Endocrine System Flashcards

Flashcards about the endocrine system, hormones, and their regulation.

Endocrine System

Works alongside the nervous system to send chemical signals, ensuring all organs respond appropriately to various situations. Consists of glands and hormones and is slower than the nervous system, but crucial for regulating long-term functions.

Hormones

Chemical messengers secreted into the bloodstream, traveling to target cells to elicit a response.

Target Cells

Contain specific receptor proteins for each hormone.

Steroid Hormones

Diffuse through the cell membrane and bind to internal receptors. The hormone-receptor complex initiates mRNA synthesis to produce specific proteins that cause changes in the cell.

Water-Soluble Hormones

Bind to receptors on the cell surface, triggering a series of chemical reactions within the cell.

Hypothalamus

Produces hormones like ADH and oxytocin, releasing them to the pituitary gland through specialized nerves.

Pituitary Gland (Posterior Lobe)

Stores and releases ADH and oxytocin produced by the hypothalamus.

Pituitary Gland (Anterior Lobe)

Produces and releases six hormones (ACTH, PRL, hGH, FSH, LH) in response to signals from the hypothalamus.

Tropic Hormones

Stimulate the release of other hormones from target glands; hormones from the hypothalamus and pituitary that target other glands.

Negative Feedback

Regulates hormone levels by preventing excessive secretion once the desired effect is achieved; a common method of control for the endocrine system.

Human Growth Hormone (hGH)

Produced by the anterior pituitary gland; targets tissues directly or indirectly via tropic effects and stimulates the liver to release growth factors.

Thyroid Gland

Produces thyroxine (T4); regulates metabolism by increasing cellular respiration rates, metabolizing fats, proteins, and carbohydrates faster.

TSH (Thyroid-Stimulating Hormone)

Released from the anterior pituitary, stimulates the thyroid to release T4.

Calcitonin

Released when calcium levels are too high in the blood; stimulates bones to absorb the excess calcium, lowering blood calcium levels.

Parathyroid Hormone (PTH)

Released when calcium levels are too low; stimulates bones to release calcium, kidneys to reabsorb calcium from urine, and intestines to absorb more calcium during digestion.