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81 Cards in this Set
- Front
- Back
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What are neurons? |
Neurons are specialized cells that transmit electrical impulses within the nervous system. |
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Where do electrical impulses in the nervous system come from? |
The nervous system converts sensory information into electrical impulses in order to detect and respond to stimuli. |
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What are the three components of neurons? |
Dendrites Axons Soma |
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Describe the structure and function of dendrites |
Dendrites are short, branched nerve fibers. Dendrites convert chemical information from receptor cells and other neurons into electrical impulses. |
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Describe the structure and function of an axon. |
The axon is an elongated fibre. The axon transmits electrical impulses/signals to the terminal regions of the neuron, in order to allow communication with other neurons. |
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Describe the structure and function of the soma. |
The soma is the body of the neuron. The soma contains the nucleus, and other organelles which maintain cell metabolism, and are essential for the cells survival. |
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In which direction do electrical impulses travel along a neuron? |
Electrical impulses travel from the dendrites to the axon terminals. |
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What is resting potential? |
Resting potential is the membrane potential (the difference in the charge of the inside and outside of the neuron membrane) when a neuron is not firing. |
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Describe typical resting potential. |
At typical resting potential, the inside of the neuron is relatively negative compared to the outside of the neuron. (-70mV) |
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How is resting potential maintained in a non-firing neuron? |
Sodium-potassium pumps, which are meme brand proteins on the neuron, pump 3 sodium ions (Na+) out of the neuron for every 2 potassium ion taken in (K+). This causes an imbalance in charge inside and outside the cell. The pumping of the sodium and potassium ions is an energy dependent process, and requires ATP. |
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What is an action potential? |
An action potential is the rapid change in charge across the cell membrane of the neuron. Action potentials occur when the neuron is firing. |
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What are the 3 stages of an action potential? |
Depolarization Repolarization Refractory period |
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Outline depolarization |
Depolarization is the first stage of an action potential. A signal is initiated at the dendrite, and triggers the sodium channels on the axon to open. Because of the concentration gradient of sodium ions, sodium ions flow into the neuron (influx). The charge of the neuron is now more positive than the outside. |
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Outline repolarisation |
Repolarization is the second stage of an action potential. After the influx of sodium ion during depolarization, the potassium pumps open. Due to the concentration gradient of potassium ions, there is an efflux of potassium ions out of the neuron. The neuron returns to a negative charge. |
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Refractory period |
The refractory period is the final stage of an action potential. After repolarization, the concentration of sodium and potassium ions is reversed. Sodium-potassium pump proteins actively (using ATP) move exchange the sodium and potassium ions to restore resting potential. |
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How does a nerve impulse propagate through a neuron? |
A never impulse is simply a series of action potential that travel along the axon as a wave of depolarization. This is because the ion channels (sodium and potassium channels) are voltage gated, meaning that they open and close in response to varying membrane potential. Therefore, depolarization at one point on the axon triggers depolarization at the next region. |
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What does it mean for a ion channel to be voltage-gated. |
Voltage-gates channels open and close in response to changes in varying membrane potential. |
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What is the name and function of the pump protein present on a neuron? |
Sodium-potassium pump Expels 3 Na+ ions for every 2 K+ ions taken in |
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What is threshold potential? |
Threshold potential is the minimum stimulus caused by an action potential that is enough to open voltage-gated channels and propagate a nerve impulse. (-55mV) |
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How is threshold potential achieved. |
Threshold potential is achieved when the combined stimulus on the dendrites exceeds the minimum level of depolarization (enough depolarization to open the voltage-gates Na+ and K+ channels) |
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What is an oscilloscope? |
An oscilloscope is a scientific instrument that is used to measure the membrane potential across the membrane of a neuron over a period of time. |
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How is data displayed on an oscilloscope |
