Spinous processes
Dendrites that do not have a spinous process are called “smooth” dendrites. They pick up nerve impulses directly. While the dendrites have the spines, the nerve impulses can be absorbed through the spines as well as through the dendrite trunk.
The thorns emerge from the dendrites like little mushroom heads. They can increase or decrease in size depending on the activity. If they increase the surface of the dendrites, they create more space for connections.
They often contain a kind of calcium storage, the function of which is still being researched. Here you can learn more about calcium With the dendrite trunk and the thorns they take up the information. Usually these are exciting impulses.
In addition, they can “buffer” information and thus protect against stimulus satiation. It is also suspected that increased activity leads to a kind of competition between the linkages. In this case, the “stronger” linkage site receives more protein and can continue to develop, while the “weaker” linkage sites decrease in size due to protein deficiency. This means that the growth of specific sites is associated with a decrease in other sites. This could explain how special abilities improve while other abilities and skills of the person concerned become more difficult.
Axonal transport
The axon is a long tube-like nerve cell process that differs in some aspects from the dendrites. The axon serves to transport substances from the nerve cell body to another cell. For example, certain messenger substances, which are packed in so-called vesicles, as well as nutrients, reach another connection point.
On the other hand, substances can also be transported to the nerve cell body. In this way, not only substances that are good for the cell can reach the inside, but also pathogens. Since the transport mechanisms are complex and slow, the cell restores the released messenger substances and repackages them into vesicles.
The transport can take place with or without the so-called microtubules. The transport of enzymes and large cell scaffold proteins takes place without microtubules. The excitatory or inhibitory information also passes through the axon to the nerve cell. The information is only passed on in one direction, namely that of the target organ. However, the information can spread in both directions in the dendrite and in the nerve cell body.
Abandonment of dendrites
The main task of dendrites is to receive information. They act like antennas, pick up information and pass it on. Within the dendrites the information can run in both directions, towards the cell body as well as back into the so-called dendrite tip.
This happens when an action potential is formed in the axon, which is then not only directed along the axon away from the nerve cell body, but also spreads back to the dendrites in the sense of feedback. This transmission is active, i.e. the dendrites are able to change and process the signals. They succeed in this with the help of proteins.
Especially near the point of connection, the dendrites have many structures that enable them to form and modify proteins. In order to fulfil their tasks, the dendrites need new proteins, which are transported from the cell body into the dendrites. Furthermore, messenger molecules, so-called mRNA, are transported into the dendrites.
These messenger molecules contain the building plan of proteins. Thus proteins can be produced in the dendrites. This plays an important role for the malleability of the nerve cells, the so-called neuroplasticity, which is of great importance for learning processes.
The connection points of the dendrites can be different. An exchange between axon and dendrite is frequent. However, an exchange between different dendrites is also possible.
There is another, rarer exchange possibility between axon and the spinous processes of the dendrites, which has not yet been further explored. Depending on the type and task of the nerve cells, different dendrite patterns can be visualized microscopically. However, their structure and function are very similar.
The so-called pseudounipolar nerve cells are an exception. Like some axons, they are surrounded by a mantle, the so-called myelin sheaths. This is why they show similarities to axons.
The dendrite takes up information from the body and passes it on to the brain. Through its sheath, this dendrite can transmit information over long distances. This is why it is also called a dendritic axon or an axon with dendritic character.
Furthermore, the thorns of the dendrites can protect the nerve cells from stimulus satiation, as they can temporarily store information. They do this when too much information is already being processed in the cell body at once. They adjust a suitable point in time to “replenish” information.
A further task of the dendrites is the nutrition of the nerve cells, whereby they support the glial cells. In addition, the dendrite branches contribute to an increase in the surface area of the nerve cell. Thus, they enable an increase in the possibilities of connection to other cells.
