Nervous System 1-2 Flashcards
What does the central nervous system comprise of?
Brain
Spinal cord
-processes and integrate incoming information
-stimulate motor function in muscles and glands
A) grey matter: collection of cell bodies, fibers and neurological cells
B) white matter: collection of myelinated and unmyelinated axons and nuerological cells
What comprises the peripheral nervous system?
Cranial nerves( I-XII)
-spinal nerves (31 pairs)
-ganglia-collection of cell bodies
Dorsal root ganglia (DRG), preaortic, sympathetic chain ganglia
- plexuses -network of nerves
- cervical, brachial, lumbar, sacral, enteric, cardiopulmonary,esophageal, etc
Sensory receptors
-Pacinian, Merkel, free nerve endings, mechanoreceptor, osmoreceptors, proprioceptor
Explain the organization of the somatic peripheral nervous system
- voluntary
- motor: skeletal muscles
- general sensory: skin, joints
- special sensory-taste, smell, hearing, vision, equilibrium
Explain the organization of the sympathetic peripheral nervous system
- origin: T1-L2 level of the spinal cord
- involuntary motor
- cardiac and smooth muscles
- sweat glands
- sensory: organs
Explain the parasympathetic nervous system organization.
Origin: CN III, VII, IX, X
S2, 3,4 level of the spinal cord
- involuntary: motor
- cardiac and smooth muscles
- all other glands
- sensory organs
Explain the enteric nervous system functional system
Little brain- independent of the brain
Belongs to ANS
-embedded in the wall of the gastrointestinal tract and digestive organs
Consists of two plexus:
- myenteric (auberc’s)
- submucosal(Meissner’s)
Describe the parts of the neuron
Body(perikaryon)-found in grey matter in CNS
Membrane
Cytoplasm(neuropplasma)
-Nissl bodies -aggregates of rough endoplasmic reticulum
- neurofibrils and microfilaments
- Lipofuschin: aging pigment
Fibers(neuronal process) -
Dendrites -receive inputs, organelles present
Axon- found in white matter in CNS
-Axon hillock
- cytoplasm(axoplasm)- mitochondria, microtubules and neurofilaments
-membrane (axolemma)
- myelin sheath deposited by Schwann cell
-axon terminal
- synaptic end bulb
What is the purpose of multipolar (efferent) neurons?
Multipolar(efferent)
- motor neurons (brain & spinal cord), inter neurons
- several branching dendrites, one axon
What is the purpose of bipolar neurons?
- one definite and axon
- found in special sensory organs
What is the purpose of Pseudo polar neurons?
Afferent
- originally bipolar
- sensory neurons
Where are pyramid cells found?
Cerebral cortex
Where are Purkinje fibers found?
Cerebellum
What are the nervous cells of the CNS?
- astrocytes
- Oligodendrocytes
- Microglia
- Ependymal
What are astrocytes?
A) protoplasmic grey matter)
B) fibrous (white matter)
- protection -blood brain barrier
- support
- metabolic exchange, regulate environment
- influence formation of synapses-learning
- tissue repair
What is the purpose of oligodendrocytes?
Insulation of multiple axons
What is the purpose of ependymal cells?
Cuboidal to columnar
- lines cavities of the CNS
- microvilli and cilia
What are the components of the blood brain barrier?
Capillaries
- tight junctions between endothelial cells
- thick basement membrane
Astrocytes
-processes
What are Schwann cells?
Neuroloemmocytes/Schwann cells-peripheral nervous system
- insulation of single axons
- encloses multiple unmyelinated axons
- axon repair
What are the satellite cells?
Peripheral nervous system
- surround the body
- regulate exchange between neurons and interstitial fluid
Explain myelination
- Begins during fetal development, groove develops in the Schwann cell.
- Schwann cells spirals around a single axon, an oligodendrocyte spirals around many axons
- Schwann cell cytoplasm and nucleus forms the outer layer, an oligodendrocyte’s cell cytoplasm and body are removed from the axon
The inner portion (sheath) multiple layers of Schwann cell membrane
What are nodes of ranvier?
- gaps between myelinated portion of axons
- allows quicker conduction of nerve impulse
Increase in amount of myelin from birth to maturity increases speed of nerve impulse conduction
What is a synapse?
Site of communication between neurons or between neurons and effector cells