Endocrine Flashcards
What do hormones control?
– Reproduction
– Growth and development
– Mobilization of body defenses
– Maintenance of much of homeostasis
– Regulation of metabolism
Hormones are classified chemically as what?
Proteins, peptides, amines, also known as proteins, fat, and steroids
When hormones arouse cells or alter cellular activity what can happen? (5 options)
- Change plasma membrane permeability or membrane
potential by opening or closing ion channels - Activate or inactivate enzymes
- Stimulate or inhibit cell division
- Promote or inhibit secretion of a product
- Turn on or turn off transcription of certain genes
What two mechanisms do hormones act by?
- Direct gene activation
- Second-messenger system
Explain direct gene activation
- Steroid hormone diffuses through the plasma
membrane of target cells - Once inside the cell, the hormone enters the nucleus
- Then, the hormone binds to a specific protein within
the nucleus - Hormone-receptor complex binds to specific sites on
the cell’s DNA - Certain genes are activated to transcribe messenger
RNA - New proteins are synthesized
Explain second-messenger system
- Hormone (first messenger) binds to a receptor
protein on the plasma membrane - Activated receptor sets off a series of reactions that
activates an enzyme - Enzyme catalyzes a reaction that produces a
second-messenger molecule (such as cyclic AMP,
known as cAMP) - Second messenger molecule oversees additional
intracellular changes to promote a specific response
in the target cell
What are hormone levels in the blood maintained by?
Negative feedback systems
What are the groups of stimuli that activate endocrine glands?
- Hormonal
- Humoral
- Neural
What is a hormonal stimuli?
Endocrine organs are activated by other hormones
What is a humoral stimuli?
Changing blood levels of certain ions and nutrients stimulate hormone release.
What is a neural stimuli?
Nerve fibers stimulate hormone release.
Name the MAJOR endocrine organs.
Hypothalamus
* Pituitary gland
* Pineal gland
* Thyroid gland
* Parathyroid glands
* Thymus
* Adrenal glands
* Pancreas
* Gonads (testes and ovaries)
What is the master endocrine gland and why?
Pituitary gland, because it controls activities of so many other endocrine glands
Other organs that are generally nonendocrine in function but also secrete hormones are…
– Stomach
– Small intestine
– Kidneys
– Heart
– placenta
What is Calcitonin?
Decreases blood calcium by causing
deposition of calcium into bone from thyroid gland
What is thyroid hormone?
Major metabolic hormone, controls rate of oxidation of glucose for body heat and formation of ATP from the thyroid gland
What is Insulin?
Released from the pancreas when blood glucose levels are high to increase uptake and metabolism of glucose.
What is Glucagon?
Released from pancreas when blood glucose levels are low, stimulates liver to release glucose to the blood
What is thymosin?
-Released from the Thymus
– Matures some types of white blood cells
– Important in developing the immune system
