Neurology lectures 1-3

White matter

Aggregation of axons/fibers in CNS

Gray matter

Aggregation of neurons/cell bodies in CNS

Nuclei

Groups of neurons in a cluster of the CNS

Ganglia

Groups of neurons in a cluster of the PNS

Tract

Bundle of nerve cell projections/axons/fibers in CNS

Nerve

Bundle of nerve cell projections/axons/fibers in PNS

Commissure

Bundle of nerve fibers that cross midline

Types of CNS cells

Ependymal cells, neurons, non-neuronal supporting cells

Ependymal cells

Specialized epithelial cells that line ventricles of brain and spinal cord; function is to move CSF through brain’s ventricular system

Ventricular system

Spaces within brain and spinal cord where CSF flows

Choroid plexus

Specialized ependymal cells only found in ventricle; function is to produce and secrete CSF; role in blood-CSF barrier

Sensory neuron

Detects change in external or internal environment and sends info (afferent) to CNS

Motor neuron

Sends signal to control contraction of muscle or secretion of a gland (efferent)

Interneuron

Communication between sensory and motor neurons; entirely within CNS

Dendrites

Input zone

Cell body/soma

Integrate zone

Contains nucleus

Function: metabolism and synthesis for cell

Axon hillock

Interface between cell body and axon; part of cell body

Function: generate action potentials

Axon

Conduction zone

Terminal bouton

Output zone

Function: Releases neurotransmitters when activated by an action potential

Neuroglia

Supporting non-neuronal cells of nervous system

No action potentials or nerve impulses, cannot form synapses, can divide

How are non-neuronal cells different from neurons?

Provide structural support, form myelin sheaths, control supply of neurons across BBB, support and clear dead neurons

Functions of non-neuronal cells

Astrocytes

Majority of non-neuronal cells in the brain

Recycle neurotransmitters

Secrete neurotrophic factors that stimulate growth and maintenance

Maintain homeostatic balance in extracellular space

Gatekeepers in CNS; line BBB

Microglia

Smallest glial cells

Intrinsic immune cells of CNS

Inflammation response following damage to CNS

Protect against microorganism invasion

Remove debris of dead/degenerating neurons and glia

Oligodendrocytes

Form myelin sheath around brain and spinal cord axons

Support axons

Schwann cells

Only type of neuroglia mentioned in the PNS

AKA lemmocytes

Form myelin sheath of PNS

Action potential

Mechanism for communication/transmission of info between neurons and from neurons to muscles

Nodes of Ranvier

Separation to myelin sheath that allows AP to be reactivated; without these AP will essentially “die off”

Saltatory conduction

Nerve impulses jumping from one node to another, which makes action potentials occur faster

Selectively permeable membrane, ions moving toward equilibrium potential, active Na/K pump

Three mechanisms that maintain the RMP