neuron-target synapse
--sympathetic
-parasympathetic
-NE on A or B adrenergic receptor
-ACh on muscarinic receptor
Somatic motor pathways
have single neuron that originates in the CNS and projects it axon to a skeletal muscle
Neuromuscular junction
site where a motor neuron synapses with a skeletal muscle
motor end plate
region of muscle membrane contains concentration of ACh receptors
Somatic motor division
-# neurons in efferent path
-Neurotransmitter/receptor @ neuron target synapse
-target tissue
-neurotransmitter released from
-effects on target tissue
-peripheral components found outside CNS
-summary of function
-1
-ACh/nicotinic
-skeletal muscle
-axon terminals
-excitatory only muscle contracts
-axons only
-posture and movement
Autonomic
-# neurons in efferent path
-Neurotransmitter/receptor @ neuron target synapse
-target tissue
-neurotransmitter released from
-effects on target tissue
-peripheral components found outside CNS
-summary of function
-2
-ACh/ muscarinic or NE A or B adrenergic
-smooth and cardiac muscle some endo and exo glands some adipose tissue
-varicositites and axon terminals
-excitory or inhibitory
-preganglionic axons, ganglia, postganglia, neurons
-visceral function including
3 categories of gated ion channels
which type is most involved in the initiation and conduction of action potentials
-Mechanical (some sensory neurons)
-chemical (ligands such as neurotransmitters)
-voltage (changes in membrane potential)
Voltage gated ion channels are most involved.
ohms law equation
increase in
V= I X R (voltage = current X resistance)
Neurons/ nerve cells
release?
Structurally specialized to carry electrical signals rapidly
-long thin processes
-release: neurotransmitters and or neurohormones
Neurohormone
is released into the blood stream
-probably acts on a distant tissue
Neurotransmitter
act on a neighboring cell
-act quickly
Neuromodulators
acts on a neighboring cell
-causes a slower response
Neurons work together that results in emergent properties such as
intelligence, consciousness, etc.
The nervous system consists of
The peripheral nervous system PNS. everything outside the CNS
The Central Nervous System CNS brain and spinal chord
The periphrial nervous system PNS consists of
-Sensory division: Afferent division send info to the CNS through afferent (sensory) neurons
-Efferent: Send info to CNS through efferent (sensory) neurons
Autonomic Nervous system
Nervous system controls involuntrary muscle contraction and other cells
Sympathetic Nervous system
promotes Fight or Flight responses
Parasympathetic Nervous system
promotes "rest and digest" responses
Enteric Nervous system
Gut, digestion (considered a seperate intergrating system)
Somatic Nervous system
motor neurons control voluntary muscles
Synapse
region where an axon terminal communicates with its postsynaptic target cell
Dendrites
carry signals to the cell body
Axons
carry signals away from cell body
Synaptic Cleft
space between pro and post synaptic cells
Axon Hillock
region where axon begins
Myelin sheath
insulating substance wrapped around a axon of some neurons
Functional categories of neurons
sensory neurons(afferent), interneurons of CNS, Efferent neurons
Psedounipolar
one axon
ex. efferent neurons
bipolar
2 axons
ex sensory neurons
anaxonic
have no apparent axons
multipolar
lack long axons
Interneurons
completley in the CNS
Slow axonal transport happens by
movement due to diffusion through cytoplasm
Fast axonal transport
uses the cytoskelton and microtubules, with motor proteins
Microtubules
one type of protein fibers of the cytoskeleton motor proteins that are also involved
Retrograde transport
back to nucleus fast
Anterograde Transport
to axon terminal
Glial cells are
support cells for neurons
Oligodendrcytes and Schwann cells are found where... do what...
