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96 Cards in this Set
- Front
- Back
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Neuroglia |
supporting cells essential to survival and functionality of neurons separate, protect, and support neurons |
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Neurons |
send and receive signals throughout body basic functional unit of nervous system individual cells |
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Central Nervous System |
consists of spinal cord and brain Responsible for integrating, processing, and coordinating sensory data and motor commands 98% of nervous tissue |
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Peripheral Nervous System |
all neural tissue outside of the CNS 2% of nervous tissue PNS delivers sensory information to the CNS and carries motor commands to peripheral tissues and systems |
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Cranial nerves |
nerves connected to the brain |
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Spinal Nerves |
nerves attached to the spine |
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PNS is divided into what two divisions? |
1. afferent division 2. efferent division |
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Afferent Division |
brings sensory information (anything that can be sensed) to the CNS from receptors in peripheral tissue and organs ex: detects pain from hot pot and sends message to the CNS |
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Efferent Division |
Carries motor commands from CNS to muscles, glands, and adipose tissues. ex: Executes message of moving hand from hot surface |
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What are effectors in the efferent division? |
target organs that respond by doing something |
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What two components make up the efferent division? |
1. Somatic Nervous System 2. Autonomic Nervous System |
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Somatic nervous system |
Skeletal Muscles controls skeletal muscle contractions |
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Autonomic nervous system |
regulated automatically provides automatic regulation of smooth muscle, cardiac muscle, glandular secretions, and adipose tissues at the subconscious level has sympathetic (fight or flight) and parasympathetic (manages at normal time) divisions |
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Cell Body (Soma) |
large, round nucleus with a prominent nucleolus |
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perikaryon |
cytoplasm that surrounds the nucleus contain organelles that provide energy and synthesize organic materials |
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Neurofibrils |
bundles of neurofilaments, extend into the dendrites and axons which provide support gives neuron its' structure |
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Nissl Bodies |
areas or perikaryon with clusters of RER and free ribosomes |
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Why can't typical CNS neurons be divided? |
because they lack centrioles; this is why spinal cord and brain injuries are permanent |
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Dendrites |
extensions that extend out from cell body key role in intracellular communication; highly branched In CNS, neurons receive info at the dendritic spines (tip of dendrites) |
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Axon |
long cytoplasmic extension capable of propagating an electrical impulse send messages to synapse/axon terminal |
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Axolemma |
membrane for neuron; surrounds the axoplasm and may be exposed or covered |
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Axoplasm |
cytoplasm for neuron |
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Initial Segment |
base of the axon in a multipolar neuron joins the cell body at a thickened region called the axon hillock 1st part of axon |
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axon hillock |
thickened region, "neck" between the cell body and axon where the initial segment joins the cell body |
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collaterals |
side branches of axons enable a single neuron to communicate with many other cells each neuron has 1 axon but many collaterals |
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telodendria |
Fine extension where the main axon and any collaterals end end at synaptic terminals which also play a role in communication with another cell |
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Synapse / Synaptic Terminal |
specialized site where neuron communicates with another cell by releasing a neurotransmitters to communicate |
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What 2 cells are involved in a synapse? |
1. presynaptic cell 2. postsynaptic cell |
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What happens with the 2 cells at a synapse? |
The presynaptic cell (always a neuron) releases neurotransmitter which sends a message and include the synaptic terminal The post synaptic cell (can be neuron, muscle, gland, adopocyte, etc) receives the message (neurotransmitter) |
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Synaptic Cleft |
narrow space that separates the pre & post synaptic cells |
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What occurs during the communication between cells at the synapse? |
The synaptic terminal releases chemicals called neurotransmitters into the synaptic cleft and then affect the activity of the postsynaptic cell. This release is triggered by an electrical event. |
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neuromuscular junction |
synapse between a neuron and muscle cell |
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neuroglandular junction |
neuron controls/regulates the activity of a secretory cell (gland, etc) |
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What are the 4 Classifications of neurons' structure? |
1. anaxonic 2. bipolar 3. unipolar 4. multipolar |
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Anaxonic |
structural classification of neurons small, no anatomical features to distinguish dendrites from axons (all look alike) located in brain and in special sense organs; all cell processes look alike |
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Bipolar |
