Nerves vs Hormones
In multicellular animals, most cells are specialized to perform only one or few functions, and the group of these cells forms organ systems in the animal body. In order to carry out their functions properly, cells need to coordinate and communicate with other cells, as well. Animals have two coordinating systems to help this coordination and communication between cells; namely, endocrine system and nervous system (Read the Difference Between Nervous System and Endocrine System). These two systems interact in controlling the internal environment of animals. Nervous system is basically composed of nerves, whereas endocrine system is made up of endocrine glands, which secrete hormones as their chemical coordinators.
Nerve system coordinates all the body activities by means of neurons, the cells that act as the functional and structural unit of the nervous system. Unlike the endocrine system, nerve responses are very quick and do not last for a long period. There are three types of nerves; namely, sensory nerves, which carry impulses from sense organs to brain, motor nerves, which carry impulses from the brain to other parts of the body, and mixed nerves, which are a mixture of sensory and motor nerve fibers.
Hormones are chemical regulators that are secreted by ductless glands called endocrine glands and are released in the blood directly. They are transported to a target organ by blood. Hormones may be proteins, polypeptides, amino acids derivatives or steroids. Generally very small amount of hormone is needed for activating its function. Hormones are very specific in their action and influence only one specific organ, even though they are circulating with the blood stream throughout the body. Major endocrine glands found in the human body are hypothalamus and pituitary, pineal gland, thyroid gland, parathyroid, adrenal gland, pancreas, ovaries and testes. Some examples for hormones are Thyroxine, aldesterone, adrenaline, growth hormone, RH, ADH, progesterone, testosterone etc.
What is the difference between Nerves and Hormones?
• Nerve impulses mainly carry the signal within nerves, whereas hormones act as a chemical signal within the endocrine system.
• Nerve signals transmit along the nerves, and are controlled by the central nervous system while hormones are transmitted through the bloodstream and are controlled by endocrine glands.
• In general, hormones have slow speed of effect while nerve signals have rapid transmission.
• Nerve signals generally short-lived, whereas the hormonal effect is long-lasting.
• In nerve transmittance, very few types of chemical coordinators called neurotransmitters are involved, which are secreted only onto target tissue. In contrast, hormonal transmittance involves many different types of hormones (chemical coordinators), where each one affecting different, specific tissue.
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