Synapse Study Guide - LS15 Peer Learning

LS15 Peer Learning | Week 9 Session 1 [email protected] The Synapse What is the synapse? A space between the acon terminal and the dendrites. In the action potential the sign...

LS15 Peer Learning | Week 9 Session 1 [email protected] The Synapse What is the synapse? A space between the acon terminal and the dendrites. In the action potential the signal is (electrical/chemical), when it gets to the synapse it becomes (electrical/chemical). Typical synaptic functioning: 1. Action Potiental arrives at theTerminal to send message 2. Calcium channels open and calcium rushes in 3. Vessicle fuse with the membrane 4. Neurotransmitter dumped into Synapse - - Neurotransmitter is chemical signals that travel across the synaptic cleft - - Can be excitatory or inhibitory (hyperpolarize instead of depolarize) - - Examples: acetylcholine (btwn neurons, muscles), GABA, dopamine, glutamate, endorphins, etc. Excitatory (make cell more positive for action potential): Neurotransmitters that increase the likelihood of the postsynaptic neuron generating an action potential. - Open ion channels that allow positive ions to flow into the neuron. (deplarization) Inhibitory (make cell more negative for repolarizaion to resting potential): Decrease the likelihood of the postsynaptic neuron generating an action potential. - Cause opening of ion channels that allow negative ions to flow into positive ions. (repolarization) 5. NT binds with Postsynaptic receptors, causes: - Muscle contraction or - Action potential - Receptors are ligand-gated and open up when chemical attaches to allow Na+ to enter post-synaptic cell (or Chloride) 6. Re-uptake/enzymatic breakdown of NT - Re-uptake through NT transporter so it can be re-used - Destroyed by enzymes (such as Acetylcholinesterase) What are pleasure centers in the brain? What is their purpose? Our brains are built with pleasure centers. Doing something pleasurable will stimulate these centers, so we LS15 Peer Learning | Week 9 Session 1 [email protected] have evolved to repeat those actions that have proven to be pleasurable in the past. (Idea behind addiction) Usually works when neurons respond to our behavior by releasing dopamine in synapse (causes happiness) 2 neurotransmitters that are commonly found in pleasure centers? What drugs are associated with them? Dopamine = neurotransmitter that influences behavior, mood, attention, memory ○ What happens when we have too little? associated w/lack of motivation, depression / feel worse ○ More dopamine? Feel better/happy ○ What do you think many of the substances people are addicted to (sugar, smoking) do to dopamine levels? Increase // Many substances/activities people are addicted to increase dopamine ○ Associated drug: Cocaine (due to bad luck, has the same shape to fit in the receptors) Binds to re-uptake receptors (dopamine reuptake transporters) and blocks them Dopamine remains in synapse and continues to attach to receptors and send feel-good signals Serotonin = maintaining mood balance, also helps bodily functions, such as sleep and digestion Low levels of serotonin linked to depression Selective serotonin reuptake inhibitors (SSRIs) ○ decrease reuptake of serotonin by blocking serotonin re-uptake transporter protein ○ more amounts in synaptic cleft causes elevate mood ___Caffeine____ is a drug that makes us less tired and more alert. Why do we get tired in the first place? Adenosine: type of cellular waste product/byproduct produced when cells use energy (from ATP-primary source of fuel/energy - produced in mitochondria). Adenosine binds to We get rid of adenosine ___adenosine receptors___. ○ signals to our body that we are tired. ○ Binding causes drowsiness by slowing down nerve cell activity ○ When adenosine receptors are filled, the ion channels open and the cell becomes less likely to fire. ○ Reduces likelihood of action potentials by __sleeping___. ○ cellular waste products such as adenosine are reabsorbed and recycled ○ feel “refreshed” in the morning. How does caffeine prevent us from getting tired? Caffeine can bind to ___adenosine___ receptors, but it does not slow down the cell’s activity ○ Remember: binding of adenosine to adenosine receptors signals to our body that we are tired ○ So if adenosine isn’t able to bind to receptors our body can’t sense if we’re tired or not ○ Caffeine = compound that binds to adenosine receptors better than adenosine itself It blocks the receptors from binding to adenosine Therefore, your neurons do not feel tired - LS15 Peer Learning | Week 9 Session 1 [email protected] 1. Neurotransmitters in a synaptic cleft have all of the following possible fates except: a. reuptake by the presynaptic neuron. b. enzymatic breakdown in the synaptic cleft. c. inactivation by acetylcholine in the synaptic cleft. (have not taled about inactivation) d. binding to a receptor in the postsynaptic cell membrane. e. All of the above are possible fates of neurotransmitters in a synaptic cleft.