Ch.11,12,13,14- anatomy
When it goes above threshold it's ________________
"all or none"
resting state
(-70 mV) all gated Na+ and K+ channels are closed
depolarizing phase
(inside the membrane becomes less negative) Na+ channels open
repolarizing phase
(restores resting membrane potential) Na+ channels are inactivating and K+ channels are open
resting membrane potential
-70mV. means everything is working the right way. membrane of resting neuron is polarized, and the potential difference of this is polarity. exists only across the membrane
Ohm's Law
-Current (I) is directly proportional to voltage. The greater the voltage (potential Difference), the greater the current. -There is no net current flow between points that have the same potential, as you can see by inserting a value of ) V into the equation. -Current is inversely related to resistance. The greater the resistance, the smaller the current.
functions of nervous system:
-gathering sensory input from sensory receptors -processing and interpreting sensory input to decide an appropriate response. -using motor output to activate effector organs, muscle and glands, to cause a response.
***(RMP)resting membrane potential
1. Na+ voltage gated channels open 2. depolarization occurs Na+ flows in 3. Na+ channels close (fast channel-close quickly) (b) K+ (potassium) channels open-it will flow out because it was pumped in. 4. repolarization occurs K+ flows out. 5. K+ (potassium) channels close (slow channel). 6. hyperolzation occurs 7. resting membrane potential, -70 ( back to where we started).
Terminal Branches And Axon terminals (terminal boutons)
10,000 or more __________ Per neurons is not unusual. The knoblike distal endings of the terminal branches are called ____________
there are 6 types of neuroglia- _______ in CNS and _____ in the PNS
4,2
Syphilis
A bacterial infection usually spread by sexual contact that starts as a painless sore
Spastic paralysis
A chronic pathological condition in which the muscles are affected by persistent spasms and exaggerated tendon reflexes because of damage to the central nervous system .
Parkinson's disease
A disorder of the central nervous system that facets movement often including tremors
Sulci
A groove of furrow especially one in the surface of the brain
Ventricles
A hollow part or cavity in an organ lined with ependymal cells and are filled with cerebrospinal fluid
Motor areas
A part of the central nervous system concerned with muscular action, especially the motor cortex
Alzheimer's disease
A progressive disease that destroys memory and other important mental functions
Gyri
A ridge in the cerebral cortex
Poliomyelitis
A virus that may cause paralysis and is easily preventable by the polio vaccine
Sensory areas
An area of cerebral cortex that receives afferent nerve fibers from lower sensory areas
Cerebrum
Anterior part of the brain in vertebrates located in the front area of the skull consisting of two hemispheres
Decussation of the pyramids
Anterior part of the lower medulla oblongata in which most of the fibers of each pyramid intersect
Nerve Fiber
Any long axon is called a ________.
Neurofibrils
Are bundles of intermediate filament, are important in maintaining cell shape and integrity. They form a network throughout the cell body.
Action Potentials
Are long-distance signals of axons.
Epidural space
Area between dura mater and the vertebral wall. Continuing fat and small blood vessels
Processes
Armlike __________ extend from the cell body by all neurons.
Concussion
Brain injury caused by a blow to the head or violent shaking of the head and body
Pons function
Breathing, communication between different parts of the brain hearing, taste , balance
TIA (transient ischemic attack)
Brief stroke attack that , despite resolving within minutes to hours, still requires immediate medical attention to disguising from an actual stroke
Hydrocephalus
Build up of fluid in the cavities deep within the brain
Spinal cord
Bundle of nerve fibers and associated tissue that is enclosed in the spine and connects nearly all parts of the body to the brian
Tracts and Nerves
Bundles of neuron processes are called ______ in the CNS and _____ in the PNS.
efferent division of the PNS transmits impulses from the
CNS to effector organs, which are the muscles and glands
The basic pattern of the CNS consists of a
Central cavity surrounded by a gray mater core, external to which is white matter
Leakage or nongated channels
Channels that are always open.
Nuclei
Clusters of cell bodies in the CNS.
Meninges
Collective term for the 3 membranes covering the brain and spinal cord
Neuron Cell Body
Consists of a spherical nucleus with a conspicuous nucleolus surrounded by cytoplasm.
The Central Nervous System
Contains both myelinated and nonmyelinated axons. However, in the ________ it is the oligodendrocytes that form myelin sheaths.
Astrocytes
Control the chemical environment around the neurons, where their most important job is "mopping up" leaked potassium ions and recapturing and recycling released neurotransmitters.
