NAS W2 - SOMATIC & SYNAPSE Flashcards
AFFERENT
- sensory - to brain
- carry sensory info from surface of body to the brain
EFFERENT
- motor - to effectors
- convey commands from brain (SNS) to skeletal muscles (lead to contraction)
- has dendrites around the cell body & connects to axon BUT afferent has a naked cell body (no dendrites)
PNS
connects CNS to target organs & connects sensory organs to CNS
INITIATION SEGMENT
where AP is generated
GLIAL CELLS
produce myelin (for myelin sheath - to protect axon)
SNS CHARACTERISTICS
- bi-stable state (always either active or inactive)
- effector organ is skeletal muscle & is responsible for muscle tone of body (tensing)
CRANIAL NERVES
transfer info to/from brain in relation to head & neck
FEATURES/JOB OF DENDRITES OF SOMATIC EFFERENTS
- outside ones are thin & dendrite gets thicker as you get closer to cell body
- increase SA of membrane cell body (for dendrite to receive signal)
DIF. IN INITIATION OF EFFERENT & AFFERENT IMPULSES
efferent - impulses generated in cell body to axons to muscles
afferent - peripheral end of axon creates impulse & passes it to side of axon which is in brain (cell body only used for metabolism & to make nutrients for cell)(not used to initiate any signals in afferent)
HOW TO TELL IF NEURONE IS HEALTHY
if nucleus in centre of body
SOMATIC MOTOR NEURONES
- in ventral horn of spinal cord or cranial nerve motor of brain
- heavily myelinated as very quick impulse transmission
STRIATED MUSCLE
- all fibres travel in one direction & has sarcomere (skeletal & cardiac)
NON-STRIATED MUSCLE
fibres flow in opp. directions (smooth)
DISEASES THAT DEMYELINATE AXON
multiple sclerosis, diabetes, Guillain barre
MYELINATION IN PNS
- 1 schwann cell myelinates each axon (insulated to speed up impulse conduction)
- satellite cells support support the neurones
- microglia used for immune & inflammatory functions