Neurotrasmettitori | NEUROSCIENZE - Lezione 7

La Biologia per tutti

6 Mar 202220:06

Summary

TLDRThis lecture delves into the world of neurotransmitters, the chemical messengers that transmit signals across synapses in the nervous system. It explains the role of neurotransmitters like glutamate, acetylcholine, dopamine, GABA, and serotonin, highlighting their excitatory or inhibitory effects and their significance in various brain functions, including learning, memory, mood regulation, and reward pathways. The importance of receptor interaction in determining the signal's nature and the impact of neurotransmitter imbalances in conditions like depression and Parkinson's disease are also discussed, offering insights into the complex communication within our nervous system.

Takeaways

🧠 Neurotransmitters are substances that carry information between neurons through synapses, with over a hundred known types.
🚀 The release of neurotransmitters occurs when a stimulus reaches the presynaptic terminal, causing synaptic vesicles to merge with the presynaptic membrane and release their contents into the synaptic cleft.
🔄 Neurotransmitters must be received by a receptor on the postsynaptic neuron to continue the signal transmission, which can be either excitatory or inhibitory.
🌀 After their release, neurotransmitters need to be removed from the synaptic cleft to prevent continuous signaling; this can be done through reuptake by the presynaptic terminal or glial cells.
📈 Neurotransmitters can be classified based on their molecular structure and size, with smaller molecules typically acting more quickly and larger molecules having a slower, more prolonged effect.
🥕 Examples of neurotransmitters include amino acids like GABA and glycine, biogenic amines like dopamine and norepinephrine, and peptides like endorphins and neuropeptide Y.
🏃‍♂️ Glutamate is the primary excitatory neurotransmitter in the central nervous system and is involved in learning and memory processes.
🔌 Acetylcholine is involved in both the central and peripheral nervous systems, playing a role in muscle movement and the parasympathetic nervous system.
🎢 Dopamine is a catecholamine neurotransmitter crucial for movement control, pleasure sensation, reward circuits, and various cognitive functions.
🛌 GABA is the primary inhibitory neurotransmitter in the brain, with three types of receptors all leading to inhibitory effects.
💊 Antidepressant medications called SSRIs work by blocking the reuptake of serotonin, increasing its availability in the synaptic cleft and prolonging its interaction with receptors.
🔄 The effect of a neurotransmitter is not solely determined by its nature but also by the type of receptor it binds to, which can be either excitatory or inhibitory.

Q & A

What is the primary function of neurotransmitters?
-The primary function of neurotransmitters is to convey information between neurons through synapses.
Where are neurotransmitters stored within the neuron?
-Neurotransmitters are stored in vesicles called synaptic vesicles within the presynaptic terminal.
What happens to the synaptic vesicles when a nerve stimulus is received?
-When a nerve stimulus is received, the synaptic vesicles fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.
What is the role of receptors in the transmission of the nerve impulse?
-Receptors on the postsynaptic neuron must receive the neurotransmitter to continue the transmission of the impulse to subsequent neurons. The binding of neurotransmitters to their receptors can trigger an excitatory or inhibitory response in the postsynaptic neuron.
How are neurotransmitters cleared from the synaptic cleft after they have been released?
-After release, neurotransmitters can be taken back up into the presynaptic terminal through a process called reuptake, or they can be broken down by enzymes or taken up by glial cells, such as astrocytes.
What is the difference between small-molecule neurotransmitters and neuropeptides?
-Small-molecule neurotransmitters, such as amino acids like GABA, glutamate, or glycine, are simpler in structure. Neuropeptides are larger, consisting of a chain of amino acids, and have longer-lasting effects on the nervous system.
Which neurotransmitter is considered the primary excitatory neurotransmitter in the central nervous system?
-Glutamate is considered the primary excitatory neurotransmitter in the central nervous system.
What neurotransmitter is responsible for the transmission of signals from sensory organs to the brain and motor commands to muscles?
-Acetylcholine is the neurotransmitter responsible for the transmission of signals from sensory organs to the brain and motor commands to muscles.
What neurotransmitter is associated with the regulation of movement, pleasure sensation, reward circuitry, and cognitive functions such as attention?
-Dopamine is associated with the regulation of movement, pleasure sensation, reward circuitry, and cognitive functions such as attention.
Which neurotransmitter is the main inhibitory neurotransmitter in the central nervous system and is targeted by most sedative medications?
-GABA (gamma-aminobutyric acid) is the main inhibitory neurotransmitter in the central nervous system and is targeted by most sedative medications.
How do selective serotonin reuptake inhibitors (SSRIs) work in treating depression?
-SSRIs work by inhibiting the reuptake of serotonin, thereby increasing its availability in the synaptic cleft and allowing it to interact with its receptors for a longer period, which contributes to their antidepressant activity.
What determines whether a neurotransmitter's signal is excitatory or inhibitory?
-The nature of the neurotransmitter's signal as excitatory or inhibitory is determined by the type of receptor it binds to. For example, serotonin is not inherently excitatory or inhibitory; its effect depends on the specific receptor it interacts with.