Cerebrum -2 hemispheres, connected by
Corpus callousness
Stroke
Damage to Brian from interruption of its blood supply
CVA (cerebrovascular accident )
Damage to brain from interruption of blood supply
Depolarization
Decrease in membrane potential: The inside of the membrane becomes less negative (moves closer to zero) than the resting potential.
Where is grey matter found in spinal cord?
Deep inside its core and the insulating white matter wrapped around the outside
The third ventricle lies within the
Diencephalin and communicates with the lateral ventricles via two intervene rivulet foramina
Two factor generate the resting membrane potential:
Differences in ionic composition of the intracellular and extracellular fluids, and differences in the permeability of the plasma membrane to those ions.
Medulla oblongata function
Digestion, sneezing,swallowing
The paired lateral ventricles lie deep within
Each cerebral hemisphere and are separated by the septum pellucidum
Central Process
Enters the CNS
The ventricles are lined with
Ependymal cells and are filled with cereospinal fluid
Axon Collaterals
Extend from the axon at more or less right angles.
Since the brain grows more rapidly than developing skull, The brain forms folds, allowing it to
Fit inside the space of the skull
The lateral and median apertures within the
Fourth ventricle connect the ventricles with the subarachnoid space surrounding the brain
5 lobes
Frontal, partiental, temporal, occipital , insula
Lipofuscin
Harmless by-product of lysosomal activity, is sometimes called the "aging pigment" because it accumulates in neurons of elderly individuals.
Neurons
Have an exceptionally HIGH METABOLIC RATE and require continuous and abundant supplies of oxygen and glucose. They cannot survive for more than a few minutes without oxygen.
Neurons
Have extreme longevity. Given good nutrition, they can function optimally for a lifetime. Neurons ARE amitotic.
The fourth ventricle lies in the
Hindbrain and communicates with the third ventricle via the cerebral aqueduct
Neurons
In many _______, the transition from local graded potential to long distance action potential takes place at the axon hillock.
Contusion
Injured tissue or skin in which blood capillaries have been ruptured ;a bruise
Functions of frontal lobe
Involved in planning organizing , problem solving , selective attention, personality
Action Potentials
Is a brief reversal of membrane potential with a total amplitude of about 100 mV. Depolarization is followed by repolarization and often a short period of hyperpolarization.
Hyperpolarization
Is in increase in membrane potential: the inside of the membrane become more negative (moves further from zero) than the resting potential.
white matter
Is responsible for communication between cerebral areas and the cerebral cortex and lower CNS centers
Prefrontal cortex
Is the cerebral cortex which covers the front part of the frontal lobe
Interneurons *Almost all Multipolar.
Lie between motor and sensory neurons in neural pathways and shuttle signals through CNS pathways where integration occurs.
Oligodendrocytes
Line up along the thicker nerve fibers in the CNS and wrap their processes tightly around the fibers, producing an insulating covering called a *Myelin Sheath*
Where is grey matter?
Located on surface of brain
Paralysis
Loss ability to move in part or most of the body typically as result of illness
Primary somatosensory cortex
Main sensory receptive area for the sense of touch
Myelin Sheath
Many Nerve fibers, particularly hose that are long or large in diameter, are covered with a whitish, fatty, segmented______________.
Potential difference
Measure of voltage between two points. The greater the __________ the higher the voltage.
Broca's area
Motor speech area that controls muscles involved in speech production. Small area of cortex on the medial surface of each cerebral hemisphere
Anterograde Movemnet
Movement away from the cell body is _____.
Retrograde Movement
Movement in the opposite direction is_________
the rising phase of the action potential is due to
Na+ flow into the cell body
The brain and spinal cord begin as the
Neural tube, which rapidly differnatiares into CNS
The ventricles of the brain are continuous with
One another and with the central canal of the spinal cord
Voltage Gated Channels
Open and close in response to changes in membrane potential.
Mechanically Gated Channels
Open in response to physical deformation of the receptor.
Chemically Gated
Open with appropriate chemical binds.
In the brain the cerebrum and cerebellum have an
Outer gray matter later, which is reduced to scattered gray matter nuclei in the spinal cord
Hemiplegia
Paralysis of one side of the body NOTE: not usually spinal injury
Functions of the partiental lobe
Protection of the brain, support the face
Receptive or Input regions
Provide an enormous surface area for receiving signals from other neurons.
