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144 Cards in this Set

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the three overlapping fuctions of the nervous system
sensory input; motor output; integration
sensory input
gathered by sensory recepors is conduction to integration centers in the brain and
the spinal cord - is called CNS
motor output
conveyed to effector cells - muscle or gland cells; integration of sensory input and motor output in continuous background activity within CNS
peripheral nervous system
carry sensory and motor info between the body and the CNS in nervers
nerves
bundles of neuron extensions wrapped in connective tissue
neuron or nerve cell
consits of cell body which contains a nucleus and organelles and a fiber like processes dendrites and axons that conduct signals
dendrites vs axons
dendrite - highly branched short, carry messages toward cell body;
axons - longer, transmit signals to other cells.
axon hillock
where axons originate in cell body
myelin sheath
wrap around axons, insulating
synaptic terminals
specialized endings in terminal branches of axons which release neuro transmitters that relay signals across synapse to a post synaptic cell, another neuron or effector cell
presynaptic cell
the transmitting cell
reflex arc
the simplest type of nerve circuit. regulates and automatic response called a reflex.
sensory neuron
transmits info from a sensory receptor to a motor neuron which signals an effector cell to carry out the response.
second neuro circuit
even a simple nerve jerk reflex has this. a sensory neuron relays info from stretch receptor in the thigh muscle to interneurons in spinal cord which inhibit motor neurons to flexor muscles.
interneurons
neurons confined wholly with the spinal cord. Spinal cord interneurons help integrate sensory information and generate coordinated muscle commands.
ganglia
nerve cell bodies, often of similar function are clustered into ganglia in the CNS;
nuclei
clusters of cell bodies in the brain
three types of nerve circuits
1.circuits in which info is spread from one pre-synaptic neuron to several post synaptic neurons.
2.convergent circuits in which several presynaptic neurons communicate info to single post synaptic neuron;
3.circular paths
supporting cells, or glia
very numerous, give structural integrity and physiological support to nervous system; recent studies indicate that glia may have synaptic communication with each other and with neurons.
radial glia
guide the embyonic growth of neurons
astrocytes
are supporting glia in the CNS that induce the formation of the blood-brain barrier which restricts the passage of most substances into the brain.
oligodendrocytes in the CNS;
Schwann cells in PNS
insulate axons in a myelin sheath by wrapping around them and forming concentric membrane layers.
nodes of ranvier
the gaps between adjacent schwann cells
resting potential or membrane potential
of a typical, non-transmitting neuron is about -70 mv.
ions inside and outside of cell
the priciple cation outside of cell is sodium; the priciple anion is outside of cell is chloride.
the principle cation inside of cells is K; and many other anions are grouped together and symbolized as A-
sodium-potassium pumps
maintain these resting concentration gradients by using energy from ATP to move sodium ions back out of the cell, K in
the excitable cells
neurons in muscle cells, they are able to generate change in their membrane potential which may generate electrical impulse.
3 other ion channels
gated ion channels that open and close in response to stimulae; chemically gated ion channels that respond to a chemical stimulus such as neurotransmitters; voltage gated ion channels that respond to a change in membrane potential.
hyperpolarization
a great increase in the membrane potential as a result of an ion channel such as K+ channels
depolarization
the inside of cell becomes less negative as a result of an ion channel
graded potential
the magnitude of a voltage change proportional to the change of the stimulus; the stronger the stimulus the more graded ion channels that open;
threshhold potential
the maxiumum amount of depolarization a cell can reach before it triggers and action potential usu. about 50-55 mv
action potential
the graded depolarization from a dendrite or cell body spreads along the membrane to an axis. It is an all or nothing event. An action potential causes the membrane potential first to reverse polarity then return rapidly to the resting potential.
rapid spike of depolarization
voltage gated ions channels in an axis plasma membrane are activated when depolarization reaches the threshhold potential. K activation gates open rapidly and K inactivation gates open at resting state close slowly.
refractory period
before K inactivation gates are reopened, the neuron cannot respond to another stimulus.
