Nervous System Flashcards
Central Nervous System consists of… vs peripheral
CNS - brain and spinal cord
PNS - Cranial and spinal nerves and associated ganglion
Somatic vs Autonomic
Somatic: Skeletal muscle (eff pathways) and sensory information (aff pathways)
Autonomic: Cardiac muscle, smooth muscle, glands (eff and aff pathways)
Neural cell bodies grouped together with a similar function are known as what?
Nuclei - in the CNS
Ganglia - PNS
Dendrites
Often short cells which expand the surface for reception of stimuli
Axons
Conduct impulses away from cell body, may have collateral and terminal branches to many target cells
Myelination occurs via which cells (CNS vs PNS)
CNS - oligodendrocytes
PNS - Schwann cells
Nodes of Ranvier are? Required for what?
Nodes of Ranvier, also known as myelin sheath gaps, are periodic gaps in the insulating myelin sheaths of myelinated axons where the axonal membrane is exposed to the extracellular space. Required for saltatory conduction.
Group A nerves are;
alpha, beta, gamma and sigma - what are they used for?
alpha 12-20um - motor and proprioception
beta 5-12um - touch and proprioception
gamma 5-12um - fusimotor to muscle spindles
sigma 1-15um - touch, pain + temp
Touch and pain are what nerves?
Group C - small nerves up to 2um, unmyelinated
How many spinal nerves are there?
C - 8 T - 12 L - 5 S - 5 Coccygeal - 1
Each spinal nerve is formed by union of anterior and posterior root from the spinal cord - what is contained in anterior vs posterior?
Anterior root - motor fibres for skeletal muscle
Posterior root - sensory fibres (cell bodies in the posterior root ganglion)
After formation the spinal nerves divide into what?
anterior and posterior rami - anterior rami form the great n. plexus.
Which two nerves have their own blood supply?
Sciatic and median. All others supplied by local arteries
Motor pool is what?
Collection of motor neurons that innervate skeletal muscle - overlap each other
Explain the stretch reflex
Stretches spindle -> stimulates aff fibres -> spinal cord via post nerve root -> synapse directly with alpha motor neurons -> causes stimulation of efferent axon -> NMJ and contraction
