Neuroscience Chapter on Nerve Impulses
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Questions and Answers

What type of muscles do autonomic motor nerves send impulses to?

  • Voluntary muscles
  • Cardiac muscle (correct)
  • Skeletal muscles
  • Smooth muscle (correct)

Which ions are primarily involved in the action of the sodium-potassium pump?

  • Calcium and chloride
  • Potassium and calcium
  • Magnesium and sodium
  • Sodium and potassium (correct)

What occurs during depolarization of a neuron?

  • Potassium ions flow into the cell
  • Sodium ions flow into the cell (correct)
  • Sodium ions flow out of the cell
  • Calcium ions block sodium channels

What term describes the electrical difference across a neuron's membrane when it is in the resting state?

<p>Resting membrane potential (B)</p> Signup and view all the answers

What structure opens in response to a stimulus, allowing sodium ions to pass through the neuron's membrane?

<p>Sodium channel (C)</p> Signup and view all the answers

What is the primary result of the action of the sodium-potassium pump?

<p>Maintaining electrical polarization of the cell (D)</p> Signup and view all the answers

In a resting neuron, what happens to sodium ions?

<p>They are pumped outside the cell. (B)</p> Signup and view all the answers

What is the result of the sudden flow of sodium ions into the neuron during depolarization?

<p>The inside of the cell becomes more positive. (B)</p> Signup and view all the answers

What is the primary function of neurotransmitters in the nervous system?

<p>To facilitate communication between nerve cells (D)</p> Signup and view all the answers

How do hormones differ from neurotransmitters in terms of action?

<p>Hormones are secreted directly into the bloodstream (D)</p> Signup and view all the answers

Which two divisions make up the nervous system?

<p>Central and peripheral systems (A)</p> Signup and view all the answers

What role do motor functions play in the nervous system?

<p>They respond to stimuli by activating muscles or glands (A)</p> Signup and view all the answers

What is the significance of the inability of neurons to reproduce?

<p>It results in permanent damage if the cell body is not intact (C)</p> Signup and view all the answers

Which of the following is NOT a category of functions performed by the nervous system?

<p>Respiratory functions (C)</p> Signup and view all the answers

What is the role of neuroglia in the nervous system?

<p>To support and protect neurons (A)</p> Signup and view all the answers

What can happen to neurons during cardiac arrest?

<p>They may become damaged due to lack of oxygen (A)</p> Signup and view all the answers

What is the primary function of the neurotransmitter released by the presynaptic neuron?

<p>To activate or inhibit the postsynaptic cell (C)</p> Signup and view all the answers

Which structure at the end of the presynaptic neuron releases neurotransmitters into the synaptic cleft?

<p>Synaptic knob (B)</p> Signup and view all the answers

What happens when excitatory neurotransmitters bind to their receptors on the postsynaptic membrane?

<p>Depolarization occurs if threshold is reached (D)</p> Signup and view all the answers

What distinguishes inhibitory neurotransmitters from excitatory neurotransmitters?

<p>Inhibitory neurotransmitters hyperpolarize the postsynaptic membrane (A)</p> Signup and view all the answers

What is the synaptic cleft?

<p>The area between two neurons or a neuron and another cell (D)</p> Signup and view all the answers

How does calcium enter the presynaptic neuron during synaptic transmission?

<p>Via calcium channels that open after depolarization of the membrane (D)</p> Signup and view all the answers

Which of the following is true about acetylcholine?

<p>It can act as either excitatory or inhibitory based on its location (B)</p> Signup and view all the answers

Which neuron is responsible for sending the signal during synaptic transmission?

<p>Presynaptic neuron (B)</p> Signup and view all the answers

What is the primary role of acetylcholine in the parasympathetic nervous system?

<p>To slow the heart rate (A)</p> Signup and view all the answers

Which neurotransmitter is primarily associated with the fight or flight response?

<p>Epinephrine (A)</p> Signup and view all the answers

What is the function of the cerebellum in the brain?

<p>Coordinating movement and balance (A)</p> Signup and view all the answers

Which structure is responsible for connecting the two halves of the cerebral cortex?

<p>Corpus callosum (A)</p> Signup and view all the answers

Which of the following statements about GABA and glycine is true?