Oligodendrocytes found in CNS
Schwann found in PNS can also secrete neurotrophic factors
both form myelin sheaths
Myelin
multiple layers of phospholipids membrane wrapped around an axon
-insulates neuron > faster transmission of electrical signals
-provides protection
Satelite cell found...does what
found in PNS
Support cell bodies
Glial Cells found in the PNS
schwann cells
satellite cells
Glial cells found in CNS
-ependymal cells
-Astrocytes
-Microglia (modified immune cells): act as scavengers/phagocytes
-oligondendrocytes
blood brain carrier
prevents cells and many chemicals/substances from moving from the blood into the brain
Ependymal cells function
-create barriers between fluid filled compartments
-source of stem cells
Astrocytes function
-take up K+ water neurotransmitters
-secrete neurotrophic factors
-help form blood brain barrier
-provide substrates for ATP production
found in CNS
Microglia
modified immune cells
-scavengers/phagocytes
Found in CNS
stem cell
can divide and differentiate into other cell types
Oliogodendrocytes
Form myelin sheath
found in CNS
Schwann cells
form myelin sheath
secrete neurotrophic factors
found in PNS
Satellite
support cell bodies
found in PNS
Neurotropic factors
chemical mediators that act on 2 neurons
ganglia
cluster of neuron cell bodies in the PNS
-satellite cells concentrated around ganglia
Nucleus
cluster of neuron cell bodies in CNS
node of ranvier
a section of unmyelinated axon membrane between two schwann cells
direct contact between neurons plasms membrane and ECF
The goldman-Hodgkins-Katz (GHK) equation
calculates membrane potential including contributions from all ions that can cross the membrane
Eion =
equilibrium potential of that ion
Ions most important for excitable cells are
K+
Na+
Cl-
Ca2+
Depolarization can be caused by
membrane potential becomes more positive
- a few Na+ ions move into the cell
Hypopolarization can be caused by
membrane potential becomes more negative
- a few K+ ions into the cell
repolarizing
returning to resting membrane potential
Conductance
ease with which an ion flows through the channel
treshhold
minimum voltage change needed to activate (open) a channel can start an action potential
For the whole neuron threshold refers to
the voltage charge needed to generate an action potential
Current in a cell/organism refers to
the movement of positively charged ions
V in ohm's law
voltage
R in ohm's law
resistance
An ions current refers to
the flow of electrical charge carried by that ion
resistance
the force that opposes movement of charge etc.
Resistance to current flow comes from
the resistance of the cell membrane (can be changed by changing permeability to ions by opening/closing ion channels) and of the cytoplasm (fairly constant)
Graded potential
variable strength(max strength changes) short term changes that lose strength as they spread down the cell
action potential
all or none" do not lose strength as they move along the cell
Graded potential type of signal? occurs where? Types of gated ion channels involved? Ions involved? Strength of signal? what initiates the signal? unique?
-input signal, depolarizing or hypopolarizing
-Dendrites and cell body
-mechancally, chem, voltage gated channels
-Na+ Cl- Ca2+
-depends on initial stimulus can be summed (in time/space)
-entry of ions through gated channels
-no min, level to initiate
2 s
Action potential type of signal? occurs where? Types of gated ion channels involved? Ions involved? Strength of signal? what initiates the signal? unique?
-regenerating conduction signal depolorizing
-trigger zone through axon
-voltage gated channels
-Na+ and K+ Different in muscles
-all or none cannot be summed
-above threshold graded potential at the trigger zone opens ion channels
-threshold stimulus req
trigger zone
the physical location in the neuron where action potential can be generated it includes the
-axon hillock
-initial segment
*voltage gated sodium channels
*SEE slide graded potentials can trigger action potentials
...
summary of an action potential
watch video on a&p flicks
FIG8.9
Refractory Period
the time needed for a cell to return to resting membrane potential or atleast to a point where another action potential can be generated
What is responsible for refractory periods following an action potential
Voltage gated Na+ channels
Open>inactive>closed
Absolute refractory period
No stimulus can trigger another action potential
Relative Refractory period
Only larger than normal stimulus can initiate a new action potential
Conduction speed is increased with
-increasing neuron size (in diameter)
-myelination
Action potential cant go backwards down the axon because
refractory period
Saltatory conduction
leeps from node to node
"saltaire": to leap
Hyperkalemia
look up
electrical synapse
gap junctions
neurons of the CNS, cardiac and smooth muscle, glial cells
-allows rapid transmission synchronized networks of the cells
Chemical Synapses
-via release of neurotransmitters (fast acting act at synapse) or neuromodulators (slower acting and can act outside the synapse)
-this is most synapses of the nervous system
ionotropic
ion channel receptor
Metabotrophic
GPCR generate a response to rough signal transduction
Synaptic transmission
transmission of a signal across a chemical synapse
Steps of neurotrasmitter release
-action potential depolarizes the axon terminal
-the depolarization opens voltage gated Ca2+ channels and Ca2+ enters the cell
-Calcium entry triggers exocytosis of synaptic vesicle contents
-neurotransmitter diffuses across the syaptic cleft and binds wi
Steps/ways neurotransmitters are terminated
-can be returned to the axon terminal to be reused or are transported into glial cells
-enzymes inactivate neurotransmitters
-can diffuse out of the synaptic cleft
Divergence
a single presynaptic neuron may branch and synapse with multiple target cells
Convergence
many presynaptic neurons may synapse with a small number of postsynaptic neurons
(come together)
In CNS up to _____ presynaptic neurons per postsynaptic cell
10,000
Synaptic plasticity
the ability of the nervous system to change the activity at synapses
Excitatory postsynaptic potentials (EPSP)
Depolarize the cell, closer to threshold
Inhibitory postsynaptic potentials (IPSP)
hyperpolarize the cell further from threshold, harder to generate an action potential
Neurotransmitters act through?
