Neuron Structure and Types

Study Notes

Structure of a Neuron

Neurons are the fundamental units of the nervous system, specialized cells responsible for transmitting information throughout the body.
Neurons have a unique structure that facilitates this function:
- Cell body (soma): Contains the nucleus and other organelles essential for cell function.
- Dendrites: Branch-like extensions that receive signals from other neurons.
- Axon: A long, slender projection that transmits signals away from the cell body to other neurons, muscles, or glands.
- Myelin sheath: A fatty insulating layer that surrounds some axons, increasing the speed of signal transmission.
- Nodes of Ranvier: Gaps in the myelin sheath that facilitate saltatory conduction (faster signal transmission).
- Synaptic terminals: The end of the axon that releases neurotransmitters to communicate with other cells.

Types of Neurons

Sensory neurons: Carry information from sensory receptors to the central nervous system (CNS).
Motor neurons: Carry information from the CNS to muscles or glands.
Interneurons: Connect sensory and motor neurons within the CNS. These are crucial for processing information and forming complex neural circuits.

Function of a Neuron: Action Potentials

Neurons communicate through electrochemical signals called action potentials.
Resting potential: The neuron's electrical charge when it's not transmitting a signal.
Stimulus: A stimulus strong enough can initiate an action potential, causing changes in the neuron's membrane potential.
Depolarization: Involves a rapid reversal of the membrane potential, as positive ions flow into the neuron.
Repolarization: After the peak action potential, restores the membrane potential to its resting state.
Saltatory conduction: The signal jumps between nodes of Ranvier, greatly accelerating transmission speed in myelinated neurons.

Neurotransmitters and Synaptic Transmission

Neurotransmitters are chemical messengers released from synaptic terminals.
These chemicals transmit signals across the synaptic cleft (space between neurons).
Neurotransmitter receptors on the receiving neuron initiate a response.
Examples of neurotransmitters include glutamate, GABA, dopamine, serotonin, and norepinephrine. Each has diverse effects on the body.
Synaptic transmission involves:
- Neurotransmitter synthesis
- Storage in vesicles
- Release into the synaptic cleft
- Binding to receptors
- Degradation or reuptake of neurotransmitters

Synaptic Plasticity

Synapses can change their strength and responsiveness based on activity levels.
This plasticity is essential for learning and memory.
Long-term potentiation (LTP) and long-term depression (LTD) are examples of synaptic plasticity.

Neural Circuits

Neurons form complex circuits to process information.
These circuits are the basis for all nervous system functions, including sensory perception, motor control, and cognitive processes.

Description

This quiz explores the intricate structure of neurons, the fundamental units of the nervous system. Delve into the roles of the cell body, dendrites, axon, myelin sheath, and synaptic terminals. Additionally, learn about the different types of neurons and their functions in information transmission.