The Somatosensory System Flashcards
Deep sensation is from where?
Fascaie, muscles and bone
What is exteroceptive sensation?
Cutaneous sensation from the surfaces of the body
Neurotransmitter released following stimulation of sensory neurone
Glutamate
What do joint and muscle mechanoreceptors sense?
Proprioception
What word describes the following:
-the principle type of adequate stimulus that is transduced into an electrical signal by a primary afferent neurone
Modality
Difference between low threshold thermoreceptors and thermal nociceptors
Low threshold thermoreceptors: mediate cold, cool, indifferent, warm and hot
Thermal nociceptors: respond to extreme degrees of heat (>45 degrees C) or extreme cole (
What do chemical nociceptors respond to?
Substances in tissue (as found in inflammation) e.g. prostaglandins, bradykinin, serotonin, histamine, K+, H+, ATP and many others
This is a feature of primary sensory neurones that determines whether they change their firing rate only in response to a stimulus of changing intesity, or if they fire continuously throughout a constant stimulus
Adaptation
Slowly adapting receptors
Stretch receptors
Rapidly adapting receptors
Some muscle spindle afferents, hair follicle afferents
detect changes in stimulus strangth e.g. rate of movement
Very rapidly adapting receptors
e.g. Pacinian corpuscle (responds only to very fast movement, such as rapid vibration)
Group I receptor
Proprioceptors of skeletal muscle
Group II receptor
Mechanoreceptors of skin
Group III receptor
Pain, temperature
Group IV receptor
Pain, temperature, itch
What is the receptive field?
The region that causes a response in a neurone if stimulated (i.e. the area that is innervated by neurone)
What do free nerve endings sense?
Pain, heat, cold
What do Meissner’s corpuscles and merkel’s discs sense?
Touch
Where are Meissner’s corpuscles not present?
Hairy skin
These receptors are often grouped in Iggo domes
Merkel’s discs
What do Krause end bulbs sense?
Touch
Where would you find Krause end bulbs?
At the border of dry skin and mucous membranes
Where would you find Meissner’s corpuscles and Merkels discs?
Abundant in skin where 2 point discrimination is highest (remember meissner’s not present in hairy skin)
Where would you find Ruffini endings?
Within the dermis and also joint capsules