fast slow?
chemically gated ion channels
fast
Neuromodulators act through? fast slow?
g coupled proteins
slow
Spatial summation occurs when
the currents from nearly simultaneous graded potentials combine
Temporal Summation occurs when
2 graded potentials from one presynaptic neuron occur close together in time
In presynaptic inhibition
an inhibitory neuron synapses on one collateral of the presynaptic neuron and selectively inhibits one target
Glutamate
neurotransmitter (mainly CNS)
Long-term potentiation important for
memory formation
NMDA receptors are normally blocked/closed by 2 things:
-an activation gate
-a Mg2+ ion
Summary of long-term potentiation
see notes chapter 8
Which phylum has the first nervous system
Cnidaria: jellyfish sea anamones have
-nerve net: sensory neurons, interneurons, and motor neurons
name First organism with integrating system (primitive)
planarea flatworms No CNS/PNS distinction
Forebrain
contains cerebrum, changes in size
-fish is tiny
-birds little bigger
-humans biggest
Cerebrum
location of integrating centers that give the organism affective behaviors (feelings emotions) and cognitive behaviors (thinking/intellect)
Cognitive behaviors
thinking intellect
Affective Behaviors
feelings and emotions
Olfactory
smell
Cerebellum
coordination of movement, balance
Gray matter
consists of unmyelinated nerve cell bodies, dendrites, and axon terminals
-found in brain and spinal chord
White matter
mostly composed of myelinated axons
meninges and list them
membrane that lie between the brain/spinal cord and the bones surrounding them
-dura mater, arachnoid membrane, and pia mater
dura mater
really tough, outer most
MENINGES
arachnoid
spongy structure, spider web looking, looser
MENINGES
pia mater
thin and delicate. innermost layer
MENINGES
subarachnoid space
filled with CSF. cerebral spinal fluid
sinus
fluid filled with CSF cavity in the brain
Choroid plexus
CSF produced here. Continuously produced and reabsorbed
CSF produced and reabsorbed by
arachnoid villi
Spinal reflexes
the spinal chord can act as the integrating center for some simple reflex pathways without input from the brain
-pain reflex, hit knee with hammer, etc.
Parts of the brain
Frontal lobe, parietal lobe, temporal lobe, occipital lobe, cerebellum, pons, medulla oblongata
Cerebral cortex
outermost part of cerebrum
pons and medulla oblongata part of? controls?
brain stem, primitive part of the brain
Parts that make up the brain stem
medulla oblongata, pons, midbrain,
Thalamus
relay/integration center for sensory and motor information
pons
coordinates breathing and rate of breathing
midbrain
controls eye movement
reticular formation
active when awake
not active when sleeping/coma
aka reticular activating system(RAS)
Frontal lobe controls
-motor association
-integrating movement info.
-intellect
-personality
-motor cortex
-motor association area
Parietal lobe controls
-somatic sensory cortex (pain touch pressure temp ect)
-sensory association area
temporal lobe controls
auditory cortex
-taste
-smell
-hearing
occipital lobe controls
vision
crossing over/ decussation
occurs in the brain, nerve tracts cross over
-ex you have left frontal lobe damage, you will see affects on the right side of body
right half of cerebral cortex
is the site where spatial-related skills
-art, creativity, recognizing 3D
left half of cerebral cortex
verbal/ analytical skills
Proprioception
awareness of the bodys position in space/ bodys movement (conscious and subconscious)
Simple receptors
neurons with free nerve endings may be myelinated or unmyelinated
Complex neural receptors
have nerve endings enclosed in connective tissue capsules
Special senses receptors
cells that release neurotransmitter onto sensory neurons that initiate an action potential
Chemoreceptors
detect chemicals like glucose oxygen pH ect
Mechanoreceptor
vibrations
Baroreceptors: pressure
osmorecptors:cell stretch
thermoreceptors
heat cold
photoreceptors
light
Receptive field
specific area in which a sensory receptor can detect a stimulus
Stimulus intensity and duration
check out the figure in the book
adaptation of a sensory neuron
stop responding to a stimulus
tonic sensory receptors
-fire a rapid burst of action potentials slow down but never stop
detect things like blood pressure and things that need to be constantly monitored
phasic sensory receptors
-fire a rapid burst of action potentials in response to stimulus and will stop firing even when stimulus still present
somatosensory cortex
integrates information from sensory neurons
-touch
-proprioception
-temperature
