Glossary of AP2 - Chapter 12

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Which two systems maintain homeostasis?
The nervous system and the endocrine system.
What is the objective in maintianing homeostasis?
Keep controlled conditions within limits to maintian life.
The nervosu system maintians homeostaiss by using?
Nerve impulses or Action Pontentials.
The endocrine system maintains homeostasis by?
Releasing hormones.
Neuron Ala
Nerve cell.
Neurogla are?
Cells that support the activites of neurons.
The autonomic nervous system is part of the nervous system that operates w/o?
Voluntary control.
What is the brain?
The part of the nervous system contained within the cranial cavity.
What is a nerve?
A cordlike bundle of axons and/or dendrites and associatted connective tissus coursing together outside the CNS.
Each nerve follows a deined path and?
serves a specific region of the body.
What is the spinal cord?
A mass of nerve tissue located in the vertebral canal from which 31 pairs of spinal nerves originate.
What is a ganglion? Or p. = ganglia.
A group of neuronal cell bodies lying otuside the CNS.
Sensory neurons aka?
Afferent neurons.
Sensory neurons do what?
Conduct impulses inward toward the brain or spinal cord.
What are the 3 basic functions of the Nervous system?
1) Sensory
2) Integrative
3) Motor
The sensory function/receptors does 2 things?
Detect internal stimulus and external stimulus
sensory neurons aka afferent neurons carry this info. into the?
brain and spinal cord.
The integrative function of the N.S. =
perception = the conscious awareness of sensory stimuli.
Where does perception occur at?
In the brain.
Many of the neurons that participate in integration are?
The vast majority of neurons of neurosn in the body are?
Sensory information integrated intot he NS may ellict a motor response - the neurons that make this motor response are called?
Motor neurons
Motor neurons aka ?
Efferent Neurons
Motor neurons aka efferent neurons carry inforamtion from the?
Brain worad the spinal cord or out the brain and spianl cord to effectors in muscles and galnds.
What are the 2 main divisions of the NS?
What is the makeup of the CNS?
The portion of the NS that consists of the brain and spinal column.
The CNS is the source of?
Thoughts, emotions and memories.
What is the PNS?
Everything else outside of the CNS
What does the PNS do?
Initiates all motor functions.
What is the long definition of the PNS?
The aprt of the nervous system that lies outside of the CNS consisting of nerves and ganglia.
What is the breakdown of the PNS?
1.) Somatic Nervous Sys.
2.) Autonomic NS
3.) Enteric NS
Somatic NS consists of sensory neurons that convey information from somatic receptors in the head, body, walls and limbs from special receptors for the?
Special senses of vision, hearing, taste and smell
The motor responses of teh SNS can be conscioulsy controlled Meaning that?
the SNS is voluntary.
The Autonomic NS consists of both?
Visceral sensory afferent and visceral motor - efferent neurons.
In the ANS motor neurons, both sympathetic and parasympathetic conduct?
nerve impulses from the CNS to smooth muscle, cardiac muscle and glands.
ANS is so named because this part of the NS was thought to be?
Self governing or spontaneous.
What type of action does the ANS make?
The motor part of the ANS consists of 2 branches.
1.) Sympathetic div.
2.) Parasympathetic Div.

