M2 - Nervous Tissue Flashcards
Collection of cell bodies - CNS
center, nucleus (nuclei)
Collection of cell bodies - PNS
ganglion (ganglia)
Collection of axons traveling to common destination - CNS
tract, column
Collection of axons traveling to common destination - PNS
nerve
Endoneurium
CT around each axon
Perineurium
CT around individual fascicles (small groups of axons)
Epineurium
CT around entire nerved
Dendrites
Receive electrical signals
Cell body
Processing
Axon
Conduct signal away from cell body
Axon terminal
Communicates w next neuron
Presynaptic (preganglionic)
First neuron in pathway
Postsynaptic (postganglionic)
Receives info from presynaptic neuron
Bipolar neurons
Dendrites merge together to form a single dendrite, single dendrite travels to cell body, axon carries info away from cell body; rare; found in olfactory system and retina
Pseudounipolar neurons
Cell body looks like it’s hanging off axon, dendrites converge, meet single axon early in neuron’s pathway, long axon extends toward target; sense of touch from PNS to CNS
Mutipolar neurons
Most common, dendrites surround cell body, cell body sends signal thru one axon to target
Convergence
Many neurons synapse on single postsynaptic neuron - allows for signal to be amplified
Nervous system (communication)
Neurotransmitters released into synaptic cleft
Divergence
One presynaptic neuron is synapsing w multiple other neurons - message sent to multiple areas so dif areas know what is happening @ same time
Endocrine system (communication)
Hormones released into the blood
Nervous system (target)
Other neurons, muscle cells, glandsE
Endocrine system (target)
Any cell in body with a receptor for that hormone
Nervous system (response time + duration)
Rapid time
Short duration (milliseconds)
Endocrine system (response time + duration)
Slow time
Long duration (minutes to days to weeks)
Nervous system (range of effect)
Localized, specific effects
Endocrine system (range of effect)
Widespread effects throughout body
Neuron
Electrical signals, life for lifetime, don’t divide, high metabolic rate, most cell bodies in CNS
Glial cells
Provide protection, insulation, nourishment for neurons, can divide, more abundant than neurons
Myelin sheath
Facilitates transmission of electrical signals along axon; the thicker the myelin layer, the faster the conduction speed
Node of Ranvier
Gaps in myelin, assist w speed of conduction along an axon
Schwann cells
In PNS:
Myelinated axon - wrap itself around axon in layers, only one part of one axon at a time
Unmyelinated axon - just surrounds axons
Oligodendrocytes
Myelinate axons in CNS, part of oligodendrocyte wraps around axon in layers, can send branches of itself to myelinate several parts of axon
Microglia
Patrol brain and spinal cord, send out processes that monitor environment, look for pathogens and damage, engulf foreign substances/damaged tissue, clean up area
Astrocytes
star-shaped, form blood-brain barrier, hold things together, regulate environment around neurons, regulate inflammatory response to damage
Ependymal cells
Filter blood, produce cerebrospinal fluid, secrete it into open spaces (ventricles) in CNS, cilia help move cerebrospinal fluid thru open spaces
Satellite cells
In PNS
Surround cell bodies, isolating and protecting them from surrounding cells
Wallerian degeneration
Injury to axon, part of axon distal to cell body breaks down
Axon regeneration
Schwann cells line up along remaining endoneurium, form regeneration tube that guides axon back to target
Afferent info
Going @ CNS, incoming sensory info
Efferent info
Exiting motor info to muscle or gland
General visceral sensory
Monitoring visceral output, sensing secretion of glands, generates visceral motor response based on input
General somatic sensory
Sense of touch, pain, proprioception (sense of how muscles and joints moving and where body is in space)
General visceral motor
Secretion of glands, contraction of smooth muscle and cardiac muscle
General somatic motor
Innervation of skeletal muscle, causes a voluntary movement
