ll AT&T; 2:09 PM a blackboard.ju.edu Chapter 11 Take Aways From Chapter 11 lectu
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ll AT&T; 2:09 PM a blackboard.ju.edu Chapter 11 Take Aways From Chapter 11 lecture and related labs, understand the following concepts and ideas, Also be able to answer all questions, definitions, figures, etc. related to the chapter in your journal Like Chapter 9, there is a lot of physiology and steps for Chapter 11. It is recommended that you start reviewing early. Rewriting the steps in order multiple times will help the process to sink in and allow you to recognve areas where you may still have questions that need addressed Define and/or descnibe the following: o Afferen o Eferent Gangsa o Tracts o Nerves o Axon o Dendrite o Soma o Action potential (AP o Depolarization o Repolarization Hyperpolarization o Resting membrane potential o Na+ (in relationship to the AP o Kolin relationship to the AP What are the 3 main functions of the nervous system? Be able to organize the nervous system (what was written on the board). What is a neuroglal cell& why is it important? . Identify the 2 PNS neuroglia and what they do. . Identify the 4 CNS neuroglia and what they do What are the main structural components of a neuron & what does each do? What is a Schwann cell? Where do you find What is the importance (functions) of the myelin sheath? How is a myelin sheach (in the PNS) created? What is the neurlemma What is the importance (function) of the nodes of Ranvier? Commpare a multipolar, bipolar, and unipolar neuron . #7 What does it do? What would happen if it became damaged What is the resting membrane potential?- Value, how it's determined, when it occurs in the axon, there are channels that open in response to electrical 4votage) changes and chemical changes Describe what happens . What is the functional feature of the nervous system? . Be able to explain what is happening during the 4 phases of anaction potential. Kow these phases in order and what is happening chemicaly and electrically What is threshold? What happens f it is NOT reached? What is the sodium-potassium pump used for?Explanation / Answer
Answers:
Afferent: Afferent neurons or sensory neurons take the information from the environment to the central nervous system . They are present in the eyes, ears, nose, mouth, skin etc. These are sensitive to light, sound, taste, smell or other stimuli.
Efferent: Efferent or motor neurons bring the information from the central nervous system to the peripheral nervous system. In other words, they carry message from brain and spinal cord to muscles and glands
Nuclei: The clusters of cell bodies of neuron present in the white matter of the central nervous system are called as Nuclei
Ganglia: Ganglia are the collections of cell bodies outside the central nervous system (brain and spinal cord). In other words, The gray matter present in the peripheral nervous system is called as ganglia
Tracts: These are also described as nerves but the nerve fibers (axons) are only found in the CNS
Nerves: One or more nerve fibers(axons) bundles which are present in the Peripheral nervous system are called as nerves
Axon: The processes of neuron which generate nerve impulses and usually conduct them away from the cell body are refered to as axons
Dendrite: These are also processes of neuron which convey the incoming electrical signals toward the cell body
Soma: The cell body which contains the nucleus is called as soma.
Action Potential (AP): The wave of electrical potential that fires down from the axon of neuron which produces a brief change of resting membrane potential of neuron from -70mV to +35 mV
Depolarization: The stage of action potential triggering, in which the membrane potential changes form -70mV to +35 mV due to the influx of sodium ions into the neuron which changes the polarity of the neurolemma
Repolarization: When potassium ions efflux out from the neuron, the negative charge in the inside of neuron is restored and positive charge develops outside which is termed as repolarization. This phase requires energy in the form of ATP
Hyperpolarization: After the neuron reaches -70mV the Potassium voltage channels remain open causing the potential to drop to -80mV which is more than the resting membrane potential and hence refered to as Hyperpolarization which is restored to normal by Na+-K+ pump
Resting membrane Potential: Resting membrane potential (-70mV) is the voltage that results in separation of opposite charges across neurolemma when the cell membrane is not stimulated. The inside of the cell is more negative than outside at rest.
Sodium (Na+ in relationship to the AP): When nerve cell gets excited, the sodium channel in the neuron opens allowing more sodium ions to flow inside making it positive inside and negative outside which rises the resting membrane potential to positive voltage
Potassium (K+ in relationship to the AP): Opening of Sodium channel is followed by opeing of potassium channel during action potential allowing Potassium ions to come inside of the cell, thus Sodium and Potassium together changes the resting membrane potential of neuron from -70mV to +35 mV
What are the 3 main functions of the nervous system?
Answer:
1. Afferent or Sensory neurons (receptors) detect changes in the internal and external environments
2. Integration and evaluation of the sensory inputs
3. Motor or Efferent output to the percepted stimuli through effectors like muscles or glands
Be able to organize the nervous system:
Ans: Nervous system can be divided into Central nervous system and Peripheral nervous system.
Central nervous system consists of Brain and Spinal cord whereas Peripheral nervous system consists of Autonomic division and Somatic division
Autonomic division regulates the internal environment and consists of Sympathetic and Parasympathetic nervous system
What is neuroglial cell and why is it important?
Ans: Neuroglial cells are associated with neurons and provides a protective and supportive network. Schwann cells, satellite cells, oligodendrocytes, astrocytes, ependymal cells, microglia are all types of neuroglial cells which help in providing nutrition, support and conveying messages across neurons
Identify the 2 PNS neuroglia and what they do?
