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139 Cards in this Set
- Front
- Back
Which systems coordinate activieties with other organ systems?
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-Nervous system
-Endocrine system |
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Which system provides swift but brief responses to stimuli?
Long terms changes and adjusts metabolic operations? |
-Nervous is fast
-Endocrine is slower |
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What are the two anatomical divisions of the Nervous system?
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CNS and PNS
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What tissues make up the nervous system?
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neural tissue
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What organs belong to the nervous system?
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-Brain, spinal cord
-Sensory receptors of sense organs (eyes, ears, etc) -Nerves connect nervous system with other systems |
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What is included in the CNS?
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The brain and the spinal cord
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What is included in the peripheral nervous system?
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all neural tissue outside the CNS (cranial and spinal nerves)
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What are the functions of the central nervous system?
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Process and coordinate:
-sensory data (inside and outside body) -motor commands (control activities of peripheral organs) -higher functions (intelligence, memory, learning, emotion) |
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What are the functions of the PNS?
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-deliver sensory information to the CNS
-Carry motor commands to peripheral tissues and systems |
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What are nerves?
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Bundles of axons with connective tissues and blood vessels that carry sensory information and motor commands in PNS
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What are the two functional divisions of the PNS?
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-afferent
-efferent |
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What is the afferent division?
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Carries sensory information from PNS sensory receptors to CNS
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What is the efferent division?
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Carries motor commands from CNS to PNS muscles and glands
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What do receptors do?
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Detect changes or respond to stimuli. Use neurons and specialized cells.
-complex sensory organs (eyes, ears) |
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What do effectors do?
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Respond to efferent signals from cells and organs.
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What are the divisions of the efferent division of the PNS?
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-Somatic nervous system
-Autonomic nervous system |
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What does the SNS do?
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Controls skeletal muscle contractions either voluntary or involuntary (reflexes)
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What does the ANS do?
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Controls subconscious actions such as contactions of smooth muscle and cardiac muscle as well as glandular secretions.
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What are the divisions of the ANS division?
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-Sympathetic (stimulating effect)
-Parasympathetic (relaxing effect) |
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What two cells make up neural tissue?
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1) Neuron
2) Neuroglia or glial cells |
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What is a neuron?
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The basic functional unit of neural tissue
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What type of cells are glial cells?
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Neuroglia which are supporting cells.
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What is the soma?
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The cell body. Have nissal bodies.
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What are nissal bodies?
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The stained portions of rough ER. Make neural tissue appear gray (gray matter).
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What are dendrites?
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Slender, sensitive processes extending from the neural cell body. Dendritic spines receive information from other neurons.
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What is the axon?
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A single, long process capable of propagating an electrical impulse. Consist of axoplasm, axolemma, axon hillock, initial segment, collaterals, telodendria, and synaptic terminals.
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What is the axoplasm of an axon?
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The cytoplasm of an axon.
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What is the axolemma of the axon?
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A specialized cell membrane of the axon.
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What are collaterals of an axon?
Telodendria? Synaptic terminals? |
-side bransches of axon
-fine extensions of collaterals -the end of telodendria |
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What is the synapse for?
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Communicating with another cell. Has a presynaptic cell and postsynaptic cell.
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Describe the presynaptic cell.
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This cell has the synaptic terminal and sends a message using synaptic vesicles that release neurotransmitters.
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Describe the postsynaptic cell.
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This cell recieves a message from the synaptic knob through either a neuromusculat or neuroglandular junction.
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Describe neurotransmitters
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-chemical messengers
-released at presynaptic membrane -affect receptors of postsynaptic membrane -broken down by enzymes -reassebled at synaptic knob |
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What are the 4 structural classifications of neurons?
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1) anaxonic
2) bipolar 3) unipolar 4) multipolar |
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Describe anaxonic neurons.
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-small
-no anatomic clues to distinguish between axon and dendrites -located in the brain and in the special sense organs -unknown functions |
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Describe bipolar neurons.
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Rare: has two distinct processes
1)One dendritic process with extensive branching at its distal tip. 2)One axon with a cell body between them |
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Describe unipolar neurons.
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-very long axons
-fused dendrites and axon -cell body on one side with only one connection to fused part -most sensory neurons of the PNS are unipolar |
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Describe multipolar neurons.
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-very long axons
-multiple dendrites with one axon -most common type in CNS |
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What are the three functional classifications of neurons?
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1) sensory
2) motor 3) interneurons |
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What do sensory neurons do?
Where are their cell bodies positioned? What are the two classifications of sensory neurons? |
-Deliver information from sensory receptors to the CNS
-Unipolar with their cell bodies located in peripheral sensory ganglia 1)somatic 2)visceral |
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What are ganglion?
