Term
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Definition
Nerve cells scattered in body
No central organ
ex: Cnidarians |
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Term
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Definition
Nerve ring and nerves extend to various parts of the body
Ex: Echinoderms |
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Term
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Definition
nerve cells concentrate, form:
-nerves, nerve cords, ganglia, brain
Sense Organs:
-typically concentrated in head
Increased # of interneurons, more complex synaptic contacts:
-permit wide range of responses |
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Term
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Definition
Cerebral ganglia
Ventral nerve cords
Transverse nerves |
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Term
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Definition
Ventral nerve cord
Numerous ganglia
-cerebral ganglia(arthropods) |
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Term
| Two main divisions of vertebrate nervous system |
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Definition
Central nervous system:
-brain, spinal cord
Peripheral nervous system:
-sensory receptors and nerves |
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Term
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Definition
Brain and spinal cord arise from the neural tube
Anterior end of neural tube differentiates into:
-hindbrain
-midbrain
-forebrain |
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Term
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Definition
Protected by bone and 3 meninges
-dura mater
-arachnoid
-pia mater
Cushioned by cerebrospinal fluid (CSF) |
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Term
| What are spaces in the brain called? |
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Definition
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Term
| Structure and function of Spinal Cord |
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Definition
Transmits impulses to and from brain:
-ascending tracts (info to brain)
-descending tracts(info from brain)
Controls many reflex actions
Gray matter
-contains nuclei that serve as reflex centers |
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Term
| Structures of the Cerebrum |
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Definition
White matter
-lies beneath cerebral cortex
Corpus callosum
-large band of white matter
-connects R & L hemispheres
Basal ganglia
-cluster of nuclei w/in white matter
-important centers for motor funct |
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Term
| What are the functional areas of the cerebrum? |
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Definition
Occipital lobe-sight
etc... |
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Term
| Limbic System of the brain |
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Definition
Affects emotional aspects of behavior
-motivation
-sexual activity
-autonomic responses
-biological responses |
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Term
| Parts of the limbic system |
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Definition
Hippocampus:
-helps categorize info
-consolidates memories
Amygdala:
-evaluates incoming info
-signals danger |
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Term
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Definition
Learning
-process of acquiring knowledge or skills as a result of experience
Memory
-process by which info is encoded, stored, and retrieved |
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Term
| What are the types of memory? |
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Definition
Implicit memory
Explicit memory
Short-term
Long-term |
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Term
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Definition
-unconscious how-to memory
-for perceptual and motor skills |
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Term
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Definition
| factual memory of people, places, objects |
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Term
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Definition
recalls info(like phone #) for a few minutes
info can be transferred from short to long memory |
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Term
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Definition
| long-term functional changes at synapses |
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Term
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Definition
| increased sensitivity to an action potential by a postsynaptic neuron |
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Term
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Definition
| long-lasting decrease in strength of synaptic connections |
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Term
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Definition
| permits the body to respond to stressful situations |
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Term
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Definition
influences organs to conserve and restore energy
ex: digestive, metabolism |
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Term
| Peripheral nervous system |
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Definition
made up of :
-sensory receptors
-neurons outside the CNS |
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Term
| What are the steps of Response to a Stimulus? |
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Definition
1. Reception
2. Transmission by afferent
3. Integration
4. Transmission by efferent
5. Action by effectors |
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Term
| What is the structure of a typical neuron? |
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Definition
Dendrites
Axon
Nodes of Ranvier
Schwann cell
Myelin Sheath
Synaptic terminals
Cell body |
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Term
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Definition
Where 2 myelin sheaths come together
axon is not covered by the myelin here
Na+ channels are concentrated |
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Term
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Definition
coats the axon to speed up signal transmission
Forms sheaths around axons in PNS |
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Term
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Definition
several hundred axons
wrapped in connective tissue |
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Term
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Definition
| Mass of neuron cell bodies in the PNS |
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Term
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Definition
support/nourish cells
A type of schwann cell
important in neural communication |
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Term
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Definition
A type of glial cell:
-physically support neurons
-regulate extracellular fluid in CNS
-communicate with one another & with neurons
-induce and stabilize synapses |
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Term
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Definition
| form myelin sheaths around axons in CNS |
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Term
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Definition
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Term
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Definition
Line cavities in the CNS
Contribute to formation of cerebrospinal fluid
serve as neural stem cells |
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Term
| How do neurons send signals? |
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Definition
-Electrical signals transmit info along axons
-Plasma membrane of resting neuron(not transmitting) is polarized
-Inner surface of plasma membrane is negatively charged relative to the extracellular fluid |
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Term
| What is the approximate resting potential of a neuron? |
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Definition
Potential difference of about :
-70 mV across the membrane |
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Term
| What determines the magnitude of resting potential? |
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Definition
-Differences in ion concentrations inside cell relative to extracellular fluid
-selective permeability of plasma membrane to these ions |
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Term
| What gives the cells charges? |
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Definition
-Ions passing through specific passive ion channels.
