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Microalgia
- Smallest least abundant neuroglia
- Phagocytes, thorny looking
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Ependymal Cells
- Simple epithelial layer
- Lines centralof brain cavity and spinal cord
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Oligodendrocytes
- Produce myelin sheath around nerve cell axons
- Fewer branches than astrocytes
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Satellite Cells
Surround cell bodies in ganglia
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Schwann Cells
- Surround axons in PNS
- Produce myelin sheath
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Nerves
- Bundle of neurons outside CNS(in PNS)
- Naked eye can see
- Contain both sensory and motor neurons
- Some sensory/motor only
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Connective Tissue
- Hold neurons together
- -Endoneurium- surrounds each axon (loose CT)
- -Perioleurium- surrounds bundle of axons (fascicle)
- -Epineurium- surrounds entire nerve (bunch of fascicles)
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Reflex Arcs
- Chains of neurons- create reflexes
- Unlearned and involuntary
- Somatic or visceral
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5 components of Reflex Arcs
- Receptor- stimulus acts
- Sensory neuron-signal to CNS
- Integration Center- 1 or more synapses
- Motor Neuron- Impulse from integration center
- Effector- muscle/gland that responds
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Monosynaptic
- 1 synapse involved
- Fastest feflex
- Ex. knee jerk
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Polysynaptic
- One or more interneurons part of reflex pathway
- Most conatin interneuron
- -3 neuron reflexes
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Gray Matter (CNS)
- Cell bodies
- H shaped in spinal cord
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White Matter (CNS)
- Axons (after myelinated)
- Tracts=bundles of axons
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Disorders of Nervous System
- Multiple Sclerosis (MS)
- -mostcommon in young adults
- -progressive-destroys patches of myelin
- -cause not well understood- autoimmune
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Nervous System
- Master control and communications center
- Communicate via electrical signals
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3 overlapping functions of nervous system
- Sensory receptors monitoring changes
- Integration (processing and interpreting)
- Response (motor ouotput)
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Somatic
Structures external to
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4 combinations
- Somatic sensory- Both part of proprioception
- Somatic motor
- Visceral sensory- Voluntary
- Visceral motor
ANS- Involuntary
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Neurons- Cell body
- One nucleus
- Group of cell bodies in CNS= nucleus
- Group of cell bodies in PNS= ganglia
- Metabolic center of neuron
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Neurons- Dendrites
- Branched processes
- Extend from cytoplasm
- Receive impulses and conduct impulses to cell body
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Neurons- Axons
- Conduct impulses away from cell body
- Myelinated or large= increase electrical conduction speed
- Lengths vary: have axon terminals at end(bulbs)
- Is a cytoplasmic extension from cell body
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Neurons Synapses
- Controls info one neuron to the next
- Presynaptic towards synapse
- Postsynaptic away from synapse
- Can be excitatory or inhibitory
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Neurons Structural
- Multipolar
- Bipolar
- Unipolar
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Multipolar
Most of body's neurons- many dendrites and an axon
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Bipolar
Processes extend from two sides of the body(rare, sensory)
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Unipolar
One process, divides like a T(sensory neurons)
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Neurons- Functional
- Sensory (Afferent)- to CNS
- Motor (Efferent)- Away from CNS
- Interneurons (association neurons)- between sensory and motor only in CNS
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Neuroglia
- Central cell body and branching processes
- Outer neurons # 10-1 in CNS
- 1/2 brains mass
- Support
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Neuroglia in CNS
Astrocytes, microalgia, ependymal cells
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Astrocytes
- Most abundant
- Key in blood brain barrier
- Regulate passage of molecule, blood to brain
- Only allows small molecules to brain
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Neuroglia in PNS
Satellite cells and schwann cells
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