Endocrine system Flashcards
What are the 6 main endocrine glands in the body?
1) Hypothalamus/pituitary
2) Pancreas
3) Ovaries/Testes
4) Parathyroid
5) Thyroid
6) Adrenal
Which gland controls most of the glands in the body?
The small pituitary gland
Which gland controls the pituitary gland?
The hypothalamus
What are the 2 functional lobes of the pituitary gland and what do they produce?
1) Anterior pituitary: produces various hormones
2) Posterior pituitary: doesn’t produce any hormones just stores those produced by the hypothalamus
What are the 5 main hormones produced by the anterior pituitary and what do they do?
1) TSH: stimulates the thyroid gland to produce thyroid hormone
2) ACTH (adrenocorticotrophic hormone): stimulates the adrenal glands to produce steroids
3) Gonadotrophins (FSH/LH): stimulates the testes or ovaries to produce sex hormones
4) GH (growth hormone): for skeletal growth
5) Prolactin (PRL): stimulates breast milk production
What 2 hormones are stored in the posterior pituitary (Which have been produced by the hypothalamus)?
1) Antidiuretic hormone (ADH): stimulates water reabsorption by the kidneys
2) Oxytocin: Helps uterine contractions during labour
What hormones are secreted by the hypothalamus to control the secretion of GH, TSH, ACTH and gonadtrophins from the anterior pituitary?
1) GHRH/GRH (growth-hormone releasing hormone): stimulates the release of GH
2) CRH (corticotrophin release hormone): stimulates the release of ACTH
3) TRH (thyrotrophin releasing hormone): stimulates the release of TSH (Thyroid stimulating hormone)
4) GnRH (gonadotrophin releasing hormone): stimulates the release of FSH and LH (gonadoptropins)
How is the release of prolactin from the anterior pituitary controlled?
No prolactin releasing hormone exists, instead it is under inhibitory control of the hypothalamus which continually secretes an inhibitor, after birth inhibitor stops being released and prolactin levels increase
How are pituitary hormones and hormones from the hypothalamus switched off?
By negative feedback systems
1) Cortisol feeds back to switch of ACTH and CRH
2) Thyroid hormones feedback to switch off TSH and TRH
3) Sex hormones feedback to switch off FSH and LH and GnRH
4) Growth hormone switches of GH and GHRH
Name 4 glands which are not controlled by the pituitary gland and what they produce?
1) Adrenal medulla: produces ADR and NA (nb. adrenal cortex which releases cortisol is controlled by pituitary)
2) Pancreas: secrets insulin, glucagon (and somatostatin)
3) Gut hormones
4) Parathyroid (controls calcium levels)
What is the rough gross structure of the thyroid gland?
2 lobes (R+L) and a midline isthmus (middle lobe, just below the circoid cartilage)
Which cells of the thryoid gland are not controlled by the pituitary and what do they secrete?
C cells, secrete calcitonin (involved in calcium metabolism) - they are not controlled by the pituitary!
How many parathyroid glands are there?
4
Other than the parathyroid glands what are the 3 other organs involved in calcium metabolism?
1) Kidneys: calcium excretion and production of Vitamin D
2) Gut: absorption of calcium
3) Bone: storage of calcium
Corticosteroids (cortisol), androgens (male hormones) and mineralcorticoid (aldosterone) are produced by which part of the adrenal gland, under control of what?
Adrenal cortex
Cortisol and androgens under control of pituitary
Aldosterone related to RAAS
NB. adrenal glands are reason females produce some male hormone
Adrenal cortex makes up how much of the adrenal gland?
90% cortex, 10% medulla
GnRH is secreted in what kind of pattern?
Not continuous but pulsatile
What is the effect of continuous GnRH secretion?
Can lead to suppression of secretion of FSH and LH (can be used therapeutically, if want to stop FSH and LH secretion then can give GnRH continuously)
What hormone is secreted from the pituitary gland for the first 14 days of the menstrual cycle and what does this cause to be released?
FSH for first 14 days
Causes increased oestradiol secretion from ovaries
What 3 things are the testes composed of and what do they produce?
1) Interstital or leydig cells: produce testosterone
2) Seminiferous tubules: made up of germ cells producing sperm
3) Sertoli cells: producing inhibin
Both testosterone and inhibin have an inhibitor effect on the release of FSH and LH from the pituitary
What is primary hormonal oversecretion/undersecretion?
Problem with the gland itself (no problem with the pituitary)
What is secondary hormonal oversecretion/undersecretion?
Problem with the pituitary gland making the gland itself overactive or pituitary gland not sending signals to the gland (nb. a secondary problem in a gland would be a primary problem in the pituitary gland)
What is tertiary hormonal oversecretion/undersecretion?
Problem with the hypothalamus however this is very rare
What glands are static tests used to find abnormalities in?
Thyroid gland
Sex glands