<p>Both are inhibitory neurotransmitters. (A)</p> Signup and view all the answers

What characterizes the gyri of the brain?

<p>They are wrinkles that increase the surface area of gray matter. (D)</p> Signup and view all the answers

Which part of the brain is primarily involved in higher-order behaviors such as learning and reasoning?

<p>Cerebrum (C)</p> Signup and view all the answers

What distinguishes sulci from fissures in the brain's structure?

<p>Sulci are shallow grooves, while fissures are deep grooves. (C)</p> Signup and view all the answers

What is the primary function of the thalamus in the diencephalon?

<p>Acting as a relay station for sensory inputs (A)</p> Signup and view all the answers

Which cranial nerve is responsible for the sense of smell?

<p>Olfactory nerve (CN I) (D)</p> Signup and view all the answers

Which of the following best describes the brainstem?

<p>It maintains basic body support functions. (D)</p> Signup and view all the answers

What role does the blood-brain barrier serve?

<p>It separates the capillaries in the brain from nervous tissue. (B)</p> Signup and view all the answers

Which cranial nerve is classified as both sensory and motor?

<p>Facial nerve (A)</p> Signup and view all the answers

What is the function of cerebrospinal fluid (CSF)?

<p>To protect and nourish the brain and spinal cord. (C)</p> Signup and view all the answers

Which of the following is not a layer of the meninges?

<p>Cerebrospinal layer (D)</p> Signup and view all the answers

Which cranial nerve is primarily responsible for controlling eye movements?

<p>Oculomotor nerve (CN III) (C)</p> Signup and view all the answers

What type of system is the sympathetic nervous system commonly referred to as?

<p>Fight-or-flight system (C)</p> Signup and view all the answers

Which neurotransmitter is secreted by neurons of the parasympathetic nervous system?

<p>Acetylcholine (C)</p> Signup and view all the answers

Where are muscarinic receptors primarily located?

<p>On target organs supplied by parasympathetic neurons (B)</p> Signup and view all the answers

Which of the following best describes autonomic reflexes?

<p>Control smooth muscle and cardiac muscle (D)</p> Signup and view all the answers

What is the primary function of a sensory receptor in the reflex arc?

<p>To detect changes in the environment (A)</p> Signup and view all the answers

In a withdrawal reflex, which of the following describes the pathway of sensory impulses?

<p>Sensory neuron sends impulses to spinal cord for integration (C)</p> Signup and view all the answers

What is the key difference between the preganglionic fibers of the parasympathetic and sympathetic nervous systems?

<p>Parasympathetic fibers are longer than sympathetic fibers (B)</p> Signup and view all the answers

Which type of reflex involves contraction of skeletal muscles?

<p>Somatic reflex (A)</p> Signup and view all the answers

Flashcards

Synapse

The junction between two neurons or a neuron and another cell where communication occurs.

Synaptic Cleft

The small gap between the presynaptic and postsynaptic cells at a synapse.

Presynaptic Neuron

The neuron that sends a signal and releases neurotransmitters at a synapse.

Postsynaptic Neuron

The neuron that receives the signal and has receptors for neurotransmitters.

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Neurotransmitter

A chemical messenger released by the presynaptic neuron that carries the signal across the synaptic cleft.

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Excitatory Neurotransmitter

A neurotransmitter that makes the postsynaptic neuron more likely to fire an action potential.

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Inhibitory Neurotransmitter

A neurotransmitter that makes the postsynaptic neuron less likely to fire an action potential.

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Acetylcholine

A neurotransmitter that can be either excitatory or inhibitory depending on the location in the body.

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Resting State of a Neuron

A neuron's inactive state where it maintains an electrical polarization across its cell membrane.

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Sodium-Potassium Pump

A specialized protein in the neuron's membrane that actively pumps sodium ions out of the cell and potassium ions into the cell.

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Polarized Membrane

The state where the neuron's cell membrane has a difference in electrical charge, with more sodium ions outside and more potassium ions inside.

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Resting Membrane Potential

The difference in electrical charge across the neuron's membrane when it's at rest. This is what keeps the 'battery' charged.

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Depolarization

The process of reducing the difference in charge across the neuron's membrane, caused by the opening of sodium channels.

