Ch. 6: Somatosensory System Flashcards
What is Exteroception?
Discrimitive touch
Outside sensation
What is Proprioception?
Ability to know where you are in space
(Gives Cerebellum something to compare plan to)
What is Sensation?
Raw modality
(touch or pin prick)
What is Perception?
Making meaning of sensation
What so Sensory Receptors respond to?
A variety of stimuli
What are “modality-specific” receptors?
Have a modality gated channel at the end
What are the 3 types of “Modality Receptors?”
- Mechanoreceptors
- Chemoreceptors
- Thermoreceptors
What do Mechanoreceptors sense?
- Touch
- Pressure
- Vibration
- Stretch
What do Chemoreceptors sense?
Chemical in extracellular fluid cause AP to start
What do Thermoreceptors sense?
Hot and cold temperatures
What are Nociceptors?
- Sense Pain!
- High threshold
- Need STRONG stimulus to activate
- Subset of: Mechano-, Chemo- and Thermoreceptors
What does a Phasic Receptor sense?
- Detect Change
- start and stop of movement or touch
- “Fast” adapting
What does a Tonic Receptor sense?
- Sustained contact
- detecting continuous duration of touch
- “Slow adapting”
Somatosensory Peripheral Neurons are our named neurons.
What is their morphology?
- Pseudounipolar
- Peripheral axon projection
- Central axon projection
What do Ia, Ib, II somatosensory neurons do?
- Proprioception
- Muscle spindle and muscle tendon
- Muscle length
What does an A-beta somatosensory neuron do?
- Exteroception
- “touch” of skin and subcutaneous tissue
- Discriminative touch - “I can describe and locate it”
What does an A-delta somatosensory neuron do?
- “Fast,” local pain & temp (superficial and deep)
- sense mechanical touch → cant describe, just scream!
What does a C somatosensory neuron do?
- “Slow.” non-localized pain & temp (superficial and deep)
- smaller = slower
- say “dang that hurts”
- Ex: stub toe, lightining bolt pain = A-delta, then it aches = C
What is a Receptive Field in cutaneous innervation?
Area of skin innervated by peripheral branch or sensory neurons
In cutaneous innervation, what parts of the body have the highest Density of receptors?
- Fingers, face, toes
- More dense = more iscriminative touch
What receptors make up Fine Touch?
What do they do?
- Combo of specialized receptor + A-beta afferent {biggest touch axon}
- Discriminative touch - describe & locate pain
What are the 2 different types of fine touch receptors?
What do they do?
- Cutaneous (smaller receptive fields) - SUPERFICIAL
- light touch, vibration, pressure, hair movement
- Subcutaneous (larger receptive fields) - DEEP
- touch, vibration, stretch of skin
What named receptors make up Coarse Touch?
What do they do?
- Free nerve endings + A-delta & C affernt
- mediated by free nerve endings
- A-delta: fast pain
- C: slow pain