-nociception
nociception
pain perception (can be chemo- mechono- thermo-)
auditory ossicles
middle ear bones
-mallus
-incus
-stapes
tympanic membrane AKA
eardrum
Sound transmission through ear list steps
see diagram
Hearing goes from the cochlear nerve to
medulla > thalamus > Temporal lobe (auditory cortex)
Pupil
amount of light going into the eye
-iris has muscles that change its size
light travels in these steps to get sight
cornea > pupil > lens > retina
Refraction of light
bending of light
Lens
bends light to focus it on the retina
aqueous humor
thin liquid filling front part of the eye
optic disc
the region where the optic nerve and blood vessels leave the eye
retina
back of the eye that contains photoreceptors
fovea
the region of sharpest vision, has the most photoreceptors
Macula
the center of the visual field
high acuity
very sharp of focus
Rods
function in low light and night vision (black and white)
Cones
responsible for high acuity vision and color vision during the daytime
20: 1 ______ to ______
except in ____ only ____
rods to cones
*except in fovea all RODs
sight leaving the eyeball goes to (steps)
optic nerve > optic chiasm > thalamus > visual cortex in occipital lobe
focal point
area at which the rays of light converge into a single point
autonomic nervous system 2 divisions
-parasympathetic
-sympathetic
autonomic nervous system
involuntary" functions like heart rate, cardiac muscle, smooth muscles, some glands, some adipose tissue
sympathetic nervous system
fight or flight response
parasympthetic nervous system
rest and digest
initiate autonomic, endocrine, and behavioral responses
hypothalamus, pons, and medulla
limbic system
emotions
Autonomic control centers are located in the
hypothalamus, pons, and medulla
most internal organs are under
antagonistic (both branches of autonomic nervous system)
list autonomic control centers
temperature control
-water balance
-eating behavior
-bladder control
-secondary respiratory control
-blood pressure control
-respiratory control
preganglionic neuron
originates in the CNS
Postganlionic neuron
has cell body in the ganglion and projects an axon to the target tissue
vagus nerve
major parasympathetic tract
heart -sympathetic response
-parasympathetic
-increases rate and force of contraction
-slows rate
arterioles veins -sympathetic response
-parasympathetic
-constricts dialates
-none
lungs -sympathetic response
-parasympathetic
-bronchioles dialate
-bronchioles constrict
digestive tract -sympathetic response
-parasympathetic
-decrease motility and secretion
-increase motility and secretion
adrenal medulla -sympathetic response
-parasympathetic
-secretes catecholamines
-none
autonomic varicosities
swollen regions
release neurotransmitter over the surface of target cells
A1 receptor
-found in
-sensitive to
-effect on second messenger
-most sympathetic target tissues
-norepinephrine > Epinephrine
-activates phospholipase C
A2 receptor
-found in
-sensitive to
-effect on second messenger
gastrointestinal tract and pancreas
-norepinephrine > epinephrine
-decreases cAMP
B1 receptor
-found in
-sensitive to
-effect on second messenger
heart muscle, kidney
-Norepinephrine = epinephrine
-increases cAMP
B2 receptor
-found in
-sensitive to
-effect on second messenger
certain blood vessels and smooth muscle of some organs
-Epinephrine > norepinephrine
-increases cAMP
B3 receptor
-found in
-sensitive to
-effect on second messenger
-adipose tissue
-norepinephrine > epinephrine
-increases cAMP
the ____ secretes epinephrine into the blood
adrenal medulla
adrenal cortex
true endocrine gland
adrenal medulla
modified sympathetic ganglion
chromatin cell
modified postganglionic sympathetic neuron
epinephrine
neurohormone that enters the blood
Point of CNS origin
-sympathetic
-parasympathetic
-1st thoracic to 2nd lumbar segments
-midbrain, medulla and 2-4 sacral segments
location of peripheral gland
-sympathetic
-parasympathetic
-primarily in paravertebral sympathetic chain
-on or near target organs
Structure of region from which neurotransmitter is released
-sympathetic
-parasympathetic
-varicosities
-varicosities
neurotransmitter @ target synapse
-sympathetic
-parasympathetic
-norepinephrine
-aCh
inactivation of neurotransmitter at synapse
-sympathetic
-parasympathetic
-uptake into varicosity by diffusion
-enzymatic breakdown, diffusion
ganlionic synapse
-sympathetic
-parasympathetic
-ACh on nicotinic receptor
-ACh on nicotinic receptor
neurotransmitter receptors on target cells
-sympathetic
-parasympathetic
-adrenergic
-muscarinic
Neurons/ nerve cells
release?
