The International Union for the Conservation of Nature (IUCN) lists 9 species of spider monkey, which can be found in rain forests from southern Mexico through Brazil. The IUCN lists 3 spider-monkey species as Critically Endangered; 5 species of spider monkey are listed as Endangered, and 1 species is Vulnerable.
The foundations of the endocrine system are hormones and glands. A gland is a group of cells that produces and secretes hormones. Hormones are the body's chemical messengers. They send and relay messages between different systems. Many different hormones move through the bloodstream.
The Nervous System and Endocrine System. The nervous system allows for communication throughout the parts of the body. Psychology. While neurons are the building blocks of the bodyâs communication system, it is the networks of neurons that allow signals to move between the brain and body. These organized networks, composed of up to one trillion neurons, make up what is known as the nervous system.