Term
| 5 Functions of the Nervous System |
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Definition
- Sensory input
- Integration
- Homeostasis
- Mental activity
- Control of muscles and glands
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Term
| Central Nervous System (CNS) |
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Definition
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Term
| Peripheral Nervous Sytem (PNS) |
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Definition
| All neural tissue outside CNS |
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Term
| Where does the spinal cord connect to the brain? |
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Definition
| Through the foramen magnum of the skull. |
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Term
| What two regions of nerves make up the PNS? |
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Definition
| Spinal nerves and cranial nerves. |
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Term
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Definition
| Brings sensory information to CNS from receptors in peripheral tissues and organs |
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Term
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Definition
| Carries motor commands from CNS to muscles and glands (aka effectors) via motor neurons (aka effector neurons) |
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Term
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Definition
| Nerve cell, consisting of a cell body, dendrites, and an axon |
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Term
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Definition
| Ending of neurons or separate, specialized cells that detect such things as temperature, pain, touch, pressure, light, sound, odors |
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Term
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Definition
| A bundle of axons plus associated connective tissue and blood vessels that connects CNS to sensory receptors, muscles, and glands |
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Term
| How many pairs of brain-originating cranial nerves are there? |
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Definition
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Term
| How many pairs of spinal-cord-originating spinal nerves are there? |
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Definition
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Term
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Definition
| Collection of neuron cell bodies outside CNS |
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Term
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Definition
| Extensive network of axons, and sometimes neuron cell bodies, located outside CNS |
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Term
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Definition
| Functional junction between two neurons or between a neuron and an effector, such as a muscle or gland; may be electrical or chemical |
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Term
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Definition
| An electrical signal that propagates along the membrane of a neuron or muscle fiber (cell) |
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Term
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Definition
| Multilayered lipid & protein covering around some axons that insulates them & increases the speed of nerve impulse (action potential) conduction |
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Term
| What does the Somatic Nervous System voluntarily control? |
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Definition
| Skeletal muscle contractions. |
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Term
| What does the Autonomic nervous system subconsciously control? |
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Definition
| Regulation of smooth muscle, cardiac muscle, and glandular secretions. |
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Term
| What system is a single neuron system that conducts impulses from the CNS? |
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Definition
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Term
| What system is a two neuron system that conducts impulses from the CNS? What makes it two neurons? |
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Definition
| Autonomic; first from CNS to ganglion; second from ganglion to effector |
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Term
| Which division of the Autonomic Nervous System is responsible for elevation of metabolic rate and increased alertness (“flight, fright, or fight” reactions)? |
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Definition
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Term
| Which division of the Autonomic Nervous System is responsible for activities that conserve energy and lower metabolic rate (“rest and digest” activities) |
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Definition
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Term
| What do the sensory neurons of the enteric division plexuses monitor? |
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Definition
| Chemical changes within GI tract as well as stretching of its walls. |
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Term
| Why would the Enteric division be considered separate from the PNS? |
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Definition
| It can control the digestive tract (control contraction of GI tract smooth muscle; secretions of GI tract) independently of the CNS |
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Term
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Definition
| Nerve cells receive stimuli and transmit action potentials |
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Term
| What does the Cell Body contain? |
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Definition
| Nucleus and Nissl bodies, which is rough endoplasmic reticulum |
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Term
| What is the input-recieving portion of the neuron? |
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Definition
| Short, often highly branched dendrites |
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Term
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Definition
| Little bulge where axons synapse with dendrite |
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Term
| What are axons responsible for? |
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Definition
| The neuron output by transmission of impulses toward another neuron, muscle fiber, or gland cell |
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Term
