Final Exam:Final Flashcards
What are the divisions of the Nervous System?
Central Nervous System (CNS) and Peripheral Nervous system (PNS)
What are the components of the CNS?
Brain (85 billion neurons) Spinal Cord (100 billion neurons)
What are the functions of the CNS?
process incoming sensory info; source of thoughts; emotions; memories; stimulate muscle contraction and glandular secretion.
What are the components of the PNS?
Nerves- bundles of hundreds to thousands of axons; 12 pairs cranial; 31 pairs spinal cord.
Ganglia
small masses of nervous tissue primarily nerve cell bodies; outside brain and cord.
Enteric plexus
extensive network of neurons in walls of organs of GI tract; regulate digestion.
Sensory receptions
monitors change in internal/external environment.
What are the divisions of the PNS?
Somatic NS and Autonomic NS
Somatic NS
sensory neurons take info from somatic receptors _ CNS; motor neurons conduct impulses from CNS _ skeletal mm only. (voluntary)
Autonomic NS
info flows from sensory receptors in visceral organs _ CNS; motor neurons conduct impulses from CNS _ smooth and cardiac mm and glands (involuntary)
What are the divisions of the motor portion of the ANS?
sympathetic; parasympathetic
Sympathetic
fight or flight
Parasympathetic
rest and digest
Enteric NS
brain of the gut - over 1 mil neurons in plexuses extend throughout GI tract.
What is nervious tissue composed of?
Neurons and Neuroglia.
Neurons
form complex processing network in brain and spinal cord; connect all regions of body to the brain and spinal cord; highly specialized cells; can reach great lengths; unique functions (sensing; thinking; remembering; control muscle activity; regulate gland secretions. Unable to undergo cell division (mitosis)
Neuroglia
smaller; greatly outnumber neurons; support; nourish; protect and maintain interstitial fluid that bathe neurons; can continue to divide throughout lifetime. _ Glue that holds nervous tissues together._
Cell Body
contains nucleus cytoplasm; with typical organelles; also free ribosomes and rough ER ( nissl bodies)
Axon
propagate nerve impulses toward another neuron; muscle fiber or gland.
Dendrite
receiving portion of neuron.
Neurofibrils
bundles of intermediate filaments provide cell shape and support.
Microtubles
assist in moving materials between cell body and axon.
Lipofuscin
yellow/brown clumps of pigmentin cytoplasm of aging neurons.
Nerve Fiber
any neuronal process that emerges from cell body of a neuron.
Axon hillock
cone shaped elevation where cell body joins axon.
Axoplasm
cytoplasm of an axon.
Axolemma
plasma membrane of an axon.
Axon Terminal
branching off of the axon collateral into fine processes.
Synapse
site of communication between 2 neurons of neuron and effector cell.
Synaptic end bulbs
swellings at tips of axon terminals
Synaptic vesicles
tiny membrane enclosed sacs store chemicals.
Neurotransmitters
chemical/molecule released from synaptic vesicle excites or inhibits another neuron; m fiber; or gland.
Describe slow axonal transport
1-5 mm per day; one direction; axoplasm from cell body toward axon terminals; supplies new axoplasm to developing axons; replenishes I for growing neurons.
Describe fast axonal transport
200-400 mm/day; proteins function as motors to move substances along surfaces of the microtubules of neurons cytoskeleton. BOTH directions- anterograde (forward cell body_axon terminals) Retrograde (backward; materials from axon terminals_cell body) Substances: trophic chemicals (nerve growth factor); harmful agents (tetanus toxin; viruses that cause rabies; herpes simplex; and polio)
What are the structural classifications of neurons?
multipolar; bipolar; unipolar; purkinji cells; and pyrmidal cells
What are the funtional classifications of neurons?
sensory; motor; interneurons
Multipolar neurons
several dendrites 1 axons; mostly in brain and cord and all motor neurons.
Bipolar neurons
1 main dendrite 1 axon; in retina; inner ear; olfactory area of brain.
Unipolar neurons
dendrites and 1 axon; fused form continuous process emerges from cell body AKA pseudounipolar; most act as sensory receptors that detect stimulus.
Purkinji cells
in cerebellum.
Pyrimdal cells
found in cerebral cortex.
Sensory function
afferent - receptors at distal ends of cells; most unipolar.
Motor function
efferent -Conveys AP away from CNS to effectors; multipolar.
Interneurons function
AKA association nerves; mainly in CNS between sensory and motor neurons; most multipolar.
What are the types of neuroglia?
Astrocytes; oligodendrocytes; microglia; ependymal cells; shwann cells; satellite cells
Nueroglia
glue that holds nervous tissue together; make up ¬ volume of CNS; do not generate/propagate AP; can multiply and divide in mature nervous system.
Astrocytes
star shaped; many processes; supporting cells for neurons; create blood brain barrier between blood and interstitial fluid; secrete chemicals in embryo to regulate growth; maintain appropriate chemical environment for generation of nerve impulse; influencing formation of neural synapses.
Oligodendrocytes
smaller than astrocytes fewer processes; processes form myelin sheaths around CNS axons.
Microglia
small cells slender processes spine like projections; phagocytes.
