Propagation of Action Potentials Quiz
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Questions and Answers

What ions are involved in the sequential movement during the action potential?

  • Na, K, Cl , Ca
  • K, Cl
  • Na, Cl
  • Na, K (correct)
  • Where is the trigger zone located in a neuron?

  • Axon hillock (correct)
  • Cell body
  • Dendrites
  • Axon terminals
  • What type of potential change occurs during hyperpolarization?

  • Hyperpolarization (correct)
  • Depolarization
  • Repolarization
  • None of the above
  • Which part of the neuron is considered as the conducting zone?

    <p>Axon</p> Signup and view all the answers

    What is the main mechanism for the transmission of action potentials along the neuron?

    <p>Electrotonic flow of current leading to depolarization of adjacent resting regions</p> Signup and view all the answers

    What happens to the information about the event that elicited the action potential as it travels along the neuron?

    <p>It may not travel far due to electrotonic current leak</p> Signup and view all the answers

    Why does the transmission of action potentials only go in one direction under normal circumstances?

    <p>Depolarization of adjacent resting regions leads to new action potentials in one direction</p> Signup and view all the answers

    What slows down the flow of information along the neuron?

    <p>Continual regeneration of action potentials</p> Signup and view all the answers

    Which of the following is responsible for the jumping of action potentials between nodes of Ranvier in myelinated nerve fibers?

    <p>Saltatory conduction</p> Signup and view all the answers

    What is responsible for the formation of myelin in the peripheral nervous system?

    <p>Schwann cells</p> Signup and view all the answers

    What covers the nodes of Ranvier in myelinated axons?

    <p>Myelin sheath</p> Signup and view all the answers

    What causes local current flow, depolarizing adjacent inactive nodes during an action potential?

    <p>$Na^+$ and $K^+$ ion channels</p> Signup and view all the answers

    Which factors affect the speed of impulse conduction?

    <p>$O_2$ levels and temperature</p> Signup and view all the answers

    What are examples of demyelination diseases?

    <p>Guillain-Barré syndrome, multiple sclerosis, dementias</p> Signup and view all the answers

    What causes Guillain-Barré syndrome?

    <p>Inflammation due to autoimmune response damaging peripheral nerves</p> Signup and view all the answers

    What characterizes multiple sclerosis?

    <p>Inflammatory disease affecting the central nervous system with multiple lesions</p> Signup and view all the answers

    What is Alzheimer's disease commonly associated with?

    <p>All of the above</p> Signup and view all the answers

    Which type of muscles and glands does the autonomic nervous system primarily control?

    <p>Smooth and cardiac muscles, internal organs, glands, and blood vessels</p> Signup and view all the answers

    What is the main focus of understanding in relation to the autonomic nervous system's arrangement?

    <p>Arrangement of the autonomic NS and its associated ganglia</p> Signup and view all the answers

    Which part of the body is primarily controlled by the somatic nervous system?

    <p>Skin, skeletal muscles, joints, bones, and ligaments</p> Signup and view all the answers

    Where do preganglionic parasympathetic motor fibers exit?

    <p>Lateral horn of sacral spinal segments S2-S4</p> Signup and view all the answers

    Which cranial nerves contain parasympathetic preganglionic fibers?

    <p>CN III, VII, and IX</p> Signup and view all the answers

    Where do the greater splanchnic nerves originate from?

    <p>T5-T9</p> Signup and view all the answers

    Which ganglia house postganglionic motor neurons for CN X (vagus)?

    <p>Parasympathetic ganglia adjacent to the target organs</p> Signup and view all the answers

    What is the main function of the enteric nervous system (ENS)?

    <p>Govern the function of the gastrointestinal tract (GIT)</p> Signup and view all the answers

    Where are neurons of the enteric nervous system located?

    <p>In the wall of the GIT</p> Signup and view all the answers

    What type of fibers are mainly concerned with detecting pain from viscera?

    <p>Visceral sensory fibers accompanying sympathetic fibers</p> Signup and view all the answers

    What is responsible for referred pain?

    <p>Axons carrying pain sense from viscera synapsing on neurons in the dorsal horn receiving somatosensory pain fibers from the skin.</p> Signup and view all the answers

    What can modify the activity of the autonomic nervous system to lower blood pressure?

    <p>Drugs blocking sympathetic nerve endings causing vasodilatation of peripheral blood vessels.</p> Signup and view all the answers

    Where are the ganglia of the Parasympathetic Division located?

    <p>Adjacent to the viscera they supply</p> Signup and view all the answers

    Which division of the ANS is associated with the 'Fight or Flight Response'?

    <p>Sympathetic Division</p> Signup and view all the answers

    Where do the sympathetic preganglionic fibers exit the spinal cord?