structural classification of neurons 2 distinct processes - one axon and one dendrite dendrite branches into dendritic branches at its distal tip and have a cell body in between occur in special sense organs, rare, the smallest |
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Unipolar |
structural classification of neurons dendrites & axons (a meter or more) are continuous and cell body is off to the side initial segment is where dendrites converge **Most sensory neurons of PNS are unipolar |
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Multipolar |
structural classification of neurons 2 or more dendrites; single axon (can be long like unipolar) **Most common neurons in the CNS Includes ALL motor neurons that control the skeletal muscles |
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What are the 3 functional Classifications of neurons? |
1. Sensory neurons 2. interneurons 3. motorneurons |
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Sensory Neurons |
functional Classifications of neurons from afferent division of PNS;deliver information from sensory receptors to the CNS unipolar neurons whose processes extend from sensory receptors to CNS |
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Somatic Sensory Neurons vs Visceral Sensory Neurons |
Somatic - monitor the outside world Visceral - monitor internal conditions and the status of other organ systems |
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What are the 3 broad groups of sensory neurons? What do they do? |
1. interoreceptors 2. exteroreceptors 3. proprioreceptors MONITOR CHANGES |
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Interereceptors |
Sensory neurons that monitor internal organs |
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Exteroreceptors |
Sensory neurons that monitor external enviornment |
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Proprioreceptors |
Sensory neurons that monitor the position and movement of muscles and joints |
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Interneurons |
functional Classifications of neurons; located w/in the brain and spinal cord; some are in autonomic ganglia (bunches of neurons near spinal cord) *distribute sensory information and coordinate motor activity; also involved in memory, planning, learning, and other higher functions *located between sensory and motor neurons; more complex response the more interneurons are involved |
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Motor Neurons |
functional Classifications of neurons efferent division of the PNS carry instructions from the CNS to peripheral effectors |
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1. ___________ detects hot pan; sends to 2. ________; sends to 3. ________ to move hand. |
1. Sensory neuron 2. interneuron - distributes info between sensory and motor neuron 3. motor neuron |
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What are the 4 different types of Neuroglia (supporting cells) in CNS? |
1. ependymal cells 2. astrocytes 3. oligodendrocytes 4, microglia |
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Ependymal Cells |
Neuroglia in CNS Line ventricles of the brain and central passageway of the spinal cord and brain Help transport and produce cerebral spinal fluid |
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Astrocytes |
Neuroglia in CNS ; largest & most numerous maintain blood-brain barrier create 3-D frameworkd for CNS repair damaged neural tissue guide neuron development control interstitial environment help form scar tissue after injury |
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Oligodendrocytes |
Neuroglia in CNS Myelinate CNS axons Many form a myelin sheath along the length of an axon |
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Microglia |
Neuroglia in CNS Phagocytic cells migrate through neural tissue Act as wandering janitorial and police service by engulfing debris, waste and pathogens |
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What are the 2 neuroglia of the PNS? |
1. satellite (amphicytes) cells 2. Schwann (neurilemma) cells |
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Satellite/Amphicyte Cells |
Neuroglia in PNS Surround neuron cell bodies in ganglia; regulate environment around neurons |
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Schwann Cells (neurilemma cells) |
Neuroglia in PNS forms a sheath around peripheral axons enclose segments of several unmyelinated axons, needed to enclose an axon along its' entire length |
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Resting Potential |
transmembrane potential of resting cell -70mV |
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graded potential |
*A stimulas creates a localized change in resting potential and the effect (which decreases with distance from the stimulus) is the graded potential *temporary/localized *Every stimulus starts as a graded potential *Depolarization - shift from resting potential toward more positive potential (towards 0) Degree of depolarization decreases with the distance away from stimuli |
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Action Potential |
electrical impulse that moves along the surface of an axon and doesn't diminish as it moves away from the stimulus -changes that once started, they affect the ENTIRE MEMBRANE -propagated along length of the axon and reaches the synapse becomes action potential at -60 mV |
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Synaptic Activity |
produces graded potentials in the plasma membrane of the postsynaptic cell; neurotransmitters released from the presynaptic cell Activity of the synapse |
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Information Processing |
integration of stimuli at the individual cell level is the simplest form of information processing in the NS Process information in brain; way in which your brain tells you what to do 1st |
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Transmembrane Potential |
High concentration of Sodium outside the cell and high concentration of potassium inside the cell. Inside membrane - neg charge Outside mem - pos charge |
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Chemical Gradients |
K concentration high inside the cell tend to move out of the cell through K channels Movement driven by concentration gradient Basically diffusion: K wants to go outside and NA wants to go in |
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Electrical Gradients |
