Exam # 3 Chapter 12 Flashcards
- consists of the brain and spinal cord
- processes many kinds of incoming sensory information
- the source of thoughts, emotions, and memories
- most signals that stimulate muscles to contract and glands to secrete originate here
central nervous system (CNS)
- consists of all nervous tissue outside the CNS
- components are nerves and sensory receptors
peripheral nervous system (PNS)
-bundles of hundreds to thousands of axons plus associated connective tissue and blood vessels that lies outside the brain and spinal cord
nerve
- structure of the nervous system that monitors changes in external or internal environment
- Ex: touch, photo receptors in the eye, and olfactory receptors in the nose
sensory receptors
-the PNS is divided into _____ and _____ divisions
sensory and motor
- the _____ or afferent division of the PNS conveys input into CNS from sensory receptors
- provides the CNS with information about the ____ and _____ senses
sensory division
somatic and special senses
-the _____ senses are tactile, thermal, pain and proprioceptive (where things are in space)
somatic
-the _____ senses are smell, taste, vision, hearing, and equilibrium (balance,ph, pressure senses)
special
- the _____ or efferent division of the PNS conveys output from the CNS to effectors (muscles and glands)
- its further divided into a somatic nervous system and autonomic nervous system
motor division
- conveys output from the CNS to skeletal muscles only
- voluntary action
somatic nervous system (SNS)
- conveys output from the CNS to smooth and cardiac muscles and glands
- involuntary action
autonomic nervous system (ANS)
-the sympathetic, parasympathetic, and enteric nervous system are the main branches of the _____
autonomic nervous system
-the ____ and ____ of the ANS consists of smooth and cardiac muscle and glands
sympathetic and parasympathetic nervous system
-the _____ of the ANA consist of smooth muscle and glands of GI tract
enteric nervous system
-the functions of the nervous system are:
- ____ detects internal and external stimuli
- _____ process info and make decisions
- _____ activate effectors and elicit a response
sensory function
integrative function * also known as integration
motor function
- the ____ is always on
- the _____ responds to changes in environment
parasympathetic
sympathetic
-are the receiving or input portions of a neuron, carry signal to cell body
dendrites
-long, thin cylindrical projection that carry signals away
axons
-prominent clusters of rough ER- materials produced here may be used to regenerate axons in the PNS
nissl bodies
-cone shaped region where axon joins cell body, nerve impulses arise in the trigger zone
axon hillock
-the cytoplasm and plasma membrane of axon
axoplasm
axolemma
-bundles of intermediate fibers, provides the cell with shape and support
neurofibrils
-the dendrites, cell body, and axon is the basic parts of a _____
neuron
-neurons can be classified with 3 ways:
shape, size, and functions
- ______ neurons have several dendrites and one axon
- most neurons of CNS
- all motor neurons
multipolar neurons
- _____ neurons have one main dendrite and one axon
- retina in eye
- inner ear
- olfactory are of brain
bipolar neurons
- _____ neurons have dendrites and one axon that are fused together (pseudo-unipolar)
- sensory receptors
- cell bodies in ganglia
unipolar neurons
- have mossy fibers
- located in the cerebellum, these neurons redulate movement
- intricate series of connections
purkinje cell
- found in the pre-frontal cortex, the home of cognition
- because many other axons can terminate on the dendrites, a single cell can have 30,000 excitatory inputs
pyramidal cell
- sensory neurons (afferent) are found in the ____
- interneuron are found in the _____
motor neurons (efferent) are found in the _____
PNS
CNS
PNS
- make up about half the volume of the CNS
- the glue that holds nervous tissue together
neuroglia
-astrocytes, oligodendrocytes, microglial, and ependymal cells are cells of the _____ system
CNS
- star-shaped, largest and most numerous, many processes that contact neurons, blood capillaries, and pia mater
- contain microfilaments for support
- isolate neurons from harmful substances in blood (blood brain barrier)
- maintain chemical environment fro impulses
- growth, migration, formation of synapses (in embryo as well as learning/memory)
astrocytes
- like astrocytes but smaller, fewer processes