Ependymal Cells ("wrapping garment")
Range in shape from squamous to columnar, and many are ciliated.
Association areas
Region of the Cortes of the brain that connects sensory and motor areas, and that is thought to be concerned with higher mental activities
Wernicke's area
Region of the brain concerned with language, located in the cortex of the dominant temporal lobe. Damage in the area causes wernicke's aphasia.
White Matter
Regions of the brain and spinal cord containing dense collections of myelinated fibers are refereed to as _____.
Brain stem general function
Regulating of the heart rate , breathing , sleeping and eating
Astrocytes
Shaped like delicate branching sea anemones, _______ are the most abundant and versatile glial cells. Play a role in making exchanges between capillaries and neurons, helping to determine capillary permeability
Graded Potentials *Called Graded Potential because their magnitude varies directly with stimulus, the more the voltage changes and the farther current flows. Triggered by some change in neuron's environment that opens gated ion channels.
Short lived, localized changes in membrane potential that can be either depolarization or hyperpolarization.
Microglial Cells
Small and ovoid with relatively long "thorny" processes.
Sodium-Potassium Pump (Na+ -K+ ATPase)
Stabilizes the resting membrane potential by maintaining the concentration gradients for sodium and potassium.
Chromatophilic Substance
Stains darkly with basic dyes.
Neurons (Nerve Cells)
Structural unites of the nervous system. They are typically large highly specialized cells that conduct messages in the form of nerve impulses from one part of the body to another.
SIDS
Sudden infant death syndrome
Satellite Cells
Surround neuron cell bodies located in the peripheral nervous system, and are thought to have many of the same functions in the PNS as astrocytes do in the CNS.
Schwann Cells
Surrounded all never fibers in the PNS and form myelin sheaths around the thicker nerve fibers. Vital ti regeneration of damaged peripheral nerve fibers.
Meninges
The 3 membranes that line the skull and vertebral canal and enclose the brain and spinal cord
Conducting Region
The axon is the __________ of the neuron. In generates nerve impulses and transmits them, typically away from the cell body, along the plasma membrane.
The medical scheme of the brain anatomy divides the adult brain into four parts:
The cerebral hemispheres, the diencephalic, the brain stem and the cerebellum
Gray matter
The darker tissue of the brain and spinal cord, consisting mainly of nerve cell bodies and branching sentries
Current
The flow of electrical charge from one point to another.
Resistance
The hindrance to charge flow provided to charge flow provided by substances through which the current must pass.
Axon Hillock
The initial region of axon arises from a cone shaped area of the cell body called the ___________
Spinal cord anatomy
The major column of the nerve tissue that is connected to the brain and lies within the vertebral canal and from which the spinal nerves emerge. 31 pairs of spinal nerves onginate in the spinal cord: 8 cervical , 12 thoracic , 5 lumbar , 5 sacral and 1 coccygeal
Voltage
The measure of potential energy generated by separated charge, is measured in either volts (V) or Millivolts. (1 mV =0.001 V).
Resting Membrane Potential
The minus sign indicates that the cytoplasmic side (inside) of the membrane is negatively charged relative to the outside. This potential difference in a resting neuron is called the ____________.
Outer collar of perinuclear cytoplasm.
The portion of Schwann cell, next to the exposed part of its plasma membrane is called ________.
The neural tube develops constructions that divide the three primary brain vesicles :
The prosencephalon (forebrain) , mesenvephalon (midbrain), and rhombensephalon (hindbrain)
Microglial Cells
Their processes touch nearby neurons, monitoring their health, and when they sense that certain neurons are injured or in other trouble, the microglial cells migrate toward them.
Ependymal Cells ("wrapping garment")
They line the central cavities of the brain and the spinal cord, where they form a fairly permeable barrier between the cerebrospinal fluid that fills those cavities and the tissue fluid those cavities and the tissue fluid bathing the cells of the CNS. The beating of their cilia helps to circulate the cerebrospinal fluid that cushions the brain and spinal cord.
Dendritic Spines
Thorny appendages having bulbous or spiky ends- which represent points of close contact (synapses) with other neurons.
Ganglia
Those that lie along the nerves in the PNS.
Electrochemical Gradiant
Together, electrical and concentration gradients constitute the _______.
Nerve Impulse
Typically generated only in axons. A neuron generates a nerve impulse only when adequately stimulated. The stimulus changes the permeability of neurons membrane by opening specific voltage-gated channels on the axon.