Us. these are opposing actions.
If Sympathetic Division then
Fight or flight actions
If parasymapthetic div. then
Rest and digest activities.
the enteric NS is aka the?
brain og the gut.
The Enteric NS is the part of the nS that is embedded in the?
submucosa and musculars if the gastro intestinal tract - GI tract.
2 parts of the NS =
1.) The CNS
2.) The Pns.
3 parts to the PNS=
1.) the Soamtic NS
2.) Autonomic NS
3.) Enteric NS
The Autonomic System is furhter broken down into these 2 parts?
1.) sympathetic
2.) Parasysmpathetic
PNS the parts
Somatic NS
Autonomic NS
Enteric NS
Autonomic 2 parts
Para sympatheitc
NS - All the Parts
1.)CNS = Brain & Spinal Cord
A.) Somatic NS - Conveys Info about the sense
B.) Autonomic NS
I.) Sympatheic - fight or flight resp.
II.) Para sympathtic - rest & Digest Resp.
C.) Enteric NS - Brain of the gut
The somatic controls things that are?
Voluntary. It conveys info. about the senses and conveys info into the CNS
Autonomic NS controls all these actions?
Involuntary actions - breathing, cardiac muscle
Conveys info. into the CNS
3 functions of the NS are
1.) Sensory function
2.) Integrative function
3.) Motor function
The sensory function senses changes in the?
Internal and external environment through sensory receptors.
The integrative function anayzes sensory information and?
Sores some aspects, makes deicions, regarding appropriate behavior.
The motor function responds to stimulis by?
Initiating action.
The integrative function asks the CNS?
How do I respond to this?
The motor function is the?
ANS SNS what is the appropriate action.
Nervous tissue 2 types?
What do neurons do?
Provide most of the unique functions of the NS such as, sensing, thinking, remembering, controlling muscle activt, regulating gland secretion.
What do neuroglia do?
Support, noursih and protect the neurons.
What is a neuron?
A nerve cell consisting of a cell body, dnedrite and an axon.
Action Potential = AP =?
Nerve impulse.
What is a stimulus?
Any change in the environment strong enough to initate an AP.
A neuron aka?
What is a nerve fiber?
this is a general term for any process or extension that emeges form the cell body of the neuron.
What is a dendrite?
A nerve process that carries electrical signals, us. grade potentials toward the cell body.
Dendrites look like?
Little trees and they are the receiving input for the neuron.
The Axon is the?
Usually the single long process of a cell that propagates a nerve impulse toward an axon.
Axon terminal is the?
Terminla branch of an Axon where synaptic vesicles undergo exocytosis to relase neurtransmitter molecules.
An axon is a long thin cylindarial projection that ofetn joins the cell body at a cone shaped elevation called the
Axon hillock
the axon hillock is where the?
AP starts in the axon hillock travels into the initial segament and then down the axon to the axon terminal.
What does the axon hillock do?
it is the region of the neuron where electrical signals are tallied or summed up.
What is the trigger zone?
In most neurons, nerve impilses araise at a junction of the axon hillock and the initial segment, this is the trigger zone.
The axon terminal or the terminal branches of an axon is where?
Synaptic vesicles undergo excocytosis to relase neurtotransmitter molecules.
What is the Synapse?
The site of communication between 2 neurons or between a neuron and an effector cell is called a synapse.
Or a synapse is a functional junction between 2 neurons or between a neuron and an effector, such as a muscle or a gland. This may be?
Electrical or chemical
What is a synaptic vesicle?
A membrane enclosed sac in a synaptic end bulb that stores neurotransmitters.
What are neurotransmitters?
one of a variety of molecules within axon terminals that are released into the synaptic cleft in response to a nerve impulse. (AP)
What is the synaptic cleft?
The space between neurons. Or.
the synaptic cleft is the narrow gap at a chemical symapse that seperates the axon terminal of one neuron from anotehr neuron or muscle fiber and across which a neurotransmitters diffuses to affect the postsynaptic cell,
Structurally neurons are classified according to the number of?
Processes extending from the cell body - dendrite.
Mulitpolar neurons have?
Several dendrites and one axon.
Most neurons of the brain and spinal cord are of this type of neuron?
Multipolar neurons with several dendrties.
A biploar neurons has this?
1 axon and 1 main dnedrite.
A biploar neuron is found where>
In the retina of the eye, inner ear, olfactory of the brain.
Unipolar neuron = is a sensory neuron that begins?
In the embryo as a bipolar neuron.
Waht is the function of the Unipolar neuron?
This dendrite monitors a sensory stimulus such as touch and stretching.
Name 2 cells named for people who found them?
Purkinje cells and Pyramidal cells.
Purkinje cells are found in the?
Pyraimidal cells are found in the?
Cerebral cortex of the brain.
Neuroglia - glia =?
What makes up 1/2 the volume of the CNS?
What is one thing neuroglia do not do?
They do not generate or propaget an AP.
The neuroglia of the CNS perform various?
Supportive functions.
What are the 4 neuroglia of the CNS?
1.) Astrocytes.
3.) Microglia
4.) ependymal cells
What are 2 neuroglia of the PNS?
Schwan Cells
Satellite Cells
Astrocytes = a neuroglia cell having a?
Star shape that participates in brain development and the metabolism of neurotransmitters.
What are the 2 functions of Astorcytes?
