07 The Endocrine System Free Online FlashCards

What is the endocrine system?

The endocrine system is a network of glands and hormone-secreting cells that release hormones into the bloodstream to coordinate body functions.

How does negative feedback regulate hormone release?

Negative feedback reduces signals that promote further hormone release when a hormone’s level or effect is sufficient, helping maintain homeostasis.

How do endocrine glands release hormones?

Endocrine glands release hormones into the blood rather than sending them through ducts.

What determines whether a cell responds to a hormone?

A cell responds to a hormone only if it has a compatible receptor. Receptor binding changes the target cell’s activity.

What are the main roles of thyroid hormones T3 and T4?

Thyroxine (T4) and triiodothyronine (T3) affect metabolic activity, growth, and development.

What does parathyroid hormone do?

Parathyroid hormone (PTH) raises blood calcium and helps regulate calcium balance with the kidneys, intestines, and bones.

How do insulin and glucagon affect blood glucose?

Insulin generally lowers blood glucose, while glucagon raises it.

What role does melatonin play?

Melatonin from the pineal gland helps coordinate daily sleep–wake rhythms.

What is the order of signals in the thyroid hormone pathway?

TRH from the hypothalamus prompts pituitary release of TSH; TSH stimulates the thyroid to release T4 and T3.

How do growth hormone and IGF-1 support growth?

Growth hormone from the anterior pituitary promotes growth and stimulates production of IGF-1, especially in the liver; these signals support tissue and bone growth.

What is metabolism?

Metabolism is the set of chemical processes by which the body obtains, uses, and stores energy.

How does the hypothalamus–pituitary–gonad pathway regulate reproduction?

The hypothalamus releases GnRH, prompting the pituitary to release FSH and LH. These hormones act on the ovaries or testes, supporting reproductive-cell development and sex-hormone production.