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. The human nervous system is composed of two parts: the central nervous system, which includes the brain and spinal cord, and the peripheral nervous system, which is composed of nerves and nerve networks throughout the body. The endocrine system is also essential to communication. This system utilizes glands located throughout the body, which secrete hormones that regulate a variety of things such as metabolism, digestion, blood pressure and growth. While the endocrine system is not directly linked to the nervous system, the two interact in a number of ways. The Central Nervous System The central nervous system (CNS) is made up of the brain and spinal cord.
A bronze propeller is made of bronze or alloys including a high percentage of bronze. These include nickel-aluminum-bronze or bronze-manganese combinations. The propeller is composed of blades affixed to a shaft. They rotate in the same plane, generating sufficient thrust to propel the craft forward. Applications. These propellers are very common.
Cut a piece 3 inches long and Â¾ inch wide, round its ends, and with the point of a nail pierce a hole through it each side of the center of the length of the piece (Fig. 55). To finish the propeller, it is only necessary to take hold of the two ends and twist the piece into the shape shown in Fig. 56. The Propeller-shaft requires a short piece of wire with one end bent into a hook (F, Fig. 56).