Helps from the brain blood barrier and helps to maintain the proper balcne of K+ for the generation of nerve impulses.
Oligodendrocytes = a neuroglail ceel that supports neurons and?
produces a myelin sheath around axons of neurons of the CNS.
Oligodendrocytes look like astrocytes but?
but are smaller with fewere porcesses.
The Myelin hseath is a mulitlayered lipid and protein coveringformed be?
Schawnn cells and oligodendrocytes aorund axons of many PNS and CNS neurons.
The myelin Sheath does this?
Increases the speed of the nerve impulse.
Microglia are neuroglia cells that carry on?
phagocytosis - removes cellualr debris.
Ependymal cells are neuroglial cells that cover
1.) choroid plexuses and produce cerebrospinal fluid, they also line the ventricles of the brain and probably assit in the circulation of CSF.
The ependyaml cells also form the ?
Blood cerebrospinal fluid barrier.
2 types of cells in the PNS are?
Schawn cells and satelite cells.
A schawan cell is a neurological cell of the PNS that forms the?
Myelin sheath around a nerve axon by wrapping around the axon in a jelly roll fashion.
Each schawn cell myelinates a?
Single axon
A single ologodendrocytes myelinates?
Several axons.
A myelin sheath increase the speed of
a nerve impulse conduction.
Satellite cells are flat neuorglia cells that surround cell bodies of PNS gaglia to provide?
Structural support and regualte the exchange of materials between a neuronal cell body and interstitial fluid.
The Nodes Of Ranvier are a space along a myelinated axon between the individula schawn cells that form a?
myelin sheath and the neurolemma.
The nodes of Ranvier are needed for?
Saltatroy conduction.
Neurons are?
Electrically excitable.
Neurons communicate with each other using 2 types of signals?
A graded potential and an AP.
A graded pontential is used for?
Shrot distance communication.
An AP allows for communication over?
Both short and long distances in the body.
When an AP occurs in a neuron (Nerve Cell) it is called a?
Nerve action potential or a nerve impulse.
What is a membrane potential?
An electrical voltage difference across the membrane.
In exctiable cells the voltage differecne across a membrane is called the?
Resting Membrane potential.
The Main path for current to flow across the membrane is through?
Ion channels.
Electro Chemical Gradient = When ion channels are open, they allow specific ions to move across the plasma membrane, and
down their electro chemical gradient - which is a concentration difference (Chemical) plus an electrical difference.
As ions flow/move they create a flow of electrical current that?
Can change the membrane potential.
Ions channels open and clsoe do tot he presence of?
The gate is part of a channle protein that can?
Close or open the channel.
What are 4 types of Channles?
1.) Leakage channels
2.) Voltage Gated C.
3.) Ligand Gated C.
4.) Mechanically Gated C.
A voltage gated channel will open in response to?
a change in membrane potential - i.e. Volatge.
Note Voltage gagted Channles will particiapte in the generation and conductions of?
Ligand Gated Channels open and close in response to a?
Specificr chemical stimulus.
Mechanically gated channels - this channel opens and closes in response to a?
Mechanical stimulus in the form of a vibration: ex. sound waves, pressure - touch, or tissue stretching.
With mechanically gated voltage channel the force?
distorts the channel from its resting potential and the gate opens.
Ex. Auditory receptors in the ears, Receptors that monitor stretching of internal organs and touch receptors in the skin.
Why does a grade potential exist?
The resting membrane potential exists becaus of a small build up of negative ions in the cytosol along the inside of the membrane and an equal buildup of positive ions in the extracelluar fluid along the outside of the surface of the membrane.
Such a sepeartion of positive and negative electrical charges is a form of?
Potential energy.
The greater the difference in charge across ht membrane the?
larger the membrane potential
What is the resting potential in aneuron?
-70mV typical, but it ranges form -90mV t0 -40mV
The resting potential of a cell arise from the unequal distribution of?
various ions in the external extracellualr fluid and the internal cytosol of the cell.
Extracelluar cellular fluid is rich in this fluid?
In the cells cytosol, fluid of the cell it is rich in htis ion?
K+ or potassium.
Graded potential = a graded potential is a small devaition from the membrane potential that makes the mebrane either?
More or less polarized.
What cause a graded potential?
When a stimulus cause a ligand gated or mechanically gated channel to open or clse in a cells plasma membrane.
When a stimulus makes the membrane even more negative it is termed a?
Hyperpoarizing graded potential.
When the stimulus makes the membrane less negative it is called a?
Depolarizing grade potential
If we go from negative to positive in an AP this pahse is called a?
Deploarizing Pahse.
If we go from postive to negative this is called a?
Repolarizing Phase.
If we go from negative to even more negative this is called a?
Hyperpolarization or after hyperpolarization.
To say that the signals are graded means that?
The signals vary in size or amplitues based on their strength.
The opening and closing of ions channels alters thes flow of specific ions across the membrane producing a?
Flow of current.
An AP or impulse is a sequence of rapidly occuring events that?
Take place in 2 phases.
What are the 2 phases of an AP.