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Definition
| Cone-shaped area of cell body where axon arises from |
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Term
| What part of the axon is closest to axon hillock? |
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Definition
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Term
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Definition
| Site where action potentials are generated; junction of axon hillock and initial segment |
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Term
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Definition
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Term
| What is the plasma membrane of axon called? |
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Definition
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Term
| What are presynaptic terminals are also known as? What are they? |
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Definition
| Terminal boutons; where axons terminate in small extensions with enlarged ends |
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Term
| In the presynaptic terminals, what is the neurotransmitter contained in? |
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Definition
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Term
| Name two viruses that can infect the nervous system because of the transportation of material, taken in by endocytosis, up the axon to the cell body. |
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Definition
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Term
| What are interneurons also known as? What is their function? |
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Definition
| Associated neurons; they conduct action potentials from one neuron to another within the CNS |
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Term
What type of neuron is this? Where is it primarily found? [image] |
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Definition
| Multipolar; most neurons of CNS |
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Term
What type of neuron is this? Where is it primarily found? [image] |
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Definition
| Bipolar; special sense organs (in retina, inner ear, olfactory area of brain) |
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Term
What type of neuron is this? Where is it primarily found? [image] |
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Definition
| Unipolar; most sensory neurons of the PNS (touch, stretch) |
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Term
| What are the four functions of neuroglia, the major support cells in the CNS? |
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Definition
- Form permeability barrier between blood and neurons
- Phagocytose foreign substances
- Produce cerebrospinal fluid
- Form myelin sheaths around axon
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Term
What type of neuroglial cell is this? What is it's main function? [image] |
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Definition
| Astrocytes; form permeability barrier between blood and neurons |
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Term
What type of neuroglial cell is this? What is it's main function? [image] |
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Definition
| Ependymal; produce cerebrospinal fluid |
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Term
What type of neuroglial cell is this? What is it's main function? [image] |
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Definition
| Microglia; phagocytose foreign substances |
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Term
What type of neuroglial cell is this? What is it's main function? [image] |
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Definition
| Oligodendrocytes; form myelin sheaths around axon |
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Term
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Definition
| The membrane covering the outside of brain and spinal cord, which Astrocyte process feet cover the surface of. |
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Term
| How do Astrocytes provide structural support and promote the blood-brain barrier? |
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Definition
| They have lots of microfilaments to provide support; they produce chemicals which promote the formation of tight junctions between epithelial cells of capillaries |
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Term
| What does the blood-brain barrier regulate in brain and blood fluid composition? |
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Definition
| Protects neurons from toxic substances, allows exchange of nutrients and waste products between neurons and blood, prevents fluctuations in composition of blood from affecting functions of the brain |
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Term
| Where are ependymal cells located? |
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Definition
| Line brain ventricles and spinal cord central canal |
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Term
| What is the function of choroid plexuses, which are specialized ependymal cells? |
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Definition
| Secrete cerebrospinal fluid that circulates through ventricles of brain; have cilia which help move fluid thru cavities of the brain |
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Term
| What do microglia respond to? phagocytose? |
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Definition
| Inflammation; necrotic tissue, microorganisms, and foreign substances that invade the CNS |
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Term
| Oligodendrocytes may form myelin sheath around several axons, name the cells that form sheaths around only one. |
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Definition
| Schwann cells or neurolemmocytes |
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Term
| How is the myelin sheath formed? |
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Definition
| During development, as cells grow around axon, cytoplasm is squeezed out and multiple layers of cell membrane, which is primarily fatty phospholipid, wrap around the axon. |
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Term
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Definition
| Surround neuron cell bodies in ganglia, provide support and nutrients |
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Term
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Definition
| Protects and insulates axons from one another, speeds transmission, functions in repair of axons |
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Term
