissner’s corpuscle

Type II Receptive Field

  • Wider area
  • Poorly defined borders
  • Has a single point of minimal sensitivity
  • E.g. Pacinian
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14
Q

Properties of receptors

A

ARNES

Adaptation
Rate of discharge
Neural coding of sensory information
Excitability
Specificity
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15
Q

Property of Receptor: Specificity

  1. The adequate stimulus follows what law?
  2. High or low threshold?
A
  1. Muller’s Law of specific nervous energy
    - So each type of receptor is highly sensitive to only 1 type of stimulus called the adequate stimulus and when it is stimulated, it yields a specific sensation called modality
  2. Low threshold for adequate stimulus
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16
Q

Property of Receptor: Excitability

1. Define

A
  1. Ability of the receptors to respond to its adequate stimulus
17
Q

Mechanism of mechanoreceptors

A

Stimulus -> deformity of the membrane of the receptor -> stretching of the membrane -> opening of Na channels -> Na influx -> depolarization

E.g. Pacinian corpuscle

18
Q

Where does the generator potential occur?

A

In the unmyelinated portion

19
Q

Characteristics of the receptor potential in terms of

  1. Amplitude
  2. Spread
  3. Summation
  4. All-or-none law
  5. Refractory period
  6. Blockage by local anesthesia
A
  1. Graded
  2. Passive localized spread
  3. Can be summated
  4. Does not obey the all or none law. It is a local potential which can be summated at the initial segment
  5. No refractory period
  6. CANNOT be blocked by local anesthesia
20
Q

Two types of summation

A
  1. Spatial
    - e.g. more than 1 neuron being stimulated -> leads to inc in the intensity of stimulation -> greater rate of transmission/discharge
  2. Temporal
    - 1 neuron stimulated several times
21
Q

Two types of receptor cells

A
  1. Nerve cell

2. Specialized epithelial cell

22
Q

Sensory Receptors Functions

A
  • As a detector (of changes in the external & internal environment)
  • As a transducer (Transform any form of energy into a receptor potential)
23
Q

Events in transduction

A

Stimulus open Na channels in the receptor membrane -> inc Na conductance and depolarize the membrane to produce a generator potential which is decrementing and nonpropagating -> Initiate an AP at the 1st node of Ranview or adjacent electrically excitable membrane in umyelinated axons

24
Q

Properties of receptors: Rate of discharge

-Follows what law?

A

Follows Weber-Fechner Law which states that the rate of discharge from the receptor is directly proportionate to the logarithm of the intensity of the stimulus

25
Q

Properties of the receptors: Adaptation (of the receptors)

  1. Define
  2. Types of adapting receptors
A
  1. There is a decline in the frequency of the discharge of nerve impulses despite constant stimulation.
  2. a. Rapidly Adapting Receptors
    - aka Phasic receptors
    - Fast
    - e.g. Pacinian Corpuscles
    - Burst of activity but quickly reduce firing rate (adapt).
  3. b. Slowly Adapting Receptors
    - aka Tonic receptors
    - Slow
    - E.g. Proprioceptors, Baroreceptors, Pain receptors, Chemoreceptor
    - Produce constant rate of firing for as long as the stimulus is applied
26
Q

Mechanism of adaptation

A

Mechanism of how adaptation is brought about
>In the img: Pacinian corpuscle
1. So there’s adaptation due to the visco-elastic nature of the receptor
>So when you apply stimulus over here, it will lead to formation of a membrane which will be transferred to the visco-elastic portion (laminated(?) siya diba, your Pacinian corpuscle) -> detected here in the inner portion but there will be redistribution to equalize the pressure. Once equalized, you can’t determine the sensation anymore. (This is 1 mechanism of adaptation.)

  1. Accommodation
    >2nd mechanism of adaptation
    >Brought abt by the inactivation of the Na channel. If inactivated at the 1st node of Ranvier -> less Na influx -> no generation of impulse
27
Q

Meissner’s corpuscle

  • location?
  • type of receptor?
  • type of receptive field
  • type of adaptation
  • detect what type of vibration
  • type of spatial resolution
  • detect what specifically?
A
  • Superficial receptor
  • Dendrites are encapsulated CT beneath the epidermis of glabrous/hairless skin
  • small receptive field
  • fast adapting
  • detect slow and low frequency vibration
  • high spatial resolution due to small receptive field
  • detect changes in texture
  • sensitive to movement of objects over the surface of the skin
28
Q

Merkel’s disks

  • location
  • type of receptor?
  • type of receptive field
  • type of adaptation
  • detect what type of vibration
  • type of spatial resolution
  • detect what specifically?
A

Merkel’s disks

  • expanded dendritic endings in the epidermis of glabrous skin
  • small receptive field
  • slow adapting
  • for precise localization of stimulus
  • sensitive to steady stable objects or continuous touch of objects against the skin
  • highest spatial resolution
29
Q

Hair root organs

  1. location
  2. Adaptation
  3. Function?
A
  1. Hairy skin
  2. Fast adapting
  3. Detect movements of objects on the surface of the skin
30
Q 
Deeper cutaneous receptors
Pacinian corpuscle
1. Type of receptor? Location?
2. Receptive field
3. Responds to?
4. Senses what sensation?
5. Adaptation
A
  1. Largest cutaneous mechanoreceptor in glabrous and hairy skin
  2. Wide receptive field
  3. Responds to deep pressure
  4. Senses tingling and vibratory sensation
  5. Fast adapting
31
Q

Ruffini’s endings

  1. Describe.
  2. Fxn?
  3. Stimulated by?
  4. Adaptation
A
  1. Enlarged dendritic endings with elongated capsules in the dermis of glabrous and hairy skin
  2. To monitor the continuous state of depolarization in tissues
  3. Prolonged touch and pressure and responds to stretch and fluttering vibration
  4. Slow adapting
32
Q

Tickle and itch

  1. Location of receptors
  2. Transmitted by?
  3. Adaptation
  4. Part of which sense?
A
  1. Superficial layers of the skin
  2. C unmyelinated fibers (free nerve endings)
  3. Rapidly adapting
  4. Tactile sense
33
Q

Fine touch vs Crude touch

A

Fine touch

- Subject is able to detect shape and texture of objects
- Receptors are capsulated and hair end organs
- Carried by DCML

Crude touch

- Poorly localization of the sensation which needs a relatively strong stimulus (So you know there’s something touching your skin but can’t pinpoint/di mo alam kung exactly nasaan)
- Receptors are less dx, free nerve endings
- There are emotionally important
- Carried by the ALS together with tickle and itch

PHY V (12 decks)

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