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Questions and Answers
What is the primary function of dendrites in a neuron?
Which part of the neuron is responsible for providing essential fuel and maintaining function?
What role does the myelin sheath play in the neuron?
What are presynaptic terminals also known as?
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What does the axon do in a neuron?
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Which of the following is NOT a component of a neuron?
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What is contained within presynaptic terminals?
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How does myelin affect nerve signal transmission?
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What is the approximate weight of a human brain?
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Which type of cells in the brain is more numerous?
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What crucial function do astrocytes (a type of glial cell) NOT perform?
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How many neurons are present approximately in the human brain?
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What is the consistency of the human brain often compared to?
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Which function is associated with glial cells in the brain?
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What fuel does the human brain primarily use?
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What is one of the extensions of a neuron responsible for?
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What is the primary reason the brain does not develop into a nose?
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How are genes structured?
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Approximately how many genes are present in humans?
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What is the weight of a mature human brain?
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What is the composition of the human brain in terms of cells?
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What aspect of development do the chemical instructions in genes influence?
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What are the three major divisions of the mature human brain?
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At what stage of development is the human brain characterized by having three major divisions?
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What happens during hyperpolarization of a neuron?
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What is the primary effect of potassium efflux on membrane potential?
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What defines the refractory period in neural processing?
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What is indicated by an undershoot of the resting membrane potential?
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At what membrane potential does hyperpolarization typically occur?
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Which event can lead to an overshoot during the action potential process?
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What role do sodium ions play in the action potential?
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What occurs immediately after a neuron has fired an action potential?
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What is the primary effect of antagonists on neurotransmitters?
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Which neurotransmitter is chemically similar to THC, the active ingredient in marijuana?
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What condition has been linked to low levels of orexin?
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What is an example of a substance that acts as an antagonist in the nervous system?
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Which neurotransmitter is known to regulate aggressive and impulsive behaviors?
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What describes a reflex response?
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Which neurotransmitter is primarily involved in the brain's pleasure and reward system?
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How does botulinum toxin affect neurotransmitter activity?
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Study Notes
Neuron Structure
- Dendrites: Branch-like extensions that receive signals from other neurons, muscles, or sense organs transmitting them to the soma.
- Soma: Cell body, an egg-shaped structure providing fuel, manufacturing chemicals, and maintaining the neuron's function.
- Axon: A single thread-like structure extending from the soma, carrying signals away to neighboring neurons, organs, or muscles.
- Myelin Sheath: Tube-like segments composed of fatty materials wrapping around the axon, insulating and preventing electrical interference from neighboring axons.
- Presynaptic Terminals (End-Bulbs/Terminal Bulbs): Tiny bubbles located at the extreme ends of the axon's branches. Each end bulb stores neurotransmitters used for communication with neighboring cells.
Human Brain: Overview
- Weight: Approximately 1,350 grams
- Color: Pinkish-white
- Consistency: Firm Jell-O
- Fuel Source: Sugar (glucose)
- Cell Count: Approximately 1 trillion cells
Two Groups of Brain Cells:
-
Glial Cells: Most numerous brain cells (about 900 billion). Glial cells (astrocytes) have three functions:
- Providing scaffolding for developing neurons.
- Insulating neurons to prevent electrical interference.
- Releasing chemicals influencing neuron growth and function.
- Neurons: Approximately 100 billion neurons in the brain. Neurons are brain cells with two specialized extensions: one for receiving electrical signals, and a longer one for transmitting them.
Brain Development:
- Six-Week-Old Brain: Has three major divisions, which develop into the mature brain.
Brain Development:
- Mature Brain: Weighs close to 3 pounds and contains 1 trillion cells, with three major divisions.
Sending Information:
- Resting Potential: The neuron's state when not transmitting an electrical signal. It has a negative charge of -70 millivolts.
- Depolarization: The rapid increase in positive charge within the neuron. It occurs when sodium ions flow into the axon, causing a shift in the membrane potential.
- Action Potential: When the membrane potential reaches a threshold of -55 millivolts, an action potential is generated and the neuron "fires."
- Repolarization: The return of the membrane potential to its resting state. It's caused by the influx of potassium ions.
- Hyperpolarization: A brief undershoot of the resting membrane potential due to potassium channels staying open briefly.
- Refractory Period: A short break after a neuron fires, preventing subsequent action potentials until the axon returns to its resting state.
Neurotransmitters and Antagonists:
- Neurotransmitters: Chemicals stored and released by neurons, transmitting signals across the synapse.
- Antagonists: Molecules that reduce a neurotransmitter's action by blocking its production or release.
- Antagonist Example: Botulinium toxin (BOTOX) treatment
Neurotransmitters:
- Acetylcholine (ACh): Involved in learning, memory, and muscle action.
- Dopamine: Influences movement, attention, learning, and pleasure.
- Norepinephrine (NE): Involved in arousal, alertness, and mood.
- Serotonin: Affects mood, appetite, sleep, and arousal.
- GABA (gamma-aminobutyric acid): The major inhibitory neurotransmitter, involved in regulating anxiety and sleep.
- Glutamate: The major excitatory neurotransmitter, involved in learning, memory, and movement.
- Anandamide: Has similar chemical makeup to THC (marijuana), involved in regulating emotions, anxiety, and stress.
- Nitric Oxide: Regulates emotions, aggressive, and impulsive behaviors.
- Orexin (Hypocretin): Plays a role in the brain's pleasure and reward system, as well as regulating sleep and wakefulness. Low levels of this neurotransmitter are linked to narcolepsy.
Reflex Response:
- A reflex is an unlearned, involuntary reaction to a stimulus.
- Example of Reflex: When you touch a hot light bulb, your hand instantly jerks away without conscious thought or effort.
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Description
Explore the fundamental components of neurons and gain insights into the human brain's structure and function. Understand how various parts like dendrites, soma, and axons contribute to neural communication. This quiz will test your knowledge on these essential concepts of neuroscience.