- form the myelin sheath around CNS axons
oligodendrocytes
-small, spiny cells, that function like macrophages (remove debris, microbes)
microglial cells
- single layer of cuboidal/columnar cells
- produce and assist in the circulation of cerebrospinal fluid
ependymal cells
-the cell bodies of most unipolar neurons are located in the _____,(collection on cell bodies) of spinal and cranial nerves
ganglia
- these cells are like oligodendrocytes, but myelinate a single axon or a parallel bundle
- participates in axon regeneration
schwann cells
- flat cell bodies of neurons or ganglia
- support and regulate exchange of material with interstitial fluid
satellite cells
-the two types of cells in the PNS are _____ and _____
schwann cells
satellite cells
-axons surrounded by a multilayered lipid and protein covering called the _____
myelin sheath
-when a axon is _____, the sheath electrically insulates the axon of a neuron and increases the speed of the nerve impulse conduction
myelinated
-axons without a covering are said to be _____
unmyelinated
-the two types of neuroglia that produce myelin sheaths are _____ and _____
schwann cells
oligodendrocytes
- the outer nucleated cytoplasmic layer of the schwaan cell, which encloses the myelin sheath is the _____
- it is found only around axons in PNS
neurolemma
-cluster of neuronal cell bodies located in the PNS
ganglion
-_____ is composed primarily of myelinated axons
white matter
- _____ of the nervous system contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia
- it appears grayish because the nissl bodies impart a gray color and there is no myelin in these areas
gray matter
-neurons are electrically excitable and communicate with one another using two types of electrical signals: the _____ and _____
graded potential
action potentials
-_____ potentials are used for short distance communication only
graded potential
-_____ potentials allow communication over long distances within the body
action potential
-an action potential in a muscle fiber is called a _____
muscle action potential
-an action potential that occurs in a neuron is called a _____
nerve action potential
-graded potentials and nerve and muscle action potentials are involved in the relay of sensory stimuli, integrative functions such as _____ and _____
perception
motor activities
- the pathway of _____
- receptor
- sensory neuron
- interneuron
- upper, lower motor neurons
- neuromuscular junction
electrical signals
-the electrical signals produced by neurons and muscle fibers rely on four types of ion channels the _____, the _____, the _____, and the _____
leak channels
ligand gated channel
mechanically gated channel
voltage gated channel
- gated channels that randomly open and close
- found in nearly all cells, including dendrites, cell bodies, and axons of all types of neurons
- passive process
leak channels
- gated channels that open in response to binding of ligand (chemical) stimulus
- dendrites of some sensory neurons such as pain receptors and dendrites and cell bodies of interneurons and motor neurons
- neurotransmitters, passive process
ligand gated channels
- gated channels that open in response to mechanical stimulus such as touch, pressure, vibration, or tissue stretching
- dendrites of some sensory neurons such as touch receptors, pressure receptors, and some pain receptors
mechanically gated channels
- gated channels that open in response to voltage stimulus (change in membrane potential)
- axons of all types of neurons
voltage gated channels
- a anion has a _____ charge
- a cation has a _____ charge
negative
positive
-an electrical potential difference (voltage) that exists across the plasma membrane of an excitable cell under resting conditions
resting membrane potential
Units for potential are in _____ and measures the difference in charge between the inside and outside
milivolts (mV)
-the _____ exists because of a small buildup of negative ions in the cytosol along the inside of the membrane, and the equal buildup of positive ions in the extracellular fluid along the outside surface of the membrane
resting membrane potential
- a cell the exhibits a membrane potential is said to be ____
- most body cells
polarized
- 3 factors that determine _____
- unequal amount of ions in the ECF and cytosol (more K+)
- inability of most anions to leave the cell
- the electrogenic nature of the Na+-K+ ATPases (3Na+ions out and 2 K+ions in)
resting membrane potential
