3.) Signals are passed from axon to axon when neurotransmitter molecules are released from the presynaptic axon and diffuses across a small distance, called the synaptic cleft, to reach the post synaptic axon. If the neurotransmitter released by the presynaptic axon is dopamine and the diffusion distance across the synaptic cleft is 20 nm then how long will it take to pass the signal? The viscosity of the interstitial fluid in the synapse is 0.012 Pa*s. (You must look up dopamine properties to solve)

Neurotransmitters, the chemicals used in signaling across synapses, can be either re-absorbed by the pre-synaptic neuron OR hydrolyzed after release by enzymes.  Acetylcholine (ACh), the neurotransmitter at neuromuscular junctions, is broken down by the enzyme acetylcholinesterase (AChE) and then its component parts are re-absorbed. Sarin gas is an extremely dangerous neurotoxin that has been utilized in terrorism and chemical warfare.  It is known as a "nerve gas" because it blocks AChE.  Based on your understanding of the neuromuscular junction and hydrolitic enzymes, hypothesize how sarin gas le ads to paralysis and nerve damage in the people to whom it is exposed.

What is the term used to describe the rounded lump located at the end of the axon? synapses receptor sites terminal button O synaptic vesicles

Which statement is true regarding the neuron synapse? B) binging of a neurotransmitter on the postsynaptic neuron membrane can generate an action potential in that neuron C) the binding of a neurotransmitter always causes an excitatory effect on that cell, never inhibitory D) the presynaptic and pastsynaptic neuron membranes are not physically separated

Which of the following is true about the conduction of action potentials?  a. Thicker axons are faster because there is more surface area on thicker axons. b. Myelin speeds conduction because the glial cells add voltage gated Na+ channels to the neuron. c. Diffusion of Na+ ions between the Nodes of Ranvier happens faster than the wave of opening and closing membrane proteins can travel. d. Neurons that don’t have myelin sheaths undergo saltatory conduction e. Action potentials move slowly.

Studies have shown that individuals with attention deficit hyperactivity disorder (ADHD) may have lower than normal amounts of dopamine and norepinephrine excitatory neurotransmitters in their synapses. Methylphenidate is one of the drugs prescribed to individuals with ADHD. It prevents the reuptake of dopamine and norepinephrine neurotransmitters from the synapses, thereby keeping these neurotransmitters in the synapses longer. Which of the following rows correctly identify the effects of methylphenidate in individuals with ADHD? Select one: a. There is an increase in the permeability of the presynaptic neuron to potassium ions. b. There is a increase in the permeability of the postsynaptic neuron to potassium ions. c. There is an increase in the permeability of the presynaptic neuron to sodium ions. d. There is a increase in the permeability of the postsynaptic neuron to sodium ions.

Which of the following rows correctly completes the following statement about synaptic transmission? The neurotransmitters contained in vesicles enter the synaptic cleft via __A______ to attach to receptor proteins in the postsynaptic membrane. Once the postsynaptic neuron has been stimulated, the neurotransmitters return via ____B_____.   a.  A  B  Exocytosis  Binding b.  A  B  Binding  Exocytosis c.  A  B  Endocytosis  Enzymatic breakdown d.  A  B  Exocytosis  Endocytosis

1) The olfactory receptor neurons in frogs resemble those of mammals, in that they express olfactory receptors that are coupled to a G protein. When the G protein is activated, it activates an adenylyl cyclase to produce cAMP, which then opens cyclic-AMP gated cation channels in the plasma membrane. The opening of these channels depolarizes the membrane, leading to the production of an action potential. Your friend is interested in why neurons stop responding to an odor after prolonged exposure to it, a process called adaptation. He has conducted experiments examining the depolarization of the olfactory receptor neuron, the binding of odorant to the receptor, the activation of the G protein, the levels of CAMP in the cell, and the phosphorylation of adenylyl cyclase. His results are summarized in Table 1. depolarization of neuron? odorant binding to receptor? activation of the G protein? CAMP levels in the cell? adenylyl cyclase phosphorylation? no odor no no no low no Table 1 brief…

Which of the following occurs during synaptic transmission? Select ALL that apply A) vesicles filled with neurotransmitter are released into the synapse B) an action potential travels through a neuron like a wave C) neurotransmitter binds to receptors on the sending neuron D) neurotransmitter binding to a receptor triggers the opening of an ion channel E) ions enter the receiving neuron's dendrites

11) Compare the propagation speeds of an action potential along an axon that is 10 µM in diameter and one that is 20 uM in diameter. You must have a quantitative answer. 12) How would the velocity of action potential propagation change if you quadrupled the membrane conductance? You must have a quantitative answer. 13) You discover a mutation in mice that causes them to suddenly lose their myelin sheaths. How would this mutation change the speed of action potential propagation and why? 9