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Flashcards in Study Guide for Exam 1 Deck (36):

the major anatomical components of nervous system and their functions

CNS: brain and spinal cord, integration and command center
PNS: spinal and cranial nerves, carries messages to and from CNS


the four major functional subdivisions of peripheral nervous system and their functions

1. sensory (afferent): conducts impulses from receptors to the CNS
2. Motor (efferent): conducts impulses from the CNS to effectors (muscles and glands)
3. Somatic: conducts impulses from CNS to skeletal muscles
4. Autonomic: conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands


define "sensory-motor integration"

sensory division of PNS detects stimuli and trasmits info to CNS


the major functions of a neuron

react to physical/chemical changes in their surroundings
transmit nerve impulses to other neurons and to cells outside the nervous system


the major anatomical regions of a neuron and their main functions

1. cell body: contains nucleus and necleolus
2. mitochondria produce energy
3. rough er synthesizes proteins
4. dendrites: receptive region of neuron, electrical signals are conveyed as graded potentials
5. axons: contain microtubules for axonal transport from cell body to end of axon, generate and transmit action potentials, secrete neurotransmitters from axonal terminals


the three types of neurons based on their structure

1. unipolar: cell body with single nerve fiber arising from each end
2. bipolar: cell body with single nerve fiber that divides into two branches
3. multipolar: cell body with many nerve fibers, one of which is an axon


the types of glial cells found in the CNS and their major functions

1. astrocytes: anchor neurons to nutrient supply, control chemical environment
2. oligodendrocytes: form myelin and wrap CNS nerve fibers
3. Microglia: respond to injury and foreign invaders
4. ependymal cells: secrete and help move cerebrospinal fluid


8. the types of glial cells found in the PNS and their major functions

1. schwann cells: surround nerve fibers of PNS
2.Satellite cells: surround neuronal cell bodies with ganglia


define the terms "nerve" and "ganglia"

nerve: bundle of axons that could be both myelinated and unmyelinated
ganglia: a structure containing a number of nerve cell bodies, typically linked by synapses, and often forming a swelling on a nerve fiber.


myelin sheath and its major functions

protection of axon
electrical insulation of nerve fibers from one another
increase in the speed of nerve impulse transmission


name the gaps in the myelin sheath

nodes of ranvier, sites where collaterals can emerge


Major consequences of degeneration of myelin sheath

Inability for underlying neurons to transmit message; muscles that no longer receive motor neurons stop contracting, and results in atrophy


Regeneration of nerve fibers in CNS vs. PNS

CNS: damaged axons unlikely to regenerate
PNS: damaged axons may regenerate with assistance of Schwann


Neuroplasticity and examples of when it happens

Neuroplasticity: the ability of neurons to change their function, chemical profile, or structure
Occurs: cellular recovery after injury; habituation; learning and memory


The major age-associated cellular and behavioral changes in the nervous system

Cell death
Neural atrophy
Loss of white matter
Behavioral reactions


The two major age-related diseases of the brain



The situation with Na and K ions inside and outside the cell during resting potential

Extracellular fluid has 10x more Na than intracellular
Intracellular fluid has 10x more K than extracellular


Factors responsible for differences in ion concentration inside and outside the cell

Intracellular has largely negatively charged molecules


The role of Na/K pump

Maintain Na and K concentration gradient by pumping K in and Na out


The types of channels found in cell membrane of neurons and their functioning

Passive (or leakage) channels: always open
Ligand- gated channels: receptor/channels that open following binding of a specific neurotransmitter
Voltage-gated channels: receptor/channels open and close in response to changes in membrane permeability to ions


Describe the three phases of an action potential including the ion movements

Depolarization: rise of membrane potential to a more positive potential
Repolarization: membrane potential returns to resting potential
Hyperpolarization: potential dips even more negative than resting potential


Define refractory period and its roles

Time during which another action potential cannot fire
Ensues that each action potential is separate and propagating forward


The role of Action Potentials

Called “nerve impulse” when in axon
Principal means of neural communication
Generated by muscle cells and neurons


The region of axon where Action Potentials are initiated

axon hillock


Compare nerve conduction in myelinated vs. unmyelinated axons

Myelinated: AP initiated at axon hillock → voltage-gated channels, therefore, electrical activity spread and triggers AP only at myelin gaps → saltatory conduction
Unmyelinated: AP initiated at axon hillock → electrical activity spread and triggers neighboring voltage-gated channels → another AP occurs in affected spot and spreads to initiate another AP → wave of AP’s move along axon


Major regions composing a synapse and their role

Axonal terminal of presynaptic neuron contains synaptic vesicles
Receptor region on dendrites) or cell body of postsynaptic neuron
Presynaptic → conduct impulses towards synapse
Postsynaptic → transmit impulses away from synapse


Major events involved in synaptic transmission

Nerve impulses reaches axonal terminal of presynaptic neuron
Depolarization of axonal terminal triggers opening of calcium voltage-gated channels and entry of Ca ions into the axonal terminal
Synaptic vesicles release neurotransmitters into synaptic cleft
Neurotransmitter crosses synaptic cleft and binds to ligand-gated receptors on postsynaptic neuron
Ions flow through ligand-gated channels causing change in postsynaptic membrane potential
*Can be excitatory or inhibitory


major function of synapse

release and reception of neurotransmitters


major types of synpases

electrical synapse
chemical synapse


role of calcium in synaptic transmission

In the presence of clacium ions, synpatic vesicles release their neurotransmitter into the synpatic cleft


what is a neurotransmitter

chemicals used for neuronal communications with the body and the brain


types of neurotransmitters based on their function

Acetylcholine: released at the neuromuscular junction
Monoamines: plays roles in emotional behaviors
Amino acids: found only in CNS
Peptides: act as natural opiates reducing perception of pain


two major types of receptors for neurotransmitters

Direct: neurotransmitters that open ion channels
Indirect: neurotransmitters that act through second messenger


mechanisms of termination of neurotransmitter action at the synapse

Neurotransmitter bound to postsynaptic neuron → Postsynaptic effect blocks reception of additional “messages” → must be removed from receptor
Removal of neurotransmitter →degraded by enzymes → reabsorbed by presynaptic terminals by astrocytes → diffuse from synaptic cell


two types of postsynaptic potentials

ESPS: excitatory postsynaptic potentials (excitatory terminal)
IPSP: inhibitory postsynaptic potentials (inhibitory terminal)


define convergence, divergence, and summation

Convergence: when information from several neurons come to interact on one neuron
-Impulses from sensory neurons
Divergence: when information from one neuron is transmitted to several neurons
-Impulses from motor neuron