Biological Bases of Behavior: Nervous System, Brain

The study of Biological bases of behavior is the union between two disciplines responsible for understanding human behavior: psychology and biology . Although an important part of our behavior is determined by our social environment, our biology has a great weight on who we are and how we act.

Although the exact relationship between our biology and our behavior is not yet clear, in recent decades much progress has been made in the study of this discipline. Among other topics, researchers have focused on better understanding the operation of our nervous system and its relation to our mental processes.

Biological bases of behavior

Of special importance is the study of our brain , a discipline known as neuroscience. On the other hand, thanks to theoretical models such as biopsychosocial, more and more emphasis is placed on the relationship between biology, environment and mental processes to explain human behavior.

Index

  • 1 Nervous system
    • 1.1 Central Nervous System
    • 1.2 Peripheral nervous system
  • 2 Brain
    • 2.1 Reptilian brain
    • 2.2 Limbic brain
    • 2.3 Cerebral cortex
  • 3 Neurons and information transmission
    • 3.1 Structure of neurons
    • 3.2 Transmission of information
  • 4 Exocrine and endocrine glands
    • 4.1 Endocrine glands
    • 4.2 Exocrine glands
    • 4.3 Classification according to the type of secretion
  • 5 References

Nervous system

The nervous system is the part of an organism responsible for detecting signals from both the outside world and the inside of the same, and to create and transmit the appropriate responses to the motor organs. It is one of the fundamental components of animal organisms.

In the case of humans, the nervous system is especially complex. It is usually considered that the bodies in charge of the transmission of information and the elaboration of answers are organized in two large groups:

- The central nervous system, formed by the spinal cord and the brain.

- He peripheral nervous system , formed by several types of nerves that transmit information from the organs to the brain and vice versa.

Both subgroups of the nervous system consist mainly of neurons, a type of special cell responsible for transmitting and processing information.

Central Nervous System

The vast majority of multicellular animals possess a central nervous system, with the exception of some simple organisms such as sponges.

However, the complexity of the central nervous system differs greatly between species, but in almost all it consists of a brain, a central nervous cord, and a large number of peripheral nerves that emerge from it.

In the case of humans, our brain is the most complex of all the animal Kingdom . This organ is responsible for processing all the information provided by the senses, which it receives through the spinal cord thanks to the action of the peripheral nerves.

Once the information is processed, our brain is able to develop an appropriate response to the situation and transmit it back to the challenge of the body, specifically the effector organs. These responses can be elaborated consciously or unconsciously, depending on where in the brain they form.

For its part, the spinal cord is made up of a set of nerves protected by the spine.

Through this is collected all the information provided by the sensory organs and peripheral nerves, to be transmitted later to the brain. Later, the cord is responsible for carrying the response to the effector organs.

Peripheral nervous system

The second subset of the nervous system is formed by all the peripheral nerves, which collect the information from the sensory organs and transmit them to the spinal cord. Later, they also carry the answers from the spinal cord to the organs responsible for carrying them out.

The nerves responsible for transmitting information from the brain to the effector organs are called"motors"or"efferents". On the other hand, those that transmit sensory information to the central nervous system are known as"sensory"or"afferent".

In turn, we can distinguish three subgroups within the peripheral nervous system:

- Somatic nervous system, in charge of voluntary movements.

- Autonomic nervous system , related to the involuntary responses of our body. It is usually divided into the sympathetic nervous system and the parasympathetic nervous system.

- Enteric nervous system , located entirely within the digestive system and responsible for carrying out correctly the digestion of food.

Brain

The brain is the most important organ of the entire nervous system. It is responsible for receiving and processing all information from the senses, as well as to develop the appropriate responses for each situation. It is also the most complex organ of vertebrate organisms.

The human brain is especially powerful, thanks to its approximately 33 billion neurons and the billions of synapse (connections between neurons) that houses.

East large number of neurons and synapses it allows us to analyze information in an incredibly fast way: some experts think that we can process about 14 million bits per second.

Besides the processing of information, the main function of the brain is to control the rest of the body's organs. This is done mainly in two ways: by controlling the muscles (voluntary and involuntary), and by secreting hormones.

Most of our body's responses need to be processed by the brain before it takes place.

The brain is divided into several different parts, but all are interconnected. The oldest parts of the brain have more weight in our behavior than those of more recent appearance.

The three main systems of the brain are the following:

- Reptilian brain , in charge of our instincts and automatic responses.

- Limbic brain, system that processes and generates our emotions.

- Cerebral cortex , responsible for logical and rational thinking and the appearance of consciousness.

Reptilian brain

The reptilian brain receives this name because evolutionarily it appeared for the first time in reptiles. In our brain, this system is formed by the Brain stem and the cerebellum .

The reptilian brain takes care of all those instinctive behaviors that we need to survive. Among its functions are to control autonomous functions such as breathing or heartbeat, balance and involuntary movements of muscles.

In this part of the brain are also located the basic needs of humans, such as water, food or sex. That is why these instincts are the strongest we can feel, and completely dominate our rational mind on many occasions.

Limbic brain

The limbic brain is formed by the amygdala , he hippocampus and the hypothalamus . This brain subsystem first appeared in mammals and is responsible for regulating emotions .

