psych 115 midterm 1 UCLA Exam Questions and Answers 100% Pass

psych 115 midterm 1 UCLA Exam Questions and Answers 100% Pass What is the role of Dorsal root ganglion cells? - Answer- • DRG = unipolar neurons in peripheral nervous system • Job is to relay somatosensory info from skin to spinal cord Describe a touch stimulus. - Answer- • Touch to skin generates a receptor potential by opening mechanoreceptor Na channels • Receptor potential passively propagates (flows) to the integration zone • Receptor potential is attenuated (becomes smaller) as it propagates due to cytoplasm being a resistive electrical conductive • If the receptor potential depolarizes the axon hillock's membrane from its resting potential of -75mV up to spike threshold ( ~ -55mV)then action potential occurs • Na+ voltage-gated channels will allow sodium to enter and depolarize membrane (this happens again, called positive feedback cycle) What are the three states of an active Na+ channel? - Answer- • Closed - Na+ ions cannot pass through pore • Open - Na+ ions can pass freely through pore • Inactive - Na+ cannot pass through pore and channel cannot be opened, even if membrane is depolarized above spike threshold What are three types of action potential conduction? - Answer- • Passive - axon without active channel propogates the spike very fast, but not far • Active - unmyelinated axon with active channels propogates very far, but not fast • Saltatory - myelinated axon with active nodes propogates the spike very fast and very far How are neurons classified? List the three principal types. - Answer- • "how many things" sticking out of a soma/ how many branches • Multipolar • Bipolar • Unipolar What are the differences between white and gray matter? - Answer- Cortical regions that contain lots of myelin are called white matter. Cortical regions that contain little myelin are called gray matter. What is myelin sheath made from? - Answer- glial cells. Schwann cells in PNS Oligodendrocytes in CNS When does an AP propagation stop? - Answer- The action potential propagates until it reaches the DRG neuron's axon terminals in the spinal cord... What happens when the presynaptic cell fires a spike? - Answer- vesicles fuse with the cell membrane to release their contents into the synaptic cleft (thin space between the presynaptic cell and postsynaptic cell). What is the the neurotransmitter release cycle? - Answer- 1) Neurotransmitter molecules are manufactured by the neuron 2) The neurotransmitter molecules are pumped into the vesicles through vesicular transporters 3) The filled vesicle moves toward the cell membrane and waits for an action potential to come along 4) When the action potential occurs, calcium enters synaptic bouton and causes the vesicle to fuse with the cell membrane and dump its contents into the synapse 5) A "clathrin coat" forms on the inner surface of the membrane and pinches a new empty vesicle from the cell membrane 6) The new vesicle sheds its coat and starts filling up with transmitter to start the cycle over again What are Ionotropic Receptors? - Answer- Ionotropic receptors are ligand-ga