    <p>T1-L2 segments</p> Signup and view all the answers

    What is the function of the Parasympathetic Division of the ANS?

    <p>Slows heart rate, increases digestive functions</p> Signup and view all the answers

    Where are autonomic ganglia located?

    <p>Outside the CNS in the PNS</p> Signup and view all the answers

    What is the main function of Sympathetic Nervous System?

    <p>Increases heart rate and blood pressure</p> Signup and view all the answers

    How many types of autonomic ganglia are there?

    <p>Sympathetic and Parasympathetic</p> Signup and view all the answers

    Where are Parasympathetic ganglia typically situated?

    <p>Adjacent to the viscera they supply</p> Signup and view all the answers

    What is a characteristic of sympathetic preganglionic fibers?

    <p>They exit at T1-L2 segments and join the sympathetic chain as white rami communicans.</p> Signup and view all the answers

    Where does the Parasympathetic Division have its ganglia located?

    <p>In the Craniosacral outflow</p> Signup and view all the answers

    Study Notes

    • New action potentials are not generated at every point in membranes due to a limited number of voltage-gated sodium channels.

    • Graded potentials do not result in action potentials at every point.

    • Saltatory conduction is the jumping of action potentials between nodes of Ranvier in myelinated nerve fibers.

    • Myelin is formed by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system.

    • Myelin sheath covers the nodes of Ranvier in myelinated axons.

    • An active node at the peak of an action potential causes local current flow, which depolarizes the adjacent inactive node, bringing it to threshold.

    • Factors affecting the speed of impulse conduction include myelination and the diameter of the fiber.

    • Nerve fibers are classified based on axon diameter and presence of myelination.

    • Examples of demyelination diseases include Guillain-Barré syndrome, multiple sclerosis, and dementias.

    • Guillain-Barré syndrome is caused by the immune system damaging the peripheral nervous system, resulting in muscle weakness and loss of reflexes.

    • Multiple sclerosis is an immune-mediated inflammatory demyelinating disease of the central nervous system, characterized by multiple lesions and neurological symptoms.

    • Dementia is a degenerative disease affecting memory, language, and other cognitive abilities.

    • Alzheimer's disease is the most common cause of dementia.

    • Self-assessment: A 27-year-old nurse named Nadia experienced tingling and numbness in her hands and feet, followed by muscle weakness and fatigue. She fell during a ward round, and electrophysiological studies revealed decreased motor nerve conduction velocity. A diagnosis of multiple sclerosis was made based on history and investigations.

    • Decreased impulse conduction speed can be attributed to demyelination or axonal damage.

    • Nadia's symptoms of muscle weakness and fatigue can be correlated with the decreased speed of impulse conduction.

    • Factors affecting impulse conduction speed include myelination, axon diameter, and temperature.

    • Other causes of demyelination include viral infections, toxins, and trauma.

    • EE (Enteric Nervous System) and ANS (Autonomic Nervous System) are two different parts of the nervous system

    • The Somatic Motor System is controlled by a single nerve, while the ANS has two nerves: the preganglionic and postganglionic nerves

    • The ANS has two divisions: the Sympathetic Division (Fight or Flight Response) and the Parasympathetic Division (Rest and Digest Response)

    • The Sympathetic Division increases heart rate and blood pressure, depresses digestive function, and increases sweating

    • The Parasympathetic Division slows heart rate, falls in pressure, increases digestive functions, and stops sweating

    • The Sympathetic Division has its ganglia located in the Thoracolumbar outflow, while the Parasympathetic Division has its ganglia in the Craniosacral outflow

    • Autonomic ganglia are located outside the CNS in the PNS, providing a location for synapse and are of two types: Sympathetic and Parasympathetic

    • Sympathetic ganglia are located along the sympathetic trunk and there are about 24 ganglia in each sympathetic trunk

    • Parasympathetic ganglia are smaller and located more peripherally than sympathetic ganglia, typically situated adjacent to the viscera they supply

    • The Sympathetic Nervous System has a wide distribution targeting peripheral effectors and internal organs in the head, neck, thorax, abdomen, and pelvis

    • Sympathetic preganglionic fibers exit the spinal cord at T1-L2 segments and join the sympathetic chain as white rami communicans

    • Parasympathetic ganglia include the Ciliary, Pterygopalatine, Otic, and Submandibular ganglia, among others, and are located adjacent to the viscera they supply

    • The Sympathetic Nervous System has a wide distribution targeting peripheral effectors as skin glands, erector pili muscles, and blood vessels, as well as internal organs in the head, neck, thorax, abdomen, and pelvis.

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    Description

    Test your knowledge on the propagation of action potentials in nerve cells, including the differences between graded and action potentials, as well as saltatory conduction in myelinated nerve fibers.

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