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.
A Bronze Age Spindle Whorl from Tipperary, Ireland (image from irisharchaeology.ie) In Neolithic times, the spindle whorls are made stone. At least those that have survived are. By the bronze age we begin to see a mix of stone and baked clay whorls.