Data of an oscilloscope is called an oscilloscope trace. This is a graph with (time) on the x-axis. And (membrane potential) on the y-axis. |
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What is myelin? |
Myelin is a white fatty substance that covers the axon in certain neurons. |
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What is the structure of the myelin sheath? |
The myelin sheath is a layer of myelin that covers an axon in segments. The gaps on the axon, between the segments of myelin, are called nodes of Ranvier. |
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Describe saltatory conduction. |
The myelin sheaths are insulators, so action potentials cannot travel across them. In myelinated axons, action potentials have to hop from one node of ranvier. This decreases the total distance of propagation of the electrical impulse, and increases the speed of transmission of electrical impulse by up to 100x |
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What are the pros and cons of a myelinated neuron? |
Electrical impulses travel faster on a myelinated neuron due to saltatory conduction. Myelination takes up space |
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What is a synapse? |
A synapse is a gap between two neurons, or between a neuron and an effector or reception cell. |
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How is information transmitted across a synapse between two neurons? |
Electrical impulses are converted to chemical signals in the form of neurotransmitters Neurotransmitters move across the synapse to transfer information. |
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What is a pre-synaptic neuron? |
The pre-synaptic neuron is the neuron that is about to transfer information to the next neuron across a synapse. |
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What is a post-synaptic neuron? |
The post synaptic neuron is the neuron that receives neurotransmitters from the pre-synaptic neuron. |
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Describe the chemical transfer of information across a synapse. |
An action potential reaches an axon terminal, and voltage-gated Ca2+ channels open. Ca2+ flow into the neuron, and trigger the formation of vesicles that contain neurotransmitters. Neurotransmitters are released from the axon terminal by exocytosis, and bind to receptors on the post-synaptic membrane. The neurotransmitters open ligand-gated ion channels on the post-synaptic neuron, and this opening of the channels generates an electrical impulse. This electrical impulse generated is called a graded potential. |
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How does an action potential travel between two neurons? |
The transfer of neurotransmitters across a synapse causes a graded potential, which is induced by the opening of the ligand-gated channels after the neurotransmitters bind to the receptors. The accumulation of graded potentials results in an action potential in the post-synaptic neuron. |
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What are neurotransmitters? |
Neurotransmitters are chemical messengers which are transfers across a synapse. |
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What are the functions of the two types of neurotransmitters? |
Excitatory neurotransmitters - triggers a response Inhibitory neurotransmitters - inhibits a response. |
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What is acetylcholine and it’s function? |
Acetylcholine is a neurotransmitter that consists of choline and an acetyl group. Acetylcholine triggers muscular contractions Acetylcholine is also released within the autonomous nervous system to promote parasympathetic responses. |
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What is acetylcholine and it’s function? |
Acetylcholine is a neurotransmitter that consists of choline and an acetyl group. Acetylcholine triggers muscular contractions Acetylcholine is also released within the autonomous nervous system to promote parasympathetic responses. |
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What are the sympathetic and parasympathetic nervous systems? |
The parasympathetic nervous system is responsible for the body’s relaxation responses, like decreasing heart rate, digestion, and rest. The sympathetic nervous system is responsible for strenuous physical activity. |
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How and where is acetylcholine created and stored? |
Acetylcholine is created in the axon terminal by combining an acetyl and choline. Acetylcholine is also stored in the axon terminal until it is released by exocytosis during the chemical transfer of information. |
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How and where is acetylcholine created and stored? |
Acetylcholine is created in the axon terminal by combining an acetyl and choline. Acetylcholine is also stored in the axon terminal until it is released by exocytosis during the chemical transfer of information. |
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Which receptors does acetylcholine bind to? |
Acetylcholine activates a post-synaptic cell by binding to muscarinic and nicotinic receptors? |
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Why is acetylcholine continuously removed from the synapse? |
Acetylcholine must be continuously removed from the synapse because an accumulation of acetylcholine can lead to seizures and paralysis due to overstimulation. |
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Why is acetylcholine continuously removed from the synapse? |
Acetylcholine must be continuously removed from the synapse because an accumulation of acetylcholine can lead to seizures and paralysis due to overstimulation. |
