Ch. 11 Study Guide-Bio 145

Anatomical:
Central Nervous System (CNS)-Brain and spinal cord
Peripheral Nervous System (PNS)-neural tissue outside CNS, nerve fibers, nerves

Functional:
Sensory/afferent division-carries sensory info to CNS, somatic and visceral sensory divisions
Motor/efferent divisions-carries motor commands from CNS to target organs, somatic and autonomic (sympathetic and parasympathetic division) nervous system
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Terms in this set (35)
Anatomical:
Central Nervous System (CNS)-Brain and spinal cord
Peripheral Nervous System (PNS)-neural tissue outside CNS, nerve fibers, nerves

Functional:
Sensory/afferent division-carries sensory info to CNS, somatic and visceral sensory divisions
Motor/efferent divisions-carries motor commands from CNS to target organs, somatic and autonomic (sympathetic and parasympathetic division) nervous system
Describe the anatomical and functional divisions of the nervous system.
Cell body: cytoplasm, nucleus, organelles, RER, ribosomes, gray matter
Dendrite: extensively branched processes & receive info from other neurons
Axons: generate and conduct action potentials
Describe the structure of a typical neuron and describes the function of each component (cell, body, dendrite, axon)
axoplasm: cytoplasm of axolemma
axolemma: the plasma membrane of an axon
telodendria: small branches at the end of an axon
axon hillock: The initial portion of an axon where an action potential is generated.
Define axoplasm, axolemma, telodendria, and axon hillock
axonal transport: where substances travel through the axoplasm
fast axonal transport: substances travel more rapidly through through the axon
slow axonal transport: substances move away from the cell body at a much slower rate
anterograde flow: components move away from cell body at a maximum rate of about 400 mm/day
retrograde: components move toward the cell body at a maximum rate of about 200 mm/day
Define axonal transport and distinguish between fast and slow axonal transport as well as between anterograde and retrograde flow.
Receptive region: dendrites, cell body
conduction region: axon (action potential)
secretary region: axon terminal
Summarize the three functional regions of a neuron and explain how they work together.
Multipolar neurons (most common)-most neurons in CNS and PNS
Bipolar Neurons- special sense organs in the PNS (retina and olfactory epithelium)
Pseudounipolar neurons- sensory neurons in the PNS associated with touch, pain, and vibration sensations
Describe the three structural categories of neurons and give an example of a location for each. Which of these structures is most common?
sensory neurons (afferent)- signal toward the CNS
interneurons (association neurons)- relay messages within the CNS
motor neurons (efferent)- carry stimuli away from their cell bodies in the CNS to muscles and glands
Distinguish between sensory neurons, motor neurons, and interneurons in terms of their functions.
maintaining the environment around neurons, protecting them, assisting in their proper functioning, retain ability to divide, and fill in gaps left when neurons die

