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Human Physiology (BIO 305W) > Neuron Signaling and the Structure of the Nervous System (Ch.6) > Flashcards

Neuron Signaling and the Structure of the Nervous System (Ch.6) Flashcards

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1
Q

central nervous system (CNS)

A

composed of the brain and the spinal cord

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2
Q

peripheral nervous system (PNS)

A

consists of the nerves that connect the brain and spinal cord with the body’s muscles, glands, sense organs, and other tissues

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3
Q

neuron

A

the functional unit of the nervous system
cell that generates electrical signals that move from one part of the cell to another part of the same cell or to neighboring cells

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4
Q

neurotransmitters

A

chemical messengers, released from neurons caused by the electrical signal, used to communicate with other cells

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5
Q

glial cells

A

do not participate directly in electrical communication from cell to cell, but are important in various supporting functions for neurons
- surround the axon and dendrites of neurons and provide them with physical and metabolic support

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6
Q

soma

A

cell body of a neuron
contains the nucleus and ribosomes and therefore the genetic information and machinery for protein synthesis

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7
Q

dendrites

A

highly branched outgrowths of the cell the receive incoming information from other neurons

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8
Q

dendritic spines

A

knoblike outgrowths that increase the surface area of dendrites further

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9
Q

axon

A

long process that extends from the soma and carries outgoing signals to its target cells

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10
Q

axon hillock (initial segment)

A

region of the axon that arises from the cell body, where propagated electrical signals are generated

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11
Q

axon terminal

A

releases neurotransmitters from the axon

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12
Q

myelin sheaths

A

cover the axons of many neurons, plasma membrane wrapped around the axon, help facilitate the transport of the signal

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13
Q

oligodendrocytes

A

type of glial cell that forms myelin found in the CNS (brain and spinal cord)

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14
Q

Schwann cells

A

type of glial cell in the PNS that form individual myelin sheaths surrounding segments at regular intervals along the axon

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15
Q

nodes of Ranvier

A

the spaces in between adjacent sections of myelin where the axon’s plasma membrane is exposed to extracellular fluid

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16
Q

axonal transport

A

the movement of various organelles and other materials from the cell body to the axon terminals to maintain the structure and the function of the axon

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17
Q

kinesin transport (anterograde)

A

cell body toward the axon terminals

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18
Q

dynein movement (retrograde)

A

from the axon terminals to the cell body

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19
Q

afferent neurons

A

convey information from the tissues and organs of the body toward the CNS
- transmit information into the CNS from receptors at their peripheral endings
- single process from the cell body splits into a long axon that is in the PNS and a short axon that enters the CNS

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20
Q

efferent neurons

A

convey information away from the CNS to effector cells like muscle, gland, neurons or other cell types
- transmit information out of the CNS to effector cells
- cell body with multiple dendrites and a small segment of the axon are in the CNS, most of the axon in the PNS

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21
Q

interneurons

A

connect neurons within the CNS
- function as integrators and signal changers
- integrate groups of afferent and efferent neurons into reflex circuits
- lie entirely in the CNS
- account for > 99% of all neurons

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22
Q

sensory receptors

A

at the peripheral ends of afferent neurons (farthest from the CNS), respond to various physical or chemical changes in their environment by generating electrical signals in the neuron

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23
Q

nerves (of the PNS)

A

groups of afferent and efferent neuron axons, together with myelin, connective tissue, and blood vessels

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24
Q

synapse

A

specialized junction between two neurons where one neuron alters the electrical and chemical activity of another

