The answer is C: endocrine glands.
Hormones are secreted by endocrine glands in the body. These glands are specialized tissues that release hormones directly into the bloodstream. The hormones then travel throughout the body to target cells where they regulate various physiological processes.
Here are some key points to explain why the answer is C:
- Endocrine glands: These glands are responsible for producing and releasing hormones into the bloodstream. They do not have ducts and their secretions are released directly into the bloodstream. Examples of endocrine glands include the pituitary gland, thyroid gland, adrenal glands, and ovaries/testes.
- Functions of hormones: Hormones act as chemical messengers that regulate various bodily functions such as growth and development, metabolism, sexual function, mood, and sleep. They help maintain homeostasis and coordinate the activities of different organs and systems in the body.
- Target cells: Once hormones are released into the bloodstream, they travel to specific target cells or tissues that have receptors for the hormone. These receptors allow the hormone to bind and initiate a cellular response. The effects of hormones can be widespread or localized, depending on the specific hormone and target cells involved.
- Exocrine glands: Exocrine glands, on the other hand, secrete their products through ducts onto a body surface or into a body cavity. Examples of exocrine glands include sweat glands, salivary glands, and mammary glands. These glands do not secrete hormones but rather substances such as sweat, saliva, and milk.
In conclusion, hormones are secreted by endocrine glands in the body. These glands release hormones into the bloodstream, which then travel to target cells to regulate various physiological processes.