D5 Hormones and Metabolism Flashcards
What is the endocrine system comprised of and what do they do?
The endocrine system is comprised of ductless glands that release chemicals into the blood to regulate body functions
What is a hormone?
A hormone is a chemical messenger that is transported indiscriminately via the bloodstream to act on distant target cells
Are hormones non/specific?
Hormones are SPECIFIC and will only activate cells or tissues that possess the appropriate target receptor
How does the endocrine system compare to the nervous system?
The endocrine system is slower to initiate, but has a more prolonged response when compared to the nervous system
What do endocrine glands secrete?
Endocrine glands secrete their product (hormones) directly into the bloodstream, rather than through a duct (e.g. exocrine gland)
What are major endocrine glands?
Major endocrine glands include the pancreas, adrenal gland, thyroid gland, pineal gland and the gonads (ovaries and testes)
What are the roles of the hypothalamus and pituitary gland?
The hypothalamus and pituitary gland are neuroendocrine glands and function to link the nervous and endocrine systems
Can only endocrine glands secrete hormones?
NO
Some organs may also secrete hormones despite not being endocrine glands (e.g. adipose tissue secretes leptin)
What are steroid hormones, how are they transported?
Steroid hormones are lipophilic (fat-loving) – meaning they can freely diffuse across the plasma membrane of a cell
Where do steroid hormones bind?
They bind to receptors in either the cytoplasm or nucleus of the target cell, to form an active receptor-hormone complex
What will the activated receptor-hormone complex do?
This activated complex will move into the nucleus and bind directly to DNA, acting as a transcription factor for gene expression
What are examples of steroid hormones?
Examples of steroid hormones include those produced by the gonads (i.e. estrogen, progesterone and testosterone)
What are peptide hormones?
Peptide hormones are hydrophylic and lipophobic (fat-hating) – meaning they cannot freely cross the plasma membrane
Where do peptide hormones bind?
They bind to receptors on the surface of the cell, which are typically coupled to internally anchored proteins (e.g. G proteins)
What does the receptor complex activate? (peptide hormones)
The receptor complex activates a series of intracellular molecules called second messengers, which initiate cell activity
What is the process of peptide hormone signalling called?
This process is called signal transduction, because the external signal (hormone) is transduced via internal intermediaries
What are examples of second messengers?
Examples of second messengers include cyclic AMP (cAMP), calcium ions (Ca2+), nitric oxide (NO) and protein kinases
What does the use os second messengers enable?
The use of second messengers enables the amplification of the initial signal (as more molecules are activated)
What do peptide hormones include?
Peptide hormones include insulin, glucagon, leptin, ADH and oxytocin
What is the hypothalamus?
The hypothalamus is the section of the brain that links the nervous and endocrine systems in order to maintain homeostasis
Where does the hypothalamus receive signals from?
It receives information from nerves throughout the body and other parts of the brain and initiates endocrine responses
What does the hypothalamus secrete (not blood)?
It secretes neurochemicals (called releasing factors) into a portal system which target the anterior lobe of the pituitary gland