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25
presynaptic neuron
neuron that conducts a signal toward a synapse
26
postsynaptic neuron
neuron conducting signals away from a synapse
27
astrocyte
type of glial cell that helps regulate the composition of the extracellular fluid in the CNS by removing K+ and neurotransmitters around synapses - also stimulates the formation of tight junctions between the cells that make up the walls of capillaries in the CNS - many other functions
28
blood-brain barrier
selective filter for exchanged substances entering the CNS that is present between the blood and most other tissues - tight junctions between capillaries in the CNS
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microglia
specialized to perform immune functions in the CNS, and may also contribute to synapse remodeling and plasticity
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ependymal cells
line the fluid filled cavities within the brain and spinal cord and regulate the production and flow of cerebrospinal fluid
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growth cone
specialized enlargement that forms the tip of an extending axon and that functions to direct a growing axon to its final destination
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plasticity
the brain's ability to modify its structure and function in response to stimulation or injury
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predominant solutes in the extracellular fluid
sodium and chloride ions (Na+ and Cl-)
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the intracellular fluid contains high concentrations of
potassium (K+) ions and ionized nonpenetrating molecule particularly phosphate compounds and proteins with negative charged side chains
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electrical potential (volts)
separated charges of opposite sign have the potential to do work - the difference in the amount of charge between two points
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current
the movement of electrical charge
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resistance
the hindrance to electrical charge movement
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ohm's law
I = V/R (current = voltage/resistance)
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insulators
materials with high electrical resistance that reduces current flow - conductors are the opposite
40
resting membrane potential
electrical potential difference across plasma membrane of an unstimulated cell - generated mainly by ion concentration differences across the membrane and the membrane's relative permeabilities to those ions
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equilibrium potential
membrane potential at which the concentration and electrical forces on an ion are equal but opposite - can be calculated by the Nernst equation
42
Nernst equation
relates potential to the logarithm of the concentration gradient
43
plasma membrane Na+/K+ ATPase pumps...
maintain low intracellular Na+ concentration and high intracellular K+ concentration by active transport
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leak channels
channels in the plasma membrane that allow ions to pass through, more available for K+ than Na+, so the membrane potential is close to the K+ equilibrium potential
45
GHK equation
used to calculate membrane potential as long as all ions that can cross the membrane through channels are known as well as their permeabilities
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electrogenic
when a pump moves net charge across the membrane and contributes directly to the membrane potential (ex. Na+/K+ ATPase pump)
47
depolarization
a change to a less negative potential
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overshoot
a reversal in polarity such that a neuronal membrane becomes positive inside with respect to the outside of the cell
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hyperpolarization
a change to a more negative potential
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repolarization
a return to the resting potential following a depolarization
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graded potentials
local potentials with magnitudes that can vary and that die out within i or 2 mm of their site of origin ( they are decremental)
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action potential
rapid, all or none (nongraded) change in membrane potential during which the membrane depolarizes and then repolarizes - provides long distance transmission of information through the nervous system
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threshold potential
the potential for initiation of the depolarizing phase of an action potential, when voltage-gated Na+ channels open in large numbers
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refractory periods
the time during and immediately following an action potential when the membrane is absolutely or relatively refractory to initiation of a new action potential
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action potential propagation
the production of local currents produced by an action potential, that trigger a new action potential at a site further along an axon
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saltatory conduction
the regeneration of action potentials only at nodes of Ranvier along a myelinated axon
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excitatory synapse
brings the membrane of a postsynaptic cell closer to threshold
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inhibitory synapse
prevents a postsynaptic cell from approaching threshold by hyperpolarizing or stabilizing the membrane potential
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electrical synapses
consist of gap junctions that allow current to flow between adjacent cells
60
chemical synapses
neurotransmitters stored in synaptic vesicles are released by a presynaptic axon terminal into the synaptic cleft, where they transmit the signal from a presynaptic neuron to an adjacent postsynaptic neuron at a region called a postsynaptic density
61
active zones
release regions at the presynaptic membrane where vesicles are docked
62
SNARE proteins
loosely docks vesicles in the active zones, some are anchored in the vesicle membrane and others that are found in the membrane of the terminal
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synaptotagmins
cytosolic proteins associated with the vesicle that bind Ca2+ ions entering during depolarization, triggers neurotransmitter release
64
ionotropic
postsynaptic cell neurotransmitter receptor that contains an ion channel in the structure
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metabotropic
