Relation Functions and Coordination Systems
Introduction
Relation functions are the result of joint action and coordination systems that ensure survival. Sensory receptors capture stimuli from the internal and external environment, allowing for the development of effective responses for survival. Coordination systems comprise the nervous system and the hormonal or endocrine system, which work together to control body functions, ensuring that the systems of the agencies act coordinately. Both systems form a single system: the neuroendocrine system.
These two systems receive information through sensory receptors and produce responses to stimuli, which can be of two types:
- Neural and hormonal responses to external environmental stimuli constitute behavior and execute actions carried out through the motor system, consisting of the skeletal and muscular systems.
- Neural and hormonal responses to internal environmental stimuli constitute physiological homeostasis.
The Nervous System
The nervous system is a vast and complex network of neurons. Its basic component is nerve tissue, and its function is to interpret, respond to, and store information received from the outside world and the state of our body. Neurons are the anatomical and physiological units of the nervous system. They perceive stimuli and produce responses based on the generation and transmission of nerve impulses. The nerve impulse propagates information between neurons through electrical and chemical phenomena.
Between neurons, there is a small gap called the synaptic cleft. The synapse is the point of communication between two neurons. Communication is accomplished through neurotransmitters, which act as chemical messengers localized in synaptic vesicles. Various types of synapses can be established: neuron to neuron, neuron to muscle cell, and neuron to glandular cell.
Divisions of the Nervous System
CNS (Central Nervous System): Located in the brain and spinal cord.
PNS (Peripheral Nervous System): Consists of the axons of neurons grouped in nerves, whose cell bodies are housed in the CNS. Nerves are made of the longest extensions of neurons (axons) and act as pathways for information flow through the body.
Types of nerves:
- Cranial nerves: Originate in the brain.
- Spinal nerves: Originate in the spinal cord.
The impulses transmitted by both types of nerves can be sensory or motor.
- Sensory impulses travel through sensory nerves from the organs to the spinal cord and brain, reporting on what happens.
- Motor impulses travel through motor nerves in the opposite direction, from the brain and spinal cord to the muscles.
- Mixed nerves carry both sensory and motor impulses.
Central Nervous System (CNS)
The CNS is an essential part of the nervous system, consisting of the brain and spinal cord, which house the structures responsible for regulation and control processes.
The Spinal Cord
The spinal cord is the central nervous system located within the spine. It communicates with the brain. Its functions can be summarized as follows:
- Conducts impulses coming from the brain.
- Serves as the center of reflex activity.
A reflex is a simple, predictable, and involuntary response to an impulse.
The spinal cord has two distinct zones:
- The gray matter: Contains interneurons that connect the axons of sensory neurons with motor neurons that innervate the muscles. There are 31 pairs of mixed spinal nerves in the spinal cord.
- The white matter: Formed by neural axons grouped together in nerve cords, carrying ascending and descending impulses.
The Brain
The brain is an organ of the CNS protected by the skull. It controls and coordinates the activity of other body systems and is connected to the spinal cord through the brainstem. Its parts include:
- Brainstem: The most primitive part of the brain, responsible for life support. It has two key structures:
- Medulla: Controls heartbeat, breathing rate, and reflex activity.
- Reticular formation: Maintains wakefulness and is involved in awakening.
- Cerebellum: Involved in maintaining balance and coordinating movements.
- Thalamus: The relay point for sensory neurons to the brain.
- Hypothalamus: The center of visceral or vegetative life, controlling the secretion of pituitary hormones and the autonomic nervous system.
- Cerebrum: The most evolved brain structure, with two closely related components:
- The limbic system: The emotional brain, involved in learning, emotions, and memory.
- Cerebral cortex or neocortex: Directs and coordinates conscious or voluntary activities.
The cerebrum is the most voluminous part of the brain, divided into two cerebral hemispheres. It contains the neocortex and the limbic system. Sensory areas collect information from the senses, association areas process the information and prepare responses, and motor areas send instructions to the muscles.
The limbic system is a paired brain structure related to attention, memory, emotions, and learning.
Sleep
Sleep is a period of rest caused by the inhibition of neurons in the reticular formation, inducing sleep. Sleep cycles include:
- Slow-wave sleep: Comprises four stages: light sleep (stage 1), sleep (stage 2), deepening sleep (stage 3), and paradoxical sleep or REM sleep (stage 4). During REM sleep, the eyes move quickly, and most nightmares and dreams occur.
The Autonomic Nervous System
The autonomic nervous system (ANS) is composed of two subsystems: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The ANS maintains relationships with both the CNS and PNS, both functionally and anatomically.
Intelligence and Drugs
Intelligence is the ability to solve everyday problems, adapt to new problems, and develop products and services valued within our own culture and other cultural fields.
Drugs are chemical substances that enhance or inhibit the action of neurotransmitters, affecting the synapse mechanism and fooling the brain. Their primary characteristic is psychoactivity, as they can alter normal brain function. Drugs can create addiction and dependency.
Drug dependence causes withdrawal syndrome, inciting drug use and involving a wide range of social and personal circumstances. Regular consumption generates tolerance, and the body adapts to the drug, developing more dependence. Dependence can be of two types:
- Physical dependence: Results from the body’s adaptation to the drug.
- Psychic dependence: The desire to consume drugs.
Withdrawal syndrome produces intense distress that can lead to drug-seeking behavior.
Alcohol is a widely used drug that is quickly absorbed into the blood and reaches the brain, hindering the transmission of nerve impulses. By inhibiting the individual, it causes euphoria and encourages actions that were previously inhibited. Chronic abuse causes irreversible destruction of neurons, psychological dependence, decreased memory, loss of cognitive abilities, and dementia.
It is important to remember that you don’t need drugs to enhance your well-being. Your internal “drugs” (neurotransmitters) are responsible for your welfare.