Campbell Biology
12th Edition
ISBN: 9780135188743
Author: Urry
Publisher: PEARSON
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Chapter 48, Problem 10TYU
EVOLUTION CONNECTION An action potential is an all-or-none event. This on/off signaling is an evolutionary adaptation of animals that must sense and act in a complex environment. It is possible to imagine a nervous system in which the action potentials are graded, with the amplitude depending on the size of the stimulus. Describe what evolutionary advantage on/off signaling might have over a graded (continuously variable) kind of signaling.
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EVOLUTION CONNECTION An action potential is an all-ornone event. This on/off signaling is an evolutionary adaptationof animals that must sense and act in a complex environment.It is possible to imagine a nervous system in which the actionpotentials are graded, with the amplitude depending on thesize of the stimulus. Describe what evolutionary advantage on/off signaling might have over a graded (continuously variable)kind of signaling.
You recently read about Justin Bieber's unfortunate run-ins with glass doors and walls. Since then, you learned about how neurons are the unique cell of the nervous system and that signals are sent via action potential along those cells. You have further learned about how signals "jump" from one neuron to the next, allowing for your nervous system to function every single day.
Explain, using language from your learning of signal transduction and the nervous system, just what Justin Bieber's neurons should have been doing to prevent his unfortunate accidents. In other words, describe how are signals received, sent, and passed along in the nervous system (a system primarily responsible for preventing people from walking into doors and walls). You may enhance your answer by comparing the effects of drug use with the inability to avoid these accidents.
*Hint: half of your response should be about neuron anatomy and action potential and the other half should be about signaling across…
In most neurons, membrane depolarization leads to the opening of voltage-dependent ion channels, generation of an action potential, and, ultimately, an influx of Ca2+, which causes release of neurotransmitter at the axon terminus. Devise a cellular strategy by which hyperpolarization in rod cells could produce excitation of the visual pathway and passage of visual signals to the brain. (Hint: The neuronal signaling pathway in higher organisms consists of a series of neurons that relay information to the brain. The signal released by one neuron can be either excitatory or inhibitory to the following, postsynaptic neuron.)
Chapter 48 Solutions
Campbell Biology
Ch. 48.1 - Prob. 1CCCh. 48.1 - Describe the basic pathway of information flow...Ch. 48.1 - WHAT IF? How might increased branching of an axon...Ch. 48.2 - Under what circumstances could ions flow through...Ch. 48.2 - WHAT IF? Suppose a cell's membrane potential...Ch. 48.2 - MAKE CONNECTiONS Review Figure 7.10, which...Ch. 48.3 - How do action potentials and graded potentials...Ch. 48.3 - In multiple sclerosis (from the Greek skleros,...Ch. 48.3 - How do both negative and positive feedback...Ch. 48.3 - WHAT IF? Suppose a mutation caused gated sodium...
Ch. 48.4 - Prob. 1CCCh. 48.4 - Some pesticides inhibit acetylcholinesterase, the...Ch. 48.4 - Prob. 3CCCh. 48 - How would severing an axon affect the flow of...Ch. 48 - Suppose you placed an isolated neuron in a...Ch. 48 - Prob. 48.3CRCh. 48 - Prob. 48.4CRCh. 48 - Level 1: Knowledge/Comprehension 1. What happens...Ch. 48 - Level 1: Knowledge/Comprehension 1. What happens...Ch. 48 - Where are neurotransmitter receptors located? (A)...Ch. 48 - Why are action potentials usually conducted in one...Ch. 48 - Which of the following is the most direct result...Ch. 48 - Suppose a particular neurotransmitter causes an...Ch. 48 - WHAT IF? Ouabain, a plant substance used in some...Ch. 48 - Prob. 8TYUCh. 48 - DRAW IT Suppose a researcher inserts a pair of...Ch. 48 - EVOLUTION CONNECTION An action potential is an...Ch. 48 - Prob. 11TYUCh. 48 - WRITE ABOUT A THEME: ORGANIZATION In a short essay...Ch. 48 - Prob. 13TYU
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- Describe the 5 basic steps of electrical and chemical neural signaling. A strong action will explain each step. Also, describe at least one way synaptic connections can change as a result of experience or learning.arrow_forwardThe giant squid axon has a diameter = 1mm and 1 = 13mm. Compared to a mammalian neuron with a diameter = 1 um and ^ = 0.2mm, which of the following is correct? graded potentials can generate action potentials in the mammalian axon but not in the squid axon. graded potential of similar magnitude would result in action potentials with larger amplitude in the mammalian axon graded potentials of similar magnitude would result in action potentials with larger amplitude in the squid axon graded potentials of similar magnitude would travel furthest from their point of origin in the mammalian axon graded potentials of similar magnitude would travel furthest from their point of origin in the squid axonarrow_forwardSensory neurons in the homeostatic pathway demonstrate spontaneous activity. For a neuron, what does spontaneous activity mean? Describe a mechanism by which a neuron would demonstrate spontaneous activity. (Good inspiration would be to look at the mechanism of behavior and effect on membrane potentials of HCN channels in the heart.) Assuming these sensory neurons used FM communication, how do they encode increases in stimulation and also to encode decreases in stimulation of receptors?arrow_forward