-the ____ in the resting membrane potential return things back to keep exchanging ions
leak channels
- steps in the _____
- Na+ and Cl- and in the ECF
- K+ and phosphates, proteins in the cytosol
- the negative ions/molecules don’t cross the membrane
- the movement of the positive ions (cations) out of a region cause it to become more negative
- typically -70mV
membrane potential
- occur in the dendrites
- vary in size
- can be hyperpolarizing or depolarizing
graded potential
- potential starts at -70, more polarized is increasingly negative
- trying to stop something
hyperpolarizing graded potential
- potential moves back towards zero, less negative
- easier for the body to do
- trying to start something
depolarizing graded potential
-_____ regions of the membrane naturally return to resting potential, so graded potentials are short term
depolarized
-successive depolarization can undergo _____, adding together to reach a new level
summation
-a _____ forms in response to the opening of mechanically gated channels or ligated channels
graded potential
-_____ or impulse is a sequence of rapidly occurring events that decrease and reverse the membrane potential and the eventually restore it to the resting state
action potential
-an action potential has two main phases the _____ and _____
depolarizing phase
repolarizing phase
-the negative membrane potential becomes less negative, reaches zero, and then becomes positive
depolarizing phase
-the membrane potential is restored to the resting state of -70mV
repolarizing phase
-after repolarizing phase, there may be a _____, which the membrane potential temporarily becomes more negative than the resting level
after-hyperpolarizing phase
-incoming signal strength does not increase the size of an _____ but the frequency
action potential (AP)
- an action potential occurs in the membrane of the axon of a neuron when depolarization reaches a certain level called the _____
- about -55mV
threshold
-an action potential will not occur in response to a _____, a weak depolarization that cannot bring the membrane potential to threshold
subthreshold stimulus
-an action potential will occur in response to a _____, a stimulus that is just strong enough to depolarize the membrane threshold
threshold stimulus
- multiple action potentials will form in response to a _____, a stimulus that is strong enough to depolarize the membrane above threshold
- each AP is the same size, the amplitude is always the same regardless of the stimulus intensity
suprathreshold stimulus
-active transport is the result of the _____
resting membrane potential
-the period of time after an AP begins during which as excitable cell cannot generate another AP in response to a normal threshold stimulus is called the _____
refractory period
-during the _____, even a very strong stimulus cannot initiate a second AP, the Na+ channels cannot reopen, they must return to the resting state
absolute refractory period
- the period of time which a second AP can be initiated, only by a larger than normal stimulus
- voltage gated K+ channels are still open after inactivated Na+ channels have returned to resting state
relative refractory period
- the ion flow through voltage gated channels during depolarizing and repolarizing phase of an _____ are:
- resting state
- depolarization phase
- repolarization phase begins
- repolarization phase continues
action potential
-all voltage gated Na+ and K+ channels are closed
resting state
-when membrane potential of axon reaches threshold the Na+channel activation gates open
depolarizing phase
- when Na+ channel inactivation gates close and K+ channels open
repolarizing phase begins
-when K+ outflow continues, K+ eventually restores resting membrane potential
repolarization phase continues
-there are two types of propagation in Ap’s the _____ and _____
continuous conduction
saltatory conduction
- involves step by step depolarization and repolarization of each adjacent segment of plasma membrane
- AP propagates only a short distance
- occurs in unmyelinated axons and in muscle fibers
continuous conduction
- AP propagation that occur along myelinated axons
- occurs b/c of uneven distribution of voltage gated channels
- looks like it is jumping from one node to another
saltatory conduction
- _____ arise from dendrites and cell body
- _____ arise from trigger zones and propagate along axon
GP
AP
- _____propagate and thus permit communication over longer distances