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Sodium Channels

Specialized structures on the neuron's surface that open when the neuron is stimulated, allowing sodium ions to flow into the cell.

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Passive Diffusion

The movement of sodium ions into the cell during depolarization, from an area of high concentration (outside) to low concentration (inside).

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Action Potential

The rapid change in electrical charge across the neuron's membrane during depolarization, which occurs after a stimulus has been received.

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Parasympathetic Nerve Effect on Heart

Acetylcholine, released by parasympathetic nerves at the heart, has an inhibitory effect, slowing the heart rate.

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Catecholamines

A group of neurotransmitters including norepinephrine, dopamine, and epinephrine, known for their role in the 'fight or flight' response.

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Norepinephrine's Role

Norepinephrine is a neurotransmitter primarily associated with the 'fight or flight' response in the sympathetic nervous system.

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Epinephrine's Role

Epinephrine is a hormone that acts as a neurotransmitter in the 'fight or flight' response in the sympathetic nervous system.

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Acetylcholine Breakdown

Acetylcholine, a neurotransmitter, is quickly broken down by acetylcholinesterase, an enzyme on the postsynaptic membrane. The broken-down components are recycled back into new acetylcholine.

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Brain Division

The brain is divided into four main parts: the cerebrum, cerebellum, diencephalon, and brainstem.

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Cerebrum Structure

The cerebrum, the largest part of the brain, is composed of gray matter in the cerebral cortex (outer layer) and white matter beneath it, including the corpus callosum, which connects the two hemispheres.

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Cerebellum Function

The cerebellum coordinates motor control, balance, posture, and complex reflexes. It compares intended movements with actual muscle and joint positions to fine-tune movements.

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Diencephalon

A region of the brain that serves as a relay station for sensory information and connects the brainstem to the cerebrum. It is also responsible for regulating sleep-wake cycles and emotions.

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Hypothalamus

A part of the diencephalon that acts as a control center for many bodily functions, including hunger, thirst, temperature regulation, and the release of hormones.

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Pituitary Gland

The 'master gland' of the endocrine system, responsible for producing and releasing hormones that regulate growth, metabolism, and other bodily functions.

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Brainstem

The base of the brain that connects to the spinal cord and is responsible for essential life-sustaining functions like breathing, heart rate, and blood pressure.

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Meninges

Protective layers of connective tissue that surround the brain and spinal cord, providing cushioning and support.

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Cerebrospinal Fluid (CSF)

A clear fluid that bathes the brain and spinal cord, providing cushioning, protection, and removing waste products.

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Blood-Brain Barrier

A protective barrier that prevents harmful substances in the bloodstream from entering the brain.

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Cranial Nerves

12 pairs of nerves that originate from the brain and control sensory functions, motor functions, or both.

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Sensory Neuron

A neuron that carries sensory information from sensory receptors to the central nervous system (CNS).

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Motor Neuron

A neuron that carries motor commands from the CNS to muscles or glands.

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Sympathetic Nervous System

The part of the autonomic nervous system that prepares the body for 'fight-or-flight' responses, increasing heart rate, respiration, and blood pressure.

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Parasympathetic Nervous System

The part of the autonomic nervous system that controls 'rest-and-digest' functions, slowing heart rate, decreasing respiration, and promoting digestion.

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Reflex

An automatic, rapid response to a stimulus, designed to protect the body or maintain its internal balance (homeostasis).

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Somatic Reflex

A reflex involving the contraction of skeletal muscles, often triggered by an external stimulus.

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Autonomic Reflex

A reflex that regulates smooth muscle, cardiac muscle, or glands, often without conscious control.

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Muscle Spindle

A specialized sensory receptor located within skeletal muscle that detects changes in muscle length and rate of stretch.

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What are the two main communication systems in the body?

The nervous system and the endocrine system.

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What are neurotransmitters?

Chemical messengers used by the nervous system to communicate between neurons.

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How do neurotransmitters and hormones differ in speed and duration?

Neurotransmitters act quickly but have a short-lasting effect, while hormones act more slowly but have a longer-lasting effect.

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What are the two main divisions of the nervous system?

The central nervous system (CNS) and the peripheral nervous system (PNS).