Structurally specialized to carry electrical signals rapidly
-long thin processes
-release: neurotransmitters and or neurohormones
Neurohormone
is released into the blood stream
-probably acts on a distant tissue
Neurotransmitter
act on a neighboring cell
-act quickly
Neuromodulators
acts on a neighboring cell
-causes a slower response
Neurons work together that results in emergent properties such as
intelligence, consciousness, etc.
The nervous system consists of
The peripheral nervous system PNS. everything outside the CNS
The Central Nervous System CNS brain and spinal chord
The periphrial nervous system PNS consists of
-Sensory division: Afferent division send info to the CNS through afferent (sensory) neurons
-Efferent: Send info to CNS through efferent (sensory) neurons
Autonomic Nervous system
Nervous system controls involuntrary muscle contraction and other cells
Sympathetic Nervous system
promotes Fight or Flight responses
Parasympathetic Nervous system
promotes "rest and digest" responses
Enteric Nervous system
Gut, digestion (considered a seperate intergrating system)
Somatic Nervous system
motor neurons control voluntary muscles
Synapse
region where an axon terminal communicates with its postsynaptic target cell
Dendrites
carry signals to the cell body
Axons
carry signals away from cell body
Synaptic Cleft
space between pro and post synaptic cells
Axon Hillock
region where axon begins
Myelin sheath
insulating substance wrapped around a axon of some neurons
Functional categories of neurons
sensory neurons(afferent), interneurons of CNS, Efferent neurons
Psedounipolar
one axon
ex. efferent neurons
bipolar
2 axons
ex sensory neurons
anaxonic
have no apparent axons
multipolar
lack long axons
Interneurons
completley in the CNS
Slow axonal transport happens by
movement due to diffusion through cytoplasm
Fast axonal transport
uses the cytoskelton and microtubules, with motor proteins
Microtubules
one type of protein fibers of the cytoskeleton motor proteins that are also involved
Retrograde transport
back to nucleus fast
Anterograde Transport
to axon terminal
Glial cells are
support cells for neurons
Oligodendrcytes and Schwann cells are found where... do what...
Oligodendrocytes found in CNS
Schwann found in PNS can also secrete neurotrophic factors
both form myelin sheaths
Myelin
multiple layers of phospholipids membrane wrapped around an axon
-insulates neuron > faster transmission of electrical signals
-provides protection
Satelite cell found...does what
found in PNS
Support cell bodies
Glial Cells found in the PNS
schwann cells
satellite cells
Glial cells found in CNS
-ependymal cells
-Astrocytes
-Microglia (modified immune cells): act as scavengers/phagocytes
-oligondendrocytes
blood brain carrier
prevents cells and many chemicals/substances from moving from the blood into the brain
Ependymal cells function
-create barriers between fluid filled compartments
-source of stem cells
Astrocytes function
-take up K+ water neurotransmitters
-secrete neurotrophic factors
-help form blood brain barrier
-provide substrates for ATP production
found in CNS
Microglia
modified immune cells
-scavengers/phagocytes
Found in CNS
stem cell
can divide and differentiate into other cell types
Oliogodendrocytes
Form myelin sheath
found in CNS
Schwann cells
form myelin sheath
secrete neurotrophic factors
found in PNS
Satellite
support cell bodies
found in PNS
Neurotropic factors
chemical mediators that act on 2 neurons
ganglia
cluster of neuron cell bodies in the PNS
-satellite cells concentrated around ganglia
Nucleus
cluster of neuron cell bodies in CNS
node of ranvier
a section of unmyelinated axon membrane between two schwann cells
direct contact between neurons plasms membrane and ECF
The goldman-Hodgkins-Katz (GHK) equation
calculates membrane potential including contributions from all ions that can cross the membrane
Eion =
equilibrium potential of that ion
Ions most important for excitable cells are
K+
Na+
Cl-
Ca2+
Depolarization can be caused by
membrane potential becomes more positive
- a few Na+ ions move into the cell
Hypopolarization can be caused by
membrane potential becomes more negative
- a few K+ ions into the cell
repolarizing
returning to resting membrane potential
Conductance
ease with which an ion flows through the channel
treshhold
minimum voltage change needed to activate (open) a channel can start an action potential
For the whole neuron threshold refers to
the voltage charge needed to generate an action potential
Current in a cell/organism refers to
the movement of positively charged ions
V in ohm's law
voltage
R in ohm's law
resistance
An ions current refers to
the flow of electrical charge carried by that ion
resistance
the force that opposes movement of charge etc.