Outlines

00:00

🧠 Neurotransmitters: The Basics

This paragraph introduces the concept of neurotransmitters, explaining their role in transmitting information between neurons through synapses. It emphasizes the importance of neurotransmitters, with over a hundred known types, and their storage in synaptic vesicles within the presynaptic terminal. The paragraph also discusses the release of neurotransmitters upon a stimulus, their interaction with receptors on the postsynaptic neuron, and the potential outcomes of these interactions, either excitatory or inhibitory. Additionally, it touches on the need for neurotransmitters to be cleared from the synaptic cleft, either by reuptake or by other mechanisms, to prevent continuous signaling.

05:00

📊 Classification and Examples of Neurotransmitters

This section delves into the classification of neurotransmitters based on their molecular structure and function. It provides examples of different types of neurotransmitters, including amino acids like GABA and glycine, and biogenic amines such as dopamine and norepinephrine. The paragraph also discusses peptides and their role in neurotransmission. It highlights the diversity of neurotransmitters and their classification into low and high molecular weight categories, with the former typically involved in rapid responses and the latter in longer-term effects. The importance of the receptor's role in determining the signal's nature is also emphasized, as the neurotransmitter's effect depends on the type of receptor it binds to.

10:01

💡 Acetylcholine and Dopamine: Functions and Receptors

This paragraph focuses on acetylcholine and dopamine, two significant neurotransmitters. Acetylcholine is described as the neurotransmitter responsible for voluntary muscle control and its presence in both the central and peripheral nervous systems. The paragraph explains the different effects of acetylcholine depending on the type of receptors it binds to, such as nicotinic and muscarinic receptors. Dopamine is highlighted for its crucial role in movement control, pleasure sensation, reward circuitry, and various cognitive functions. The paragraph also discusses the implications of abnormal dopamine levels, such as in psychosis and Parkinson's disease, and the role of dopamine in the reward circuit and the development of addictions.

15:01

🌀 GABA and Serotonin: Inhibition and Modulation

The final paragraph discusses GABA and serotonin, two neurotransmitters with inhibitory and modulatory roles. GABA is presented as the primary inhibitory neurotransmitter, with its activation leading to a decrease in neuronal activity. The paragraph explains the three types of GABA receptors and their effects, as well as the action of benzodiazepines and alcohol on these receptors. Serotonin is described as having a wide range of physiological effects, including mood regulation, sleep, body temperature, and cognitive functions. The paragraph emphasizes the complexity of serotonin's role, as it can act through various receptor types, leading to either excitatory or inhibitory outcomes. It also mentions selective serotonin reuptake inhibitors (SSRIs), a class of antidepressants that increase synaptic serotonin levels by inhibiting its reuptake.

Mindmap

Keywords

💡neurotransmitters

Neurotransmitters are chemical messengers that transmit signals across a synapse, the junction between two neurons, facilitating communication in the nervous system. In the video, they are described as substances that carry information between neurons, playing a critical role in processes such as learning, memory, mood regulation, and muscle control.

💡synapses

Synapses are the points of communication between two neurons where the signal is transmitted from the presynaptic neuron to the postsynaptic neuron. They are crucial for the functioning of the nervous system, allowing for rapid and precise transmission of information.

