Animal Nervous and Endocrine Systems: Coordination Explained

Animal Coordination: Nervous and Endocrine Systems

Stimuli are transmitted to focal points. Animals have two systems for coordinating information received through sensory receptors: the nervous system, which transmits electrical signals through nerves, and the endocrine system, which sends chemical signals through the blood. Both systems produce responses to stimuli that are transmitted to effector organs (muscles or glands), thereby regulating the organism's activity at all times.

The Nervous System

The nervous system is the control center and coordinating agency.

Function: To gather information from various receptors, interpret it, generate responses, and transmit these responses to other parts of the body to inform them of what action to take.

The actions of the nervous system are fast, though their effects may not last long.

All animals possess a nervous system. As this system evolves, responses become faster and more complex.

Nerve Cells

Neurons: Cells that form the nervous system, including elongated cells that are the prolongations of nerves.

Parts of the Nervous System

• Brain: The control center for information coordination. It regulates all bodily functions and is protected by the skull.
• Spinal Cord: Protected by the spine, it serves as the pathway through which information travels from the body to the brain and vice versa. Together with the brain, it forms the central nervous system.
• Nerves: The network that connects the central nervous system with the rest of the body.
• Reflex: A simple and automatic response to a stimulus. It occurs involuntarily, without conscious thought.

Voluntary actions (reading, running, writing, etc.) do not occur automatically; they involve the brain and depend on individual will.

The Endocrine System

In addition to the nervous system, many animals have another system of coordination: the endocrine system, which uses chemical messengers (hormones).

Hormones: Chemicals produced in endocrine glands, released into the blood, and distributed throughout the body. They act only on specific target cells.

Hormones are crucial in controlling growth, chemical reactions (metabolism), and reproductive functions.

They also monitor changes during the metamorphosis of some animals.

For example, in silkworms, hormones regulate the duration of each stage and the body changes required to transition to the adult insect form.

Hormones also act on cells in the tail of tadpoles, facilitating the absorption of the tail as the frog's legs develop.

The actions of the endocrine system are slower but more prolonged than those of the nervous system.