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Describe the breakdown of acetylcholine in the synapse. |
Acetylcholine is broken down by an enzyme called acetylcholinesterase (AChE). The acetylcholine is broken down into choline and acetyl. The choline is returned to the pre-synaptic neuron where it is coupled with another acetate to reform acetylcholine. |
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Why is acetylcholine continuously removed from the synapse? |
Acetylcholine must be continuously removed from the synapse because an accumulation of acetylcholine can lead to seizures and paralysis due to overstimulation. |
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Describe the breakdown of acetylcholine in the synapse. |
Acetylcholine is broken down by an enzyme called acetylcholinesterase (AChE). The acetylcholine is broken down into choline and acetyl. The choline is returned to the pre-synaptic neuron where it is coupled with another acetate to reform acetylcholine. |
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Where is acetylcholinesterase released? |
Acetylcholinesterase is released into the synapse from the pre-synaptic neuron OR it is embedded on the membrane of the post-synaptic cell. |
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What is neonicotinoid? |
Neonicotinoid is a substance that irreversibly binds to acetylcholine receptors. Neonicotinoids are not able to be broken down by acetylcholinesterase Therefore, neonicotinoids can therefore cause a buildup of acetylcholine in the synapse. This leads to paralysis and seizures. |
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What is neonicotinoid? |
Neonicotinoid is a substance that irreversibly binds to acetylcholine receptors. Neonicotinoids are not able to be broken down by acetylcholinesterase Therefore, neonicotinoids can therefore cause a buildup of acetylcholine in the synapse. This leads to paralysis and seizures. |
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Explain the use of neonicotinoid pesticides |
The nicotinic acetylcholine receptors in insects has a different composition than that of mammals, and neonicotinoids bind more strongly. The harmful effect of neonicotinoids is therefore much more severe for insects than it is for mammals. Hence neonicotinoid pesticides are used. |
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What is neonicotinoid? |
Neonicotinoid is a substance that irreversibly binds to acetylcholine receptors. Neonicotinoids are not able to be broken down by acetylcholinesterase Therefore, neonicotinoids can therefore cause a buildup of acetylcholine in the synapse. This leads to paralysis and seizures. |
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Explain the use of neonicotinoid pesticides |
The nicotinic acetylcholine receptors in insects has a different composition than that of mammals, and neonicotinoids bind more strongly. The harmful effect of neonicotinoids is therefore much more severe for insects than it is for mammals. Hence neonicotinoid pesticides are used. |
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What are the two types of neurotransmitters? |
Inhibitory Excitatory |
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What is neonicotinoid? |
Neonicotinoid is a substance that irreversibly binds to acetylcholine receptors. Neonicotinoids are not able to be broken down by acetylcholinesterase Therefore, neonicotinoids can therefore cause a buildup of acetylcholine in the synapse. This leads to paralysis and seizures. |
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Explain the use of neonicotinoid pesticides |
The nicotinic acetylcholine receptors in insects has a different composition than that of mammals, and neonicotinoids bind more strongly. The harmful effect of neonicotinoids is therefore much more severe for insects than it is for mammals. Hence neonicotinoid pesticides are used. |
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What are the two types of neurotransmitters? |
Inhibitory Excitatory |
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How do excitatory neurotransmitters trigger neurons to fire? |
Excitatory neurotransmitters cause depolarization by opening ligand-gated sodium or calcium channels. When there is more depolarization than hyperpolarization, membrane potential increases, and action potential is reached, thereby slowing the neuron to fire. |
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What is neonicotinoid? |
Neonicotinoid is a substance that irreversibly binds to acetylcholine receptors. Neonicotinoids are not able to be broken down by acetylcholinesterase Therefore, neonicotinoids can therefore cause a buildup of acetylcholine in the synapse. This leads to paralysis and seizures. |
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Explain the use of neonicotinoid pesticides |
The nicotinic acetylcholine receptors in insects has a different composition than that of mammals, and neonicotinoids bind more strongly. The harmful effect of neonicotinoids is therefore much more severe for insects than it is for mammals. Hence neonicotinoid pesticides are used. |
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What are the two types of neurotransmitters? |
Inhibitory Excitatory |
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How do excitatory neurotransmitters trigger neurons to fire? |
Excitatory neurotransmitters cause depolarization by opening ligand-gated sodium or calcium channels. When there is more depolarization than hyperpolarization, membrane potential increases, and action potential is reached, thereby slowing the neuron to fire. |