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What does the central nervous system (CNS) consist of?

The brain and spinal cord.

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What are the three main functions of the nervous system?

Sensory functions, integrating functions, and motor functions.

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What are neurons and what makes them unique?

Neurons are nerve cells that are responsible for transmitting information in the nervous system. They are unique because they can't reproduce and need oxygen to survive.

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What are glial cells and what is their function?

Glial cells are support cells of the nervous system that provide structural and functional support for neurons.

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Study Notes

Body Communication Systems

  • The body has two main communication systems: the nervous system and the endocrine system.
  • The nervous system uses chemical messengers called neurotransmitters, which are produced by neurons (nerve cells).
  • Neurotransmitters travel across synapses (spaces between nerve cells) quickly.
  • The endocrine system uses hormones, which travel through the bloodstream.
  • Hormones have a slower response than neurotransmitters but can sustain activity longer.

Nervous System Divisions

  • The nervous system has two main divisions: central nervous system (CNS) and peripheral nervous system (PNS).
  • The CNS is made up of the brain and spinal cord.
  • The PNS connects the CNS to the rest of the body.

Nervous System Functions

  • Sensory functions: gather information from inside and outside the body.
  • Integrating functions: process the sensory information.
  • Motor functions: respond to the integrated information, causing an action.

Neurons

  • Neurons are the basic units of the nervous system.
  • Neurons cannot reproduce, so damage is irreversible unless the cell body is intact.
  • Neurons need oxygen to survive.
  • They respond to stimuli and transmit impulses between parts of the body.
  • Neurons cannot live without oxygen.

Neuroglia (Glial Cells)

  • Neuroglia (glial cells) support and protect neurons.
  • They do not transmit impulses, but aid in structure and protection.

Neuron Structure

  • Neurons have a cell body (soma).
  • Dendrites receive signals, and axons send signals.
  • Axons are sometimes covered with myelin sheaths.
  • Myelin sheath is made of glial cells called oligodendrocytes (in brain and spinal cord) and Schwann cells (outside brain and spinal cord).
  • Myelin speeds up nerve impulses. Gaps in the myelin sheath (nodes of Ranvier) facilitate faster impulse transmission.

Central Nervous System (CNS) and Peripheral Nervous System (PNS)

  • The CNS includes the brain and spinal cord.
  • The PNS consists of nerves that carry information to and from the CNS.

Nervous System Component Functions

  • Cranial nerves: nerves that emerge from the brain.
  • Spinal nerves: nerves that emerge from the spinal cord.
  • Nerves containing both sensory and motor fibers are called mixed nerves.
  • Afferent fibers conduct sensory impulses to the CNS.
  • Efferent fibers conduct impulses away from the CNS.

Synaptic Transmission

  • The synapse is a junction between two neurons or a neuron and another tissue.
  • Presynaptic neuron releases neurotransmitters across the synaptic cleft.
  • Postsynaptic neuron receives the neurotransmitters, triggering an impulse.
  • Neurotransmitters are released by the presynaptic neuron into the synaptic cleft.
  • The postsynaptic neuron contains receptors for these neurotransmitters.
  • The combination of neurotransmitter receptors and neurotransmitter triggers a change in either the postsynaptic cell membrane potential or enzyme activity.
  • The speed of signal transmission between the synapse is determined by the type of neurotransmitter released and the type of receptors present on the postsynaptic membrane.

Types of Neurotransmitters

  • Acetylcholine: involved in muscle contraction and can be excitatory or inhibitory.
  • Norepinephrine: plays a role in the "fight-or-flight" response.
  • Dopamine: involved in movement and pleasure.
  • Epinephrine: involved in the "fight-or-flight" response.
  • GABA and glycine have inhibitory effects.

Reflexes

  • Reflexes are automatic responses to stimuli.
  • Some reflexes involve the spinal cord, while others involve the brain.
  • The pupillary light reflex (PLR) is an example of an autonomic reflex.

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Description

Test your knowledge on the fundamentals of nerve impulses, including the role of autonomic motor nerves, ion movement, and neurotransmitter functions. This quiz will challenge your understanding of neuronal depolarization and the nervous system's organization. Perfect for students studying basic neuroscience concepts.

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