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66 Cards in this Set
- Front
- Back
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What is the process of saltatory conduction?
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propagation of action potentials along a myelinated axon such that the action potentials jump from one node of Ranvier in the myeline sheath to the next
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Why is the propagation of the action potential from the dendritic to the axon terminal end typically one way?
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the absolute refractory period follows along in the wake of the moving action potential
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What phase is caused by the rapid opening of the Na+ channels?
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rapid-depolarization phase at the beginning of the action potential
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What phase is caused by the slower opening of the K+ channels?
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the repolarization and after hyperpolarization phases that complete the action potential
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What is a synapse? What are the 2 types?
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anatomically specialized junction between two neurons where electrical activity in one neuron influences excitability of second
Electrical & Chemical synapses |
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What is the excitatory postsynaptic potential?
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depolarizing graded potential in postsynaptic neuron in response to activation of excitatory synapse
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What is the inhibatory postsynaptic potential?
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hyperpolarizing graded potential that arises in postsynaptic neuron in response to activation of inhibitory synaptic endings upon it
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What is summation?
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increase in muscle tension or shortening in response to rapid, repetitive stimulation relative to single twitch
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What are the 5 major types of neurotransmitters?
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1. acetylcholine
2. biogenic amines 3. amino acids 4. gases like NO and CO 5. ATP and adenosine |
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What are the conditions needed to fire an action potential when a nerve cell receives both excitatory and inhibitory inputs from presynaptic neurons?
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the sum of the EPSP's and IPSP's must reach threshold
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What happens when calcium channels are opened during depolarization?
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calcium flows into axon terminal because the electrochemical gradient favors calcium influx, it binds to a protein and triggers a conformational change in the SNARE complex that leads to membrane fusion and neurotransmitter release
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What are the two gluatamate receptors involved in the process of long term potentiation? What channels are they located in?
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AMPA receptors in Na+ channels and NMDA receptors in Ca2+ channels
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What are the two types of Acetylcholine receptors?
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nicotinic and muscarinic
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What are the three types of biogenic amines?
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Catecholamines, serotonin, and histamine
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What are the three types of catecholamines?
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dopamine, norepinephrine, epinephrine
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What happens when adenylyl cyclase becomes activated?
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catalyzes the conversion of ATP to cAMP which activates a protein kinase which phosphorylates other proteins and brings about the cell's response
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Define saturation regarding receptors
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the degree to which receptors are occupied by messengers. If all are occupied the receptors are fully saturated.
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Define competition regarding receptors
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ability of different molecules very similar in structure to compete with each other to combine with the same receptor
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Define agonist regarding receptors?
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chemical messenger that binds to a receptor and triggers the cell's response; often refers to a drug that mimics a normal messenger's action
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Define antagonist regarding receptors
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molecule that competes for a receptor with a chemical messenger normally present in the body, it binds to the receptor but doesnt trigger a respone (example antihistamine)
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What is down-regulation and what causes it?
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when a high extracellular concentration of a messenger is maintained for some time , the total number of the target cell's receptors may decrease
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What is up-regulation and what causes it?
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cells exposed for a prolonged period to very low concentrations may have more receptors for that messenger
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What happens when phospholipase becomes activated?
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increases IP3 and DAG which work together to activate enzymes and to increase cellular calcium levels
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What are ionotropic receptors?
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plasma membrane receptors that function as ion channels
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What do tyrosine kinase receptors do?
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initiate a cascade of events in the cell that affect cell proliferation and/or differentiation
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What can the activation of metabotropic (G proteins or tyrosine kinases) receptors lead to?
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enormous signal amplification
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Many hormones are lipid soluble, where are their receptors located?
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in the cell nucleus
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What do hormone/receptor complexes act as?
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transcription factors to alter gene transcription
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What is the anatomical difference between the central and peripheral nervous system?
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The central nervous system is the brain and spinal cord, the peripheral nervous system is everything else
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List the spinal nerves in order starting at the top and the number of nerves in each category
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Cervical 8; Thoracic 12; Lumbar 5; Sacral 5; Coccygeal 1
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What are the 3 defining characteristics of the somatic nervous system that separate it from the autonomic?
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1. consists of a single neuron between cns and skeletal muscle cells
2. innervates skeletal muscle 3. can lead only to muscle excitation |
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What are the 3 defining characteristics of the autonomic nervous system that separate it from the somatic?