Pseudounipolar Neurons
Unipolar Neurons are more accurately called _____ because they origiinate as bipolar neurons. Then during early embryonic development, the two processes converge and partially fuse to form the short single process that issues from the cell body.
Graded Potentials
Usually incoming signals operating over short distances.
Additional protection of spinal cord
Vertebrae protect the spinal cord. The vertebrae are separated by disks made of cartilage, which act as cushion
Midbrain function
Vision,hearing,motor control, sleep, wake, arousal, temperature regulation
Current
Voltage (V) = ------------------------- Resistance (R)
Flaccid paralysis
Weakness or paralysis and reduced muscle tone without other obvious cause
Neurotransmitters
When impulse reaches the axon terminals, it causes _____- signaling chemicals usually stored in vesicles--- to be released into extracellular space.
Receptor Potential
When the receptor of a sensory neuron is excited by some form of energy, the resulting graded potential.
Postsynaptic Potential
When the stimulus is a neurotransmitter released by another neuron, the graded potential is called _______.
Motor, or efferent, neurons *Also Multipolar.
_____ Carry impulses away from the CNS to the effector organs of the body periphery.
Gray Matter
_____ Contains mostly nerve cell bodies and nonmyelinated fibers.
Multipolar Neurons (Major neuron type in CNS)
_____ Have three or more processes- one axon and the rest dendrites.
Bipolar Neurons
_____ Have two processes- an axon and a dendrite- that extend from opposite sides of the cell body.
Positive Ions
_____ Ions migrate toward more negative areas (the direction of cation movement is the direction of current flow).
Myelin
_____ Protects and electrically insulates fibers, and it increases the transmission speed of nerve impulses.
Neutrons
_____ are grouped structurally according to the number of processes extending from their cell body.
Axon
_____ as generating and transmitting an impulse.
Unipolar Neurons
_____ have a single short process that emerges from the cell body and divides T-like into proximal and distal branches.
Peripheral Process
_____ is often associated with sensory receptor.
Myelin sheath and Thickness
______ , and its ____ depends on the number of spirals.
Ions
______ Move along chemical concentration gradients when they diffuse passively from an area of their higher concentration to an area of lower concentration.
Negative Ions
______ Simultaneously move toward more positive areas.
Neurons
______ uses changes in their membrane potential as communication signals to receive integrate, and send information.
Myelinated Fibers and Nonmyelinated Fibers
_______ conduct nerve impulses rapidly, whereas _______ conduct impulses more slowly. *Note that mylein sheaths are associated only with axons. Dendrites are ALWAYS nonmyelinated.
Sensory, or afferent, neurons
_______ transmit impulses from sensory receptors in the skin or internal organs toward or into the central nervous system. All_____ are unipolar , and their cell bodies are located in sensory ganglia outside the CNS.
Myelin Sheathe gaps, or Nodes of Ranvier
________ occur at regular intervals (about 1 mm apart) along a myelinated axon.
Dendrites
__________ of motor neurons are short, tapering, diffusely branching extensions.
Oligodendryctes
__________Has multiple flat processes that can coil around as many as 60 axons at the same time.
specific receptor
a cell or group of cells that recieves stimuli
the chief contributer to the negative charge of a resting neuron's intracellular fluid is ___________.
a high intracellular concentration of anionic proteins
lidocaine
a medication used to numb tissue in a specific area (to treat ventricular tachyardia).
cell death
about 2/3 of neurons die before birth. many cells also die due to apoptosis during development
the period after an initial stimulus when a neuron is not sensative to another stimulus is the _______.
absolute refractory period
axon terminal
action potential comes down them
saltatory action potential (AP)
action potentials along myelinated axons from one node to the next node, increasing in conduction
multiple sclerosis
affects mostly young people, it gradually destroys myelin sheaths in the central nervous system, reducing them to nonfunctional hardened lesions called scleroses.
primary motor cortex
allows conscious control of precise, skilled, skeletal muscle movements
excitatory post synaptic potential (EPSP)
allows it to be less negative
bipolar neuron
almost always sensory neurons, has two extensions
acetylcholine
always excitatory, first identified; best understood
some examples of neurotransmitters
amino acids, glutamate, aspartate, D-serine, GABA, glycine, monoamines
reverberating (or oscillating) circuits
are characterized by feedback by axon collaterals to previous points in the pathway resulting in ongoing stimulation of the pathway.