-K+ leak out faster than Na+ leak in
-Cl- accumulates at inner surface of plasma membrane
-Large ions can't cross membrane, so contribute to negative charge. |
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Term
| Describe the Sodium-Potassium pump |
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Definition
It maintains gradients that determine resting potential by transporting 3 Na+ out for ever 2 K+ in.
It requires ATP |
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Term
| Resting potential of a neuron is maintained by.. |
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Definition
Differences in concentrations of specific ions inside the cell relative to extracellular fluid
Selective permeability of the plasma membrane to these ions |
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Term
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Definition
-A local change in electrical potential
-Varies in magnitude depending on the strength of the applied stimulus
-Fades out within a few mm of point of origin |
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Term
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Definition
-An electrical signal resulting from depolarization of the plasma membrane in a neuron or muscle cell
-wave of depolarization that moves down the axon |
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Term
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Definition
depolarized:
-if stimulus causes membrane potential to become less negative
hyperpolarized:
-if membrane potential becomes more negative than resting potential |
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Term
| How is an action potential generated? |
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Definition
-When voltage across membrane declines to a threshold level
-voltage-activated ion channels open
-Na+ ions flow into the neuron |
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Term
| Describe transmission of an Action Potential |
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Definition
An all or none response:
-No variation in strength of a single impulse
-either exceeds or doesn't
Once begun, it must finish
As moves down an axon, repolarization occurs behind it |
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Term
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Definition
| The brief period that elapses after the response of a neuron or muscle fiber, during which it cannot respond to another stimulus. |
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Term
| What are the 2 types of refractory periods? |
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Definition
Absolute:
-can not transmit another action potential
Relative:
When enough gates controlling Na+ have ben reset, the threshold is higher for an action potential to reach |
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Term
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Definition
-The transmission of a neural impulse along a myelinated neuron
-ion activity at one node depolarizes the next node along the axon
-more rapid than continuous |
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Term
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Definition
-Involves entire axon plasma membrane
-takes place in unmyelinated neurons
-must pass entire length of axon, so is slower than saltatory |
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Term
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Definition
Junction between 2 neurons or between a neuron and an effector
Most are chemical, some are electrical |
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Term
| What do synaptic vesicles contain? |
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Definition
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Term
| How do neurons signal other cells? |
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Definition
| By releasing neurotransmitters at synapses |
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Term
| What ion makes a synapse work? |
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Definition
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Term
| How is a neural impulse transmitted across a synapse? |
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Definition
-Calcium ions cause synaptic vesicle to fuse with presynaptic membrane and release neurotransmitter into synaptic cleft
-Neurotransmitter diffuses across synaptic cleft and combines with specific receptors on a post synaptic neuron |
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Term
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Definition
| a presynaptic neuron releases neurotransmitter(chemical messenger) from its synaptic vesicles. |
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Term
| Excitatory postsynaptic potential (EPSP) |
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Definition
| A change in membrane potential that brings a neuron closer to the firing level |
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Term
| Inhibitory postsynaptic potential (IPSP) |
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Definition
| A change in membrane potential that takes a neuron farther from the firing level. |
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Term
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Definition
| Occurs when repeated stimuli cause new EPSPs to develop before previous EPSPs have decayed |
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Term
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Definition
Occurs when several closely spaced synaptic terminals release neurotransmitter:
simultaneously stimulating postsynaptic neuron at several different places |
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Term
| What happens during integration? |
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Definition
-Incoming neural signals are summed
-temporal and spatial summation can bring a neuron to threshold level |
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Term
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Definition
| several presynaptic neurons synapse with one postsynaptic neuron |
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Term
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Definition
| A single presynaptic neuron synapses with many postsynaptic neurons. |
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Term
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Definition
Important in rhythmic breathing, mental alertness, short-term memory
Depend on positive feedback:
-new impulses generated again and again until synapses fatigue |
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Term
| What are the 2 types of reverberating circuits? |
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Definition
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Term
| Reverberating circuit with interneuron |
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Definition
-An axon collateral of the second neuron synapses with an interneuron.
-Interneuron synapses with the first neuron in the sequence
New impulses are triggered again and again in the first neuron, causing reverberation |
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Term
| Simple reverberating circuit |
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Definition
| An axon collateral of the 2nd neuron turns back on its own dendrites, so the neuron continues to stimulate itself |
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