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1. has two neurons connected by a synapse between cns and effector organ
2. innervates smooth and cardiac muscle, glands, and GI neurons 3. can be either excitatory or inhibitory |
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What is a ganglion?
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cluster of neuron cell bodies outside CNS
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What is an axon?
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extension from neuron cell body, propagates action potentials away from cell body; aka nerve fiber
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What is a tract?
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large, myelinated nerve fiber bundle in CNS
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What does afferent mean?
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conveys information from sensory receptors to the CNS
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What does efferent mean?
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conveys commands from the CNS to target tissues
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What is a nucleus?
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large membrane-bound organelle that contains cell's DNA; (neural) cluster of neuron cell bodies in CNS
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What types of cells are in the peripheral nervous system?
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sensory nervous cells and motor nervous cells
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What types of cells are in the central nervous system?
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glial cells and neurons
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What are the 3 types of muscle?
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skeletal, cardiac, smooth
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Which two muscle types are striated?
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skeletal & cardiac
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Which two muscle types have a single nucleus?
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cardiac & smooth
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What causes malignant hyperthermia?
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hyperactivity of the muscles after exposure to volatile anesthetics due to disregulation of calcium release from the sarcoplasmic reticulum
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What causes hypocalmic tetany?
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low extracellular calcium concentration leads to hyperexcitability of Na channels in the plasma membrane
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What causes muscular dystrophy?
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x-linked disorder
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What causes myasthenia gravis?
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autoimmune disorder that results in the loss of Ach receptors
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What causes multiple sclerosis?
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due to a loss of the myelin coating on neurons
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What are 2 different theories for the cause of Amyotropic Lateral Sclerosis?
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1. cell death caused by toxic levels of glutamate
2. cell death caused by oxidation injury |
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What is polymyositis?
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systemic connective tissue disease characterized by inflammation and degeneration of the muscles
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What is a motor unit?
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a motor neuron and the collection of muscle it innervates
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What is a motor neurons?
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somatic efferent neuron, which innervates skeletal muscle
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What is the first step in the cross-bridge cycle?
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energized myosin cross-bridge binds to a thin filament actin molecule,
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What is the 2nd step in the cross-bridge cycle?
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cross bridge moves and Pi and ADP are released causing myosin to produce force
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What is the 3rd step in the cross-bridge cycle?
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ATP binds to myosin causing cross-bridge to detach
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What is the 4th step in the cross-bridge cycle?
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hydrolysis of ATP energizes the cross-bridge
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How does the sliding-filament mechanism work?
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overlapping thick and thin filaments in each sarcomere move past eachother propelled by movements of the cross-bridges
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What are the 3 ways a muscle fiber can form ATP?
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1. phosphorylation of ADP by creatine phosphate
2. oxidative phosphorylation of ADP in mitochondria 3. glycolysis (phosphorylation of ADP by the glycolylic pathway in) the cytosol |
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What are three reasons that muscles may become fatigued?
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1. conduction failure
2. lactic acid buildup 3. inhibition of cross-bridge cycling |
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What muscles are best suited for extended low-intensity exercise?
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slow-twitch oxidative (red)
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What muscles are best suited for short high-intensity exercise such as weight lifting?
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glycolytic (white)
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Where is a t-tubule and what does it do?
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extends from striated-muscle plasma membrane into the fiber, passing between opposed sarcoplasmic reticulum segments; conducts muscle action potential into muscle fiber
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What major pathway do slow fibers use to form ATP?
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oxidative phosphorylation
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What major pathway do fast fibers use to form ATP?
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fast-oxidative-glycolytic fibers have high oxidative capacity and intermediate glycolytic activity
fast-glycolytic-fibers use high glycolytic capacity |
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What are the 4 steps leading from increased cystolic calcium to cross-bridge cycling in smooth muscle?
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1. calcium binds to calmoudulin in cytosol
2. this complex binds to myosin light-chain kinase 3. myosin light-chain kinase uses ATP to phosphorylate myosin cross bridges 4. phosphorylated cross-bridges bind to actin filaments |
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What are the 3 steps leading from increased cystolic calcium to cross-bridge cycling in skeletal muscle?
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1.calcium binds to troponin on thin filaments
2.conformational change in troponin moves tropomyosin out of blocking position 3.myosin cross-bridges bind to actin |