diverging (or amplifying) circuits
are common in sensory and motor pathways. they are characterized by an incoming fiber that triggers responses in ever-increasing numbers of fibers along the circuit
converging circuits
are common in sensory and motor pathways. they are characterized by reception of input from many sources and a funneling to a given fircuit, resulting in strong stimulation or inhibition.
neuronal pools
are functional groups of neurons that intergrate incoming information from receptors or other neuronals pools and relay the information to other areas.
schwann cells (in PNS)
are glial cells of the PNS that surround nerve fibers, forming myelin sheath.
satallite cells (in the PNS)
are glial cells of the periferal nervous system whose function is largely unknown . they are found surrounding neuron cell bodies within ganglia
schwann cells (in the PNS)
are glial cells of the periperal nervous system that surround nerve fibers, forming myelin sheath
satallite cells (in PNS)
are glial cells of the pros whose function is largely unknown. they are found surrounding neuron cell bodies within ganglia
microglia cells
are small and ovoid with relatively long "thorny" processes. their processes touch nearby neurons, monitoring their health and when they sense a certain neuron are injured or in trouble, the microglial cells migrate toward them.
neurons
are specialized cells that conduct messages in the form of electrical impulses throughout the body. function optimally for a lifetime, mostly amithotic and have high metabolic rate requiring oxygen and glucose.
chemical synapse
are specialized for release and reception of chemical neurotransmitters
premotor cortex
area of motor cortex lying within the frontal lobe of the brain
Neuroglia in the CNS inlude
astrocytes, microglial cells, ependymal cells, and oligodendrocytes.
neurons have to connected or they go through
atoposis
serial processing
attending to and processing all items simutaneously
axon structure
axon hillock, distal endings called axon terminals, and neurotransmitters released.
neurotransmitters are released from?
axon terminals
G-protein
bind to guanine nucelotides
cranial nerves carry impulses to and from the
brain
central nervous system(CNS)
brain and spinal cord, which occupy the dorsal cavity
certain psychoactive drugs exert their effects by keeping the concentration of neurotransmitters elevated within the synapse. these drugs could act by __________.
by doing neither (A) inhibiting enzymes associated with the postsynaptic membrane that degrade the neurotransmitter and (B) inhibiting reuptake of the neurotransmitter by astrocytes or the presynaptic terminal.
efferent
carries impulses from the central nervous system to effector organs, which are muscles and glands
afferent
carries impulses toward the central nervous system from sensory receptors located throughout the body
visceral sensory fibers
carry impulses from organs within the ventral body cavity.
somatic sensory fibers
carry impulses from receptors in the skin, skeletal muscles and joints.
association neuron (interneuron)
central nervous system, one of three neurons found in the human body. create neural circuits, enabling communication between sensory or motor neurons and central nervous system.
hyperpolarization
change in cell's membrane potential that makes it more negative. some K+ channels remain open, and Na+ channels reset.
repoloarization
change in membrane potential that returns to a negative value just after the depolarization phase of action potential.
membrane proteins:
channel proteins (leakage channels), sodium and potassium pump (more potassium than sodium pumps 3 potassium out for every 2 sodium)and gated proteins
neurotransmitter
chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse
which of the following synapse types is the most rapid?
chemical synapse
central nervous system (CNS)
complex nerve tissues that controls the activities of the body. in vertebrates it comprises the brain and spinal cord of the nervous system.
interneurons (association neurons)
conduct impulses between sensory and motor neurons, or in central nervous system integration pathways.
motor (or efferent) neurons
conduct impulses from the central nervous system to effectors
sensory (or affernet) neurons
conduct impulses toward the central nervous system from receptors
the most important thing a neuron can do is they
connect and send a synapse message
sensory areas
conscious awareness of sensation, visual areas
somatic nervous system
consists of somatic motor nerve fibers tat conduct impulses from the central nervous system to skeletal muscles and allow conscious (voluntary) control of motor activities.
autonomic nervous system
consists of visceral motor nerve fibers that regulate the activity of smooth muscles, cardiac muscles and glands.
ganglia
contains a number of nerve cell bodies, typically linked by synapses, often forming a swelling on a nerve fiber.
motor areas
control voluntary movement
summation
cumulative action or effect, the process by which a sequence of stimuli that are individually inadequate to produce a response are cumulatively able to induce a nerve impulse.
