![]() ![]() Each vesicle contains about 10,000 neurotransmitter molecules. (b) In this pseudo-colored image from a scanning electron microscope, a terminal button (green) has been opened to reveal the synaptic vesicles (orange and blue) inside. The neurotransmitter binds to any receptor that it fits.įigure 3.9 (a) The synapse is the space between the terminal button of one neuron and the dendrite of another neuron. How does a neurotransmitter “know” which receptor to bind to? The neurotransmitter and the receptor have what is referred to as a lock-and-key relationship-specific neurotransmitters fit specific receptors similar to how a key fits a lock. Receptors, proteins on the cell surface where neurotransmitters attach, vary in shape, with different shapes “matching” different neurotransmitters. Once neurotransmitters are released into the synapse, they travel across the small space and bind with corresponding receptors on the dendrite of an adjacent neuron. The synapse is a very small space between two neurons and is an important site where communication between neurons occurs. In healthy individuals, the neuronal signal moves rapidly down the axon to the terminal buttons, where synaptic vesicles release neurotransmitters into the synapse ( Figure 3.9). While some treatments may help to modify the course of the disease and manage certain symptoms, there is currently no known cure for multiple sclerosis. The resulting interference in the electrical signal prevents the quick transmittal of information by neurons and can lead to a number of symptoms, such as dizziness, fatigue, loss of motor control, and sexual dysfunction. Multiple sclerosis (MS), an autoimmune disorder, involves a large-scale loss of the myelin sheath on axons throughout the nervous system. To understand how this works, let’s consider an example. The myelin sheath is crucial for the normal operation of the neurons within the nervous system: the loss of the insulation it provides can be detrimental to normal function. ![]() In some axons, glial cells form a fatty substance known as the myelin sheath, which coats the axon and acts as an insulator, increasing the speed at which the signal travels. The terminal buttons contain synaptic vesicles that house neurotransmitters, the chemical messengers of the nervous system.Īxons range in length from a fraction of an inch to several feet. These signals are transmitted electrically across the soma and down a major extension from the soma known as the axon, which ends at multiple terminal buttons. The neuron is a small information processor, and dendrites serve as input sites where signals are received from other neurons. The soma has branching extensions known as dendrites. The nucleus of the neuron is located in the soma, or cell body. This membrane allows smaller molecules and molecules without an electrical charge to pass through it, while stopping larger or highly charged molecules.įigure 3.8 This illustration shows a prototypical neuron, which is being myelinated. A neuron’s outer surface is made up of a semipermeable membrane. Like all cells, neurons consist of several different parts, each serving a specialized function ( Figure 3.8). Neurons are the central building blocks of the nervous system, 100 billion strong at birth. This section briefly describes the structure and function of neurons. Neurons, on the other hand, serve as interconnected information processors that are essential for all of the tasks of the nervous system. Glial cells provide scaffolding on which the nervous system is built, help neurons line up closely with each other to allow neuronal communication, provide insulation to neurons, transport nutrients and waste products, and mediate immune responses. Glial cells, which outnumber neurons ten to one, are traditionally thought to play a supportive role to neurons, both physically and metabolically. ![]() The nervous system is composed of two basic cell types: glial cells (also known as glia) and neurons. Learning how the cells and organs (like the brain) function, help us understand the biological basis behind human psychology. Psychologists striving to understand the human mind may study the nervous system. Explain how drugs act as agonists or antagonists for a given neurotransmitter system.Describe how neurons communicate with each other.Learning Objectives By the end of this section, you will be able to: ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |