Somatic sensory Flashcards
Functional divisions of the nervous system
CNS
PNS
Sensation is detected by receptors
Senses: Information on your surroundings
Processed in the CNS
Receptor types / Type of stimuli they respond to
Mechanoreceptors
Chemoreceptors
Photoreceptors
Thermoreceptors
Nociceptors
Mechanoreceptors
ear, muscle and joints, skin and viscera, cardiovascular
Chemoreceptors
tongue, nose, skin and viscera
Photoreceptors
eye
Thermoreceptors
skin and CNS
Nociceptors
respond to stimuli that result in sensation of pain
step by step; functions of senses
1) Stimulus
2) Receptor
3) Change in membrane potential
4) Generation of action potential
5) Transmission to CNS
6) Integration of information by CNS
SENSES - broken down
GENERAL > SOMATIC {touch, pressure, temperature, pain, proprioception} + VISCERAL { pain, pressure}
SPECIAL > smell, taste, sight, hearing, balance
Where is the Somatic senses located?
skin, muscles, joints
Where is the Visceral senses located?
internal organs
Where is the general senses disturbed?
over a large part of the body
Where is the receptors located for special senses?
Receptors localised within specific organs
Receptors and Sensory units
A sensory unit is a single afferent neuron and all of its receptor endings.
Sensory receptors may be…
1) Neuron with free nerve endings
2) Neuron with encapsulated ending
3) Specialised receptor cells closely associated with neuron
Sensory receptors function to trigger neuronal response
Environmental changes cause a change in membrane potential in receptor
Receptor or generator potential
GRADED
What happens if the signal reaches threshold?
It will trigger an action potential
This information goes to the brain via ascending fibres; what type of fibres?
afferent nerve fibres
The stronger the stimulus the ________ the graded receptor potential, the more frequent the action potentials of the afferent neurone the more neurotransmitter is released at the synapse
larger
is AP graded?
No
Each Neuron Has A Receptive Field
Region of space where the presence of a stimulus will induce the production of a signal in that neuron
What is unique about the receptive fields in the sensory neurones?
Several sensory neurones may have overlapping receptive fields
What is unique about the receptive fields in the sensory neurones?
Several sensory neurones may have overlapping receptive fields
The smaller the receptive fields, the more ______ a representation of the stimulus is signaled to the brain
accurate
Brain cannot differentiate between two stimuli acting on the same receptive field
Tested clinically to test for damage : Two point discrimination task
Somatosensory NS - pathways
many different paths
Somatic nervous system
Linked to skeletal muscles
What does somatic nervous system do?
Gives us perception of touch, temperture, body position and pain
External - somatic NS role
Process stimuli received from receptors within the skin muscles and joints
Are responses voluntary or involuntary?
Both =
Reflexes & Breathing
Pathways for Somatic Perception Project to the _______ and _______
a) Cortex
b) Cerebellum