Nerve Impulse and Synaptic Tranmission Flashcards
Synapses (34 cards)
Describe the two types of synapses.
The two types of synapses are chemical and electrical.
Explain the function of neurotransmitters in chemical synapses.
Neurotransmitters function to open or close ion channels that influence membrane permeability and, consequently, membrane potential.
Define the components of a chemical synapse.
A chemical synapse typically consists of the axon terminal of the presynaptic neuron, which contains synaptic vesicles filled with neurotransmitter, and the receptor region on the postsynaptic neuron’s membrane, which receives the neurotransmitter.
How is the synaptic cleft characterized?
The synaptic cleft is a fluid-filled space that measures 30-50 nm in width, separating the presynaptic and postsynaptic neurons.
List the six steps involved in neurotransmitter release at a chemical synapse.
- Action potential arrives at the axon terminal of the presynaptic neuron. 2. Voltage-gated Ca2+ channels open, allowing Ca2+ to enter the axon terminal. 3. Ca2+ entry causes neurotransmitter release. 4. Neurotransmitter diffuses across the synaptic cleft and binds to postsynaptic receptors. 5. Binding of neurotransmitter opens ion channels, creating graded potentials. 6. Neurotransmitter effects are terminated.
What regulates the duration of neurotransmitter effects in a chemical synapse?
The duration of neurotransmitter effects is regulated by reuptake by astrocytes or the axon terminal, degradation by enzymes, or diffusion away from the synaptic cleft.
Explain the factors that influence the strength of graded potentials caused by neurotransmitter receptors.
The strength of graded potentials is influenced by the amount of neurotransmitter released and the time the neurotransmitter stays in the synaptic cleft.
Differentiate between EPSP and IPSP.
EPSP stands for excitatory postsynaptic potentials, which increase the likelihood of an action potential, while IPSP stands for inhibitory postsynaptic potentials, which decrease the likelihood of an action potential.
Describe ionotropic receptors and their function.
Ionotropic receptors mediate rapid synaptic transmission, are sensitive to molecules and sometimes membrane potential, and are selective for specific ions.
What are metabotropic receptors and their structure?
Metabotropic receptors are G-protein coupled receptors characterized by a single polypeptide with 7 transmembrane alpha helix domains.
Identify types of neurotransmitters that bind to metabotropic receptors.
Amines are one type of neurotransmitter that binds to metabotropic receptors.
Describe the role of G protein-linked receptors in neurotransmission.
G protein-linked receptors mediate indirect, complex, and prolonged responses in neurotransmission. They involve transmembrane protein complexes that cause widespread metabolic changes.
Explain the function of second messengers in the nervous system.
Second messengers, such as cyclic AMP and diacylglycerol, can open or close ion channels, activate kinase enzymes, phosphorylate channel proteins, and induce protein synthesis.
Define biogenic amines and provide examples.
Biogenic amines are neurotransmitters derived from amino acids, including catecholamines like dopamine, norepinephrine, and epinephrine, and indolamines like serotonin and histamine.
How is acetylcholine synthesized and degraded in the body?
Acetylcholine is synthesized from acetic acid and choline by the enzyme choline acetyltransferase and is degraded by the enzyme acetylcholinesterase.
Explain the significance of neurotransmitters in the nervous system.
Neurotransmitters, along with electrical signals, are essential for communication in the nervous system, with over 50 identified, each classified chemically and functionally.
Describe the function of endorphins in the body.
Endorphins, such as beta endorphin, dynorphin, and enkephalins, act as natural opiates and play a role in pain relief and emotional regulation.
What is the role of Substance P in the nervous system?
Substance P is a neuropeptide that serves as a mediator of pain signals in the nervous system.
How are neurotransmitter imbalances related to mental illness?
Imbalances in neurotransmitters, such as biogenic amines, are associated with various mental illnesses, affecting emotional behaviors and overall mental health.
Describe the synthesis of serotonin and its role in the brain.
Serotonin is synthesized from the amino acid tryptophan and plays a significant role in emotional behaviors and regulating the biological clock.
Explain the relationship between neurotransmitters and the autonomic nervous system (ANS).
Certain neurotransmitters, like norepinephrine, are utilized by ANS motor neurons, influencing involuntary bodily functions.
Describe the role of gut-brain peptides in digestion regulation.
Gut-brain peptides such as somatostatin and cholecystokinin (CCK) play a role in regulating digestion.
Define excitatory postsynaptic potential (EPSP).
EPSP is a local net graded potential depolarization that occurs when Na+ influx is greater than K+ efflux, potentially triggering an action potential (AP) if of threshold strength.
How does an EPSP lead to the generation of an action potential?
If an EPSP is of threshold strength, it can spread to the axon hillock, triggering the opening of voltage-gated channels and generating an action potential.