Ependymal cells
cuboidal to columnar; microvilli and cilia; line ventricles of brain and central canal of spinal cord; circulation of CSF; blood CSF fluid barrier.
Schwann cells
in PNS; around PNS axons; form myelin sheaths around axons; axon regeneration.
Satelite cells
around cells bodies of neurons on PNS ganglia; structural support; regulate exchange of material between neuronal cell bodies and interstitial fluid.
What is myelin comprised of?
multi-layered protein and lipid covering
What are the similarities and differences between schwann cells and oligodendrocytes
Schwann cells form myelin sheaths around axons in the PNS; have ganglion cell bodies (clusters) and nerves (bundle of axons in PNS) contain neurolemma (only on axons of PNS); Oligodendrocytes processes form myelin sheaths around axons in the CNS; have nucleus cell bodies and tracts; no neurolemma. Both have nodes of Ranvier (gaps in sheaths) but less numerous in oligodendrocytes.
Compare and contrast clusters of neuronal cell bodies. What are they? Where are they found?
Ganglion- cluster of cell bodies in the PNS associated with spinal/cranial nerves; found in Schwann cells.; Nucleus- cluster in bodies of CNS; found in oligodendrocytes.
Know the difference between white and grey matter. Know where they will be found.
White matter- primarily mylenated axons.; Gray matter- primarily cell bodies dendrites; unmylenated axons; axon terminals and neuroglia; appears gray due nissl bodies and lack of myelin.; Spinal cord- white matter outside; gray inside. Brain- gray outside; white outside.
Where is white matter found?
outside
Where is grey matter found?
inside
What is the difference between an upper and lower motor neuron?
Upper motor neuron- a motor neuron that synapses with a lower motor neuron farther down in the CNS as opposed to the brain. Lower Motor Neuron- motor neuron that directly supplies skeletal muscle fibers.
What is resting membrane potential?
the voltage (charge) difference across the cell membrane when the cell is at rest. Its created by a small build-up of negative ions in the cytosol along the inside surface of the membrane and an equal build up of positive ions in the ECF along the outside surface of the membrane.
What is the typical RMP of a nueron
.-70 mV.
What are the factors that determine resting membrane potential?
3 factors-unequal distribution of ions in the ECF/cytosol; inability of most cytosolic anions to leave the cell; electrogenic nature of the Na+ -K+ ATPase_s.
What are the four types of a ion channel?
Leak channels; ligand gated channels; mechanically gated channels; and voltage gated channels
Leak channels
randomly alternate between open and closed positions; nearly all cells.
Ligand gated channels
opens and closes in response to binding of a ligand (chemical) stimulus; dendrites of some sensory neurons such as pain receptors.
Mechanically gated channels
opens or closes in response to mechanical stimulation in the form of stretching of internal organs; touch/pressure receptors in skin.
Voltage gated channels
opens in response to a change in membrane potential (voltage) all neurons.
What is a graded potential?
small deviation from resting membrane potential that makes a membrane either more polarized (inside more negative) or less polarized (inside less negative).
Hyperpolarizing GP
response makes inside more negative.
Depolarizing GP
response makes membrane less polarized.
What is the sequence of an action potential?
- Depolarization- reversal of the membrane polarization from -70mV to +30mV 2. Repolarization- recovery of the resting membrane potential from +30mV to -70mV 3. Absolute refractory period- during first part of this period; no matter how strong an impulse is another impulse cannot be stimulated. 4. Relative refractory period- a little later; an AP can be generated if it is larger than normal stimulus.”
What is salutatory conduction?
Action potentials can travel long distances w/ out getting small (unlike graded potentials) nerve impulses are able to jump from one node of Ranvier to another along a mylenated axon. This allows for faster than normal; continuous conduction and is called salutatory conduction.
What are the factors that affect the speed of propagation?
- Amount of myelination; myelination= faster speed 2. Axon diameter; larger = faster speed 3. Temperature; Cooler = slower speeds”
What are the classifications of nerve fibers?
A fibers; B fibers; and C fibers
A fibers
largest diameter; +myelination; 27-290 mph; sensory neurons associated with touch; pressure; pain and temp.
B fibers
medium diameter; +myelination; 34 mph; sensory nerve impulse from viscera to brain and spinal cord; autonomic nervous system.
C fibers
smallest diameter; all unmyelinated; 1-4 mph. Conduct some sensory (pain and temp) autonomic fibers that extend from autonomic ganglia to stimulated heart; smooth mm and glands.
What are the classifications of neurotransmitter recepters?
Iontropic recepters; and metabotropic receptors
What neurotransmitter interacts with an ionotropic receptor?
ligand-gated channel
What neurotransmitter interacts with an metabotropic receptor?
contains NT binding site but lacks an ion channel
What are the effects of the specific neurotransmitters.
Some NT are excitatory at some synapses and inhibitory at others; depends on the structure of the NT receptor it binds to. Ach can bind to ionotropic receptors containing cation channels and generate EPSP in the postsynaptic cell. Some inhibitory synapses Ach binds to metabotropic receptors couples to G proteins that open K+ channels_IPSP.