BIO 242 EXAM 2 PRACTICE QUESTIONS CH 4

BIO 242 EXAM 2 PRACTICE QUESTIONS CH 4 The resting potential is typically - CORRECT ANSWER--70mV Membrane channels are formed by ______ that span the thickness of the membrane - CORRECT ANSWER-Proteins _____ carry signals toward the cell body, while ____ carry action potentials away from the cell body - CORRECT ANSWER-Dendrites; Axons The first portion of the axon plus the region of the cell body from which the axon leaves is known as the - CORRECT ANSWER-Axon hillock Contains nucleus and organelles - CORRECT ANSWER-Cell body Nerve fiber - CORRECT ANSWER-Axon Neuron's trigger zone - CORRECT ANSWER-Axon hillock Contains synaptic vesicles - CORRECT ANSWER-Axon terminal Receives signals - CORRECT ANSWER-Dendrites Constant membrane potential - CORRECT ANSWER-Resting membrane potential Membrane becomes more polarized - CORRECT ANSWER-Hyperpolarization The greater the magnitude is of a triggering event, such as a stimulus, the _______ the graded potential - CORRECT ANSWER-Greater The graded potential is a _____ event - CORRECT ANSWER-Local Any flow of electrical charges is called a - CORRECT ANSWER-Current Myelinated fibers conduct impulses about _____ times faster than non-myelinated fibers of comparable size - CORRECT ANSWER-50x The ______ threshold is present at the axon hillock because this region has an abundance of voltage-gated sodium channels - CORRECT ANSWER-Lowest The refractory period ensures ______ propagation of action potentials - CORRECT ANSWER-one-way A period when a recently activated patch of membrane is completely unresponsive is known as - CORRECT ANSWER-Refractory Period During an action potential, _____ moves into the cell and _____ moves out of the cell - CORRECT ANSWER-Sodium, potassium The myelin-forming cells are _____ in the central nervous system and ______ in the peripheral nervous system - CORRECT ANSWER-Oligodendrocytes, Schwann cells The process by which a signal jumps from node to node on an axon is called - CORRECT ANSWER-Saltatory conduction _______ is a pathophysiologic condition in which nerve fibers lose their myelin sheaths - CORRECT ANSWER-Multiple Sclerosis Synapses permit _______ transmission of signals between 2 neurons - CORRECT ANSWER-One-way Neurons are specialized for rapid ____________ signaling - CORRECT ANSWERElectrical and chemical ___________ prevents release of GABA from inhibitory presynaptic inputs resulting in uncontrolled muscle spasm - CORRECT ANSWER-Tetanus Toxin Neurotransmitters are released into the synaptic cleft by - CORRECT ANSWERExocytosis The space between the presynaptic and postsynaptic neurons is called the - CORRECT ANSWER-Synaptic Cleft The change in postsynaptic potential occurring at an excitatory synapse is called an - CORRECT ANSWER-EPSP If the release of a neurotransmitter is enhanced, the effect is called - CORRECT ANSWER-Presynaptic facilitation ________ refers to the branching of axon terminals so that a single cell synapses with many other cells - CORRECT ANSWER-Divergence _______ is the socially abused drug that blocks reuptake of the neurotransmitter dopamine at presynaptic terminals - CORRECT ANSWER-Cocaine A situation in which a neuron has many other neurons synapsing with it is called - CORRECT ANSWER-Convergence Some neurotransmitters function through intracellular ________ systems rather than by directly altering membrane permeability - CORRECT ANSWER-Second messenger Most _________ hormones bind receptors inside the cell - CORRECT ANSWERLipophilic _________ hormones are poorly soluble in lipids so they bind to receptors on the outer plasma membrane surface of their target cell - CORRECT ANSWER-Hydrophilic Steroids are classified as _______ hormones - CORRECT ANSWER-Lipophilic Nerve and muscle cells are - CORRECT ANSWER-Excitable Nerve and muscle cells produce ______ when excited - CORRECT ANSWER-Electrical signals Membrane potential becomes _________ negative during depolarization - CORRECT ANSWER-Less Membrane potential becomes _______ negative during hyperpolarization - CORRECT ANSWER-More Depolarization - CORRECT ANSWER--Decrease in potential -Membrane less negative Repolarization - CORRECT ANSWER-Return to resting potential after depolarization Hyperpolarization - CORRECT ANSWER--Increase in potential -Membrane more negative How are electrical signals produced? - CORRECT ANSWER-By changes in ion movement across the plasma membrane An event triggers a change in membrane potential which - CORRECT ANSWER-Alters the membrane permeability and consequently alters ion flow across the membrane Graded potentials - CORRECT ANSWER-Are local changes in membrane potential - Occur in varying grades or degrees of magnitude or strength - Spread by passive flow - Die out over short distances The stronger the triggering event, the ________ the resultant graded potential - CORRECT ANSWER-Larger Current - CORRECT ANSWER-Any flow of electrical charges