Test 3: Types of Neurons & Supportive Cells

Flashcard maker : Ewan Tanner
What type of neuron has one axon and multiple dendrites?multipolar neuron
What is the most common type of neuron, most neurons in the CNS?multipolar neuron
What type of neuron has one axon and one dendrite?bipolar neuron

What type of neuron is found in olfactory cells, the retina, and the inner ear?bipolar neuron
What type of neuron has a single process leading away from the neuron?unipolar neuron
What type of neuron are sensory cells (from skin and organs to spinal cord)unipolar neuron
What type of neuron has many dendrites but no axon?anaxonic neuron
What type of neuron is found in the retina, brain, and adrenal gland?anaxonic neuron
There are about _____ _____ neurons in the nervous system, and neuroglia outnumber neurons by at least ____ to 1.one trillion, 10
______ protect neurons and help them function.neuroglia (glial cells)
Neuroglia bind neurons together and form framework for ____ tissue. In the fetus, neuroglia guide migrating ____ to their destination. If a mature neuron is not in ____ ____ with another neuron, it is covered by ____ ____. They prevent neurons from touching each other which gives precision to _____ pathways.nervous, neurons, synaptic contact, glial cells, conduction
What are the four types of glia found in the CNS?oligodendrocytes, ependymal cells, microglia, astrocytes
Which type of CNS glia form myelin sheaths in the CNS that speed signal conduction?oligodendrocytes
What are the arm-like processes that wrap around nerve fibers?myelin sheaths
Which type of CNS glia line internal cavities of the brain?ependymal cells
Which type of CNS glia secrete and circulate cerebrospinal fluid (CSF)- cuboidal epithelium with cilia on apical surface?ependymal cells
Which type of CNS glia wander through CNS looking for debris and damage?microglia
Which type of CNS glia develop from white blood cells (monocytes) and become concentrated in areas of damage?microglia
Associate _____ with myelin sheaths. Associate ______ with lining cavities and CSF. Associate _____ with helping with debris and damage. Associate ____ with being the most abundant.oligodendrocytes, ependymal cells, microglia, astrocytes
What is the most abundant glial cell in the CNS, covering brain surface and most nonsynaptic regions of neurons in the gray matter?astrocytes
Astrocytes provide a supportive ______, have extensions (_____ ____) that contact blood capillaries and stimulate them to form a seal called the ___-____ _____, convert ____ to _____ and supply this to neurons, secrete nerve ____ factors, communicate _____ with neurons, and regulate chemical composition of tissue fluid by absorbing excess ______. When neuron is damaged, astrocytes form hardened ____ ___ and fill in space.framework, perivascular feet, blood-brain barrier, glucose, lactate, growth, electrically, neurotransmitters, scar tissue
What are the two types of glial cells of the PNS?satellite cells, schwann cells
Which PNS glial cells surround the neurosomas in ganglis of the PNS?satellite cells
Which PNS glial cells provide electrical insulation around the soma?satellite cells
Which PNS glial cells regulate the chemical environment of the neuron?satellite cells
Which PNS glial cells envelope nerve fibers in the PNS?schwann cells
Which PNS glial cells wind repeatedly around a nerve fiber?schwann cells
Which PNS glial cells produce a myeling sheath similar to the ones produced by oligodendrocytes in the CNS?schwann cells
Which PNS glial cells assist in regeneration of damaged fibers?schwann cells
Myelin sheath provides _____ around a nerve fiber. It consists of the plasma membrane and ____ ____ (20% ____, 80% _____).insulation, glial cells, protein, lipid
What is the production of myelin sheath called?myelination
Myelination: In the PNS, _____ ____ spiral repeatedly around a single nerve fiber. They lay down as many as one hundred layers of _____. There is no ____ between the membranes.schwann cells, membrane, cytoplasm
What is the thick, outermost coil of myelin sheath that contains the nucleus and most of its cytoplasm in the PNS?neurilemma
External to the neurolemma is ____ ____ and a thin layer of fibrous connective tissue called _____.basal lamina, endoneurium
Myelination: In the CNS, ______ myelinate several nerve fibers in their immediate vicinity. They are anchored to multiple nerve fibers and cannot migrate around any one of them (unlike ____ ____). They must push newer layers of myelin ____ the old ones, so myelination spirals ____ towards the nerve fiber. Nerve fibers in the CNS __(do/do not)__ have neurilemma and endoneurium.oligodendrocytes, schwann cells, under, inwards, do not
Many schwann cells and oligodendrocytes are need to cover _____ nerve fiber with myelin.one
What are the four segments of myelin sheath?nodes of ranvier, internodes, initial segment, trigger zone
What are the gaps between segments in the myelin sheath called?nodes of ranvier
What are the myelin-covered segments from one gap to the next called?internodes
What is the short section of nerve fiber between the axon hillock and the first glial cell?initial segment
What are the axon hillock and initial segment of the myelin sheath together called? It plays an important role in initiating nerve signals.trigger zone
Many CNS and PNS nerve fibers are ______.unmyelinated
In the PNS, ____ ____ hold 1 to 12 small nerve fibers in surface grooves.schwann cells
The membrane folds ____ around each fiber.once
What are the two determining factors in the conduction speed of nerve fibers?diameter of the fiber, presence or absence of myelin
_____ fibers have more ____ ____ and conduct signals more rapidly.large, surface area
Myelin _____ speed signals.furthers
Slow signals are sent to the ____ ____ where speed is less of an issue.GI tract
Fast signals are sent to the _____ ____, where speed relates balance and coordination.skeletal muscles
Regeneration of a nerve fiber can occur 1). if the ____ is in tact. 2). at least some of the _____ remains; however, regeneration is not always perfect or fast (can take up to ___ years).soma, neurilemma, 2

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