saltatory conduction
voltage gated ion channels are concentrated in the nodes of ranvier; action potentials can be generated only at these nerves and the nerve impulse jumps from node to node resulting in this faster mode of transmission.
neurons in which synapses can occur
between sensory receptors and neurons or between neurons and muscle or gland cells.
electrical synapse
allow action potentials to flow directly from presynaptic to postsynaptic cells via gap junctions.
chemical synapse
the electrical message is converted to a chemical message that travels from teh spresynaptic cells across a synaptic cleft to the post synaptic cell, where it is converted back into an electrical signal.
synaptic terminal
contains many synaptic vessicles in which 1000's of neurotransmitters are stored.
presynaptic membrane
the depolarizaiton of this membrane causes the release of neurotransmitters into the cleft;
postsynaptic membrane
contains receptor proteincs associated with particular ion channels; binding of neurotransmitter to the receptors on these chemically gated channels allows ions to cross the membrane either depolarizing or hyperpolarizing it. enzymes rapidly break down the neurotransmitter or it is taken up into adjacent cells
excitatory postsynaptic potential EPSP (are graded potentials)
at an excitatory synapse, binding of neurotransmitters to receptors opens a chemically gated channel - allows Na+ in and K+ out of cell. Electorchemical dgadient drives more Na+ in - positive charge depolarizes membrand creating EPSP and brings membrane potential closer to threshold potential.
Inhibitory postsynaptic potential IPSP (graded potentials)
at in hibitory synapse, binding of nt opens ion gates allowing K+ out and/or CL- in, hyperpolarizing membrand and producing IPSP
what determines magnitude of EPSP's and IPSP's
number of nt molecules that bind to receptors - they spread their voltage changes alone the membrane of postsynaptic cell.
Summation
summation of several EPSP's is usually necessary to bring axon hillock to theshold potential.
what determines membrane potential of axon hillock
sum of all EPSP's and IPSP's
different effects same neurotransmitter can have on different types of cells
alter membrane permeability of postsynaptic cell by binding to receptors on ion channels
trigger signal-transduction pathways in postsynaptic cell
Acetylcholine
very common nuerotransmitter in invertebrates and vert.'s depending on type of receptor - can be inhibitory or excitatory in vertebrate CNS.
in neuromuscular junctions - acetylcholine released from a motor axon deplarizes the postsynaptic muscle cell
biogenic amines
neurotransmitters derived from amino acids, often trigger signaltransduction pathways in p.s. cells
epinephrine, norepinephrine and dopamine
biogenic amines derived from tyrosine.
serotonin
syntehsized from tryptophan
which biogenic amines affect sleep, mood, attention and learning
dopamine and serotonin
glycine, glutamate, aspartate, gamma aminobutyric acid (GABA)
amino acids that function as nt's on the CNS
which is most common inhibitory transmitter in brain?
GABA
neuropeptides
short chains of amino acids that function as nt's - often through signal-transduction pathways.
Substance P
excitatory nt that functions in pain perception
excitatory postsynaptic potential EPSP (are graded potentials)
at an excitatory synapse, binding of neurotransmitters to receptors opens a chemically gated channel - allows Na+ in and K+ out of cell. Electorchemical dgadient drives more Na+ in - positive charge depolarizes membrand creating EPSP and brings membrane potential closer to threshold potential.
Inhibitory postsynaptic potential IPSP (graded potentials)
at in hibitory synapse, binding of nt opens ion gates allowing K+ out and/or CL- in, hyperpolarizing membrand and producing IPSP
what determines magnitude of EPSP's and IPSP's
number of nt molecules that bind to receptors - they spread their voltage changes alone the membrane of postsynaptic cell.