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How do inhibitory neurotransmitters inhibit the firing of neurons? |
Inhibitory neurotransmitters cause hyperpolarisation by opening ligand-gated potassium and chlorine channels. Hyperpolarisarion decreases membrane potential, which inhibits the action potential from reaching the threshold potential. The neuron is thereby inhibited from firing. |
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What is neonicotinoid? |
Neonicotinoid is a substance that irreversibly binds to acetylcholine receptors. Neonicotinoids are not able to be broken down by acetylcholinesterase Therefore, neonicotinoids can therefore cause a buildup of acetylcholine in the synapse. This leads to paralysis and seizures. |
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Explain the use of neonicotinoid pesticides |
The nicotinic acetylcholine receptors in insects has a different composition than that of mammals, and neonicotinoids bind more strongly. The harmful effect of neonicotinoids is therefore much more severe for insects than it is for mammals. Hence neonicotinoid pesticides are used. |
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What are the two types of neurotransmitters? |
Inhibitory Excitatory |
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How do excitatory neurotransmitters trigger neurons to fire? |
Excitatory neurotransmitters cause depolarization by opening ligand-gated sodium or calcium channels. When there is more depolarization than hyperpolarization, membrane potential increases, and action potential is reached, thereby slowing the neuron to fire. |
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How do inhibitory neurotransmitters inhibit the firing of neurons? |
Inhibitory neurotransmitters cause hyperpolarisation by opening ligand-gated potassium and chlorine channels. Hyperpolarisarion decreases membrane, which inhibits the action potential from reaching the threshold potential. The neuron is thereby inhibited from firing. |
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Which ligand-gated channels open for depolarization? |
Sodium and Calcium channels. |
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What is neonicotinoid? |
Neonicotinoid is a substance that irreversibly binds to acetylcholine receptors. Neonicotinoids are not able to be broken down by acetylcholinesterase Therefore, neonicotinoids can therefore cause a buildup of acetylcholine in the synapse. This leads to paralysis and seizures. |
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Explain the use of neonicotinoid pesticides |
The nicotinic acetylcholine receptors in insects has a different composition than that of mammals, and neonicotinoids bind more strongly. The harmful effect of neonicotinoids is therefore much more severe for insects than it is for mammals. Hence neonicotinoid pesticides are used. |
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What are the two types of neurotransmitters? |
Inhibitory Excitatory |
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How do excitatory neurotransmitters trigger neurons to fire? |
Excitatory neurotransmitters cause depolarization by opening ligand-gated sodium or calcium channels. When there is more depolarization than hyperpolarization, membrane potential increases, and action potential is reached, thereby slowing the neuron to fire. |
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How do inhibitory neurotransmitters inhibit the firing of neurons? |
Inhibitory neurotransmitters cause hyperpolarisation by opening ligand-gated potassium and chlorine channels. Hyperpolarisarion decreases membrane, which inhibits the action potential from reaching the threshold potential. The neuron is thereby inhibited from firing. |
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Which ligand-gated channels open for depolarization? |
Sodium and Calcium channels. |
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Which channels open for hyperpolarization? |
Chlorine Potassium |
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Which ligand gates channels open for hyperpolarization? |
Chlorine Potassium |
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Which ligand gates channels open for hyperpolarization? |
Chlorine Potassium |
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What are the three voltage-gated ion channels and their functions? |
Sodium channel - influx of Na+ ions to cause depolarization during an action potential. Potassium channel - efflux of K+ ions to cause repolarization during an action potential. Calcium channel - influx of Ca+ ions to promote the formation of vesicles containing neurotransmitters for exocytosis. |
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Which ligand gates channels open for hyperpolarization? |
Chlorine Potassium |
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What are the three voltage-gated ion channels and their functions? |
Sodium channel - influx of Na+ ions to cause depolarization during an action potential. Potassium channel - efflux of K+ ions to cause repolarization during an action potential. Calcium channel - influx of Ca+ ions to promote the formation of vesicles containing neurotransmitters for exocytosis. |
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Which ligand-gated channels open for hyperpolarization? |
Chlorine Potassium |
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What are the four ligand-gated ion channels and their functions? |
Na and Ca channels - are opened by inhibitory neurotransmitters to induce hyperpolarization. K and Cl channels - are opened by excitatory neurotransmitters to induce depolarization. |