- _____ decremental (not propagated), permit communication over short distances
AP
GP
- _____ligid gated or mechanically gated ion channels
- _____voltage gated channels for Na+ and K+
GP
AP
- _____all or none, typically about 100mV
- _____depending on strength of stimulus, varied from less than 1mV to more than 50 mV
AP
GP
- _____typically longer, ranging from several milliseconds to several minutes
- _____shorter, ranging from 0.5 to 2 msec
GP
AP
- _____ always consist of depolarizing phase followed by repolarizing phase and return to resting phase
- _____may be hyperpolarizing (stopping AP), or depolarizing (exciting AP)
AP
GP
- _____if not present, summation can occur
- _____ if present, summation cannot occur
GP
AP
-is the connection between an axon terminus of one neuron and another neuron or an effector
synapse
-nerve cell that carries nerve impulse towards synapse, the cell that sends the signal
presynaptic neuron
-a cell that receives a signal
postsynaptic cell
-nerve cell that carries nerve impulse away from a synapse
postsynaptic neuron
-responds to the impulse at the synapse
effector cell
- most synapse between neurons are _____
- from axon to dendrite
axodendritic
-synapse from axon to cell body
axosomatic
-synapse from axon to axon
axoaxonic
-_____ neurons connects to _____ neurons or effector cells
presynaptic
postsynaptic
-two types of synapses are _____ and _____
gap junctions
chemical synapse
- contains tubular connexons, which acts like tunnels to connect cytosol to cells
- as ions flow from once cell to the next through connexons, the AP spreads from cell to cell
gap junctions
-NT’s carry signal across the gap is a _____
chemical synapse
- time it takes to cross the synapse, virtually absent in gap junctions
- the reason that chemical synapses relay signals more slowly than electrical synapses
synaptic delay
- current is created by _____ crossing the cell membrane and changing the potential
- if you bridge the two _____, the current is allowed to travel from one cell to the next
ions
cytosols
-a _____ transmits a signal as follows:
- presynaptic neuron brings Gp or AP
- volt gated Ca2+ channels open
- Ca2+ induces exocytosis of NT’s
- post synaptic channels bind NT’s
- NT’s cause Na+ channels to open
- influx of N causes post synaptic potential (PSP)
- nerve impulse is conducted away from synapse
chemical synapse
- which integral changes the signal from electrical to chemical ?
- from chemical to electrical ?
voltage gated Ca2 channels
ligand-gated
-the depolarizing phase of the nerve impulse opens _____, which are present in the membrane of synaptic end bulb
voltage gated Ca2+ channels
- as ions flow through the opened channels, the voltage across the membrane changes, this is a _____
- depending on which ions the channels admit, it may be depolarization (excitation) or hyperpolarization (inhibition)
postsynaptic potential
- these are simply changes in membrane potential
- a depolarizing (positive) postsynaptic potential is called _____, more like to cause an impulse, moving from resting (-70mV) towards threshold (-55mV)
- a hyperpolarizing (negative) postsynaptic potential is called _____, less likely to cause impulse
excitatory postsynaptic potential (EPSP)
inhibitory postsynaptic potential (IPSP)
- is type of NT receptor that contains a NT binding site and an ion channel
- the NT binding site and the ion channel are components of the same protein
ionotropic receptor
- a type of NT receptor that contains a NT binding site but lacks an ion channel as part of its structure
- is coupled to a separate ion channel by a type of membrane protein called a G protein
- there are 2 integral proteins, binding ACh activates the G protein, which in turn opens the channel allowing K+ to flow out of the cell
- is IPSP (positive moving in wrong direction)
metabotropic acetylcholine receptor
- when ACh binds 2 sites on channel, allows cations to flow, depolarizing the membrane, this is a _____ receptor
- is EPSP
iontropic acetylcholine receptor
- _____ opens Cl- channels
- the influx of anions hyperpolarizes the membrane, this is the _____ receptor
- is IPSP (positive moving in wrong direction)
GABA (gamma-aminobutyric acid)
ionotropic GABA receptor
-both the _____ and _____ receptors are ionotropic, binding their NT directly causes the movement of ions by opening the ion channel
ACh
GABA
-receptors need to clear the NT, they are removed in 3 ways _____, _____, and _____
diffusion
enzymatic degradation
