1. What term is used to describe a neuron that is not transmitting a signal? 2. Describe the conditions inside and outside of a neuron during resting potential. 3. Describe the conditions inside and outside of a neuron during action potential. 4. What causes a neuron to change from resting potential to action potential? 5. What causes a neuron to return to a resting potential from an action potential? 6. How is a signal transmitted through a single neuron? 7. What is a neurotransmitter? 8. How are neurotransmitters secreted into the synaptic cleft? 9. How does a neurotransmitter cause an action potential in a receiving neuron? 10. How is the signal between neurons stopped?
Answer
1. The term used to describe a neuron that is not transmitting a signal is “resting state” or “resting potential.” In this state, the neuron is not actively sending or receiving information.
2. During resting potential, the conditions inside and outside of a neuron are characterized by a difference in electrical charge, known as the resting membrane potential. Inside the neuron, the concentration of positively charged ions, such as potassium (K+) and negatively charged ions, such as chloride (Cl-), is higher compared to the outside. Additionally, there are large negatively charged proteins inside the neuron. Outside the neuron, the concentration of positively charged ions, such as sodium (Na+) and calcium (Ca2+), is higher.
3. During action potential, the conditions inside and outside of a neuron change dramatically. The neuron experiences a rapid and temporary increase in electrical charge, allowing it to transmit an electrical signal. Inside the neuron, there is a sudden influx of positively charged ions, primarily sodium (Na+). As a result, the charge inside the neuron becomes more positive, known as depolarization. Outside the neuron, there is a decrease in the concentration of positively charged ions.
4. A neuron changes from resting potential to action potential when it receives enough stimulation or input from other neurons or sensory stimuli. This stimulation leads to the opening of ion channels, allowing an influx of positively charged ions, primarily sodium ions, which depolarizes the neuron and triggers the action potential.
5. After an action potential, a neuron returns to a resting potential through a process known as repolarization. During repolarization, the neuron actively transports the positively charged ions, such as sodium and potassium, back to their original concentrations inside and outside the neuron. This restores the resting membrane potential and prepares the neuron for another potential action.
6. A signal is transmitted through a single neuron via a process known as synaptic transmission. When the action potential reaches the end of the axon, it triggers the release of chemical messengers called neurotransmitters into the synaptic cleft, a small gap between the axon terminal and the receiving neuron. The neurotransmitters bind to receptors on the receiving neuron, thereby transmitting the signal from one neuron to another.
7. A neurotransmitter is a chemical messenger used by neurons to communicate with each other and transmit signals. These chemicals are released by the presynaptic neuron and bind to receptors on the postsynaptic neuron, initiating a response in the receiving neuron.
8. Neurotransmitters are secreted into the synaptic cleft through a process called exocytosis. When the action potential reaches the end of the axon, it triggers the release of neurotransmitter-containing vesicles from the presynaptic neuron into the synaptic cleft. These vesicles fuse with the presynaptic membrane, releasing the neurotransmitters into the synaptic cleft.
9. Once a neurotransmitter binds to its specific receptor on the receiving neuron, it can elicit various effects. In most cases, the binding of a neurotransmitter causes ion channels on the postsynaptic membrane to open or close. This, in turn, influences the flow of ions into or out of the postsynaptic neuron, leading to a change in the electrical charge across the membrane. If this change is significant enough, it can reach the threshold for an action potential to occur in the receiving neuron.
10. The signal between neurons is stopped through a process called synaptic inhibition. After neurotransmitter binding, enzymes may break down the neurotransmitter molecules in the synaptic cleft. Alternatively, the neurotransmitter molecules may be taken back up into the presynaptic neuron, a process called reuptake. Once inside the neuron, the neurotransmitters can either be recycled or degraded. This cessation of neurotransmitter signaling allows the neuron to return to its resting potential state and prepares it for further signaling.
