nervous system Flashcards
21: 3 subdivisions of somatosensory system
cutaneous sensations (skin) visceral (internal organs) proprioception (limbs in body)
21: action potential initiation
receptor potential exceeds threshold
nerve fibre fires a.p.
21: sensory transduction - steps
- receptor potentila
- integration at trigger zone
- a.p
- neurotransmitter release
21: cutaneous skin receptors
superficial merkels disk epidermal dermal border free nerve ending messiers corpuscle deep pacinian corpuscle ruffians corpuscle
21: receptive field
area over which stimulus activates receptor
21: receptive field - eye
retina
21: receptor adaptation - rapidly adapting receptor vs slowly adapting receptor
rapid = neuron stop firing a.p even though stimulus is maintained
slow - nerve continues firing a.p throughout stimulus
21: rapid adaptation of pacinian corpuscle when capsule is present vs when its removed
present - rapid adaptation of receptor potential
removed - less adaptation of receptor potential, adaptation eliminated
21: temperature receptors - warm vs cold
warm - C fibres
cold - Asigma
21: 2 pathways that transmit cutaneous signals to the brain
dorsal column pathway (DC)
spinothalamic tract pathway (STT)
21: where are cell bodies of primary sensory nerve fibres found
dorsal root ganglion
21: where do fibres enter
spinal cord at dorsal root
21: dorsal column pathway
- first synapse - dorsal column nuclei in medulla
- pathway crosses over (left to right cortex and right to left cortex)
- feedback to motor systems
21: forsal column pathway - carries information about
stimuli moving over skin
recognition of objects
21: connections of the spinothalamic tract (STT)
spinothalamic pathway crosses over with spinal cord and travels up spinal cord in thalamus
21: what does the STT carry information about
coarse touch
temperature
nociception painful stimuli
21: body region with largest area of representation on somatosensory cortex
hands and face
21: muscle spindles respond to
muscle stretch
21: golgi tendons respond to
muscle tension
22: muscle coordination - flexion
contract flexors and relax extensors