- Which of the following would you NOT expect with respect to variation in neural conduction velocity? Neural conduction speed increases over developmental time as Schwann cells synthesize myelin sheaths, insulating neurons Neural conduction velocity is higher in invertebrate species with insulating sheaths functionally equivalent to vertebrate myelin Neurons and species with larger axon diameters should have greater conduction velocities Neural networks with greater serial processing (i.e., lines of connecting neurons) should have greater neural conduction velocities. The thyroid hormones (triiodothyronine and thyroxine) have a range of roles in regulating growth and metabolism. Thyroid hormones act throughout the body to regulate protein synthesis, long bone growth, and neural maturation. This represents an ______ effect of thyroid hormones. At the same time, through some unknown mechanism, application of thyroid hormones results in an immediate reduction in body temperature, which…arrow_forwardPut the steps of the process of signal transduction in the order they occur (hint - try to decide which signaling pathway this is before working on the order): 1. A conformational change in the signal-receptor complex activates an enzyme. 2. Protein kinases are activated. 3. A signal molecule binds to a receptor. 4. Target proteins are phosphorylated. 5. Second messenger molecules are released. O 1, 2, 3, 4, 5 O 3, 1, 2, 4, 5 O 1, 2, 5, 3, 4 O 3, 1, 5, 2, 4 Iarrow_forwardComplete the Venn diagram that compares stimulatory with inhibitory signal transductionpathways.Inhibitory signaltransduction pathwayStimulatory signaltransduction pathwayarrow_forward
- Transient receptor potential (TRP) channels are ion channels found on animal cells. Some TRP channels are activated by spice molecules, such as garlic, chilli pepper, and wasabi. To study the effects of raw and cooked garlic on the opening of TRP channels, researchers isolated 10 neurons containing the TRP channels. Droplets of raw garlic extract were added to five of the neurons, and droplets of cooked garlic extract were added to the remaining five neurons. Both groups of neurons were monitored to see whether the channels were opening in response to the different types of garlic extracts. TRP channels were activated and opened in the neurons treated with raw garlic extract but not in the neurons treated with cooked garlic. Identify the manipulated, responding, and controlled variables in the experiment described above. Types of Variables Manipulated Responding Controlled Number: Answer Answer Answer Answer Variable: Number of extract droplets Number of neurons Addition…arrow_forwardConsider the circuit from Q5 (above). We want to add another inhibitory neuron to this circuit to increase the likelihood that neuron D will have an action potential. With which cell (A, B, C or D) should our new inhibitory neuron make a synapse to make it more likely that the post - synaptic neuron will have anaction potential?The diagram below shows a simple neural circuit with three pre - synaptic cells labelled 'A', 'B' and 'C', and a post - synaptic cell labelled 'D ' (see image below). Assume neurons A and B each have outputs of +2 and neuron C has output of -1.arrow_forwardDopamine is a major neurotransmitter in the mammalian brain that regulates mood, cognition and locomotion. Which of the following are true about dopamine signaling in the synapse? Select all that apply. Presynaptic nerve cell Dendrites Axon Nerve impulse Myelin sheath Nerve impulse Neuro- transmitter Synapse Postsynaptic nerve cell Postsynaptic receptors Dopamine receptors are localized in the presynaptic membrane Action potential in presynaptic axon terminal results in the opening of chloride channels Dopamine receptors are localized in the postsynaptic membrane Action potential in presynaptic axon terminal results in the opening of calcium channelsarrow_forward
- Graded (Local) Potentials All or none Do not reach threshold Change in RMP Size depends on size of stimulus Chemically or mechanically gated channels Decreases in intensity Found in axon Found in dendrites Involve gated channels Involve K+ diffusion Involve Na+ diffusion Self-propagating Has a threshold Action Potentials Voltage gated channels Local signaling Long distance signalingarrow_forwardHow can molecules pass through a closed gate such as in ligand-gated channel protein? Group of answer choices Receptor must receive pressure to open the gate. Receptor must receive electrical signals to open the gate. Receptor must receive signals or stimulus from the neurotransmitter to open the gate. The ligand-gated channel protein is always open, and it does need any stimulusarrow_forwardYou learned in this chapter that Na+/K+ active transport pumps in the plasma membrane of the axons are responsible for creating the imbalance between Na+ and K+ inside and outside of the neuron that produces the resting membrane potential. In early research studying the role of ions and the involvement of active transport of ions in neural signaling, investigators used the giant axon of a squid as a model. The diameter of a giant axon is far greater than that of a mammalian axon, which enabled researchers to isolate it easily and use it in in vitro experiments. In one early experiment, researchers investigated the active transport of Na+ out of the axon in response to the presence of cyanide. Experimentally they hooked up a section of axon to a syringe, immersed the axon in artificial seawater, introduced radioactive 22Na (as 22NaCl) into the axon, and then quantified the transport of 22Na out through the axons plasma membrane. The rate of 22Na transport out of the axon was determined by measuring the radioactivity released into the fluid sur- rounding the axon over a period of time. The Figure shows the results of the experiment. What is the effect of cyanide on Na1 transport out of the squid axon? How do the data show the effect? Source: P. C. Caldwell et al. 1960. The effects of injecting energy-rich phosphate compounds on the active transport of ions in the giant axons of Loligo. The Journal of Physiology 152:561590. Cengage Learning 2017arrow_forward
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