Chapter 5 Flashcards

Question

Excitatory Synapse characteristics

Answer 1

Located on dendrites Round vesicles Dense material on membranes Wide cleft Large active zone

Answer 2

Located on cell body Flat vesicles Sparse material on membranes Narrow cleft Small active zone

Answer 3

Location of excitatory synapse: dendritic tree closer to cell body Excitation coming in over dendrites and spreading past axon hillock to trigger action potential at initial segment

Answer 4

Location of inhibitory synapse: Close to initial segment Best stopped by inhibiting cell body close to initial segment → inhibition blocks or cuts excitation from passing through postsynaptic cell

Answer 5

1.) transmitter must be synthesized or present in the Neuron 2.) when active, chemical must be released and produce a response in some target 3.) same response must be obtained if done experimentally 4.) mechanism must exist for removing transmitter

Answer 6

Carry message from one Neuron to another by influencing voltage on postsynaptic membrane Change structure of a synapse Communicate by sending messages in the opposite direction

Answer 7

Small-molecule transmitters Peptide transmitters Lipid transmitters Gaseous transmitters

Answer 8

Class of quick-acting NT Synthesized inside of cell from dietary nutrients and packaged in Axon terminals Can be quickly replaced at presynaptic terminal Some drugs designed to emulate the route of small molecule transmitters

Answer 9

Acetylcholine (ACh)→ present at junction of neurons and muscles and the CNS Amines (common biochemical pathway/relatedness) → dopamine (DA), norepinephrine (NE), epinephrine (EP), serotonin (5-HT) Amino acids → glutamate: main excitatory transmitter, and GABA: Mann inhibitory transmitter (2 most abundant NT in brain) Purines→ synthesized as nucleotides: regulate blood flow, sleep, arousal, etc.

Answer 10

Neuropeptides → short, multifunctional amino acid chain that acts as a NT and can act as a hormone Synthesized through translation of mRNA from instructions in neurons DNA Most assembled in ribosomes, packaged in membrane by Golgi bodies, and transported by microtubules to axon terminals Act slowly and not replaced quickly Wide range of functions: ↳ act as hormones that respond to stress (cortisol) ↳ enable mother to bond with infant (oxytocin) ↳ regulate eating/drinking and pleasure/pain Have NO direct effects on postsynaptic membrane voltage → activate receptors that indirectly influence cell

Answer 11

Opioids → Met-enkephalin, beta-endorphin, dynorphin Neurohypohyseals → vasopressin, oxytocin Secretins → secretin, motility, glucagon, growth hormone-releasing factor Insulins → insulin, insulin growth factors Gastrins → Gastrin, cholecystokinin

Answer 12

Can't be stored in resides → created on demand at level of cell membrane Affect appetite, pain, sleep, mood, memory, anxiety, stress response

Answer 13

Synthesized at postsynaptic membrane to act on receptors at the presynaptic membrane → postsynaptic Neuron reduces amount of incoming neural signal: Reduces amount of small-molecule transmitter being released Hypothesized: synthesized on demand after a Neuron has depolarized and calcium has entered CB1 receptor is target of all cannabinoids Found at both glutamate and GABA synapses ↳ act as neuromodulators to inhibit release of glutamate and GABA ↳ thus dampen neuronal excitation and inhibition

Answer 14

Gaseous → synthesized in cell as needed: not stored in synaptic vesicles; easily can cross cell membrane ↳ chemical messengers in body→ modulate NT production Ion transmitters → zinc as transmitter: actively transported,packaged into vesicles (usually with another transmitter ie. Glutamate) and released into cleft

Answer 15

Embedded membrane protein with two parts: - binding site for a NT and a PORE that regulates ion flow to directly and rapidly change membrane voltage Allows movement of ions such as Na+, K+, and Ca2+ across a membrane When neurotransmitter attaches to binding site, the pore opens or closes, changing flow of ions

Answer 16

Embedded membrane protein with a binding site for a NT but NO PORE Indirectly produces changes in nearby ion channels or in the cells metabolic activity Linked to a G protein that can affect other receptors or act with second messengers to affect other cellular processes

Answer 17

A single NT binding to a metabotropic receptor can activate an escalating sequence of events Protiens can be activated or deactivated

Answer 18

Transmitter binds to receptor Activates gene protein then ion channel is indirectly activated The cx subunit of the G protein binds to a channel causing a structural change in the channel that allows ions to pass through it

Answer 19

Transmitter binds to receptor Binding of transmitter triggers the activation of a G protein in both reactions The cx subunit binds to an enzyme which activates a second messenger The second messenger can activate other cell processes

Answer 20

Neurotransmitter → ionotropic → metabotropic Acetylcholine → nicotinic→ 5 muscarinic Dopamine → none → 5 dopamine GABA → GABAa → GABAb Serotonin → 5-HT3 → 12 5-HT

Answer 21

A single Neuron may use one transmitter at one synapse and a different transmitter at another Different transmitters may coexist in the some terminal or synapse or even vesicle Caution against cause-and-effect assumptions regarding relationship between NT and behavior