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a collection of neuron cell bodies in teh PNS.
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What type of fibers make up the processes of sensory neurons?
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-afferent fibers
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What do somatic sensory neurons monitor?
Visceral sensory neurons? |
-They monitor the effects of external environment
-Monitor internal environment |
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What are sensory receptors and what types are there?
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The processes of specialized sensory neurons or cells monitored by sensory neurons.
-exteroceptors -proprioceptors -interoceptors |
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What do exteroceptors do?
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Sense external environment (touch, temperature, pressure, sight, smell, and hearing).
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What do proprioceptors do?
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Sense the position and movement of skeletal muscles and joints.
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What to interoceptors do?
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Monitor inside organ systems and sense tastes, depp pressure and pain.
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What do motor neurons do?
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-Carry instructions from the CNS to peripheral effectors via efferent fibers.
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What are the two classes of motor neurons and what does each do?
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Somatic: innervate skeletal muscles
visceral: innervate all peripheral effectors other than skeletal muscles |
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What are the two groups of efferent axons.
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-preganglionic fibers
-postganglionic fibers |
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What are interneurons?
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-Responsible for analyzing sensory information and coordinating motor outputs. Also involved in memory, planning, and learning in humans.
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Where are interneurons and how many are in humans?
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Most located in brain and spinal cord (some in autonomic ganglia). One or more between sensory neurons and motor neurons.
-about 20 billion in a human |
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What are the four (4) types of neuroglia?
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1) ependymal cells
2) astrocytes 3) oligodendrocytes 4) microglia |
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Where are ependymal cells and what do they do?
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They line the central canal of the spinal cord and ventricles of brain.
-secrete cerebrospinal fluid -monitor CSF -contain stem cells for repair |
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What are astrocytes?
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The largest and most numerous neuroglia in CNS. They maintain teh blood-brain barrier: lining CNS capillaries, so blood does not freely access CSF.
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What are microglia?
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-Act as wandering police force: engulfing cellular debris, waste products and pathogens.
-Least numerous and smallest -Many fine branches from the cytoplasmic processes. |
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What are oligodendrocytes?
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Similar to Schwann cells, they cheath the axons of the CNS.
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What forms the gray matter of the CNS?
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Unmyelinated axons and densely packed neuron cell bodies with the concentration of Nissel bodies.
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What forms white matter in teh CNS?
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Regions dominated by myelinated axons.
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What are the neuroglia of the PNS?
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1) Satellite cells
2) Schwann cells |
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What do satellite cells do?
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Surround the neuron cell bodies in ganglia.
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What are Schwann cells?
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-Form a sheath around every peripheral axon
-Can only myelinate one segment of a single axon, however it can enclose segments of several unmyelinated axons. |
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What are neurilemma?
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The outer surface of the schwann cell covering an axon.
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How is the resting membrane potential determined?
What controls this? |
-Membrane permiability to Na+ and K+ ions.
-The sodium potassium exchange pump stabilizes this |
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What is the Equilibrium potential?
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The transmembrane potential at which there is no net movement of a prticular ion across the cell membrane.
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What causes transmembrane potential to rise or fall?
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-response to temporary changes in membrane permeability
-resulting from opening or closing specific membrane channels. |
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What are passive channels?
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Always open and leaky
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What are active channels?
What are the three states of these? |
Gated channels that open or close in response to specific stimuli.
1) closed but capable of opening 2) Open (activated) 3) Closed an inactivated |
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What are the three classes of active channels?
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1) chemically regulated
2) voltage-regulated 3) mechanically regulated |
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How do chemically regulated channels work and where are they?
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In the presence of specific chemicals at a binding site, channel opens. They are found on neuron cell body and on dendrites.
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How do voltage-regulated channels work and where are they found?
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Respond to changes in transmembrane potential and have activation and inactivation gates. These are found in neural axons, skeletal muscle sarcolemma, and cardiac muscles.
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How do mechanically regulated channels work and where are they found?
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Respond to membrane distortion and found in sensory receptors (touch, pressure, vibration).
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What are graded potentials?
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Magnitude is proportional to magnitude of stimulus (more channels open). Changes in transmembrane potential can't spread far from stimulation site.
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What are the stages of a graded potentials?
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-exitiation
-inhibition -repolarization |
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What is excitation in a graded potential?
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When a stimulus triggers the opening of additional Na+ channels, allowing membrane potential to move toward zero (depolarization). The effect spreads passively owing to local currents and decreases with distance.
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What is the inhibition part of a graded potential?
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When a stimulus triggers the openin gof addition K+ channels, increasing the membrane potential (hyperpolarization).
