Class notes
Endocrinology (IMS)
- Course
- Institution
Introduction to Medical Sciences TOPIC 6 - Endocrinology
[Show more]
Seller
Follow
medicsummaries
Reviews received
Content preview
Medic_Summaries (IMS) Topic 6Endocrinology
Endocrine glands: hypothalamus/pituitary, thyroid, parathyroid, pancreas, adrenal, ovaries/testes
Hypothalamic-pituitary axis: connection between the two; hypothalamus CONTROLS pituitary
Pituitary gland:
- CONTROLS most glands in the body
- Two lobes:
- Anterior pituitary: PRODUCES various hormones
- Posterior pituitary: STORES hormones
Anterior pituitary produces hormones:
- Growth hormone (GH) - for skeletal growth
- Adrenocorticotrophic hormone (ACTH) - stimulates testicles/ovaries to make sex hormone
- Thyroid stimulating hormone/thyrotrophin (TSH) - stimulates thyroid make thyroid hormone
- Prolactin (PRL) - stimulates breast milk production
Posterior pituitary: stores hormones produced in hypothalamus (does NOT produce them)
- Antidiuretic hormone (ADH) - stimulates water reabsorption by the kidneys
- Oxytocin - helps uterine contractions during labour
Pituitary gland is under the control of the hypothalamus:
- Corticotrophin releasing hormone (CRH) - stimulates ACTH secretion - adrenal (steroids)
- Growth hormone releasing hormone (GHRH) - stimulates GH secretion
- Thyrotrophin releasing hormone (TRH) - stimulates TSH secretion - thyroid (T3 and T4)
- Gonadotrophin releasing hormone (GnRH) - stimulates FSH and LH secretion - ovaries/
testes - sex hormones
- Prolactin releasing hormone does not exist as prolactin is under the INHIBITORY effect of
the hypothalamus
Switching pituitary hormones:
- Cortisol: switches off ACTH and CRH
- Growth hormone: switches off GH and GHRH
- Thyroid hormones: switches off TSH and TRH
- Sex hormones: switch off FSH/LH and GnRH
- NEGATIVE FEEDBACK
Glands NOT controlled by the pituitary:
- Adrenal medulla: produce adrenaline and noradrenaline
- Parathyroid: controls calcium levels
- Pancreas: controls sugar levels
- Gut hormones
Thyroid gland: midline isthmus, just below the cricoid cartilage (right lobe and left lobe)
- Thyroid cells are arranged in follicles and produce thyroid hormones
- Thyroid contains C cells that produce calcitonin (calcium metabolism)
- Thyroid hormones interact with their receptors in various organs regulating gene
expression and aspects of organ function
- Hypothalamus - TRH - pituitary - TSH - thyroid - thyroid hormones - negative feedback on
hypothalamus and pituitary
1 Adapted from Lectures at the University of Leeds Medical School
, Medic_Summaries (IMS) Topic 6
Calcium metabolism: controlled by four parathyroid glands sitting behind the thyroid
- Other organs involved in calcium metabolism:
- Kidneys: calcium excretion and production of active vitamin D
- Gut: absorption of calcium
- Bone: storage of calcium
- Thyroid
Adrenal glands: adrenal cortex and medulla
- 90% of the gland is ADRENAL CORTEX and produces:
- Corticosteroids (cortisol)
- Androgens (male hormones)
- Mineralocorticoids (aldosterone)
- Secretion is not controlled by the pituitary (RAAS system - related to BP)
- 10% of the gland is ADRENAL MEDULLA and produces:
- Catecholamines (adrenaline, noradrenaline, dopamine)
- Secretion is not controlled by the pituitary (related to BP)
The reproductive system: ovaries/testes
- Ovaries:
- Situated in the pelvis, either side of the uterus
- Contain follicles, each containing an oocyte at different stages of maturation
- Hypothalamus - GnRH - pituitary - FSH/LH - ovaries - progesterone:
- Switched on = oestradiol
- Switches off = inhibin
- Testes:
- Adults, found in the scrotum, except minority (testicular maldescent)
- Interstitial/leydig cells (produce TESTOSTERONE)
- Seminiferous tubules (germ cells producing SPERM)
- Sertoli cells (help in SPERM production and produce INHIBIN)
- Hypothalamus - GnRH - pituitary - FSH/LH - testis - inhibin: sertoli cells or testosterone -
Leydig cells
Clinical abnormalities:
- Hormonal over-secretion (primary/secondary)
- Hormonal under-secretion (primary/secondary)
- Tumour/nodules in the gland without affecting hormone secretion
Static tests: diagnose abnormalities of thyroid and sex glands
- Primary hyperthyroidism (thyroid hormone overproduction)
- Test for thyroid hormones T3 & T4, and TSH
- T3 and/or T4 increase with suppressed undetectable TSH
Stimulation tests: for suspected hormonal under-secretion, static test not enough
- ACTH to test for adrenal insufficiency (SYNACHTEN TEST)
- Failure to respond leads to gland failure
- Glucagon stimulation/insulin stress test for pituitary failure (test for ACTH/GH response)
Suppression test: for some hormonal over-secretion
- Giving steroids and testing for endogenous steroid production
- External steroids should switch off internal steroid production
- Giving glucose and testing GH secretion (glucose switches off GH secretion normally)
Disease of the endocrine glands:
- Over-secretion: usually benign tumours
- Under-secretion: gland destruction due to:
- Inflammation (autoimmune conditions)
- Infarction
- Other
- Tumour/nodules with normal hormone production
2 Adapted from Lectures at the University of Leeds Medical School
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller medicsummaries. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.98. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
84866 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now