Assume presynaptic excitatory neuron A terminates on a postsynaptic cell near the axon hillock and presynaptic excitatory neuron B terminates on the same postsynaptic cell on a dendrite located on the side of the cell body opposite the axon hillock. Explain why rapid firing of presynaptic neuron A could bring the postsynaptic neuron to threshold through temporal summation, thus initiating an action potential, whereas firing of presynaptic neuron B at the same frequency and the same magnitude of EPSPs may not bring the postsynaptic neuron to threshold.
Trending nowThis is a popular solution!
Chapter 4 Solutions
Human Physiology: From Cells to Systems (MindTap Course List)
Additional Science Textbook Solutions
Human Physiology: An Integrated Approach (7th Edition)
Genetic Analysis: An Integrated Approach (3rd Edition)
Microbiology with Diseases by Body System (4th Edition)
Microbiology: An Introduction
Campbell Biology in Focus
Campbell Biology: Concepts & Connections (9th Edition)
- A neuron responds to adequate stimulation with _______, a type of self-propagating signal.arrow_forwardAssume a neuron is at rest and the following changes happen: Step 1: Neurotransmitter binds to an ionotropic excitatory neurotransmitter receptor causing an EPSP. Step 2: With the neurotransmitter still bound either a NAM or non-competitive antagonist bind to the allosteric site of the receptor. Answer the following questions that explains how the NAM and non-competitive antagonist would differ in their actions. 4.) A. Going from step 1 to step 2 what would happen to the ionotropic receptor (ion channel) as a result of the NAM. B. Going from step 1 to step 2 what would happen to the ionotropic receptor (ion channel) as a result of the non-competitive antagonist. C. Going from step 1 to step 2 how would membrane potential change as a result of the NAM D. Going from step 1 to step 2 how would the membrane potential change as a result of the non-competitive antagonist.arrow_forwardIf a postsynaptic cell has synapses from five different cells, and three cause EPSPs and two of them cause IPSPs, give an example of a series of depolarizations and hyperpolarizations that would result in the neuron reaching threshold.arrow_forward
- You generate action potentials in a neuron bathed in solution in a petri dish by applying a threshold-level depolarizing stimulus near its axon hillock. If the solution surrounding the neuron contained 5mM K+, 150 mM Na+, and 0 mM Ca2+ which of the following would you expect? The neuron would not be able to propagate action potentials down the entire length of the axon The neuron would not release neurotransmitter from the axon terminal The neurons action potentials would have an unusually long duration The neuron would have a resting membrane potential of zeroarrow_forwardwhich one of the following statements is incorrect? a. temporal summation occurs when a single synaptic input is activated twice in succession, with the second postsynaptic potential occurring before the first postsynaptic potential is over. b. blocking voltage-gated k* channels in the presynaptic membrane of a typical chemical synapse is likely to reduce the amount of neurotransmitter released in response to a single action potential in the presynaptic axon. c. in the optic tectum of the hunting rattlesnake, spatial summation is used to combine inputs from visual and thermoreceptive layers in order to make a decision whether to strike at a mouse-like object. d. a single type of neurotransmitter can have different postsynaptic actions depending on the type of receptor to which it binds.arrow_forwardAn undisclosed drug (Drug A) is a drug that can block voltage-gated K+ channels when being introduced into the bloodstream. Explain the effects of Drug A on the action potentials produced by a neuron. If Drug A could be applied selectively to a presynaptic neuron that releases an excitatory neurotransmitter, analyse how would it alter the synaptic effect of the neurotransmitter on the presynaptic cell. Remark: The word count limit (250 words only), no less than 100 wordsarrow_forward
- Help mearrow_forwardDepression is a condition in which sufferers may feel low mood, lack of motivation and sleep. It is caused by a lack of serotonin in the synaptic cleft of neurone pathways. Serotonin is a neurotransmitter. a) Describe how serotonin acts as a neurotransmitter. Using your understanding of synaptic transmission, explain how communication between neurones in serotonin pathways of the brain would be affected in someone with depression. b) Doctors use tubocurarine drug as an anaesthetic as it temporarily paralyses muscles. It blocks receptors at neuromuscular junctions. Why does this lead to paralysis?arrow_forwardImmediately after the repolarization phase of an action potential, the neuronal membrane is temporarily unable to respond to the stimulation of a second action potential, a phenomenon referred to as the refractory period. What is the mechanistic basis for the refractory period?arrow_forward
- When an impulse arrives at the synapse, the synaptic vesicles open and release neurotransmitters into the cleft within a thousandth of a second. Within another ten thousandth of a second, these molecules have diffused across the cleft and bound to receptor sites in the effector cell. In what two ways is transmission across a synapse terminated so that the neuron’s signal is concluded?arrow_forwardA postsynaptic neuron has three presynaptic inputs from neurons X, Y, and Z. When X and Y are stimulated simultaneously and repeatedly, the postsynaptic neuron reaches threshold and undergoes an action potential. When X and Z are stimulated simultaneously, however, there is no change in the membrane potential of the postsynaptic neuron. Which of the following is correct? Select one: A. The simultaneous stimulation of X and Z is an example of temporal summation. O B. The simultaneous stimulation of X and Y is an example of temporal summation. O C. The repeated rapid stimulation of X is an example of spatial summation. O D. The stimulation of Y causes an IPSP in the postsynaptic neuron. O E. The stimulation of Z causes a hyperpolarization in the postsynaptic neuron.arrow_forwardWhat effect would you expect an antagonist that targets the voltage sensing domain of perisynaptic calcium channels of an inhibitory interneuron have on the firing frequency of a finically active neuron that interneuron synapses onto? Explain in detailsarrow_forward
- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage LearningHuman Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage Learning