Introduction to the Nervous System Flashcards
What does the CNS consist of?
brain and spinal cord protected within skull and vertebral column
What does the PNS consist of?
most cranial and all spinal nerves, various ganglia
What are aggregations of nerve
cell bodies called in the CNS and
PNS?
PNS - ganglia
CNS - nuclei
Afferent Neurons
sensory (somatic, visceral, special)
carries nerve impulses from sensory stimuli toward CNS
Efferent Neurons
motor (somatic, autonomic - sympathetic, parasympathetic, enteric)
carries neural impulses away from CNS
Interneurons + local & projection neurons
communication between neurons within CNS
projection - cerebral cortex to spinal cord
local - spinal cord reflex (interneuron links sensory neuron from PNS to a motor neuron in PNS)
What is the role of astrocytes? (4)
maintains levels of nt around synapses, metabolic support, contribute to BBB thru perivascular endfeet that surround capillaries, neurovascular coupling (increase blood flow thru vasodilation when increased neuronal activity)
Blood-brain barrier
regulates movement of substances from circulating blood to extracellular fluid of CNS
Oligodendrocytes & Schwann cells
forms myelin
Schwann cells maintain unmyelinated axons
Satellite glial cells
astrocytes of PNS
covers the surface of neuron cell bodies in ganglia, controls microenvironment, metabolic support
What is the purpose of myelin?
forms electrical insulation around axons and dendrites (allows electrical signal to travel faster over long distances)
gaps in the myelin (nodes) permit regeneration of electrical signals passing down the axon
What is white matter?
regions of myelinated axons
What is grey matter?
regions rich in unmyelinated nerve cell bodies
Microglia
quiescent - homeostasis
reactive - disease, illness, injury response
Ependymal cells
developmental glia that lines the wall of ventricles
produces the fluid in the ventricles (cerebrospinal fluid)