Think Doctor or Dr.
Depolarizing Pahse
Repolarising Phase
What happens in the depolarizing Phase?
The negative membarne potential becomes less negative reaches 0 and then becomes positive.
What happens in the repolarizing Phase?
The postive membrane potential goes from positive to zero to negative and finally returns the cell to its resting state of -70mV.
In the resting state which channels in the cell membrane are open and clsoed?
Sodium (Na+) Channels are in resting state.
Potassium Channels (K+) channels are closed.
What cause the cell membrane to go from resting state to threshold?
a stimulus.
What happens to the channels wehn we go from resting state to threshold becasue a stimulus has occured?
Some sodium (Na+) channels open.
In effect what does the stimulus start?
It starts the depolrization phase.
What is the voltage for threshold?
What happens during depolarization with the channels?
More sodium channels open until all sodium channles are open.
What happens at peak between depoalrization and repoalriazation?
Sodium channels Close and

Potassium channels open (K+)
What happens when we reach the hyperpoalization Phase with the channels?
As the potentail becomes more negative potassium channels begin to close and wehn we reach -70mv all the potassium channels will be closed.
What haapens at the end of hyperpoalization when we get to the resting rate of -70mV?
Sodium channels are in resting state

All potassium channels closed.
What is the all or none principle?
Once we hit the threshold of -55mV this action potential is going to fire. Nothing will stop it.
Or the all or nothing principle states that when druing the depolarization phase we hit a -55mV then
This AP is firing.
The depolarizing phase is an example of what type of feedback?
Postive feedback. i.e. something external happens to shut the process down.
Explain the absolute refractory period?
The absolute refractory period is from when the Threshold reaches - 55mV during depoarization to we come back to - 55mV during repolarization, during this time we cannot initiate another AP.
What is saltatory conduction?
Its faster than continous conduction.
Saltatory conduction = leaping, this is hte special mode of?
Impilse propagation that occurs along myelinated axons.
Why does saltatory conduction occur?
Because of the uneven distribution of voltage gated channels.
What stimulates or causes an AP?
Frequenices is what stimulates an AP; NOT the strength of the stimulus.
an AP will travel along the Axon w/o losing what?
The repolarizing phase is the phase that turns?
The cell back to the resting phase.
What happens to volatage during the hyperpoalrization pahse (After-Hyperpoarization)
The voltage will become more negative before it returns to its resting portential of -70mV.
What is the refractory period?
The period of time after an AP begins during which an excitable cell cannot generate another AP.
What is the aboslute refractory period?
During th absolute refractory period, even a very strong stimulus cannot initiate a second AP.
What can happen during the realtive reafractory period?
This is the period of time druing which an a second AP can be initiated, but only by a larger than normal stimulus.
What 2 periods make up the absolute refractory period?
Depolarization Period and the Repolarization period.
What make up the relative refractory period?
The Hyperpoalization period aka after-hyperpoalrization.
Nerve impulses move faster along Myelinated axons thanalong?
Unmyelinated axons.
Synaptic cleft =
The space between neurons
Across wihch Neurotransmiiters diffuse to
affect the postsynaptic cell.
What is the name of the neuron that sends the message?
Presynaptic neuron.
What is the name of the neuron that receives the message?
Post synaptic neuron.
What are the 2 possible types of synapses?
Chemical synapses
Electrical synapses
At electrical synapses AP impulses conduct directly between adjacent cells through structures called?
Gap junctions