axon
each neuron has a single axon that arises from the axon hillock and generates and conducts nerve impulses from the cell body to the axon terminals
conductor
electrical impulses down periferal nervous via action potential
when considering the relationship between a structural classification of neurons, it can be said that _____.
essentially all bipolar neurons are sensory neurons
have to go through whole action potential before __________________________________________.
gates can open again
nerve fiber classification
grouped based on diameter signal conduction velocity, and myelination state of axons
bipolar neurons
have a single axon and dentrite
unipolar neurons
have a single process extending from the cell body that is associated with receptors at the distal end
channel proteins
have leakage proteins it goes from high to low
electrical synapse
have neurons that are electrically coupled via protein channels and allow direct exchange of ions from cell to cell
multipolar neurons
have three or more processes
an inhibitory postsynaptic potential (IPSP) is associated with ________.
hyperpolarization
What is an axon?
impulse generating and conducting region
nodes of Randvia
in between shwan cells
graded potentials
incoming short distance signals. are short-lived local changes in membrane potentials, can either be depolorizations or hyperpolarization, and are critical to the gneration of action potentials.
sodium ion concentration in the cytoplasm of a neuron ____________ when its voltage-gated sodium channels open.
increases
generally speaking, opening chloride channels in the postsynaptic membrane will result in an _______.
inhibitory postsynaptic potential
association areas
integrate diverse information
automatic nervous system
involuntary system consisting of visceral motor nerve fibers that regulate the activity of smooth muscle, cardiac muscle and glands.
motor neuron
involves the skeletal muscle made up of symatic nervous system, smooth muscle made up of aeronautic nervous system, gland- made up of aeronautic nervous system. peripheral nervous system.
leak channels
ion channels which are always open; responsible for the resting membrane potential
herpes virus
is an infection that causes herpes. herpes can appear in various parts of the body, most commonly on the genitals or mouth. there are 2 types of the herpes
Peripheral nervous system (PNS)
is outside the central nervous system
peripheral nervous system
is part of the nervous system outside the CNS
denalatecyclase
it's an enzyme, speeding up chemical reaction. opens up a channel, and the one next to it (opens a lot of channels)
neurons
key to neural communicataions
myelinated
lack voltage-gated channels along the myelinated internodes
neurotransmitters
language of nervous system, most neurons make two or more neurotransmitters, neurons can exert several influences
ion channels that are always open are called ____________channels.
leak
ependymal cell(in CNS)
line the central cavities of the brain and spinal cord and help circulate cerebrospinal fluid.
oligodendrocytes
line up along the thicker nerve fibers in the central nervous system and wrap their processes tightly around the fibers, producing an insulating covering called myelin sheath.
action potentials
long distance signals of axons. occur on axons and are the principle way neurons communicate
depolarization
loss of polarization, loss of difference in charge between the inside and outside of the plasma membrane
pumps
low to high
GABA
major inhibitory neurotransmitter in the nervous system, results in hyperpolarization
multipolar neuron
many extensions come off of the neuron cell body, almost always sensory and motor neurons.
nervous system
master control and communication
neuroglia
may support the thin neurons in the nervous system. are closely associated with neurons
voltage
measure of the amount of difference in electrical change between two points, called potential difference
microglial cells(in CNS)
monitor health and perform defense functions for neurons
cotransport
more than one ion in a direction
symport
more than one material, in one direction, opposite directions
antiport
more than one material, moving in same direction
glutimate
move across symatic cleft. major excitatory nurotransmitter in the nervous system
action potential
move uni directional down the soma, nerve impulse is a trransient allertion of the membrane potential across an excitable membrane
passive
movement of materials across the cell membrane
glutamate
moves across somatic cleft. major excitatory neurotransmitter in the nervous system.
in what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external enviornment? the interior is _________.
negatively charged and contains less sodium
facilitated zone
neuron synapses with other neurons in pool
the substance released at axon terminals is to propagate a nervous impulse is called a(n)_______.
neurotransmitter
postsynaptic potentials
neurotransmitters receptors cause graded potentials that vary in strength
propagation of action potential
occurs as the local currents of an area undergoing depolarization cause depolarization of the forward adjacent area
uni port
one substance, one direction
gated channels
open and close. ALWAYS high to low. group of transmembrane ion channel proteins which open to allow ions such as Na+, K+ to pass through the membrane in response to binding of chemical messenger
voltage-gated channels
open in response to a change in membrane potential
mechanically gated channels
open when a membrane receptor is physically deformed
chemically gate channels
open when the appropriate chemical binds
chemically gated channels
open when the appropriate chemical binds
sensory neuron
peripheral nervous system, are nerve cells within the nervous systemresponsible for converting stimuli from organism's enviornment into internal electrical impulses.
