PSB2000 Brain and Behavior Exam 1 Study Guide PDF

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Complete study guide for A. Wilber exam 1...

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Brain and Behavior Exam 1 Study Guide Part A  Answer the following questions about synaptic transmission: o Depolarization of the axon terminal causes influx of what ion?  Threshold is where NA+ (sodium) voltage gated channels open, NA+ influx  Rising phase is continued NA+ influx  Falling phase is when NA+ voltage gated channels close, K+ (potassium) channels open, K+ influx  Undershoot is when K+ voltage gated channels close  Absolute refractory period is when NA+ voltage gated channels remain inactivated for some time o What are the two basic mechanisms for inactivating neurotransmitter in the synaptic cleft? –  Degradation: transmitter molecules can be rapidly broken down and thus inactivated by special enzymes (ex: AChE breaks down ACh very rapidly into products that are recycled  Reuptake: transmitter molecules are swiftly cleared from synaptic cleft by being absorbed back into the axon terminal that released them (ex: dopamine, norepinephrine, and serotonin are terminated mainly by reuptake). Transporters are located on the presynaptic terminal and bring the transmitter back inside. Once taken back in, transmitter molecules may be repackaged into newly formed synaptic vesicles to await rerelease  A axo-dendritic synapse is comprised of an axon of a “transmitting” neuron synapsing on the dendrite of a “receiving” neuron  List one catecholaminergic drug and its effects on synaptic transmission, being sure to indicate which catecholamines the drug affects – Cocaine; inhibits dopamine reuptake and causes dopamine builds up in the synaptic cleft and constantly binds  List one cholinergic drug and its effects on synaptic transmission – botulin toxin; it works as an antagonist and blocks the release of ACh into the synaptic cleft  List one seretonergic drug and its effects on synaptic transmission – MDMA (ecstasy); increases serotonin release and inhibits the reuptake  G protein linked receptor – the binding of neurotransmitter activates the G protein and the G protein is released from the receptor to open/close ion channel or trigger the production of a 2nd messenger which in turn opens/closes ion channel, alterns metabolic activity, or alters gene expression  Nicotonic receptor – an acetycholine ionotropic receptor that can be found at the neuromuscular junction of the automatic nervous system. It has NA+ voltage gated channels that are excitatory  Autoreceptor – a receptor for a synaptic transmitter that is located in the presynaptic membrane and tells the axon terminal how much transmitter has been released  Diagram answers o A is a voltage gated ion channel o B is a reuptake in progress

o G stores the neurotransmitters Study Guide Part B Chapter Two  What are dendrites? – an extension of the cell body that receives information from other neurons  Which type of stain is used to reveal the entire neuron with all its processes? – golgi stains fill the entire cell, including details such as dendritic spines  What is the most common sequence of information flow through a neuron? – o Input zone: dendrites receive information from other neurons o Integration zone: the neuron’s cell body integrates the information that has been received to determine whether or not to send a signal of it’s own o Conduction zone: the axon conducts the neuron’s output information, in the form of electrical impulses, away from the cell body o Output zone: axon terminals transmit the neuron’s signals across synapses to other cells  Gaps between segments of myelin are known as: node of ranvier; the gaps between successive segments of myelin sheath where the axon membrane is exposed  Which glial cell(s) interact with blood vessels?: o Astrocytes – weave around/between neurons and stretch to fine blood vessels to control local blood flow and increase the amount of blood reaching more-active brain regions o Microglial cells – tiny and mobile, work to contain and clean up sites of injury Chapter Three  What are the electrical and chemical forces acting on ions inside vs outside of a neuronal axon at rest? What does electrostatic pressure derive from? What is the sodium-potassium pump responsible for? o Resting potential lies between -50 and -80 mV o Diffusion is the force that causes molecules of a substance to spread from regions of high concentration to regions of low concentration. This process keeps K+ flowing until the particles are equally concentrated on each side of the neuron o Electrostatic pressure is when charged particles exert electrical force on one another. Like charges repel and opposite charges attract. Positively charged K+ is attracted to the negatively charged interior of the cell o Sodium potassium pumps pump three NA+ ions out of th cell for every two K+ ions pumped in. This leads to a buildup of K+ inside the cell and NA+ outside the cell. Cell membrane is selectively permeable to K+, so it can flow freely to the outside and move down their concentration gradient which causes the negative charge to build back up inside the cell. Electrostatic pressure then comes into action to pull K+ ions back inside. Eventually opposing forces exerted by the K+ concentration gradient and electrostatic pressure reach equilibrium potential, which is the electrical charge that exactly balances the concentration gradient.

