Chapter 12 Packet Review Flashcards Preview

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Flashcards in Chapter 12 Packet Review Deck (94):
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Neurophysiology

The study of the nervous system

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Central Nervous System

The brain and spinal chord. Deciphers info and initiates responses. I.E: Intelligence, memory, emotions

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Peripheral Nervous System

Cranial and spinal nerves. Relays info to and from the CNS: Cranial and spinal nerves

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Afferent Division

A division of the PNS Sensory input: detect changes and feel sensations. Takes FROM stimulus TO the CNS

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Receptors

Detect changes, respond to stimuli

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Efferent Division

A division of the PNS Motor output: carries motor commands from CNS to an effector

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Effector

Target organs which respond by doing something; muscles, glands, adipose tissue

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Somatic Nervous System

controls skeletal muscle contractions on a voluntary conscious and a subconscious level (reflex)

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Autonomic Nervous System

Controls smooth muscle, cardiac muscle, adipose tissue and glands; a visceral control center. Sub divisions are sympathetic and parasympathetic divisions

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Neurons

"Nerve fibers"; regardless of function all neurons have the same physical properties: cell body, 1 axon and dendrites

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Cell body

contains nucleus surrounded by perikaryon found in the CNS for protection by the skeleton . Do not divide because they lack centrioles

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Perikaryon

Cytoplasm surrounding the nucleus; mitochondria present for ATP production, ribosomes and rough er present for protein synthesis; clusters of rough er and ribosomes stain darkly and are called nissel bodies which make up gray matter in the cerebral cortex

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Dendrites

Branched processes increase surface area for cell bodies to receive impulses. Transmit TOWARD the cell body

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Axon

process of the cell body that transmit impulses AWAY from the cell body

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Axoplasm

cytoplasm of the axon

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Axolemma

specialized plasma membrane surrounding the axoplasm

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Initial Segment

base of the axon

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Axon Hillock

thickened area where the axon joins the cell

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Telodendria

extensions on the distal end of the axon; terminal branches

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Axoplasmic transport

two-way transport between the cell body and synaptic terminals

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Anterograde and Retrograde Flow

Ante=materials carried TOWARD the synaptic terminals
Retro=materials carried toward the CELL BODY

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Synaptic Terminal

point of communication with another cell

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Synapse

space between the axon of one neuron and dendrites or cell body of the next neuron. The site of one way impulse transmission

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Presynaptic Neuron

conducts impulses TOWARD the synapsis; info giver

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Postsynaptic Neuron

transmit the impulse AWAY from synapses; info receiver

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Synaptic Cleft

space separating the two cells

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Neruotransmitter

chemical released into synapse by electrical nerve impulses

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Synaptic Vesicles

within the synaptic terminal neurotransmitters are found within small sacs

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Neuromuscular Junction

synapses between a neuron and a muscle

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Neuroglandular Junction

synapse between a neuron and a gland

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FIGURE 12-3 will be on test

Axonic, bipolar, unipolar, multipolar

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Anaxonic

in brain and special sense organs; cannot determine the axon from the dendrites; poorly understood

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Bipolar

rare sense receptors like smell, sight, hearing; two processes separated by the cell body

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Unipolar

Sensory neurons of the PNS; longest extends from toes to spinal chord; dentrites and axon are continuous with cell body off to the side

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Multipolar

Most common; all motor neurons in PNS; TWO or MORE dendrites and a single axon

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Sensory Neurons

Afferent division; carry impulses from receptor to CNS. They are unipolar, 2 types: Somatic Sensory Neurons=receive info about ouside world via receptors in the skin, skeletal muscles and joints
Visceral Sensory Neurons=monitor internal conditions within the organs

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Interoceptors

monitor digestive, respiratory, cardio, urinary and reproductive systems; distention, deep pressure, pain

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Exteroceptors

monitor external environment with touch, temp, pressure, taste, smell, sight, equilibrium and hearing

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Proprioceptors

monitor the position and movement of skeletal muscles and joints

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Motor Neurons

EFFERENT division carry impulses from CNS to the EFFECTORS

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Somatic Motor Neurons

voluntary, linked to skeletal muscles

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Visceral Motor Neurons

Involuntary, linked to smooth and cardiac muscles, adipose tissue and glands

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Effectors

the organ or tissues that respond to info from the CNS; muscles and glands

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Interneurons

Found in CNS; Shuttles signals between sensory and motor neurons. "Association Neurons"

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Neuroglial Cells of the CNS

provide support and protection to the neural tissues

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Ependymal Cells

Line the central canal of the spinal cord and ventricles of the brain forming an epithelium called EPENDYMA: secrete and circulate the Cerebral Spinal Fluid=in spinal chord and brain, feeds brain tissue nutrients and removes waste, also cushions and protects

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Astrocyte

Star-shaped supporting cell; largest and most numerous

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Blood-Brain Barrier

capillaries in the brain limit the entry of substances to the brain hormones, waste/harmful substances are not allowed to pass; it could cause the brain to fire off impulses unnecessarily. Capillaries not as permeable. The astrocytes send signals to the capillaries to form tight junctions in their endothelium

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Oligodendrocytes

neuroglial cells that form the myelin sheath in CNS; processes extend into pad shape and wrap around the axon forming concentric layers of plasma membrane; this insulates the axons from contact w/extracellular fluid

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Myelin Sheath

Phospholipid sheath that protects it electrically insulates neurons from one another and increases the speed of impulses along the axon

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Internode

A length of axon that is covered in myelin; the lipids give it a glossy white appearance. (white matter)

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Nodes of Ranvier

spaces between adjacent internodes

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Microglia

Phagocytic cells of the CNS; "garbage collectors"