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What is repolarization in graded potentials?
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Restore of normal RMP after depolarization by channels and ion pumps.
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What is the initial stimulus for action potentials?
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A graded depolarization of axon hillock large enough to change resting membrane to threshold level of voltage-regulated sodium channels (-60 - -55mV).
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What is the all-or-none principal?
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If a stimulus exceeds threshold amount, the action potential remains the same no matter how large the stimulus.
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What are the 4 steps in generation of action potentials?
*See video for indepth explanation. |
1) depolarization to threshold (-60mV)
2) Activation of voltage-regulated Na+ channels 3) Inactivation of Na+ channels, activation of K+ channels 4) Return to normal permeability. |
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What is the absolute refractory period?
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The brief period during which a local area of a neurons membrane resists restimulation and will not respond to a stimulus, no matter how strong.
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What is the relative refractory period?
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Time during which the membrane is repolarized and restoing the resting membrane potential; will respond only to a very strong stimulus.
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What is propagation of action potentials?
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Moving of action potentials generated in axon hillock along entire length of axon in a series of repeated actions, not passive flow.
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What are the two methods of propagating action potentials?
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1) continuous propagation
2) saltatory propagation |
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List 5 characteristics of continuous propagation.
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-local current depolarizes next segment and cycle repeats
-cell body lacks coltage-regulated channels, no repsonse to action potential -action potential only moves foward becuase of absolute refractory period Slow speed ~1m/s |
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What is the saltatory potential propagation? List 4 points.
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-action potential appears to leap from node to node, skipping intervening membrane surface
-occurs on myelinated axons -carries imulses much faster than continuous propagation -use proportionately less energy |
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What are the three groups of axons?
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Type A fibers
Type B fibers Type C fibers *Information transfer in the nervous system reflects a compromise between time and space. |
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Describe type A fibers
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They are 4-20um, are myelinated, and move 140m/s
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Describe type B fibers
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They are 2-4um, myelinated, and move 18m/s
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Describe type C fibers
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They are less then 2um, unmyelinated, and move 1m/s
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What are the two types of synapses?
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1) electrical
2) chemical |
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Describe a chemical synapse.
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-Cells not in direct contact
-unidirectional -action potential may or may not continue to postsynaptic cell -more dynamic (tune-up to grade or action potentials) |
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What determines if action potentials are passed to postsynaptic cells in a chemical synapse?
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-amount of neurotransmitter released
-sensitivity of postsynaptic cell |
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What are two types of neurotransmitters and what does each cause?
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1) excitatory: depolarization of postsynaptic membrane to promote action potentials
2) inhibitory: cause hyperpolarization of postsynaptic membranes to supress action potentials |
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What effect on a postsynaptic membrane does a neurotransmitter have?
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-Depends of receptor not on neurotansmitter
-Usually promotes action potentials, but inhibits cardiac neuromuscular junctions. |
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What is a synaptic knob?
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A tiny bulge at the end of a terminal branch of presynaptic neurons axon that contains vesicles housing neurotransmitters.
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What is the synaptic cleft?
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The space between a synaptic knob and the plasma membrane of a postsynaptic neuron.
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What does the plasma membrane in a postsynaptic neuron have?
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Has protein molecules that serve as receptors for the neurotansmitters.
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What chemical does a Cholinergic synapses use and where?
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ACh released at:
-all neuromuscular junctions incolcing skeletal muscle fibers -many synapses in CNS -All neuron-to-neuron synapses in PNS -All junction sof the parasympathetic division of ANS. |
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What is synaptic fatigue?
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The synapse remains inactive until ACh has been replenished.
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What does ACh cuase to move and what does this do?
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ACh triggers Ca+ channels open
Exocytosis occurs allowing transmission of neurotransmitters. |
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What are some other important neurotransmitters?
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-norepinephrine (NE)
-dopamine -serotonin -gamma aminobutyric acid (GABA) |
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At the simplest level, how does information processing occur?
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-Graded potentials developed in a postsynaptic cell in response the neurotransmitters
-many dendrites receive neurotransmitter messages simultaneously -some excitatory, some inhibitroy -net effect on axon hillock determines if action potential is produced |
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What are 2 types of postsynaptic potentials?
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1) excitatory
2) inhibitory |
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Describe each type of postsynaptice potentials.
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EPSP: a graded depolarization caused by the arrival of a neurotransmitter at the postsynaptic membrane
IPSP: a transient hyperpolarization of the postsynaptic membrane |
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What is inhibition?
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When a neuron recieves many IPSP's, it is inhibited from producing an action potential becuase of the stimulation needed to reach threshold is increased.
