Biological Coordination: Stimuli, Receptors, and Response Systems

The Relationship Function: Capturing Stimuli and Responding

The relationship function allows human beings to capture specific changes (stimuli) that occur within or outside the body and respond as best as possible. Stimuli are variations in the environment, both external and internal, capable of triggering a response.

Categories of Stimuli

• Physical: Such as light, temperature, and sound.
• Chemical: Such as the presence or absence of chemicals in the internal or external environment; for example, water, salts, or pollutants.
• Biotic: Caused by the presence or absence of other living organisms.

Sensory Receptors and Stimulus Detection

Sensory receptors are specialized structures that capture both external and internal stimuli.

Receptor Classification by Location

• Exteroceptors: Located on the surface of the body.
• Interoceptors: Located internally.

Receptor Classification by Stimulus Type

• Mechanoreceptors: Sensitive to touch, pressure, movement, and sound.
• Chemoreceptors: Capture the presence of certain substances in the environment.
• Thermoreceptors: Perceive temperature changes in the environment.
• Photoreceptors: Capture light and are necessary for vision.

Coordination Systems in Animals and Plants

Animal Coordination

Animals utilize two main systems for coordination:

1. Nervous System: Regulates and coordinates functions of the body through nerve impulses.
2. Hormonal System (Endocrine System): Regulates and coordinates functions by producing chemical substances.

Plant Coordination

The plants coordinate their functions through the production of certain chemicals, plant hormones, in a manner similar to the hormonal system of animals.

Structure and Function of the Animal Nervous System

The nervous system is the set of organs and structures formed by nerve cells. It receives information, interprets it, prepares, and transmits responses to effectors, thereby coordinating the animal body.

Nervous System Components

In animals, including simple invertebrates, the nervous system includes:

• Nerve Centers: These are recipient organs that receive information and create responses that are sent to effectors. They include the brain (located in the head) and the spinal cord (located along the back of the animal).
• Nerves: Formed by nerve fibers, which consist of extensions of neurons.

Nervous System Functioning

The information received by the sense organs (receptors) is processed by the nervous system, which produces a response. The operation is similar in all animals.