postsynaptic cell neurotransmitter receptor which is linked with second messenger systems and indirectly alter ion channels
66
reuptake
excess neurotransmitters are removed from the synaptic cleft back into the presynaptic cell for reuse
67
excitatory postsynaptic potential (EPSP)
the electrical response (depolarization) in a postsynaptic cell at an excitatory chemical synapse - usually due to Na+ flux through nonspecific cation channels open in postsynaptic cell
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inhibitory postsynaptic potential (IPSP)
a hyperpolarization or a stabilization of the membrane potential at an inhibitory chemical synapse - usually due to opening of Cl- or K+ in postsynaptic cell
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temporal summation
summed potential created by more than one EPSP and/or IPSP arriving at a single synapse on a postsynaptic cell membrane in quick succession
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spatial summation
summed potential created by more than one EPSP and/or IPSP arriving together at different synapses on a postsynaptic cell membrane
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synaptic strength
effectiveness of a synapse - can be modified pre and postsynaptically
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presynaptic inhibition
inhibitory action produced by an axon terminal of one neuron directly on the terminal of another - results in less neurotransmitter release
73
presynaptic facilitation
stimulatory action produced by the axon terminal of one neuron directly on the terminal of another - results in more neurotransmitter release
74
desensitization
causes less response from receptor, can lead to postsynaptic alteration of synaptic strength
75
neuromodulators
cause, via second messengers, more complex metabolic effects in a postsynaptic cell
76
major classes of neurotransmitters
- acetylcholine - biogenic amines (catecholamines, serotonin) - amino acids (glutamate, GABA, glycine) - gases (nitric oxide, hydrogen sulfide) - neuropeptides / neuromodulators (endogenous opioids)
77
neuroeffector junction
the synapse between a neuron and an effector cell
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forebrain
cerebrum, diencephalon
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hindbrain
pons, medulla oblongata, cerebellum
80
brain consists of
forebrain, midbrain, hindbrain
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white matter
primarily bundles of myelinated axons traveling together in pathways (tracts)
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gray matter
composed primarily of cell bodies of neurons but also unmyelinated fibers
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cerebrum
made up of right and left cerebral hemispheres and several structures such as the cerebral cortex, limbic system, basal nuclei
84
cerebral cortex
outer shell of the cerebrum - composed of parietal, frontal, occipital, and temporal lobes - participates in conscious thought, memory, perception, learning, and generation of skilled movement
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limbic system
subcortical nuclei associated with learning and emotion
86
basal nuclei
subcortical nuclei involved with control of movement and posture
87
diencephalon
composed of thalamus, epithalamus, hypothalamus
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thalamus
sensory relay, general arousal
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epithalamus
includes pineal gland, circadian rhythms
90
hypothalamus
controls many aspects of the internal environment
91
cerebellum
functions in posture, movement, and some kinds of memory
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brainstem
composed of the midbrain, pons, medulla oblongata, reticular formation essential for life
93
reticular formation
regulates arousal states, attention, control of heart and lung functioning, certain motor functions
94
spinal cord
together with the brain, comprises the CNS, lies within vertebral column
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peripheral nervous system (PNS)
consists of 43 paired nerves (12 cranial, 31 spinal) as well as neurons found in the gastrointestinal tract wall
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afferent division
(of the PNS) brings sensory information to the CNS
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efferent division
(of the PNS) is divided into somatic and autonomic divisions
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somatic nervous system
voluntary; sends motor neurons that innervate skeletal muscle cells and release the neurotransmitter acetylcholine, causing contraction of muscle
99
autonomic nervous system
involuntary; innervates smooth muscles cells, gland cells, neurons of the intestinal tract, and others; can be excitatory or inhibitory sympathetic and parasympathetic divisions
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sympathetic division
mediates fight or flight responses characterized by increased activity of organs that mediate increased physical activity - neurons release norepinephrine onto target cells
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norepinephrine
in sympathetic division to trigger fight or flight and acts by binding to alpha or beta adrenergic receptors
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adrenal medulla
hormone secreting part of the sympathetic nervous system that secretes mainly epinephrine
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parasympathetic division
mediates rest and digest state (generally the opposite actions of the sympathetic division) - neurons release acetylcholine onto target cells
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dual innervation
control of many effector organs by both the sympathetic and parasympathetic divisions of the autonomic nervous system
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meninges
three layers of protective membranous coverings around the brain and spinal cord - dura mater (outer) - arachnoid mater (middle) - pia mater (inner, closest to the surface of the brain)
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cerebrospinal fluid
fluid produced by the choroid plexus that circulates within the brain ventricles and subarachnoid space and acts as a shock absorber
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blood brain barrier
formed in part by cells lining blood vessels of the brain - tight junctions between blood vessel cells prevent many substances from entering the fluid around neurons - specific transport systems allow certain molecules to move between the blood and extracellular fluid around neurons

Human Physiology (BIO 305W) (5 decks)

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