K ions leave faster than Na enter; b/c of this cytosol near the membrane has a net loss of positive charges leaving extra negatively charged proteins Outer surface of Plasma Membrane is slight positive; + and - charges separated by plasma membrane |
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Resting Potential |
-70mV potential differences that arise from positive and negative ions are held apart |
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Na-K Pumps |
Bring K ions in, and Na ions out help keep resting potential at -70 |
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Electrochemical Gradient for Na and K do they oppose each other? reinforce each other? |
Pg 401 fig 12.10 box a |
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What are the 3 types of gated channels? |
1. Chemically gated 2. Volatge Gated 3. Mechanically Gated |
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Chemically gated Channels |
open/close when they bind specific chemicals (neurotransmitters) |
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Voltage gated channels |
open/close in response to changes in the transmembrane potential change in voltage so gate either opens or closes Characteristic of excitable membrane (membranes that can conduct a signal) |
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Mechanically gated channels |
open/close in response to a physical distortion of the membrane Membranes are distorted for ions to enter found in sensory neurons |
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How are gated channels at resting potential? What happens to them? |
Most gated channels are closed; when they open, rate of ion movement across the PM increases and changes the transmembrane potential dramatically |
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Local Current |
Graded potential; movement of positive charges parallel to the inner and outer surfaces of a membrane -once pos ions get in a cell, move along edge of the PM in a parallel way |
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Depolarization |
shift from resting potential to more positive potential (closer to 0); opening Na channels |
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Repolarization |
process of restoring the normal resting potential after depolarization by opening K pumps; involves combination of ion movement through channels and activities of ion pumps more negative, closer to -70 mV (resting pot) |
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Explain the change in transmembrane potential in a graded potential |
the max change in TP is proportionals to the size of the stimulus |
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What happens when we open a Na channel? What happens when we open a K channel? |
open gated K channel - TP decreases open gated Na channel - TP increases |
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Hyperpolarization |
produced by a loss of positive ions; increase in the negativity of the resting potential above and beyond resting potential -80mv, -90mv have to get to -90 for K channels to close |
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Graded potentials occur in a wide variety of cells! |
LOOK AT PG 404 TABLE 12.2 |
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Threshold |
-60mV the TP at which an action potential starts This is where Na gates open |
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All-or-none principle |
either get to -60mV, reach threshold, and an action potential starts or it does not. Either gets to -60 or it doesn't! Initial segment HAS TO REACH threshold |
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Generation of an Action Potentials |
Look as Fig 12.14 pg 409 What happens at what potential? What opens/closes at each potential? What happens a -30 or +30? Is any channel open at -70? What is -60? |
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Refractory Period: what are the 2 parts? |
Enables neurons to recover: get all Na out & K in to restore resting potential Membrane doesn't respond normally to additional stimuli absolute refractory period: can't respond to any stimuli relative refractory period: only respond to very strong stimuli; begins when Na channels regain their normal resting condition and continues until resting potential is restored |
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Propagation of Action Potentials Pg 410 Table 12.3 |
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What are the 3 groups of axons? |
1. Type A fibers 2. Type B Fibers 3. Type C Fibers |
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type A Fibers |
largest myelinated axons carry sensory information esp about survival and injury information carry action potentials up to 268 mps |
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type B Fibers |
smaller myelinated axons 40 mph carry information to and from the CNS |
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type C fibers |
unmyelinated axons 2 mph carry information to and from CNS |
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Cholinergic Synapse |
Synapses that release ACh ex: neuromuscular junction |
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Where is ACh released? |
*at all NMJ involving skeletal fibers *at many synapses in the CNS *at all neuron-to-neuron synapses in PNS *at all NMJ and NGL in the parasympathetic divisions of the ANS |
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What triggers the release of ACh at a Cholinergic Synapse? |
CALCIUM |
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Norepinepherine |
widely distributed in brain & in portions of ANS excitatory, depolarinzing effect in postsyn membrane |
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Dopamine |
CNS neurotransmitter in brain inhibit excitatory effects Parkinson's can occur if neurons that produce dopamine are damaged |
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Serotonin |
CNS neurotransmitter plays role in emotional state and attention inadequate production = depression |
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EPSP vs IPSP |
EPSP - excitatory postsynaptic potential; graded depolarization caused by arrival of neurotransmitter at the post synaptic membrane IPSP - inhibitory postsynaptic potential; graded hyperpolarization of the postsynaptic membrane |
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Gamma-aminobutric Acid (GABA) |
CNS reduce anxiety roughly 20% of synapses in brain release GABA |