| What interrupts the myelin-covered areas of the axon? What are these ares called? |
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Definition
| Nodes of Ranvier; Internodes |
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Term
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Definition
These rest in invaginations of Schwann cells or oligodendrocytes, so they're not fully sheathed by myelin [image] |
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Term
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Definition
| Bundles of parallel axons with associated myelin sheaths |
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Term
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Definition
| Collections of neuron cell bodies, dendrites, and unmyelinated axons |
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Term
| What do axons that make up white matter of CNS form to propagate action potentials from one area in the CNS to another? |
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Definition
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Term
| What do all living cells have across their plasma membrane? |
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Definition
| An electral charge difference or voltage gradient. |
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Term
| What is the purpose of selective ion channels? |
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Definition
| Ions are charged and cannot diffuse through the plasma membrane on their own. |
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Term
| Are cells more permeable to potassium or sodium? |
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Definition
| There are more potassium channels than sodium, so potassium. |
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Term
| Besides ion channels what else contributes to the ion chemical gradient? |
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Definition
| The Sodium/Potassium exchange pump. |
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Term
| Where is Cloride found and why? |
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Definition
| Cl- ions are found in the extracellular fluid because they repel from the negatively charged proteins inside the cell and are able to move outside via non-gated channels. |
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Term
| Which ions are moving when the cell is at rest? |
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Definition
| Cl- moves out of the cell and K+ tends to move out as well. Na+ channels are closed so it stays outside the cell. |
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Term
| What is the process of the Sodium/Potassium exchange pump? |
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Definition
Three intracellular Na+ and one ATP bind on inside of carrier molecule. Phosphorylation changes the shape of the carrier molecule, transporting Na+ outside the cell. Now two extracellular K+ bind to the carrier molecule, which gets dephosphorylated, resumes its orginal shape, and transports K+ inside the cell. [image] |
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Term
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Definition
| Tthe unequal distribution of charge that exists between the immediate inside and immediate outside of the plasma membrane |
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Term
| What is a cell that has this potential difference across its plasma membrane said to be? |
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Definition
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Term
| What is the range of Resting Membrane Potential(mV) in neurons? |
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Definition
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Term
| Characteristics Responsible for the Resting Membrane Potential |
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Definition
The number of charged molecules and ions inside and outside the cell is nearly equal The concentration of K+ is higher inside than outside the cell, and the concentration of Na+ is higher outside than inside the cell. The plasma membrane is 50-100 times more permeable to K+ than to other positively charge ions such as Na+. The plasma membrane is impermeable to large intracellular negatively charged molecules such as proteins. K+ tend to diffuse across the plasma membrane from the inside to the outside of the cell. Because negatively charged molecules cannot follow the postively charged K+, a small negative charge develops just inside the plasma membrane. The negative charge inside the cell attracts positively charged K+. When the negative charge inside the cell through the plasma membrane, an equilibrium is established. The charge difference accross the plasma membrane at equilibrium is reflected as a difference in potential, which is measured in millivolts (MV). The resting membrane potential is proportional to the potential for K+ to diffuse out of the cell but not to the actual rate of flow for K+ At equilibrium there is very little net movement of K+ or other ions across the plasma membrane. |
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Term
| At resting potential most gated channels are ________, so that when they are ________ they change the permeability of the cell membrane. |
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Definition
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Term
| What are the three types of gated ion channels and what do they respond to? |
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Definition
- Ligand-gated channels respond when a specific ligand binds to them
- Voltage-gated channels respond to small voltage changes across the cell membrane
- Mechanically-gated channels can respond to vibration, touch, temperature, or stretch
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Term
| How do alterations in [K+] change the membrane potential? |
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Definition
If extracellular [K+] increases, there is less of a gradient resulting in depolarization. If extracellular [K+] decreases, there is more of a gradient resulting in hyperpolarization. |
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Term
| How do changes in K+ membrane permeability affect the membrane potential? |
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Definition
| If gated K+ channels open, more K+ diffuses out resulting in hyperpolarization of charge. |
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Term
| How do changes in Na+ membrane permeability affect the membrane potential? |
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Definition
| If gated Na+ channels open, Na+ diffuses in resulting in depolarization. |
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Term