Answer 22

Cholinergic Neuron (motor neurons) → use acetylcholine as its main neurotransmitter: excites skeletal muscles to cause contractions Nicotinic ACh receptor (nAChr)→ opens exclusively to ACh and depolarizes muscle fiber: when ACh or nicotine binds to this receptor, its pore opens to permit ion flow, depolarizing muscle fiber The nicotinic receptor pore permits the simultaneous efflux of K+ and influx of Na+

Answer 23

Sympathetic division: arouses body for action, producing fight-or-flight response Controlled by acetylcholine neurons that emanate from CNS (spinal cord) → CNS neurons synapse with sympathetic neurons that contain norepinephrine Cholinergic neurons in CNS synapse with NE neurons to produce fight or flight During sympathetic arousal norepinephrine turns up heart rate and turns down digestive functions ↳NE receptors on heart = excitatory ↳NE on gut = inhibitory

Answer 24

Controlled by acetylcholine neutrons that emanate from 2 levels of spinal cord Cholinergic neurons in CNS synapse with autonomic ACh neurons in parasympathetic division to prep body for rest-and-digest Acetylcholine turns down heart rate and turns up digestive functions because receptors on these organs are reversed: On heart = inhibitory On gut = excitatory

Answer 25

Can act without input from CNS Uses all four classes of NT → more than 30: mainly serotonin and dopamine Sensory ENS neurons detect mechanical and chemical conditions in the gastrointestinal system Neurons attached to gut lining

Answer 26

Cholinergic, dopaminergic, noradrenergic, and serotonergic→ one system for each small-molecule transmitter Activating system: neural pathways that coordinate brain activity through a single NT ↳ cell bodies lie in a nucleus in the brainstem, and their axons are distributed throughout brain

Answer 27

Normal waking behavior → thought to function in attention and memory Loss of cholinergic neurons associated with Alzheimer disease

Answer 28

Involved with movement and motor behavior Nigrostriatal pathways: active in maintaining normal motor behavior (coordination) → loss of DA is related to muscle rigidity and dyskinesia in Parkinson disease Mesolimbic pathways: dopamine release causes repetition of behaviors → most affected in addiction behaviors: related to impulse control Increases in DA may be related to schizophrenia Decreases in DA activity may be related to deficits of attention

Answer 29

Norepinephrine plays a role in learning by stimulating neurons to change structure Also may facilitate normal development of the brain and organize movements Imbalances associated with depression and mania Decreased NE activity related to ADHD and hyperactivity

Answer 30

Plays a role in wakefulness and learning → maintaining waking EEG pattern Imbalances associated with depression, schizophrenia, obsessive-compulsive disorder, sleep apnea, sudden infant death syndrome

Answer 31

The nervous systems potential for change, which enhances its ability to adapt Required for learning and memory → reconfigure synapses and tissues to maximize learning Cells that fire together wire together

Answer 32

Axon of cell A near enough to excite cell B and repeatedly takes part in firing it, some metabolic change or growth process takes place in one or both cells → A's efficiency as one of the cells firing B is increased 2 neurons proximal to each other → I cell fires enough → firing rate influences other cell → strengthen neural connections Cells that fire together wire together

Answer 33

Awarded 2000 Nobel prize for basis of learning experiment using Aplysia (snails) Used enduring changes in simple defensive behaviors to study underlying changes in nervous system Habituation: learning behavior in which a response to a stimulus weakens with repeated presentations of the stimulus → Gill withdrawal response to being sprayed with water: lessened

Answer 34

Habituation develops → excitatory postsynaptic potentials in motor neuron become smaller: motor neuron is receiving less NT from sensory neuron across synapse (limit action potentials) Habituation must take place in axon terminal of sensory neuron Less activity from a habituated Neuron relative to nonhabituated one → Ca2+ influx decreases in response to voltage changes Less Ca2+ influx results in less NT being released → opposite of sensitization Reduced sensitivity of Ca2+ channels and decreased release of NT

Answer 35

Learning behavior where response to stimulus strengthens with repeated presentations BECAUSE stimulus is novel or stronger than normal Present Stimulus once, wait a while, show more powerful stimulus

Answer 36

Response to action potential on axon of sensory Neuron → K+ channels are SLOW to open K+ ions cannot repolarize membrane quickly → AP last longer than normal: prolongs inflow of Ca2+ and more transmitter is released More Ca2+ influx results in more transmitter being released → opposite of habituation at molecular and behavioral levels

Answer 37

Neural changes associated with learning MUST LAST LONG ENOUGH to account for a relatively permanent change in an organism's behavior Repeated stimulation produces habituation and sensitization → can persist for MONTHS Number and size of sensory synapses CHANGE ↳ habituated: less connections due to overstimulation ↳ sensitized: builds more connections Transcription and translation of nuclear DNA initiates structural changes → formation of new synapses and spines Second-messenger cAMP molecule plays important role in carrying instructions regarding structural changes to nuclear DNA