Resistance to current flow comes from
the resistance of the cell membrane (can be changed by changing permeability to ions by opening/closing ion channels) and of the cytoplasm (fairly constant)
Graded potential
variable strength(max strength changes) short term changes that lose strength as they spread down the cell
action potential
all or none" do not lose strength as they move along the cell
Graded potential type of signal? occurs where? Types of gated ion channels involved? Ions involved? Strength of signal? what initiates the signal? unique?
-input signal, depolarizing or hypopolarizing
-Dendrites and cell body
-mechancally, chem, voltage gated channels
-Na+ Cl- Ca2+
-depends on initial stimulus can be summed (in time/space)
-entry of ions through gated channels
-no min, level to initiate
2 s
Action potential type of signal? occurs where? Types of gated ion channels involved? Ions involved? Strength of signal? what initiates the signal? unique?
-regenerating conduction signal depolorizing
-trigger zone through axon
-voltage gated channels
-Na+ and K+ Different in muscles
-all or none cannot be summed
-above threshold graded potential at the trigger zone opens ion channels
-threshold stimulus req
trigger zone
the physical location in the neuron where action potential can be generated it includes the
-axon hillock
-initial segment
*voltage gated sodium channels
*SEE slide graded potentials can trigger action potentials
...
summary of an action potential
watch video on a&p flicks
FIG8.9
Refractory Period
the time needed for a cell to return to resting membrane potential or atleast to a point where another action potential can be generated
What is responsible for refractory periods following an action potential
Voltage gated Na+ channels
Open>inactive>closed
Absolute refractory period
No stimulus can trigger another action potential
Relative Refractory period
Only larger than normal stimulus can initiate a new action potential
Conduction speed is increased with
-increasing neuron size (in diameter)
-myelination
Action potential cant go backwards down the axon because
refractory period
Saltatory conduction
leeps from node to node
"saltaire": to leap
Hyperkalemia
look up
electrical synapse
gap junctions
neurons of the CNS, cardiac and smooth muscle, glial cells
-allows rapid transmission synchronized networks of the cells
Chemical Synapses
-via release of neurotransmitters (fast acting act at synapse) or neuromodulators (slower acting and can act outside the synapse)
-this is most synapses of the nervous system
ionotropic
ion channel receptor
Metabotrophic
GPCR generate a response to rough signal transduction
Synaptic transmission
transmission of a signal across a chemical synapse
Steps of neurotrasmitter release
-action potential depolarizes the axon terminal
-the depolarization opens voltage gated Ca2+ channels and Ca2+ enters the cell
-Calcium entry triggers exocytosis of synaptic vesicle contents
-neurotransmitter diffuses across the syaptic cleft and binds wi
Steps/ways neurotransmitters are terminated
-can be returned to the axon terminal to be reused or are transported into glial cells
-enzymes inactivate neurotransmitters
-can diffuse out of the synaptic cleft
Divergence
a single presynaptic neuron may branch and synapse with multiple target cells
Convergence
many presynaptic neurons may synapse with a small number of postsynaptic neurons
(come together)
In CNS up to _____ presynaptic neurons per postsynaptic cell
10,000
Synaptic plasticity
the ability of the nervous system to change the activity at synapses
Excitatory postsynaptic potentials (EPSP)
Depolarize the cell, closer to threshold
Inhibitory postsynaptic potentials (IPSP)
hyperpolarize the cell further from threshold, harder to generate an action potential
Neurotransmitters act through?
fast slow?
chemically gated ion channels
fast
Neuromodulators act through? fast slow?
g coupled proteins
slow
Spatial summation occurs when
the currents from nearly simultaneous graded potentials combine
Temporal Summation occurs when
2 graded potentials from one presynaptic neuron occur close together in time
In presynaptic inhibition
an inhibitory neuron synapses on one collateral of the presynaptic neuron and selectively inhibits one target
Glutamate
neurotransmitter (mainly CNS)
Long-term potentiation important for
memory formation
NMDA receptors are normally blocked/closed by 2 things:
-an activation gate
-a Mg2+ ion
Summary of long-term potentiation
see notes chapter 8
Which phylum has the first nervous system
Cnidaria: jellyfish sea anamones have
-nerve net: sensory neurons, interneurons, and motor neurons
name First organism with integrating system (primitive)
planarea flatworms No CNS/PNS distinction
Forebrain
contains cerebrum, changes in size
-fish is tiny
-birds little bigger
-humans biggest
Cerebrum
location of integrating centers that give the organism affective behaviors (feelings emotions) and cognitive behaviors (thinking/intellect)
Cognitive behaviors
thinking intellect
Affective Behaviors
feelings and emotions
Olfactory
smell
Cerebellum
coordination of movement, balance
Gray matter
consists of unmyelinated nerve cell bodies, dendrites, and axon terminals
-found in brain and spinal chord
White matter
mostly composed of myelinated axons
meninges and list them
membrane that lie between the brain/spinal cord and the bones surrounding them
-dura mater, arachnoid membrane, and pia mater
dura mater
really tough, outer most
MENINGES
arachnoid
spongy structure, spider web looking, looser
MENINGES
pia mater
thin and delicate. innermost layer
MENINGES
subarachnoid space
filled with CSF. cerebral spinal fluid
sinus
fluid filled with CSF cavity in the brain
Choroid plexus
CSF produced here. Continuously produced and reabsorbed
CSF produced and reabsorbed by
arachnoid villi
Spinal reflexes
the spinal chord can act as the integrating center for some simple reflex pathways without input from the brain
-pain reflex, hit knee with hammer, etc.
