Topic 9 - Endocrinology Flashcards
What are the main endocrine glands?
- Hypothalamus/Pituitary
- Thyroid
- Parathyroid
- Pancreas
- Adrenal
- Ovaries/testicles
What is the hypothalamic-pituitary axis?
A complex set of direct influences and feedback interactions among three components: the hypothalamus, the pituitary gland (a pea-shaped structure located below the thalamus), and the adrenal glands (small, conical organs on top of the kidneys).
What are the two lobes of the pituitary gland?
- Anterior pituitary
- Posterior pituitary
What is the function of the anterior pituitary gland?
To produce various hormones
What is the function of the posterior pituitary gland?
To store various hormones (produced in the hypothalamus)
Which hormones does the anterior pituitary gland produce?
- Growth hormone
- Adrenocorticotrophic hormone (ACTH)
- Gonadotrophins (FSH and LH)
- Thyroid stimulating hormone or thyrotrophin (TSH)
- Prolactin (PRL)
What is the function of growth hormone?
Skeletal growth
What is the function of ACTH?
Adrenocorticotrophic hormone stimulates the adrenals to produce steroids
What is the function of gonadotrophins?
Stimulate the testicles or ovaries to produce sex hormones
What is the function of TSH?
Thyroid stimulating hormone or thyrotrophin stimulates the thyroid to produce thyroid hormones
What is the function of prolactin?
Stimulates breast milk production
Which hormones does the posterior pituitary gland store?
- Antidiuretic hormone (ADH)
- Oxytocin
What is the function of ADH?
Stimulates water reabsorption by the kidneys
What is the function of Oxytocin?
Helps uterine contractions during labour
How is the pituitary gland controlled?
By the hypothalamus
Which hormones produced in the hypothalamus control the anterior pituitary gland?
- Corticotrophin releasing hormone (CRH)
- Growth hormone releasing hormone (GHRH)
- Thyrotropin releasing hormone (TRH)
- Gonadotrophin releasing hormone (GnRH)
Why is there no prolactin releasing hormone?
Prolactin is under the inhibitory effect of the hypothalamus
What is the function of Corticotrophin releasing hormone?
stimulates ACTH secretion
What is the function of Growth hormone releasing hormone (GHRH)?
stimulates GH secretion
What is the function of Thyrotropin releasing hormone (TRH)?
stimulates TSH secretion
What is the function of Thyrotropin releasing hormone (TRH)?
stimulates TSH secretion
What is the function of Gonadotrophin releasing hormone (GnRH)?
stimulates FSH and LH secretion
Which hormones does cortisol switch off?
ACTH and CRH
Which hormones does GH switch off?
GH and GHRH
Which hormones do thyroid hormones switch off?
TSH and TRH
Which hormones do sex hormones switch off?
FSH/LH and GnRH
Which glands are not controlled by the pituitary?
- Adrenal medulla
- Parathyroid
- Pancreas
- Gut hormones
What does the adrenal medulla produce?
adrenaline and noradrenaline
What does the parathyroid control?
Calcium levels
What does the pancreas control (as a gland)?
Sugar levels
What are the parts of the thyroid gland?
- Midline isthmus (just below the cricoid cartilage)
- Right lobe
- Left lobe
What is the function of thyroid C cells?
Production of calcitonin (calcium metabolism)
What controls calcium metabolism?
4 parathryoid glands sitting behind the thyroid
Which organs are involved in calcium metabolism?
- Kidneys (calcium excretion and production of active vitamin D)
- Gut (Absorption of calcium)
- Bone (Storage of calcium)
- Thyroid
Where are the adrenal glands located?
On the kidneys
What are the adrenal glands composed of?
- Adrenal cortex (90%)
- Adrenal medulla (10%)
What does the adrenal cortex produce?
- Cortocosteroids (cortisol)
- Androgens (male hormones)
- Mineralocorticoid (aldosterone)
What does the adrenal medulla produce?
-Catecholamines (adrenaline, noradrenaline and dopamine)
What are the testes composed of?
- Interstitial or Leydig cells
- Seminiferous tubules
- Sertoli cells
What is the function of interstitial or leydig cells?
Produce testosterone
What is the function of seminiferous tubules?
Made up of germ cells producing sperms
What is the function of sertoli cells?
Help in sperm production and produce inhibin
What are the clinical abnormalities possible in various glands?
- Hormone over-secretion (primary/secondary)
- Hormonal under-secretion (primary/secondary)
- Tumour/nodules in the gland that don’t affect hormone secretion
What are static tests used for?
-diagnosing abnormalities of thyroid and sex glands
What do the static tests for primary hyperthyroidism test for?
- Thyroid hormones (T3 and T4)
- TSH
- If primary hyperthyroidism is present then T3 and/or T4 is elevated with suppressed (undetectable) TSH
What are the types of tests used to detect hormonal abnormalities?
- Static tests
- Stimulation tests
- Suppression tests
What are stimulation tests used for?
for suspected hormonal under-secretion where a static test is NOT ENOUGH
What are suppression tests used for?
some hormonal over-secretion
What are some examples of stimulation tests?