| How do alterations in [Ca2+] change the membrane potential? |
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Definition
Voltage-gated Na+ channels are sensitive to [Ca2+] changes. If extracellular [Ca2+] increases, Na+ gates close resulting in hyperpolarization. If extracellular [Ca2+] decreases, Na+ gates open resulting in depolarization. |
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Term
| What stimuli cause local potentials? |
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Definition
- Ligands binding to their receptors
- Changes in charge across plasma membrane
- Mechanical stimulation
- Temperature changes
- Spontaneous changes in membrane permeability
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Term
| What does it mean for local potentials to be "graded"? |
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Definition
Their magnitude varies from small to large depending on stimulus strength or frequency. [image] |
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Term
| Local potentials rapidly decrease in magnitude as they spread over the surface of the plasma membrane but because they can summate or add onto each other a sufficiently large depolarizing local potential can ... |
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Definition
... cause the generation of an action potential. [image] |
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Term
| When local potential causes depolarization of plasma membrane to a level called the ________, a series of permeability changes occur that result in an ________. |
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Definition
| Threshold; action potential |
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Term
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Definition
| A large change in membrane potential that propagates, without changing its magnitude, over long distances along the plasma membrane. |
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Term
| List and describe the three phases of an action potential. |
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Definition
[image] - Depolarization phase: membrane potential moves away from resting membrane potential and becomes less polar
- Repolarization phase: membrane potential returns toward the resting membrane state, becoming polarized again
- May get afterpotential: slight transient hyperpolarization, overshot of repolarization
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Term
| Explain in term of voltage-gated channels what goes on in the resting membrane potential. |
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Definition
[image] Na+ activation gates are closed, but inactivation gates are open. K+ channels are closed. |
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Term
| Explain in term of voltage-gated channels what goes on in depolarization.[image][image] |
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Definition
[image] Na+ channels open because activation gates open , Na+ diffuses in and the resulting voltage change causes further Na+ channels to open. K+ channels start to open. |
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Term
| Explain in term of voltage-gated channels what goes on in repolarization. |
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Definition
[image] Na+ channels close because inactivation gates close, so diffusion of Na+ in stops. K+ channels are now open and K+ diffuses out. |
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Term
| Explain in term of voltage-gated channels what goes on in the end of repolarization and afterpotential. |
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Definition
[image] Na+ channels are now in resting condition. The continued diffusion of K+ produces the afterpotential. The resting membrane potential is reestablished after the K+ channels close. |
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Term
| Why can't another action potential be generated during the absolute refractory period – no matter how strong the stimulus? |
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Definition
| Because all voltage-regulated sodium channels either are already open or are inactivated. |
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Term
| Why can only very strong stimuli initiate another action potential during the relative refractory period? |
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Definition
Many K+ channels are still open so the membrane is hyperpolarized and it will take a stronger signal to reach the threshold.
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Term
| How can you determine the difference in intensity between stimuli? |
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Definition
| Number of sensory neurons activated by the stimulus and the frequency of impulses. |
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Term
| What are the five classifications of stimulus strength? |
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Definition
- subthreshold
- threshold
- submaximal
- maximal
- supramaximal
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Term
| What determines the maximum frequency of action potentials? |
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Definition
| The duration of the absolute refractory period. |
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Term
| What are some methods of local anesthetics? |
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Definition
| By blocking the opening of voltage-gated Na+ channels so impulses are stopped from reaching the CNS; by localized cooling so impulses propogate at lower speeds. |
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Term
| How does positive feedback propagate an action potential? |
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Definition
| When Na+ ions flow in, they cause voltage-gated Na+ channels in adjacent segments of membrane to open. |
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Term
| Why can't an action potential normally go backwards? |
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Definition
| Because the absolute refractory period of a previous action potential site prevents generation of action potential in reverse direction. |
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Term
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Definition
| The action potential is conducted from one node of Ranvier to another by generating local currents that flow through the extracellular fluid surrounding the myelin sheath and through the cytosol toward the next node of Ranvier. |
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Term
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Definition
| Where the myelin sheath covers the axolemma. |
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