💡receptors

Receptors are protein molecules located on the surface of cells, including neurons, that receive and respond to specific signals from neurotransmitters. They are essential for signal transduction, determining whether the signal will be excitatory or inhibitory.

💡acetylcholine

Acetylcholine is a neurotransmitter that plays a significant role in the peripheral nervous system, including the control of voluntary muscles, and in the central nervous system, particularly in the parasympathetic division. It is the first neurotransmitter discovered and is involved in various functions such as muscle movement and memory.

💡dopamine

Dopamine is a neurotransmitter associated with the control of movement, pleasure sensations, and the reward circuit in the brain. It is also involved in the regulation of prolactin production, sleep mechanisms, and various cognitive functions, including attention and creativity.

💡GABA (gamma-aminobutyric acid)

GABA is the primary inhibitory neurotransmitter in the central nervous system. It reduces neuronal excitability throughout the brain, playing a crucial role in calming the nervous system and inducing relaxation, sleep, and reducing anxiety.

💡glutamate

Glutamate is the primary excitatory neurotransmitter in the central nervous system. It is involved in many brain functions, including learning and memory, and is present in over 80% of excitatory synapses.

💡serotonin

Serotonin is a neurotransmitter with a wide range of effects on the body and brain, including mood regulation, sleep, appetite, and cognitive functions. It is also involved in the regulation of various physiological processes such as blood vessel constriction and platelet aggregation.

💡neurotransmitter classification

Neurotransmitters can be classified based on their molecular structure and weight, such as small-molecule neurotransmitters like acetylcholine and amino acids, and larger peptide neurotransmitters. This classification helps in understanding their roles and mechanisms in the nervous system.

💡neurotransmitter reuptake

Reuptake is the process by which neurotransmitters are removed from the synaptic cleft and taken back into the presynaptic neuron, ending their signaling action. This mechanism is critical for preventing continuous activation of the postsynaptic neuron and for the regulation of neurotransmitter levels in the synaptic cleft.

💡antidepressants

Antidepressants are medications that are used to treat depression and other mood disorders. They often work by affecting the levels of certain neurotransmitters in the brain, such as serotonin, by inhibiting their reuptake, which increases their availability in the synaptic cleft and enhances their signaling effects.

Highlights

Neurotransmitters are substances that convey information between neurons through synapses.

There are over a hundred known neurotransmitters, and they are contained in synaptic vesicles within the presynaptic terminal.

When a stimulus reaches the neuron, synaptic vesicles fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.

Neurotransmitters can be either excitatory or inhibitory, depending on their interaction with specific receptors on the postsynaptic neuron.

After their release, neurotransmitters need to be removed from the synaptic cleft, either by reuptake or by other mechanisms such as glial cell clearance.

Neurotransmitters can be classified based on their molecular structure, such as amino acids, biogenic amines, and peptides.

Amino acid neurotransmitters include GABA, glutamate, and glycine, which play roles in excitation and inhibition within the nervous system.

Peptide neurotransmitters are larger than amino acids and include substances like endorphins and neuropeptide Y.

Neurotransmitters can also be categorized by their molecular weight, with low molecular weight neurotransmitters typically having faster actions.

Glutamate is the primary excitatory neurotransmitter in the central nervous system and is involved in learning and memory.

Acetylcholine is responsible for nerve transmission in both the central and peripheral nervous systems and is the first neurotransmitter to be discovered.

Dopamine is a catecholamine neurotransmitter that plays a crucial role in controlling movement, pleasure sensations, and the reward circuitry.

GABA is the principal inhibitory neurotransmitter and is associated with three types of inhibitory receptors.

Serotonin is involved in a wide range of physiological functions, including mood regulation, sleep, body temperature, and cognitive functions.

Selective serotonin reuptake inhibitors (SSRIs) are commonly used antidepressants that increase synaptic serotonin levels by inhibiting its reuptake.

The effect of a neurotransmitter is not solely determined by the molecule itself but also by the type of receptor it binds to.

Serotonin can act on both excitatory and inhibitory receptors, demonstrating its role as a modulatory neurotransmitter.

The interaction between neurotransmitters and their receptors is essential for the transmission of signals within the nervous system.

Understanding neurotransmitters and their functions is crucial for developing treatments for various neurological and psychiatric disorders.