The main function of limbic system is to classify our experiences as pleasant or unpleasant, in such a way that we can learn what hurts us and what helps us. Therefore, it also takes care of the memory, in such a way that our experiences are stored in the hippocampus.

In the case of humans, although we have a series of basic emotions, our interpretation of them is mediated by the cerebral cortex. In this way, our rationality influences our emotions, and vice versa.

Cerebral cortex

The last subsystem of the brain is also known as neocortex. It is responsible for the superior functions of the brain, such as rationality, cognition or especially complex movements. In turn, it is the part that gives us the ability to think and to be aware of ourselves.

This part of the brain is the most recent appearance, being present only in some species of higher mammals such as dolphins or chimpanzees. However, in no species is it as developed as in humans.

It is worth mentioning that the neocortex has less influence on our behavior than the other two subsystems. Some experiments indicate that its main function is to rationalize the decisions we make unconsciously using the reptilian and limbic brains.

Neurons and information transmission

Neurons are the cells that make up the vast majority of the nervous system. It is a highly specialized type of cell that receives, processes and transmits information through electrical impulses and chemical signals. The neurons are connected to each other through the synapses.

Neurons differ from other cells in many ways, one of the most important being the fact that they can not reproduce.

Until very recently it was believed that the brain of an adult human was not capable of producing new neurons, although the latest studies seem to indicate that this is not true.

There are several types of neurons based on the function they perform:

-Neural sensory, capable of detecting a type of stimulus.

- Motor neurons , who receive information from the brain and spinal cord, causing muscle contractions and hormonal responses.

-Interneurons, responsible for connecting brain or spinal cord neurons forming neural networks.

Structure of neurons

Neurons are mainly composed of three components: soma, dendrites, and axon.

- The soma is the body of the neuron, occupying the largest percentage of cell space. Inside are the organelles that allow the neuron to perform its function.

- The dendrites are small extensions that arise from the soma, and that connect with the axon of another neuron. Through these connections, the cell is able to receive information.

- The axon is a prolongation of larger size of the neuron, through which it is able to transmit information through a synapse. In humans, the axon of a neuron can reach up to one meter in length.

Transmission of information

Through the synapses, neurons are able to transmit information to each other extremely rapidly. This process of transmission of information is produced by electrical impulses, which travel between the different neurons through the alteration of the neuronal chemical equilibrium.

The electrical potentials of the neurons are controlled by the amount of sodium and potassium present both inside and outside; the alteration of these potentials are those that cause the transmission of information in the synapses.

Exocrine and endocrine glands

The last component of the human nervous system are the glands. These are sets of cells whose function is to synthesize substances such as hormones, which are later released into the bloodstream (endocrine glands) or in specific parts of the body (exocrine glands).

Endocrine glands

These glands are responsible for producing hormonal responses in our body. Hormones transmit chemical signals that help control different bodily functions, working in conjunction with the central nervous system and peripheral.

The most important endocrine glands are the Pineal gland , the pituitary, the pancreas, the ovaries and testes, the thyroid gland and the parathyroid gland, the hypothalamus and the adrenal glands.

The substances they generate are directly released into the bloodstream, altering the functioning of the organs and producing all kinds of responses.

Exocrine glands

The other type of glands present in the human body, the exocrine glands, differ from the first in that they release the substances they produce in different conduits of the human body or in its exterior. For example, salivary glands or sweat glands are part of this group.

There are different classifications for the exocrine glands, although the most used is the one that divides them into apocrine, holocrine and merocrine.

- The apocrine glands are those that lose a part of their cells when they produce their secretion. Some of these glands are part of this type, such as sweat glands or mammary glands.

- The holocrine glands are those whose cells disintegrate completely when their secretion occurs. An example of this type of gland are the sebaceous ones.

- The merocrine glands generate their secretions through a process known as exocytosis. The salivary glands and the lacrimal glands are part of this group.

Classification according to the type of secretion

Another of the most common classifications for the exocrine glands is what differentiates them according to the type of substance they release. According to this classification, there are three main types of exocrine glands:

- Serous glands, which produce an aqueous secretion, normally rich in proteins. An example of this type are the sweat glands.

- Mucous glands, responsible for producing a viscous and rich in carbohydrate secretion. The main example of this type of gland are the calciform cells, responsible for coating the digestive and respiratory systems with a mucous layer to prevent damage from contact with the outside.

- Sebaceous glands, which secrete a fatty fluid rich in lipid substances. One of the types of sebaceous glands are the Meibomian glands, which are found inside the eyelids and are responsible for protecting the eye from the outside.

References

  1. "Nervous system"in: Wikipedia. Retrieved on: 7 April 2018 from Wikipedia: en.wikipedia.org.
  2. "Brain"in: Wikipedia. Retrieved on: 7 April 2018 from Wikipedia: en.wikipedia.org.
  3. "Neuron"in: Wikipedia. Retrieved on: 7 April 2018 from Wikipedia: en.wikipedia.org.
  4. "Triune Brain"in: Wikipedia. Retrieved on: 7 April 2018 from Wikipedia: en.wikipedia.org.
  5. "Gland"in: Wikipedia. Retrieved on: 7 April 2018 from Wikipedia: en.wikipedia.org.


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