Neurons

what are neurons?

the structural units of the nervous system that conduct messages in the form of electrical impulses throughout the body

what are the specialized characteristics of neurons?

extreme longevity, amitotic(interphase G0), and have a high metabolic rate requiring a continuous supply of oxygen and glucose

what is the other name for a cell body?

perikaryon or soma

what is the neuron cell body?

biosynthetic centre of the neuron, where proteins, membranes and chemicals are synthesized.

what is the name for a rough Er that is inside of a neuron?

chromatophilic substance or nissl bodies

What are nuclei?

clusters of neuron cell bodies in the CNS

what are ganglia?

clusters of neuron cell bodies in PNS

what are tracts?

bundles of neuron processes in the CNS

what are nerves?

bundles of neuron processes in the PNS

what are dendrites?

cell processes that are the receptive regions of the cell and provide surface area for receiving signals from other neurons

what do dendrites in the brain do?

collect information and contain dendritic spines, appendages with bulbous or spiky ends

what are axon hillocks?

Cone-shaped areas

what are long axons called?

nerve fibres

What are axon collaterals?

branches of axon

what are axon terminals?

endings where axons make synaptic contact with other nerve or effector cells (ex muscle) also called terminal buttons

what are action potentials?

long distance signals

what is the axolemma?

neuron cell membrane

what do axon terminals release?

neurotransmitters that either excite or inhibit other neurons or effector cells

what is anterograde movement?

movement away from the cell body, toward the axon terminal

what is retrograde movement?

movement going back towards the cell body

what would use retrograde movement? why?

some viruses such as polio to attack the CNS without having to cross the blood-brain barrier

what are multipolar neurons?

the most common type of neuron. have 3 or more processes, found in the brain and spinal cord, one axon and many dendrites

what are bipolar neurons?

one axon and one dendrite. they are located within the retina of the eye, and olfactory mucosa

what are unipolar neurons?

single T-shaped process

what is peripheral structure?

associated with a sensory receptor

what is a proximal sturcture?

enters the CNS

what are purkinje cells?

have many branches and are used to synchronize activity(eg throwing a ball)

what are pyramidal cells?

they listen to sensory info(eg touching a hot cup)

what are sensory(afferent) neurons?

conduct impulses toward the CNS from receptors. almost all are unipolar and cell bodies are located in ganglia in the PNS

what are motor(efferent) neurons?

conduct impulses from the CNS to effectors. these neurons are multipolar and most cell bodies are located in the CNS

what are interneurons?

conduct impulses between sensory and motor neurons, or in CNS integration pathways

what is another name for interneurons?

association neurons