Endocrine System Flashcards
What does the endocrine system do?
- secretes chemicals (hormones) into blood
- is then transported to target cells via circulation and act on target cells
What is a target cell?
a cell with a receptor specific for a hormone
What are the 3 hormone classes?
steroids, hormones derived from amino acids, and peptide + protein hormones
Describe steroid hormones
- synthesized from cholesterol (lipid soluble)
- testosterone, estrogen, vitamin D
Describe peptide and protein hormones
- chains of amino acids
- mainly water soluble
- ex: oxytocin, antidiuretic hormone (ADH), growth hormone (GH), insulin
Where is the pituitary gland located? What is it connected to?
Connected to hypothalamus in the sella turcica of the sphenoid bone
What are the 2 lobes of the pituitary gland called? What type of tissue are they made of?
- anterior: epithelial
- posterior: nervous
What regulates the hormones the anterior pituitary releases?
hormones secreted by the hypothalamus
what metabolism hormones does the anterior pituitary gland release?
growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone
what reproductive hormones does the anterior pituitary release?
luteinizing hormone, follicle stimulating hormone, prolactin
what does prolactin do?
stimulates milk formation
the posterior pituitary is an extension of…?
the hypothalamus
hormones produced in the hypothalamus are…?
stored and secreted from the posterior pituitary gland
what hormones does the posterior pituitary gland secrete?
oxytocin, and antidiuretic hormone
what does oxytocin do?
stimulates uterine contractions and milk ejection
what does the antidiuretic hormone do?
water reabsorption in kidney
describe the thyroid glands location and shape
butterfly shaped, on anterior surface of the superior part of the trachea
what is the histology of the thyroid gland?
follicles - walls made up of epithelial cells (follicle cells), produces T4
Parafollicular cells - between follicles, secrete calcitonin which increases calcium uptake into bone formation which lowers blood calcium
what does the parathyroid gland do?
secrete parathyroid hormone
what does the parathyroid hormone do?
increases blood calcium by:
- increased calcium release from bone (= bone resorption) - activates osetoclasts
- decreased calcium loss in urine (kidney)
- increased vitamin D activation (kidney), Vitamin D then increases calcium absorption at the small intestine
where are adrenal glands located?
superior surface of each kidney
what are the 2 parts of the adrenal glands, and what are they made of?
- adrenal cortex (outer), made up of epithelial tissue
-adrenal medulla (inner), made up of nervous tissue
the adrenal cortex secretes what?
steroids only!
what are the 3 layers of the adrenal cortex ?
- zona glomerulosa
- zona fasciculata
- zona reticularis
what does the zona glomerulosa do?
secretes mineralocorticoids (mainly aldosterone), balances salt
what does the zona fasciculata do?
secretes glucocorticoids (eg. cortisol), long term stress hormone and carbohydrate metabolism
what does the zona reticularis do?
secretes androgens and small amounts of testosterone, some converted to estrogens in other tissues (especially fat)
what hormones does the adrenal medulla secrete?
(80%) epinephrine and (20%) norepinephrine
what do the cells of the pancreatic islets of langerhans do?
alpha cells- produce glucagon, which increases blood glucose
beta cells- produce insulin, which decreases blood glucose
hypothalamus regulates the anterior pituitary using what hormones?
growth hormone releasing hormone, growth hormone inhibiting hormone, gonadotropin releasing hormone
what hormone does the testes release?
testosterone via the leydig cells
what hormones do the ovaries release
-estrogen via cells of secondary and vesicular follicles
-estrogen + progesterone via corpus luteum
what other organs have edocrine functions?
~kidney - renin
~duodenum - secretin
~skin - Vitamin D
~heart - atrial natriuretic peptide (ANP)
~etc….