Summation
summation of several EPSP's is usually necessary to bring axon hillock to theshold potential.
what determines membrane potential of axon hillock
sum of all EPSP's and IPSP's
different effects same neurotransmitter can have on different types of cells
alter membrane permeability of postsynaptic cell by binding to receptors on ion channels
trigger signal-transduction pathways in postsynaptic cell
Acetylcholine
very common nuerotransmitter in invertebrates and vert.'s depending on type of receptor - can be inhibitory or excitatory in vertebrate CNS.
in neuromuscular junctions - acetylcholine released from a motor axon deplarizes the postsynaptic muscle cell
biogenic amines
neurotransmitters derived from amino acids, often trigger signaltransduction pathways in p.s. cells
epinephrine, norepinephrine and dopamine
biogenic amines derived from tyrosine.
serotonin
syntehsized from tryptophan
which biogenic amines affect sleep, mood, attention and learning
dopamine and serotonin
glycine, glutamate, aspartate, gamma aminobutyric acid (GABA)
amino acids that function as nt's on the CNS
which is most common inhibitory transmitter in brain?
GABA
neuropeptides
short chains of amino acids that function as nt's - often through signal-transduction pathways.
Substance P
excitatory nt that functions in pain perception
endorphines
neuropeptides produced in brain during physical or emotional stress that have painkilling and other functions. opiates bind to endorphin receptors in brain
local regulators for vertbrate CNS anbd PNA
nitric oxide NO and C0
hydra nervous system
nerve net - simple diffuse, controls the radially symetrical body cavity
ehinoderm nervous system
central nerve ring with radial nerves connected to a nerve net in each arm
cephalization
concentration of sense organs, feeding structures and neural structures in teh head - evolved in bilaterally symmetrical animals
flatworm cns
simple brain and 2 longitudinal nerve cords
cns of mollusks and arthorpods
complicated brain and venral nerve cord with segmantally arranged ganglia
vertebrate
dorsal nerve cord
CNS of vertebrates
spinal cord and brain
PNS function in vertebrates
carries info to and from CNS and regulates homeostasis.
from what does CNS develop (vertebrates)
embryonic dorsal hollow nerve cord
ventricles
spaces in the brain continuous with narrow central canal of spinal cord, filled with cerebrospinal fluid.
function of cerebrosinal fluid
cushions brain, carries out circularoty functions.
meninges
portective layers of connective tissues that cover brain and spinal cord. axons are in bundles or tracts
white matter
named for white matter in myelin sheaths.
gray matter
neuron cell bodies, dendrites, unmyelinated axons
what makes us vertbrate PNS
cranial nerves and spinal nerves with associated ganglia
how many pairs of cranial nerves and spinal nerves in mammal PNS
12 pairs of c.n.
31 pairs of s.n.
most cranial and all spinal nerves contain both sensory and motor neurons
two divisions in PNS
sensory division - sensory, or afferent neurons that bring info to CNS
motor division - efferent neurons that carry signals away from CNS to effector cells
2 parts of motor division
somatic nervous system - carries signals to skeletal muscles
autonomic nervous system - maintains internal environment by involuntary control of smoothe and cardiac muscles
2 divisions of ANS
sympathetic division - accelerates heart and metabolic rate, arousing organism for action, generating energy
parasympathetic division - carries signals that enhance self-maintenance activities that conserve energy - such as digestion and slowing heart rate
3 differentiations of neural tube (embryonic development)
forebrain, midbrain, hindbrain - evident as 3 bilaterally symmetrical anterior bulges.
cerebrum
most sophisticated integrative center, outgrowth of forebrain
5 brain regions that develop from inital bulges in humans
telencephalon and diencephalon from forebrain
mesencephalon from midbrain
metencephalon and myelencephalon from hindbrain
cerebral cotex
highly convoluted outer gray matter.
what develops from diencephalon portion of forebrain
thalamus, epithalamus and hypothalamus
what is included in adult brainstem
midbrain - from mesencephalon
pons - from metencephalon
medulla oblongata from myelencephalon
cerebellum
not a part of brainstem, develops from the metencephalon.