special summation
process by which stimuli that are individually inadequate to produce response
uni polar neuron
process extends from the cell, almost always sensory neurons
neuron cell body
produces protein, protein that get embedded into the body, contains some pigments (pigments that are found in the back of the eye- based upon wave lengths that allow you to see color).
receptor proteins
protein molecule that recieves chemical signals from outside a cell
functions of neuroglia
provides a protective and supportive network, form myelin, protect, support, and maintain equilibrium in your nervous system.
ependymal cells
range in shape from squamous to columnar and are many ciliated.they line the central cavities of the brain and spinal cord, where they form a fairly permeable barrier between the cerebrospinal fluid that fills those cavities and the tissue fluid bathing the cell of central nervous system.
synaptic delay
rate limiting step of neural transmission. limit synaptic delay by adding more neurotransmitter
astrocytes(in CNS)
regulate the chemical environment around neurons and exchange between neurons and capillaries.
astrocytes
shaped like delicate branching sea anemnes, they are the most abundant and versatile glial cells. they support and brace the neurons and anchor them to their nutrient supply lines. they play a role in making exchanges between capillaries and neurons, helping determine capillary permeability.
dentrites
shorter in length than axons. recieveing regions. receptive area. produce dentric spines. cell processes that are receptive regions of the cell and provide surface area for recieveing signals from other neurons
somatic sensory fibers convey impulses from the
skin, skeletal muscles and joints
voltage gated channels
sodium and potassium, class of transmembrane proteins that form ion channels that are activated by changes in electrical membrane
the neuron cell body
soma, the major biosynthetic center containing the usual organellels except for centriules
"trigger"
something that sets off a disease in a person
axon hillock
specialized part of the cell body of a neuron that connects to the axon.
spinal nerves carry impulses from the
spinal cord
role of sodium-potassium pump
stabilizes the resting membrane potential by mainting the concentration gradients for sodium and potassium
polarized
state of the resting cell, net negative charge
All or none principle
strength by which a nerve or muscle fiber responds to a stimulus
neurons (nerve cells)
structural/function unit, do not divide on their own, live 100 years old, use glucose at a high rate, and have a cell body, multiple cytoplasm extensions. positive and negative charged ions.
the location at which a neuron interacts with its target cell (another neuron or a muscle cell or other effector cell) is called the _______________.
synapse
action potential
the change in electrical potential with the passage of and impulse along the membrane of the muscle or nerve cell.
resting membrane potential is generated by
the distribution of ions and its diffusion across the membrane.
current
the flow of electrical charge from point to point, and is dependent pm voltage and resistance
resistance
the hinderance to charge flow provided by substances through which the current must pass
threshold
the level that must be reached for an effect to be produced, as the degree of intensity of stimulus
saltory conduction is made possible by ____________.
the myelin sheath
PNS consists of
the nerves(bundles of axons) that extend from the brain and spinal cord.
motor output
the nervous system activates effector organs-the muscles and the glands-to cause a response
integration
the nervous system processes and interprets sensory input and decides what should be done at each moment
sensory input
the nervous system uses its millions of sensory receptors to monitor changes occuring both inside and outside the body.
insulator
the surrounding of space within material designed to prevent entrance or escape of radient energy
neurilemma
the thin sheath around a nerve axon
action potential is an all or none phenomena
they either happen completely, in the case of a threshold stimulus, or not at all, in the event of subthreshold stimulus
summate
to add together, total, sum up
Axons and dentrites DO NOT ___________ ____________.
touch each other
viseral sensory fibers
transmit impulses from the visceral organs
neuron function:
transmit signals through the body.
potential difference
two points in and electrical charge
neurons generally repolarize once the membrane potential reaches appoximately +30 mV because _____________.
voltage-gated potassium channel gates open
discharged zone
volume rte of water flow
The autonomic nervous system (ANS) is also called involuntary nervous system because
we generally can not control such activities as the pumping of our heart or the movement of food through out digestive tract.
myelin sheath
whtish, fattu.begin to fold or wrap around axon/ cell membrane, wrap around more than two times, wrap around about 4 times. shwan cells insulate. individual axons are an insulator.
oligodendrocytes(in CNS)
wrap around neuron fibers, forming myelin sheath
