Term
| Describe/diagram the general nervous pathway |
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Definition
| divided into 2 division: central(brain& spinal cord) & peripheral(nerves,nerve endings,&receptors). The P.N.S is divided into sensory and motor divisions depending on the direction of info travel. TOWARD CNS is afferent and AWAY from CNS is efferent. Motor info comes in 2 varieties: autonomic(involuntary-for smooth & cardiac muscle/glands) and somatic(voluntary & for skeletal muscle only). The autonomic system has sympathetic(fight&flight) and parasympathetic(rest and digest) |
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Term
| List and describe the two main divisions of the N.S. List and describe the two directions of information travel in the N.S |
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Definition
2 main divisions are central nervous system(brain&spinal cord)& peripheral nervous system(nerves, nerve endings,&receptors)
2 directions of travel are afferent(toward CNS) and efferent(away from CNS)
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Term
| List and describe the 2 subdivisions of the autonomic nervous system |
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Definition
sympathetic-"flight & fight"
parasympathetic-"rest & digest" |
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Term
| What is the structural unit of the N.S? What is its function? |
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Definition
the structural unit is the neuron
the function is to generate and conduct electrical impulses for communication & control of the body |
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Term
| Describe the structure of a nerve |
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Definition
| A bundle of nerve fibers(axons of neurons) traveling to a similar destination, wrapped in a connective tissue sheath, located in the PNS |
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Term
| Describe "referred and "phantom" pain |
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Definition
referred- pain perceived as coming from an area of the body other than the location of the actual origin of the painful stimulus.
Phantom- pain is perceived sensation coming from a limb of the body that no longer exists(ie:amputation) |
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Term
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Definition
| an area of the skin innervated by the same spinal nerve pair |
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Term
| List and describe the function of the neuroglia in the CNS |
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Definition
1.astrocyte-CNS-helps nourish and take away waste from neurons as part of the blood-barrier. Also helps form synapses between neurons.
2.microglia-CNS-phagocyte to help provide immunity & ensure the health of the CNS tissue
3.ependymal-CNS-lines the ventricles,central canal and subarachnoid space and is part of the blood-brain barrier. Controls what substances pass form the cerebral spinal fluid to the CNS tissue. Their cilia keep CSF circulation adequate.
4.oligodendocytes-CNS-myelinates neurons in the CNS. Can myelinate up to 60 axons at once |
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Term
| List and describe the function of the neuroglia in the PNS |
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Definition
1.Schwann-PNS-myelinates one part of one axon in the PNS
2.Satellite-PNS-always found around the cell body, but function in unknown |
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Term
| Describe the "degrees of myelination". How do they affect the rate of conduction of an electric impulse? |
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Definition
1.unmyelinated-no myelin. This is the slowest form of conduction
2.continuously myelinated-faster conduction
3.myelinated with nodes of Ranvier-myelation is segments with exposed regions of axons(nodes). Performs saltory conduction and is the fastest form of conduction |
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Term
| Describe the process of myelination |
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Definition
| The schwann(or oligodendrocyte) cell wraps around an axon and secretes myelin onto the surface of the axon |
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Term
| Describe the general anatomy of a neuron |
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Definition
| the neuron has a cell body that contains the normal cell organelles(except for a centriole) and is the biosynthetic center of the cell. The process includes dendrites and one axon that arises from the body. Dendrites contain receptors for stimuli and are the receptive,or input, region of the cell. The axon is the conduction region of the neuron and end in terminal boutons that release neurotransmitter |
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Term
| Describe why the neuron has such a well developed and active ER |
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Definition
| the neuron has to make an immense amount of receptors, channels, and neurotransmitter, which are all proteins. So it has a very well developed and active ER for making all of that protein |
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Term
| Why are neurons amitotic? |
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Definition
| because they lack centrioles, which grow the mitotic spindle needed for division |
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Term
| What is lipofuscin and why is it important to humans? |
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Definition
| It is a pigment made by neurons that accumulates in the cell. Although there is no known function for it, humans use it to help distinguish the age of a tissue sample-the darker the neurons, the older the tissue |
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Term
| What is the difference between nuclei and ganglia? |
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Definition
| nuclei are clusters of neuron cell bodies in the CNS and ganglia are clusters of neuron cell bodies in the PNS |
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Term
| Describe the nature of the neuron's cell membrane |
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Definition
| it is a typical plasma membrane as described by the fluid mosaic model, but it has A LOT of receptors and channels embedded into it to serve the function of generating and conducting electrical potential |