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Neuroglial Cells of the PNS (fig 12-6)

provide support and protection to the ganglia - clusters of cell bodies outside the CNS

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Satellite Cells (amphicytes)

surround neuron cell bodies in ganglia, regulation surrounding environment

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Schwann Cells (neurilemma cells)

Provides the myelin of the PNS. They coil their plasma membrane around the axon of nerves to protect them from surrounding fluids and other axons

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Neurilemma

Nucleus and cytoplasm of the schwann cell wrapped around the outside of the myelin sheath

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Response to Injury (fig 12-7)
Wallerian Degeneration=repairing of damaged nerves

1. fragmentation of axon and myelin occurs in distal stump
2. shwann cells form a chord, unites the stumps. macrophages engulf degeneration axon and myelin
3. Axon sends buds into network of schwann cells, then starts growing along cord
4. Axon continues to grow into distal stump and is enclosed by schwann cells

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Resting Potential

transmembrane potential of a resting cell; a change in this potential starts neural activity

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Graded Potential

stimulus produces a temporary, localized change in transmembrane potential; decreases with distance from the stimulus

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Action Potential

Graded potential can trigger an electrical impulse that spreads along the surface of the axon and maintains the potential despite distance from the stimulus; travels to a synapse

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Synaptic Activity

arrival of the action potential to a synapse causes the release of neurotransmitters from the presynaptic membrane which bind to receptors on the postsynaptic membrane allowing permeability and graded potential

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Information Processing

response of the post synaptic cell

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Chemical Gradient (fig 12-9) and Electrical Gradient (fig 12-9)

see book and packet

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Current

movement of charges to eliminate a potential difference

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Resistance

how much a barrier restricts movement of those charges
resistance high=low current
resistance low=high current

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Electro Chemical Gradient
Potassium Ion Gradient
Sodium Ion Gradient

see fig. 12-10 and packet (copy and paste to watch)
http://www.youtube.com/watch?v=Z9tPTDRjCYU
The electrochemical gradient is a form of potential energy. Any stimulus that increases the permeability of the plasma membrane to Na+ or K+ ions causes sudden and dramatic ion movement. If a sodium channel opens, sodium will flow in fegardless of what the stimulus was.

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Na+ K+ exchange pump

(see youtube video above and fig 3-19) ATPase pump out 3 Na+ molecules from the cell and carries 2 K+ molecules into the cell to per 1 ATP molecule, maintaining homeostasis

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Changes in the transmembrane potential

cells respond to stimuli which brings them out of a resting potential in order to modify their activities

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Passive or Leak Channels

Always open but permeability can vary

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Active Channels

gated channels that open or close in response to a stimuli

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chemically gated channel (fig 12-11a)

open or close when they bind specific chemicals; receptors that bind ACh are chemically gated channels; most common on dendrites and cell bodies

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Voltage-gated Channel (fig 12-11b)

opens or closes based on changes in the transmembrane potential; an excitable membrane, or one capable of generating and conduction an action potential is commonly found in an axon of unipolar and multipolar neurons and the sarcolemma

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Mechanically gated Channels (fig 12-11c)

opens or closes based on a distortion in the plasma membrane; found in sensory receptors responding to touch, pressure, or vibration

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Graded Potentials (fig 12-12)

Resting state...stimulation...graded potential

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Action Potentials

A nerve impulse that is propagated along an axon like dominoes reaching the synaptic terminals; dependent on voltage-gated channels

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All or Nothing Principle

Graded potentials like putting pressure on the trigger of a gun. Action potentials are like shooting the gun. If the pressure is strong enough the gun will fire

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Generation of an Action Potential

fig 12-14
http://www.youtube.com/watch?v=ifD1YG07fB8

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Propagation

Flow or charge with the message repeated over and over as it flows sown the pathway of an axon

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Continuous Propagation (fig 12-15)

Occurs in an unmyelinated axon; an action potential at the initial segment spreads the infer one segment of membrane at a time; flows in one direction because the previous section is in a refractory period and cannot be depolarized yet

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Saltatory Propagation (fig 12-16)

unmyelinated nodes respond to depolarization because myelin insulates and creates resistance to ion flow; action potetial jumps from node to node allowing the impulse to move more rapidly and uses less energy than continuous propagation

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Electrical Synapses

pre and post synaptic membranes are locked together at gap junctions allowing flow of ions between cells. Allows currents to flow from one cell to another; rare (found in eye)

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Chemical Synapses

Uses a neurotransmitter to send info between pre and postsynaptic membranes

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Excitatory Neurotransmitter

promotes action potentials

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Acetylcholine, ACH

common neurotransmitter found at neuromuscular junction in the CNS and PNS. typically excitatory

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Inhibitory Neurotransmitter

causes hyperpolarization to suppress an action potential

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Acetylcholinesterase, AChE

inactivator of ACH

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7 Steps of Choinergenic Synapses

Synapses that release acetylcholine (fig 12-17, table 12-4)

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Neuromodulators

alter the rate of neurotransmitter release by the presynaptic neuron or change the postsynaptic cells response to neurotransmitters

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Opioids

Pain relieving neuromodulators: endorphins, enkephalins, endomorphins, dynorphins

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Synaptic Fatigue

occurs if the presynaptic membrane cannot keep up with neurotransmitter resynthesis demands

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Norepinephrine

NE; neurotransmitter=excitatory, depolarizing effect on the postsynaptic membrane

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Dopamine

a CNS neurotransmitter. Inhibitory or excitatory

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Serotonin

CNS neurotransmitter. Inadequate seotonin production can effect attention span and emotional states