Parts of the brain
Frontal lobe, parietal lobe, temporal lobe, occipital lobe, cerebellum, pons, medulla oblongata
Cerebral cortex
outermost part of cerebrum
pons and medulla oblongata part of? controls?
brain stem, primitive part of the brain
Parts that make up the brain stem
medulla oblongata, pons, midbrain,
Thalamus
relay/integration center for sensory and motor information
pons
coordinates breathing and rate of breathing
midbrain
controls eye movement
reticular formation
active when awake
not active when sleeping/coma
aka reticular activating system(RAS)
Frontal lobe controls
-motor association
-integrating movement info.
-intellect
-personality
-motor cortex
-motor association area
Parietal lobe controls
-somatic sensory cortex (pain touch pressure temp ect)
-sensory association area
temporal lobe controls
auditory cortex
-taste
-smell
-hearing
occipital lobe controls
vision
crossing over/ decussation
occurs in the brain, nerve tracts cross over
-ex you have left frontal lobe damage, you will see affects on the right side of body
right half of cerebral cortex
is the site where spatial-related skills
-art, creativity, recognizing 3D
left half of cerebral cortex
verbal/ analytical skills
Proprioception
awareness of the bodys position in space/ bodys movement (conscious and subconscious)
Simple receptors
neurons with free nerve endings may be myelinated or unmyelinated
Complex neural receptors
have nerve endings enclosed in connective tissue capsules
Special senses receptors
cells that release neurotransmitter onto sensory neurons that initiate an action potential
Chemoreceptors
detect chemicals like glucose oxygen pH ect
Mechanoreceptor
vibrations
Baroreceptors: pressure
osmorecptors:cell stretch
thermoreceptors
heat cold
photoreceptors
light
Receptive field
specific area in which a sensory receptor can detect a stimulus
Stimulus intensity and duration
check out the figure in the book
adaptation of a sensory neuron
stop responding to a stimulus
tonic sensory receptors
-fire a rapid burst of action potentials slow down but never stop
detect things like blood pressure and things that need to be constantly monitored
phasic sensory receptors
-fire a rapid burst of action potentials in response to stimulus and will stop firing even when stimulus still present
somatosensory cortex
integrates information from sensory neurons
-touch
-proprioception
-temperature
-nociception
nociception
pain perception (can be chemo- mechono- thermo-)
auditory ossicles
middle ear bones
-mallus
-incus
-stapes
tympanic membrane AKA
eardrum
Sound transmission through ear list steps
see diagram
Hearing goes from the cochlear nerve to
medulla > thalamus > Temporal lobe (auditory cortex)
Pupil
amount of light going into the eye
-iris has muscles that change its size
light travels in these steps to get sight
cornea > pupil > lens > retina
Refraction of light
bending of light
Lens
bends light to focus it on the retina
aqueous humor
thin liquid filling front part of the eye
optic disc
the region where the optic nerve and blood vessels leave the eye
retina
back of the eye that contains photoreceptors
fovea
the region of sharpest vision, has the most photoreceptors
Macula
the center of the visual field
high acuity
very sharp of focus
Rods
function in low light and night vision (black and white)
Cones
responsible for high acuity vision and color vision during the daytime
20: 1 ______ to ______
except in ____ only ____
rods to cones
*except in fovea all RODs
sight leaving the eyeball goes to (steps)
optic nerve > optic chiasm > thalamus > visual cortex in occipital lobe
focal point
area at which the rays of light converge into a single point
autonomic nervous system 2 divisions
-parasympathetic
-sympathetic
autonomic nervous system
involuntary" functions like heart rate, cardiac muscle, smooth muscles, some glands, some adipose tissue
sympathetic nervous system
fight or flight response
parasympthetic nervous system
rest and digest
initiate autonomic, endocrine, and behavioral responses
hypothalamus, pons, and medulla
limbic system
emotions
Autonomic control centers are located in the
hypothalamus, pons, and medulla
most internal organs are under
antagonistic (both branches of autonomic nervous system)
list autonomic control centers