brainstem
a stalk with a caplike swelling atht eh end of the spinal cord that extends deep within the brain
medulla oblongata (or medulla)
contains control centers for such homeostatic functions as breathing, swallowing, heart and blood vessel actions and digestion
pons
fucntions with the medulla in some of above activities and in conducting information between the rest of the brain and s.c.
why does right side of brain control much of movement in left side, and vice versa
tracts of motor neurons fro mid and forebrain coss in medulla
midbrain
receives and integrates sensory info and send info to specific regions of forebrain.
where do fibres involved in hearing pass
pass through or terminate in inferior colliculi
in vision?
superior colliculi - form optic lobes in nonmamals, only coordinate visual reflexes in mammals where vision is integrated in cerebrum
reticular formation
a system of voer 90 nuclei that extends through the brain stem and filters the sensory informaiton reaching the cerebral cortex
RAS reticular activating system
part of filtering system and regulates sleep and arousal
what causes level of arousal
amount of input the cortex receives.
where are sleep-producing nuclei located
pons and medulla
where is center that causes arousal
midbrain
EEG
electorencephalogram. recording of brain waves.
What are produced by person lying quietly with eyes closed.
slow syncrhonous alpha waves
what is associated with opened eyes or thinking about complex problem
rapid, irregular beta waves
what occurs during deep sleep
quite slow and synchronized delta waves
REM sleep
periods of delta waves alternae with periods of a desynchronized EEG and rapid eye movements - most dreaming occurs
cerebellum
develops from part of teh metencephalon may be involved in learning motor responses.
integrates info from auditory and visual systems with sensory input from joints and muscles - provide automatic coordination of movements and balance.
where do epithalamus, thalamus and hypothalamus develop from
embryonic diencephalon.
epithalamus
includes projecting pineal gland and a choroid plexus - producing cerebrospinal fluid
thalamus
major input center for sensory information going to cerebrum and an output center for motor info from cerebrum.
also receives input fro cerebrum and other parts of brain regulating emotion and arousal.
hypothalamus
major brain region for homeostatic regulation. produces posterior pitutitary hormones and releasing of hormones that control anterior pituitary.
contains regulating centers for many autonomic functions - and in sexual and mating behaviors, alarm resonse and pleasure
biological clock
internal mechanism important for maintainging these circadian thythms.
suprachiasmatic nuclei SCN
located in hypothalamus - function as bioloical clock
what keeps mamal clock synchronized with natural cycles of light and dark
sensory neurons providing visual info to the SCN
what is human cycle
25 hours.
cerebral hemisphers
right and left lobes of cerebrum
what does cerebrum develop from
embryonic telencephalon
basal nuclei (also called basal ganglia)
located deep in white matter, important in planning and learning movements
neocortex
out six layers of neurons running along the brain surface - unique to mammals
corpus callosum
thick band of fibers through which communication between two brain hemispheres travel
cognitive functions of cerebrum
learning and cognition - proces of knowing, consciousness and decision making.
how many lobes is the surface of each hemisphere divided into
4
primary motor cortex
at boundary between fronal and parietal lobe of CC - sends signals to skeletal muscles
primary somatosensory cortex
receives and partially ingegrates input from touch, pain, pressure, and temp. receptors
where does sensory info go first
primary sensory areas located in different lobes of the brain.
what integrates the different sensory inputs
association areas adjacent to the primary sensory areas. They send signals to association areas in frontal lobes. these areas determine motor response directed by pirmary motor cortex
left hemisphere specilization
language, math and logic; fine visual and auditory data and directing detailed mvmt.
right brain
pattern recognition, spatial perception and emotional processing. perceiving images within a whole context
Broca's area
in frontal lobe - involved in speech generation
Wernicke's area
posterior temporal love - involved in speech comprehension
limbic system
hippocampus and olfactory cortex - with sections of thalamus, hypoth. and inner portions of cortex - forming a ring aournd the brain stem.
generates emotions.
transferring info from short-term to long-term memory involves what
hypocampus
what facilitates above
rehersal, positive or negative emotional state and associatiosn with previously learned and stored material.