ependymal cells- circulate cerebrospinal fluid
astrocytes- anchor neurons and blood vessels in place, regulate the extracellular environment of the brain, assisting in the formation of the blood brain barrier, and repairing damaged brain tissue.
oligodendrocytes- cytoplasmic extensions cover axons & myelin sheaths
microglia- engulf debris, waste, and pathogens
Describe the general function of neuroglia. List the four major types of neuroglia in the central nervous system and describe the functions of each.
Schwann cells- form sheath around peripheral axons
satellite cells- surround neuron cell bodies in ganglia & regulate interstitial environment
List the two major types of neuroglia in the peripheral nervous system and describe the functions of each.
structure: layers of phospholipid membrane
Functions: insulates electrical current, speeds up action potentials, and gaps myelination
In PNS: axons that lack a myelin sheath associate with Schwann cells
In CNS: able to see which regions of brain and spinal cord contain myelinated axons
Describe the structure and function of the myelin sheath. How does the myelin sheath in the PNS differ from the sheath in CNS.
The axon and myelin sheath distal to the injury degenerate, growth processes form from the proximal end of the axon, Schwann cells and the basal lamina form a regeneration tube, a single growth process grows into the regeneration tube, and the axon is reconnected with the target cell. Wallerian degeneration: phagocytes digest the cellular debrisSummarize the process of regeneration of neutral tissue in the PNS. Define wallerian degeneration. How does this process compare to the potential for regeneration of neural tissue in CNS?leak channels: always open gated channels: closed when "at rest" & open in response to a specific stimuli ligand-gated: open in repose to a certain chemical called ligand voltage-gated: open or close in response to changes in the cell's membrane potential mechanically gated: open or close in response to mechanical stimulation such as stretch, pressure, or vibrationDifferentiate between leak and gated channels. Distinguish among the three major types of gated channels: ligand-gated, voltage-gated, and mechanically gated channels.membrane potential: The electrical gradient across the plasma membrane.Define membrane potential and explain how the resting membrane potential is created and maintained. What are the passive and active forces involved in generating and maintaining resting potential?opposite charges attract and electrical gradients may oppose or enhance concentration gradientDefine and discuss the significance of the electrochemical gradient.Changing permeability of membrane, depolarization, repolarization, hyper polarizationDescribe how the membrane potential can changeDepolarization: addition of + charges repolarization: return to resting potential hyper polarization: becomes even more negative than at restDefine depolarization, repolarization, and hyper polarizationlocal potential: small local change in the membrane potential of the neuron is produces (depolarization or hyper polarization) action potential: uniform rapid depolarization and repolarization of the membrane potential of a cell.Distinguish between local potential and action potentialdepolarization to threshold, rapid depolarization, repolarization begins, repolarization continues, hyper polarization and return to normalDescribe the steps involved in the generation of an action potential. Explain what is happening to the membrane potential and what events are causing those changes.refractory period: the time where, a brief time after a neuron has produced an action potential and the membrane can't be stimulated to fire another one. absolute refractory period: no additional stimulus no matter how strong is able to produce and additional action potential (no response possible & Na+ channels are open or inactivated) relative refractory period: during which only a strong stimulus will produce an action potential (after Na+ channels return to normal and requires larger than normal stimulus to overcome loss of K+ and hyper polarization)What is meant by the " refectory period"? Distinguish between the absolute and relative refractory period.voltage-gated Na+ channels open at approx. -55mV (threshold) & stimulus will either cause depolarization to the threshold or notExplain the "all-or-none principal" as it relates to action potential generationthe spread of an action potential along the length of a cell's plasma membrane Local potentials depolarize axolemma to threshold in trigger zone, activated sodium channels trigger action potential in next segment of axolemma, previous segments are in refractory period, so can only move "forward", and repeats until axon terminalExplain propagation and explain the sequence of events involved.continuous conduction: myelin sheath is absent saltatory conduction: myelin sheath is presentDistinguish between continuous conduction and saltatory conduction. Discuss some of the major differences between the two processes.diameter of axon and the presence or absence of myelin sheathDiscuss the factors that affect the speed with which action potentials are propagated.type A fiber: large, myelinated, 120 m/sec type B fibers: smaller, myelinated 15 m/sec type C fibers: smallest, unmyelinated 2 m/sec or slowerDistinguish between type A, B, and C fiberssynapse: the location where a presynaptic neuron communicates with its target cell electrical synapse: occurs between cells that are electrically coupled via junctions chemical synapse: vast majority of the type of synapse in nervous system and most common synaptic vesicles, synaptic cleft, and neurotransmitter receptors cause signals to go more slowly across chemical synapse. synaptic delay: the short delay between the arrival of the action potential.Define synapse and the difference between electrical and chemical synapses. Why are signals transmitted more slowly across chemical synapse? Define synaptic delay and its significance.presynaptic neuron: a neuron in a synapse that delivers a message to a target cell post synaptic neuron: a neuron in a synapse that receives a message from a presynaptic neuronDistinguish between the presynaptic and post synaptic neuron of the cell.an action potential in the presynaptic neuron triggers calcium ion channels in the axon terminal to open, influx of the calcium ion cause the synaptic vesicles to release neurotransmitters into the synaptic cleft, neurotransmitters bind to receptors on the postsynaptic neuron, ion channels open leading to a local potential and possibly and action potential.List the events of a chemical synapsePostsynaptic potential: local potentials in the membrane of the postsynaptic neuron. inhibitory postsynaptic potential: small local hyper polarization moves the membrane potential at the trigger zone farther away from threshold. This inhibits an action potential from firing. excitatory postsynaptic potentials: small local depolarization brings the membrane potential at the trigger zone closer to the threshold. An action potential is generated.Define postsynaptic potential. Distinguish between inhibitory and excitatory postsynaptic potentials and give an example of what event might cause each.diffusion and absorption degradation in the synaptic cleft reuptake into the presynaptic neuronSummarize the three methods of terminating synaptic transmission.temporal summation: one synapse, repeatedly active spatial summation: multiple synapse, active at same timeDistinguish between temporal and spatial summationinotropic receptors: receptors that are part of ligand-gated channels metabotropic receptors: receptors within the plasma membrane that are connected to a separate ion channel in some fashion second messenger: a chemical formed inside a cell that triggers some sort of change within the cellDistinguish between inotropic and metabotropic receptors for neurotransmitters and explain the role of second messengers.It depends on which postsynaptic neuron receptors they bind toHow can the same neurotransmitter be excitatory at one synapse and inhibitory at another?excitatory regulate sleep/wake cycle, attention, and feeding behaviors similar to epinephrine coordinates movement, emotions, and movements mood regulation inhibitorywhat's the significance of acetylcholine, norepinephrine, epinephrine, dopamine, serotonin, and GABAgroups of interneurons in CNS that process specific types of stimuli a type of circuit in which a single input neuron contacts several output neurons axon terminals from multiple input neurons converge onto a single postsynaptic neuron allowing for spatial summation of synapse where a signal passes through the progressively greater number of neuronsDefine and discuss the significance of neuronal pools. Distinguish between diverging circuits and converging circuits. What is an amplifying circuit?intrinsic inhibitory negative feedback and synaptic fatigue The second mechanism for stabilizing neural circuits is a property of synapsesWhat are the two basic mechanisms that the CNS uses to stabilize neural circuits? Define synaptic fatigue.