Faster communication and synchonization.
Neurons in a chemical synapse are close but do not touch they are sperated by a?
Synaptic cleft.
The presynaptic neuron converts an electrical signal ( Nerve impulse) into a?
chemical siganl - released neurotransmitter
The post synaptic neuron receives the chemical signal and in turn generates an?
Electrical signal - or post synaptic potential.
What does the Ca2+ channel do?
An increase in the concentration of Ca2+ inside the presynaptic neuron serves as a signal that triggers the exocytosis of the synaptic vessel.
What is a neurotransmitter?
One of a variety of molecules within an axon terminal that are relased into the synaptic cleft in response to a nerve impulse and that changes the membrane potential of the psot synaptic neuron.
What 2 things can a neurtransmitter cause?
Either ans excitatory or an inhibitory graded potential.
A neurotransmitter that depolarise a postsynaptic membrane is?
Excitatory, becasue it brings the membrane closer to threshold.
Excitiatory post synaptic potential
EPSP's bring the post synaptic potential of the membrane clsoer to?
EPSP's are more likely to?
A neurotransmitter that causes hyperpolarization of a post synaptic membrane is?
Inhibtory Post Synaptic potential
IPSP's do what?
decrease the membranes potential.

i.e. the neuron will not produce an AP
What are 3 ways to remove a neurotransmitter?
enzyme degradation
Uptake by cells
What is spatial summation?
when summation results from the build up of neurotransmitters relaesed simultaneously by several presynaptic end bulbs.
Spatial summation =
Neuron receives SEVERAL different neurotransmitters from several differnt presynaptic bulbs, that when received they all cause the AP to move to threshold.
What is temporal summation?
When summation results from a buildup of a neurotransmitters released by a single presynaptic bulb tow or three times in rapid succession.
Spatail summation =
post synaptic Neuron recives several neurotransmitters from several different presynaptic end bulbs.
Temperoal Summation =
Postsynapitc neuron recives several differetn neurotransmittes BUT its only form ONE presynaptic bulb.
Temperol summation is compared to 1 presynaptic neuron firing in?
rapid succession to trigger the postsynaptic neuron to move from resting potential to threshold.
ACH - Acetycholine is a neurotransmitters released by the CNS and the PNS. It both what?
its excitatory at neuro muscular junctions and inhibitory at other synapses - it slows heart rate.
Glutamet is a neurotransmitter and its an amino acid it is the ?
Most excitatory neuron in the CNS and
Perhpas half the synapses in the brain communicate via glutamate.
GABBA - Gamma aminobutyric Acid what type of neurotransmitter?
GABA is found only in the?
CNS where it is the most common inhibitory neurotransmitter.
NE - Norepinephine is a neuortransmitter and it plays a role in?
sleep, dreaming and regulating mood.
Epinephrine is a neurotransmitter and it is used by a?
smaller number of neurons in the brain.
Epinephrine - cells of the adrenal medulla the inner portion of the adrenal galnd, relases them into?
The Blood.
Dopamine - Brain neurons containing the neurotransmitter dopamines are active during?
Emotional responses, addictive behaviors, and pleasurable experiences.
Dopamine releasing neurons help to regulate this?
skeletal muslce tone and aspects of movement doe to contraction of skeletal muscle.
Seartonin - aka 5HT is concentrated in the neurons in part of the brain called teh?
Raphe nuclues
Seratonin is thought to be involved in?
sensory perception, temperatur, regulation, control of mood, appetite and the induction of sleep.
AP = action potential

APs are of this nature?
all or none.
APs satrt in the axon hillock andtravel down to the?
Axon, where they travel along the axon to the terminla bulbs.
a graged potential can be one of these 2 types.
The frequency of the AP dictates the?
the beginning of the AP.

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