3.3 - Endocrine System Continued Flashcards
What does the thyroid gland do?
Affects metabolism, among other things
What does the pituitary gland do?
Secretes many different hormones, some of which affect other glands
What does the hypothalamus do?
Brain region that controls the pituitary gland
What do parathyroids do?
Help to regulate level of calcium in the blood
What do adrenal glands do?
Help trigger the fight-or-flight response
What does the pancreas do?
Regulates the level of sugar in the blood
What are tropic hormones?
Hormones with the job of stimulating OTHER ENDOCRINE organs to make a different hormone.
What are the two componenets of the pituitary gland?
- Anterior pituitary (the actual gland/front portion: produces and secretes the 7 pituitary hormones (TSH, LH, FSH, ACTH, PRL, GH, MSH under control of the hypothalamus))
- Posterior pituitary (extension of the hypothalamus/back portion: stores and releases the 2 hypothalamus produced hormones (ADH and Oxytocin))
What is the process that causes a release in sex hormones for spermatogenesis/oogenesis?
- Hypothalamus stimulates anterior pituitary hormone production
- Anterior pituitary stimulates gonad hormone production
FSH and LH - Gonadal hormones downregulate hypothalamus and anterior pituitary
- Testosterone and inhibin
Estrogen, progesterone, and inhibin
What is the negative feedback loop in spermatogenesis?
High levels of both Testosterone and Inhibin work on Pituitary and Hypothalamus to REDUCE production of FSH and LH, and thus LOWER sperm and testosterone production NEGATIVE FEEDBACK
Beyond sperm production, how is testosterone important in males?
Testosterone is important for developing and maintaining male primary and secondary sexual characteristics:
- Growth of penis
- Development of testes
- Growth and changes in bone and muscle mass/distribution
- Sex drive
- Change in voice
- Hair development
What is andropause?
Reduction in sex hormone production in later life for men:
- reduced fertility and sex-drive
- loss of muscle and bone mass
- Male menopause
How is the regulation of female hormones cyclical?
High levels of ESTROGEN ↓ FSH ( – fdbk) and ↑LH (+ feedback).
High levels of INHIBIN ↓ FSH ( – feedback) .
High levels of PROGESTERONE ↓FSH and ↓LH ( – feedback).
When both ESTROGEN AND PROGESTERONE levels drop (end of cycle), triggering ↑FSH to restart the process.
How are hormones during the follicular phase (pre-ovulation): days 1-14?
- FSH causes follicle to mature and secrete estrogen (peaks at day 14)
- Estrogen stimulates endometrial preparation and LH release
- LH peak triggers ovulation and transition of follicle into corpus luteum
How are hormones during the luteal phase (post-ovulation): days 15-28?
Corpus luteum secretes progesterone to continue preparation of endometrial lining
How does fertilization change the hormone levels during oogenesis?
- If fertilization does not occur dropping hormone levels lead to menstruation aka shedding of uterine lining = cycle restarts
- If fertilization does occur, hormone production taken over by placenta
Beyond oocyte and endometrial lining production, how is estrogen important in females?
Estrogen is important for developing and maintaining female primary and secondary sexual characteristics
- Development of external genitalia
- Growth and changes in bone and muscle mass/distribution
- Sex drive (aided by testosterone)
- Change in voice (less dramatic than males)
- Hair development
- Breast development
What is menopause?
With age ovaries become less sensitive to FSH and LH, leading to dysregulation of the uterine cycle aka MENOPAUSE
- Menstrual cycles become irregular, eventually ceasing
- Reduced sex-drive
- Loss of muscle and bone mass
What are the general associations with brain masculinization?
- Increased sex drive
- Increased aggression
- Increased spatial faculties but decreased fine motor skill tuning
What are the general associations with brain feminization?
- Increased empathy
- Increased fine motor skill tuning but decreased spatial faculties
- Increased verbal fluency
Why is the pancreas a mixed gland?
The pancreas is a mixed gland because it has both endocrine (directly into bloodstream) and exocrine (travelling via duct) functions
What is the exocrine function of the pancreas?
-Production of digestive enzymes, buffers
- 99% of pancreas by volume
What is the endocrine function of the pancreas?
Occurs in special patches called ISLETS of LANGERHANS/PANCREATIC ISLETS
- Approximately 2 million pancreatic islets scattered between exocrine cells
- 1% of all pancreatic cells
- Major hormones: INSULIN and
GLUCAGON (Glucose metabolism)
When is insulin produced?
Insulin is produced when the pancreas detects high levels of glucose in the blood (ex: after eating)
How does the liver respond to insulin being produced?
In response to insulin, the liver takes glucose out of the blood to build glycogen
When is glucagon produced?
Glucagon is produced when the pancreas detects low levels of glucose in the blood (ex: after fasting)
How does the liver respond to glucagon being produced?
In response to glucagon, the liver breaks apart glycogen and releases glucose into the blood
What is Type 1 Diabetes?
Deficiency (often genetic) in pancreatic cells so they do not produce sufficient insulin
Treatment: Provide insulin injections based on blood glucose levels to get the liver to do what it’s supposed to
- Langerhans don’t produce insulin anymore, Beta cells are destroyed by immune system
What is Type 2 Diabetes?
Often related to lifestyle diet, liver gets desensitized to insulin and doesn’t respond properly
Treatment: Provide higher amounts of insulin to provide sufficient stimulation to the liver to behave as it should
Loss of insulin sensitivity in TARGET CELLS aka insulin resistance
- Beta cells still produce insulin, but target cells are “blind” to it so glucose remains in blood and cells think they are starving