uptake
-when a NT is not near its receptors, it cannot bind
diffusion
- certain NT’s are inactivated through _____
* ex: acetylcholinesterase
enzymatic degradation
- when NT’s are transported back by neighboring neuroglia, _____
- when NT’s are transported back by pre-synaptic neuron
uptake
re-uptake
-the presence of free Ca2+ in the pre-synaptic neuron means NT vesicles can more easily be exocytosed
facilitation
-lack of NT vesicles due to rapid signals and failure to re-uptake NT’s
synaptic fatigue
-results from the buildup of NT released simultaneously by several presynaptic end bulbs
spatial summation
-results from buildup of NT released by a single presynaptic end bulb two or more times in rapid succession
temporal summation
-the sum of all the excitatory and inhibitory effects at any given time determines the effect on the postsynaptic neuron, which may respond in the following ways _____ and _____
EPSP and IPSP
-if the net summation of EPSP’s and IPSP’s is a depolarization that reaches threshold, then an _____ will occur at the trigger zone of a postsynaptic neuron
action potential
- EPSP > IPSP, but can not reach threshold, a new EPSP is genearated
- ESPS > IPSP, threshold, one or more impulses (AP) genearated
- IPSP > EPSP, new IPSP generated
- this is the 3 outcomes of _____
summation
- best studied NT, is released by many PNS neurons and by some CNS neurons
- is an excitatory NT at some synapses, such as neuromuscular junction
- inhibitory at metabotropic channels
acetycholine (ACh)
-an amino acid NT, has powerful excitatory effects
glutamate aspartate
- plays roles in arousal (awakening from deep sleep), dreaming, and regulating mood, a stimulatory process, _____
- a smaller number of neurons in the brain use _____, as a NT, stress response
*biogenic amines
norepinephrine (NE)
epinephrine
- brain neurons containing the NT _____, are active during emotional responses, addictive behaviors, and pleasurable experiences
- regulation of skeletal muscles
*biogenic amines
dopamine
- a NT involved with sensory perception, temperature regulation, control of mood, appetite, and the induction of sleep
- biogenic amines
serotonin
-substance P, endorphins, angiotensin II, and cholecystokinin (CKK) are all _____
neuropeptides
-found in sensory neurons, spinal cord pathways, and parts of the brain associated with pain, enhances perception of pain
substance P
- inhibit pain by blocking release of substance P
- may have role in memory and learning, sexual activity, control of body temp, and mental illness
endorphins
- stimulates thirst, may regulate blood pressure in brain, can raise BP
- as a hormone, causes vasocontriction and promotes release of aldosterone, which increases rate of salt and water reabsorption by kidneys
angiotensin II
- found in the brain and small intestine, may regulate feeding as a “stop eating” signal
- as a hormone, regulates pancreatic enzyme secretion during digestion, and contraction of smooth muscle in GI tract
cholecystokinin
*diverging circuit
- a neuron terminating on a single post-synaptic neuron, is considered a _____
- if one nerve terminates on several post-synaptic cells, the signal _____
- this _____ the amplifies the signal, not in intensity but in reach
simple series circuit
diverges
amplifies
- a _____ is many-to-one instead of one-to-many
- allows for integration of many EPSP and IPSP’s
- allows an effector to be stimulated by different regions of the brain
converging circuit
-_____ have branches that synapse with earlier neurons in the circuit
the signal could last seconds or hours, until turned off by inhibitory neurons
-like a positive feedback loop
*ex: breathing, coordinated muscle activities, waking up, short term memory
reverberating circuit
-_____ diverge from a single neuron, and run in parallel pathways of different lengths
- the length of time it takes to travel longer distances cause a _____, when the signals converge they arrive at different times
- this allows coordination of precision activities such as math calculations
parallel after-discharge circuits
- axon and myelin sheath degenerate, but neurolemma remains
- schwaan cells replicate to form regeneration tube to facilitate axon repair
- hard to regenerate w/o neurolemma
- most nerve damage happens in PNS
nerve regeneration
- nervous system exhibits _____, throughout your life
- the capability to change based on experience
plasticity
_____ releases binding sites in muscles
calcium