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Term
| Which part of the neuron is the receptive region |
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Definition
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Term
| Describe the function of a dendrite. What structural components allow it to have this function? |
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Definition
| They are extensions of the cell body that are riddled with receptor channels sensitive to stimuli and the permeability to ions |
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Term
| Which part of the neuron is the conductive region? |
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Definition
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Term
| Describe the function of an axon. What structural components allow it to have this function? |
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Definition
| To conduct electrical potentials. Its membrane is littered with voltage-gated channels that allow the permeability of ions to allow electric conduction |
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Term
| Which part of the neuron is the secretory region? |
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Definition
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Term
| Describe the function of an axonal terminal (terminal bouton)? What structural components allow it to have this function? |
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Definition
| To exocytose(release) neurontransmitter for the propagation of the electrical signal as a chemical across the synapse. It has Ca++ voltage gated channels that allows the entrance of Ca++ into the cell to bind to the synaptic vesicles that contain NT, which then dock with the membrane for exocytosis |
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Term
| What is membrane potential? What is a typical neuron's membrane potential? |
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Definition
It is the difference in charge across a plasma membrane. This is created by different ion concentrations on either side of the membrane. Sodium and potassium ions play the major roles.
-70mV |
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Term
| What device is used to measure membrane potential? |
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Definition
| voltmeter that reads in mV |
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Term
| What causes an electric potential across a membrane? What controls membrane potential? |
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Definition
| Differences in ions on either side of the membrane. Channels in the membrane control the permeability of the membrane to these ions, and thus their concentration differences on either side |
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Term
| What types of things can start an electrical potential in a neuron (or other special cells)? |
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Definition
| stimulus-pressure, temperature, light, chemical |
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Term
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Definition
| occurs in the dendrites and cell body by the influx of sodium into the cell. It's called graded potential because it can occur over a range of millivoltages |
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Term
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Definition
| occurs at +30mV in neurons and begins at the hillock and will travel down the axon |
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Term
| What is the difference between graded and action potentials? |
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Definition
| the difference other than location is that the action potential occurs at a specific mV and a graded potential depends on the amount of stimulus present that changes the membrane potential accordingly |
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Term
| List and describe the types of receptors that are available on neurons |
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Definition
a.chemoreceptors- respond to chemicals
b.thermoreceptors-respond to changes in temp.
c.mechanoreceptors-respond to pressure
d.photoreceptors-respond to light energy
e.voltage receptors- respond to changes in membrane potential
f.nocireceptors-respond to excess stimuli and the info is interpreted as pain |
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Term
| Describe the process of propagating an action potential in a neuron. Describe what determines the RATE of propagation? |
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Definition
| as potassium continues to get repelled by the entrance of sodium, localized regions of the membrane depolarize to -55mV and sodium voltage gated channels open leading to depolarization to +30mV. Then potassuim voltage gated channels open, leading to repolarization and hyperpolarization. This process repeats over and over in each successive membrane region as potassuim keeps getting pushed. The rate is determined by the diameter of the axon-bigger is better; and the degree of myelination |
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Term
| What determines the intensity of an action potential? Frequency? |
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Definition
| The greater the stimulus the greater the intensity of the signal. They are directly proportional. The frequency of the signal will also depend on the stimulus-it will occur as often as the stimulus occurs |
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Term
| Describe the general structure of a synapse. How can a neuron's signal propagate across the synapse? |
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Definition
| the synapse is a space of ECF between the neuron and the next neuron in line(or an effector organ). The signal(neurotransmitter) is exocytosed by the presynaptic neuron, then diffuses across the synapse in the ECF and binds to a receptor on the next neuron(or effector organ). |
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Term
| How can the signal be removed from the synapse once it reaches the next neuron or effector organ? |
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Definition
3 ways:
a.it can be endocytosed by the neuron that released it
b.an enzyme can degrade it
c.it may simply diffuse out of the synapse region |
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