Peripheral sensation and reflexes: sensory receptors in skin Flashcards
what are sensory neurone
Carry sensory information from periphery to CNS for perception and motor coordination
What are motor neurones?
carry commands from brain/spinal cord to muscles & glands
what are interneurons
not specifically sensory or motor
What is the purpose of the sensory system
provides CNS with representation of the external and internal world
What type of cell is the typical somatic sensory neurone known as?
pseudo-unipolar
How does somatic sensory neurone look schematically?
central process, cell bodies in Dorsal root ganglion, then peripheral process
what are peripheral processes referred as?
Afferent nerve endings
What do peripheral processes of somatic sensory neurons respond to?
- mechanical, thermal, painful stimuli
What are the 3 types of receptors
Interocepters
Exteroceptors
Proprioceptors
What are interoceptors?
Receptors in viscera that respond principally to mechanical and chemical stimuli
What are exteroceptors
Receptors that lie superficially in the skin that respond to different sensory modalities
What are proprioceptors
Receptors in muscles, joints and tendons that provide awareness of posture and movement
What 2 states can sensory neurones be in
- encapsulated
- unencapsulated
What does encapsulated mean
surrounded by a structural specialisation of non-neural tissue (corpuscle)
What does unencapsulated mean
terminal branch of sensory nerve fibre lying freely in innervated tissue
What does modality mean
Discrimination of sensory experience
What are 4 levels of modality
Mechanical
Body position
Temperature
Painful
What are receptors for pain called
nociceptors
When does a hair follicle receptor activate?
when it is deformed
What is depolarisaton at the sensory terminals called
Receptor potential
What does more stimulus cause?
More transmitter to be released
What is rapid adaptation?
A mechanism to prevent sensory overload
What happens in slow adaptation
The generator potential set up by a constant stimulus will wane slowly over time
What happens in no adaptation
The generator potential and thus action potential frequency will remain constant if the stimulus remains constant
What are 2 properties of nerve fibres
Nerve fibres have different diameter
can be myelinated/non-myelinated
What does afferent mean
Conducting or conducted inwards to something
What does efferent mean
Conducting or conducted away from something
