Human Physiology

Question

How do neurotransmitters get transported within a single neuron?

What is are the differences and similarities between serotonin and dopamine?

Answer 1

How do neurotransmitters get transported within a single neuron?

Neurotransmitters are neurotransmitter molecules that transmit signals from a neuron to a target cell and interact with receptors on the membrane of the target cell. These chemicals are secreted by neurons and act on nearby cells, either exciting them or inhibiting them. They move across synapses in an electrochemical process that converts an electrical signal into a chemical one (a type of synaptic transmission). When they reach their destination, they bind to specific sites called receptors and produce changes in how those cells function.The movement of these neurotransmitters across the synapse is called neurotransmission. The general structure of neurotransmission involves the following steps:

1. Neurotransmitter molecules are released into the synapse, where they change conformation to allow them to be packaged into vesicles for synaptic transmission. These vesicles contain enzymes that act on them and break them down, releasing their contents at the synapse.
2. The neurotransmitters bind to receptors on the postsynaptic membrane and cause an excitatory or inhibitory signal to be sent to the postsynaptic cell. Additionally, some neurotransmitters can also affect nearby cells by binding to receptors located on their surface, independent of whether there is a synapse between them.
3. The signal is received by the postsynaptic neuron, which may release its transmitters into the synapse; this is called volume transmission. The neurotransmitters can also be broken down into their inactive constituents, usually by enzymes in the pre-synaptic neuron.

1. The process of releasing neurotransmitters at the synapse is called exocytosis. Exocytosis of neurotransmitters occurs in response to a stimulus when an action potential arrives at the presynaptic terminal.
2. The neurotransmitters are released from vesicles and diffuse across the synapse before finally being picked up by receptors on the postsynaptic membrane. This process is called synaptic transmission. The neurotransmitter binds to a receptor, and the receptor opens ion channels that lead to changes in the charge state of the membrane.
3. The change in charge state causes a voltage-dependent conformational change in an electrochemical gradient across it, and this causes the neurotransmitter to move further along the gradient to where it can be taken up by enzymes that catalyze its metabolism. This process is called the diffusion of the neurotransmitters across the synapse. The enzymes are located on or extremely close to the postsynaptic membrane, which is why they are also called presynaptic enzymes.
4. The volume transmission of neurotransmitters occurs when an impulse arrives at the presynaptic terminal and causes a release of the transmitter into the synaptic cleft through vesicles and not from the release sites. The transmitter binds to receptors on nearby membranes and induces a response, possibly through secretion into the extracellular fluid.
5. Neurotransmission is a mechanism that is vital to many body functions. Neurotransmitters are used in the nervous systems of animals. They are also present in and essential for the functioning of some single-celled organisms, such as "Paramecium." Their presence in plants has been demonstrated, but their role is not yet understood.

What are the differences and similarities between serotonin and dopamine?

similarities

1. They are both neurotransmitters that play a role in regulating mood, behavior, and cognition.
2. They both affect how we feel pleasure, as well as how we experience a sense of reward.
3. They both are involved in the regulation of appetite, sleep, and energy levels.

differences

1. Serotonin is a slower acting neurotransmitter while dopamine acts quickly.
2. Serotonin can last for up to five hours but dopamine only lasts for about ten minutes.
3. Serotonin is usually found in cells of the nervous system while dopamine is mainly located in the brain and also in cells in other parts of the body.
4. Serotonin systems are found all over the body while dopamine mostly occurs in brain tissue and in cells of the central nervous system.
5. Serotonin is a neurotransmitter that alters and controls emotions and moods while dopamine modifies learning, memory, movement and other basic functions of the brain.