In general, the action potential is initiated where? - generally triggered at the threshold Hyperpolarization makes a neuron, what? – enter the relative refractory phase, when only strong stimulation well beyond the threshold can trigger another action potential  The peak of the action potential is caused by – the opening of NA+ voltage gated channels. After peaking, it returns to resting potential because K+ voltage gated channels open and NA+ voltage gated channels close  During the relative refractory phase, what voltage gated channels are open? – K+  The conduction velocity of an action potential varies as a result of what? – the diameter of the axon. Larger axons allow the depolarization to spread faster through the interior. Myelin sheathing also speeds conduction.  The form of conduction that is characteristic of myelinated axons is called? – saltatory conduction. The action potential jumps from one node of ranvier to the next  A neuron can be pushed to threshold if many EPSPs arrive at the axon hillock in quick succession. This process is referred to as? – temporal summation. When EPSPs arrive quickly one after another to a cell with only one input, they sum and the postsynaptic cell reaches threshold  A neuron can be pushed to threshold if many EPSPs arrive at the axon hillock at the same time from different locations across the cell body. This process is referred to as – spatial summation. They sum and depolarize the cell to threshold  Action potentials are all-or-none phenomena. What does this mean? – either a cell fires at it’s full amplitude or it doesn’t fire at all. The size of action potentials are all the same, but stronger stimuli can produce more action potentials  A key causal event in the release of neurotransmitter molecules from vesicles into the synaptic cleft is the? – Ca2+ (calcium ions) enter the axon terminal and causes synaptic vesicles filled with neurotransmitters to fuse with the presynaptic membrane and rupture, which releases the transmitter molecules into the synaptic cleft  Whether a synapse is excitatory or inhibitory is determined by the? – o At excitatory synapses, the binding of Ach to one type of receptor opens channels for NA+ and K+ ions and depolarizes the receiving neuron o At inhibitory synapses, ACh may act on another type of receptor to open channels that allow C1- ions to enter, thereby hyperpolarizing membrane (making it more negative and less likely to create an action potential)  Spontaneous electrical rhythms that can be recorded from the surface of the scalp are called – electroencephalograms (EEGs) record gross activity of the brain via large electrodes placed on the scalp  One of the benefits of ERPs is they? – Event-related potentials (ERPs) are EEG responses to a single stimulus. They can be taken multiple times from the same stimulus and the background noise of the cortex can be averaged out to create a reliable estimate of brain activity Chapter 4  The active ingredient in tobacco products: nicotine produces the action of stimulant to increase heart rate, blood pressure, digestive action, and alertness. It acts as an agonist (mimics or potentiates the actions of a transmitter or other signaling molecules) to a large class of cholinergic receptors  

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The substance curare which is used by native South Americans for poisoning the tip of arrowheads does what and how to neuronal transmission? – inhibits acetylcholine from binding to the nicotinic receptor Cholinergic receptors use what as their synaptic transmitter? – Ach Which type of synaptic connection allows the presynaptic neuron to strongly facilitate or inhibit the activity of the postsynaptic neuron? – axo-axonic synapses form on axons, often near axon terminal, allowing the presynaptic neuron to strongly facilitate or inhibit the activity of the postsynaptic neuron After release, neurotransmitters are deactivated in the synapse by? – o Degradation; for example AChE inactivates ACh by breaking it down rapidly into products that are recycled to make more ACh in the axon terminal o Reuptake; transmitter molecules are cleared from the synaptic cleft by being absorbed back into the axon terminal that released them. Transporters located on the presynaptic axon terminal bring the transmitter back inside where they are repackaged into newly formed synaptic vesicles to await re-release Which of the following are the specific criterion for classifying a substance as a neurotransmitter? – must be synthesized and stored within neuron, released in response to AP and has measureable effect on postsynaptic cell, can duplicate its action experimentally, mechanism must exist for termination of effect What are the catecholamine neurotransmitters? – a subset of monoamines; dopamine, norepinephrine, epinephrine. Usually inhibitory and involved in arousal, attention, mood, and motor control What are the monoamine neurotransmitters? – Acetylecholine (ACh), Catecholamines (dopamine, norepinephrine, epinephrine), indolamines (serotonin, melatonin) What are the amino acid neurotransmitters? – glutamate (excitatory), GABA and glycine (inhibitory), and 6 others In the mammalian brain, the major inhibitory neurotransmitter – Gamma-aminobutyric acid (GABA) The NMDA receptor is a type of receptor for the neurotransmitter – Glutamate Drugs that mimic GABAa receptors might be effective in treating what? – anxiety relief. GABAa receptors are ionotropic and when activated they allow more c1- ions to flow into the postsynaptic cell, thus inhibiting that cell’s activity. These drugs produce a widespread decrease in neural activity (valium and Ativan) If a newly-developed drug is found to bind to dopamine receptors but does not activate them, the drug is classified as a what? – antagonist; a substance that blocks or attenuates the actions of a transmitter or other signaling molecule Muscarinic receptors are? – metabotropic acetylcholine receptors found predominantly in the brain; can be excitatory or inhibitory A patient in the hospital requires anti-nausea medication. Which would provide the most rapid route of administration? – Central injection would be the fastest option, followed by peripheral injection, followed by inhalation, followed by ingestion being the slowest option

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Downregulation of a neuron’s receptors might be caused by? – repeated doses of an agonist drug can decrease the number of available receptors for the drug to bind (downregulation), therefore becoming less sensitive and countering the drug effect The venom of the black widow spider increases the release of what? – ACh How do selective serotonin reuptake inhibitors (SSRIs) work? – they are antidepressant drugs that block the reuptake of transmitter at specifically serotonergic synapses (ex: Prozac and Celexa) Benzodiazepines, such as diazepam, or other anxiolytics, appear to modulate the activity of receptors for what neurotransmitter? – they bind to specific sites on GABAa receptors and enhance the activity of GABA. Because GABAa receptors are inhibitory, benzodiazepines help GABA produce larger inhibitory postsynaptic potentials than GABA would produce alone Alcohol’s calming influence may be attributed to its ability to do what? – similar to anxiety reducing benzodiazepines, it acts via the GABA receptors to reduce postsynaptic excitations, causing social disinhibition, poor motor control, and sensory disturbances. It also actives dopamine-mediated reward systems of the brain The hallucinogenic effects of LSD are mainly attributed to its stimulation of what receptors? – Seretonin 5-HT2a receptors that are found in especially heavy concentrations in the visual cortex...