Sensory Physio - Introduction Flashcards
Epicritic sensations are
the mild or light sensations. Such sensations are perceived more accurately.
Examples of epicritic sensations are:
- Fine touch or tactile sensation
- Tactile localization
- Tactile discrimination
- Temperature sensation with finer range between 25°C and 40°C.
Protopathic sensations are
the crude sensations. These
sensations are primitive type of sensations.
Examples of Protopathic sensations are:
i. Pressure sensation
ii. Pain sensation
iii. Temperature sensation with a wider range, i.e. above 40°C and below 25°C
Synthetic senses are
…the sensations synthesized at cortical level, by integration of impulses of basic sensations. Two or more basic sensations are combined in some of the synthetic senses.
Best examples of synthetic senses are
vibratory sensation, stereognosis and two-point discrimination.
Mechanoreceptors function
They detect mechanical deformation (compression or stretching of the receptor or of tissues adjacent to the receptor) of the receptor.
Cutaneous corpuscular receptors may be categorized as
encapsulated and nonencapsulated receptors.
Which receptors have encapsulated endings?
Pacinian corpuscle Meissner corpuscle Ruffini ending Krause end-bulb Golgi-Mazzoni corpuscle (pressure)
Golgi-Mazzoni corpuscle is a receptor for
pressure
The expanded or encapsulated endings are not necessary for cutaneous sensation. True or false?
True. They only function as mechanoreceptors for tactile stimuli.
What are the mechanoreceptors?
(I) Merkel’s discs
(ii) Meissner’s corpuscle
(iii) Pacinian corpuscle
(iv) Ruffini corpuscle
(v) hair-follicle plexus.
Fine touch or discriminatory touch sensation is carried by
…the so-called low-threshold mechanoreceptors.
Two types of sensory afferents are associated with these mechanoreceptors
Fast-adapting (FA) and slow-adapting (SA).
Both the FA and SA afferents are further subdivided into two types, based on their receptive field properties into…
i) Type I units, with small receptive fields with well-defined borders. (ii) Type 2 units with wider receptive fields
What is the receptive field?
The area covered by the receptor
There are cold-sensitive spots and heat-sensitive spots in the skin. True or false?
True
There are __ times more cold-sensitive spots as compared to heat-sensitive spots.
4-10
Number of cold spots per cm2 of skin in lips, fingers, trunk
Lips (15-25)
Fingers (3-5)
Trunk (1)
Types of receptors for skin tactile sensibilities (epidermis and dermis)
- Free nerve endings
- Expanded tip endings
- Spray endings
- Ruffini’s endings
- Encapsulated endings
-Hair end-organs
Types of receptors with expanded tip endings
Merkel’s discs
Plus several other variants
Types of receptors with encapsulated endings
Meissner’s corpuscles
Krause’s corpuscles
Free nerve endings - Location, Modaity, Fibre Type
- Location: Everywhere in the skin
- Detects: pain, touch, pressure
- C-fibres
Meissner’s corpuscle - Location, Modaity, Fibre Type
- Location: Non-hairy part of the skin (glabrous skin), fingertips, lips
- Description: Elongated, encapsulated nv endings, excite Aβ fibres
Free nerve endings are found in…
…hairy skin, root of hair, cornea but not encapsulated endings.
Merkel’s discs - Location, Description
Location: Fingertips, hairy skin parts
Description: Expanded tip, forms Iggo dome receptor, excite Aβ fibres
Which receptor forms Iggo dome receptor?
Merkel’s discs