temperature control
-water balance
-eating behavior
-bladder control
-secondary respiratory control
-blood pressure control
-respiratory control
preganglionic neuron
originates in the CNS
Postganlionic neuron
has cell body in the ganglion and projects an axon to the target tissue
vagus nerve
major parasympathetic tract
heart -sympathetic response
-parasympathetic
-increases rate and force of contraction
-slows rate
arterioles veins -sympathetic response
-parasympathetic
-constricts dialates
-none
lungs -sympathetic response
-parasympathetic
-bronchioles dialate
-bronchioles constrict
digestive tract -sympathetic response
-parasympathetic
-decrease motility and secretion
-increase motility and secretion
adrenal medulla -sympathetic response
-parasympathetic
-secretes catecholamines
-none
autonomic varicosities
swollen regions
release neurotransmitter over the surface of target cells
A1 receptor
-found in
-sensitive to
-effect on second messenger
-most sympathetic target tissues
-norepinephrine > Epinephrine
-activates phospholipase C
A2 receptor
-found in
-sensitive to
-effect on second messenger
gastrointestinal tract and pancreas
-norepinephrine > epinephrine
-decreases cAMP
B1 receptor
-found in
-sensitive to
-effect on second messenger
heart muscle, kidney
-Norepinephrine = epinephrine
-increases cAMP
B2 receptor
-found in
-sensitive to
-effect on second messenger
certain blood vessels and smooth muscle of some organs
-Epinephrine > norepinephrine
-increases cAMP
B3 receptor
-found in
-sensitive to
-effect on second messenger
-adipose tissue
-norepinephrine > epinephrine
-increases cAMP
the ____ secretes epinephrine into the blood
adrenal medulla
adrenal cortex
true endocrine gland
adrenal medulla
modified sympathetic ganglion
chromatin cell
modified postganglionic sympathetic neuron
epinephrine
neurohormone that enters the blood
Point of CNS origin
-sympathetic
-parasympathetic
-1st thoracic to 2nd lumbar segments
-midbrain, medulla and 2-4 sacral segments
location of peripheral gland
-sympathetic
-parasympathetic
-primarily in paravertebral sympathetic chain
-on or near target organs
Structure of region from which neurotransmitter is released
-sympathetic
-parasympathetic
-varicosities
-varicosities
neurotransmitter @ target synapse
-sympathetic
-parasympathetic
-norepinephrine
-aCh
inactivation of neurotransmitter at synapse
-sympathetic
-parasympathetic
-uptake into varicosity by diffusion
-enzymatic breakdown, diffusion
ganlionic synapse
-sympathetic
-parasympathetic
-ACh on nicotinic receptor
-ACh on nicotinic receptor
neurotransmitter receptors on target cells
-sympathetic
-parasympathetic
-adrenergic
-muscarinic
neuron-target synapse
--sympathetic
-parasympathetic
-NE on A or B adrenergic receptor
-ACh on muscarinic receptor
Somatic motor pathways
have single neuron that originates in the CNS and projects it axon to a skeletal muscle
Neuromuscular junction
site where a motor neuron synapses with a skeletal muscle
motor end plate
region of muscle membrane contains concentration of ACh receptors
Somatic motor division
-# neurons in efferent path
-Neurotransmitter/receptor @ neuron target synapse
-target tissue
-neurotransmitter released from
-effects on target tissue
-peripheral components found outside CNS
-summary of function
-1
-ACh/nicotinic
-skeletal muscle
-axon terminals
-excitatory only muscle contracts
-axons only
-posture and movement
Autonomic
-# neurons in efferent path
-Neurotransmitter/receptor @ neuron target synapse
-target tissue
-neurotransmitter released from
-effects on target tissue
-peripheral components found outside CNS
-summary of function
-2
-ACh/ muscarinic or NE A or B adrenergic
-smooth and cardiac muscle some endo and exo glands some adipose tissue
-varicositites and axon terminals
-excitory or inhibitory
-preganglionic axons, ganglia, postganglia, neurons
-visceral function including
3 categories of gated ion channels
which type is most involved in the initiation and conduction of action potentials
-Mechanical (some sensory neurons)
-chemical (ligands such as neurotransmitters)
-voltage (changes in membrane potential)
Voltage gated ion channels are most involved.
ohms law equation
increase in
V= I X R (voltage = current X resistance)