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SECTION 1
HORMONES
Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism. It is essentially a chemical messenger that transports a signal from one cell to another. All multicellular organisms produce hormones; plant hormones are also called phytohormones. Hormones in animals are often transported in the blood. Cells respond to a hormone when they express a specific receptor for that hormone. The hormone binds to the receptor protein, resulting in the activation of a signal transduction mechanism that ultimately leads to cell type-specific responses.
Endocrine hormone molecules are secreted (released) directly into the bloodstream, while exocrine hormones are secreted directly into a duct, and from the duct they either flow into the bloodstream or they flow from cell to cell by diffusion in a process known as paracrine signalling.
Hormone effects vary widely, but can include:
• stimulation or inhibition of growth,
• In puberty hormones can affect mood and mind
• induction or suppression of apoptosis (programmed cell death)
• activation or inhibition of the immune system
• regulating metabolism
• preparation for a new activity (e.g., fighting, fleeing, mating)
• preparation for a new phase of life (e.g., puberty, caring for offspring, menopause)
• controlling the reproductive cycle
MEN
Testosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands. It is the principal male sex hormone and an anabolic steroid.

Testosterone has effects on both men and women examples include enhanced libido, increased energy, increased production of red blood cells and protection against osteoporosis. On average, an...