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What are the two types of summation?
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Both formed from individual EPSP's combining
1) temporal 2) spatial |
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What is temporal summation?
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Summation of repeated stimulation by a single synapse.
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What is spatial summation?
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Adds together the effects of several knobs being activated simultaneously (multiple synapses, simultaneously).
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What is divergence?
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The spread of information from on eneuron or neuronal pool to several neurons or pools.
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What is convergence?
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Several neurons synapse on the same postsynaptic neuron.
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What is serial processing?
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Neurons or pools work in sequence.
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What is parallel processing?
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Several neurons or neuronal pools process the same information at one time.
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What is reverberation?
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Collateral axons establish a circuit that further stimulates presynaptic neurons. Positive feedback.
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What are the 5 higher levels of orgnaization and processing?
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1) divergence
2) convergence 3) serial processing 4) parallel processing 5) reverberation |
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What are the small components of the CNS?
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-cerebrospinal fluid (CSF)
-spinal cord -the brain -cranial nerves -bone and meningers (covering of brain and spinal cord) |
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How many segments of the spine are there and what "pair" are they associated with?
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31 segments each with a pair of dorsal roots and a pair of ventral roots.
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Describe a ventral root?
Dorsal root? |
ventral: contains axons of motor neurons and carry motor information out of the spinal cord
dorsal: contains axons of sensory neurons and carry sensory information into the spinal canal. |
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What is a spinal nerve?
Dorsal root ganglia? |
-A single mixed nerve on each side where the dorsal and ventral nerve roots join together.
-contain cell bodies of sensory neurons |
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What is white matter in the spinal cord?
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Myelinated and unmyelinated axons.
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What is gray matter in the spinal cord?
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Cell bodies of neurons and neuroglia and unmyelinated axons.
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What are the different parts of the gray horns?
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-posterior horns
-anterior horns -lateral horns -gray commissures |
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Describe posterior gray horns.
Anterior? |
-contain somatic and visceral sensory nuclei
-contain somatic motor nuclei |
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Describe lateral gray horns and gray commissures.
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-Laterals are located in thoracic and lumbar segments and contain visceral motor nuclei.
-Commissures are axons that cross from one side to the other. |
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How is white matter organized?
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-into six columns
-each column has tracts -ascending and descending tracts carry information from the brain to the spinal cord. |
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What is dorsal ramus (of peripheral distribution of spinal nerves).
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Sensory and motor innervation to skin and muscles of the back.
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What is the ventral ramus (of peripheral distribution of spinal nerves)?
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Sensory and motor innervation to muscles and glands in the body wall, and the limbs.
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What is the white ramus and gray ramus (of peripheral distribution of spinal nerves)?
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Innervate glands and smooth muscles in the visceral organs (sympathetic nerves).
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How are spinal nerves distributed peripherally?
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-dorsal ramus
-ventral ramus -white ramus and gray ramus |
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What are the functions of the spinal cord?
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-provides conduction routes to and from the brain
-services as the integrator (or reflex center) for all spinal reflexes |
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What are conduction routes composed of?
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-ascending tracts
-descending tracts -bundles of axons compose all tracts |
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How are structural tracts organized?
Functional? |
-all acons of any one tract originate in the same structure and terminate in the same structure
-all axons that compose one tracts serve one general function. |
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What are reflexes?
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Rapid, automatic responses to stimuli showing very little variability (monosynaptic and polysynaptic).
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What is the purpose of neural reflexes?
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Being an involuntary motor response by the nervous system, it helps maintain homeostasis by rapidly adjusting the functions of organs or organ systems.
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What is a reflex arc and what are it's five steps?
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The neural "wiring" of a single reflex.
1) the arrival of a stimulus and activation of a receptor 2) The activation of a sensory neuron 3) Information processing 4) The activation of a motor neuron 5) A response by an effector |
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What are monosynaptic reflexes?
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Stretch reflexes: automatically regulates skeletal muscle length and muscle tone (such as patellar reflex)
-Many stretch reflexes are postural reflexes (reflexes that maintain normal upright posture -The sensory stimulus and motor response occur on the same side of the body (ipsilateral reflex arcs). |
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What are two types of polysynaptic reflexes?
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Withdrawal and crossed extensor reflexes.
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Describe withdrawal polysynaptic reflexes.
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-Move affected portions of the body away from a source of stimulation
-interneurons in spinal cord coordinate muscular contractions and reduce resistance to movement *The flexor reflex is a withdrawal reflex affecting the muscles of a limb |
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Describe a crossed extensor reflex.
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-Complements withdrawal reflexes
-The motor response occurs on the side opposite the stimulus (contralateral reflex arc). |