Ans: Schwann cells and Satellite cells are the neuroglia in the PNS. Schwann cells help in providing an insulating covering around the fibers and also help in cleaning up the neuronal debris, thus maintaining the health of the neuron. Satellite cells provide support, brace and anchor the neurons to provide them the nutrient supply
Identify the 4 CNS neuroglia and what they do?
Ans: Astrocytes, Microglial cells, ependymal cells and Oligodendrocytes are the 4 CNS neuroglia.
Astrocytes functions similar to satellite cells by providing support and anchor neurons to get them the nutrient supply. Microglial cells functions similar to schwann cells helps in maintaining the health of neuron by cleaning up neuronal debris, Ependymal cells line the ventricles of the CNS and help in circulation of CSF. Oligodendrocytes wrap their process tightly around the nerve fibers and serves as insulating material called myelin sheath
What are the main strutural components of a neuron and what does each do?
Ans: Dendrites receives the input information while axon conducts the electric signal away from the body and the synapse is the place where the electric signal is converted to chemical signal
What is Schwann cell? Where do you find it? What does it do? What would happen if it became damaged?
Ans: Schwann cells are the type of neuroglia in the PNS. Schwann cells help in providing an insulating covering around the fibers and also help in cleaning up the neuronal debris, thus maintaining the health of the neuron. Damage to schwann cells leads to impair axonal integrity, leading to loss of axons action potential conduction
What is the importance (functions) of myelin sheath?
Ans: Mylein sheath protects the neuron, provides the insulation during axon potential conduction and helps in increase of the speed of impulse transmission
How is a myelin sheath (in the PNS) created? What is the neurolemma?
Ans: Myelin sheath in the PNS is formed by Schwann cells. Neurilemma is the outer nucleated cytoplasmic layer of schwann cells enclosing the myelin sheath
What is the importance (function) of the nodes of Ranvier?
Ans: Nodes of ranvier are the gaps in the myelin sheath. Axons can send out branches from Nodes of ranvier and they help in further increase in the speed of impulse transmission as the impulse jumps from node to node (saltatory movement)
Compare a multipolar, bipolar and unipolar neuron
Ans: Unipolar neuron: Only one process emerge from the cell and these are exclusively sensory neurons. The dendrites are receiving sensory information or they form the direct stimulus. The cell bodies of unipolar neurons always found in ganglia
Bipolar neuron: Have two processes namely axon and dendrite which extend from each end of the cell body. They are found in special senses like olfactory epithelium, retina and inner ear
Multipolar neuron: Have one axon and 2 or more dendrites. Motor neurons and most of the neurons in CNS are multipolar neurons
What is the resting membrane potential? Value, how it is determined, when it occurs?
Ans: The electrical potential difference between the inside and outside of cells like neurons,muscle cells is called as Resting membrane potential (RMP). The value is -70mv. RMP can be determined by using Intracellular microelectrodes or patch clamp pipettes which measure the value of Sodium ions that helps to determine the RMP.
When nerve cell gets excited, the sodium channel in the neuron opens allowing more sodium ions to flow inside making it positive inside and negative outside which rises the resting membrane potential to positive voltage. Opening of Sodium channel is followed by opeing of potassium channel during action potential allowing Potassium ions to come inside of the cell, thus Sodium and Potassium together changes the resting membrane potential of neuron from -70mV to +35 mV.
When potassium ions efflux out from the neuron, the negative charge in the inside of neuron is restored and positive charge develops outside which is termed as repolarization. This phase requires energy in the form of ATP
After the neuron reaches -70mV the Potassium voltage channels remain open causing the potential to drop to -80mV which is more than the resting membrane potential and hence refered to as Hyperpolarization which is restored to normal by Na+-K+ pump and then the RMP occurs (-70mV)
In the axon, there are channels that open in response to electrical changes and chemical changes. Describe what happens.
Ans: Describe in the above sections already (Sodium channels, Potassium channels, Na+-K+ pump)
What is the functional feature of the nervous system?
Ans: Nerve impulses or Action potentials which is always the same regardless of the stimulus is the underlying functional feature of nervous system
Be able to explain what is happening during the 4 phases of an action potential. Know these phases in order. What is happening chemically and electrically
Ans:
Resting state: Na+ and K+ channels are closed-à Leakage accounts for small movements of Na+ and K+---->Each Na+ channel has two voltage-regulated gates
Depolarization phase: Na+ gates are opened; K+ gates are closed---->Cell becomes more positive. Depolarization threshold phase: a critical level of depolarization (-55 to -50 mV)--->At this point, the process becomes self-generating
Repolarization phase: sodium gates close, voltage-sensitive K+ gates open----> K+ exits the cell and cell becomes more negative, as usual
Hyperpolarization phase: Potassium gates remain open, causing an excessive efflux of K+ ----> The neuron is insensitive to stimulus and depolarization during this time
What is threshold? What happens if it is NOT reached?
Ans: Depolarization threshold phase: a critical level of depolarization (-55 to -50 mV)--->At this point, the process becomes self-generating. When threshold is not reached, action potential will not fire
What is sodium-potassium pump used for?
Ans: Sodium pump is useful for repolarization. It restores the resting membrane potential of the neuron. But it should be remembered that It does not restore resting ionic conditions inside the cell
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