Endocrine System Flashcards
What type of glands is the endocrine system made up of?
Endocrine glands that are ductless
What do the endocrine glands do?
Release product into the bloodstream for transportation to target tissues
What chemical signals are produced by the endocrine gland?
Hormones
What makes something a target for hormones?
Cells or organ that have receptors that bind to the hormone
What are the names of the 2 types of target receptors for hormones?
Surface and Nuclear Receptors
Where is the pancreas close to?
1st part of the small bowel and anatomically in contact with stomach and other areas
What hormones do the pancreas secrete?
Insulin, glucagon, gastrin, somatostatin and vasoactive intestinal peptide (vip)
What does gastrin do?
Stimulates gastric acid production and tells you when you’re hungry
What does somatostatin do?
Inhibits release of other hormones like growth, thyroid, insulin and glucagon
What does vasoactive intestinal peptide do?
Regulates gut water and electrolyte secretion
What do the anterior and posterior pituitary both do?
Communicate with the hypothalamus and are the orchestra of the endocrine system. Secreting hormones that are affectors of other glands
What hormones do the anterior pituitary secrete?
Prolactin - breasts
LH & FSH - Ovarian and testosterone levels
ACTH - Adrenal cortex drives cortical hormones
TSH - Thyroid gland for thyroid hormones
What hormones do the posterior pituitary secrete?
Oxytocin - breast and uterus during childbirth
Vasopressin (ADH) - maintain salt and water balance in the kidneys
What does pituitary dysfunction lead to?
Hormone excess, hormone deficiency and tumour mass effects (causing bitemporal hemianopia)
Where is the thyroid gland located?
In the neck, just below the thyroid cartilage and is butterfly shaped.
Where it the laryngeal nerve?
Runs posterior to the thyroid
Where are the internal jugular vein and common carotid artery in relation to the thyroid?
Postero-lateral to the thyroid
What two hormones do the thyroid secrete?
T4 (thyroxine) and T3 (tri-idothyronine)
What is the role of thyroid hormones?
To regulate basal metabolic rate (i.e. metabolism)
Is there more T4 or T3?
T4! It’s a 14:1 ratio
What’s the difference between T3 and T4?
T3 is the biologically active hormone whereas T4 is the circulating store that’s converted to T3 outside of the thyroid at the target tissues
What happens if there isn’t enough T3 or T4?
If there isn’t enough T3 or T4 this is fedback to the pituitary and the hypothalamus that release hormones. Pituitary releases Thyroid Stimulating Hormone (TSH) and the Hypothalamus releases Thyrotropin Releasing Hormone (TRH) that act on the thyroid to increase hormone T3 or T4 secretion)
What are the symptoms of an overactive thyroid?
Weight loss, heat intolerance, tachycardia, diarrhoea, tremor and hyperactivity
What are the symptoms of an underactive thyroid?
Weight gain, cold intolerance, bradycardia, constipation and lethargy
How does Grave’s Disease occur?
The result of an overactive thyroid.
What happens in Grave’s Disease?
Where Thyroid Stimulating Hormone (TSH) receptor auto-antibodies attack the thyroid causing it to produce too much T3 and T4. It also attacks the periorbital muscles to cause swelling which damages the cornea.
How many parathyroids do we have?
Usually 4, size of a grain of rice
What’s the role of the parathyroid?
To regulate serum calcium, any drop in it is sensed by the parathyroid gland that releases parathyroid hormones that act on the kidney for the reabsorption of Ca2+ in the gut and bones.
What are the symptoms of an overactive parathyroid (hypercalcaemia)?
Thirst, polyuria, fatigue, constipation, renal stones, osteoporosis and cardiac dysrhythmia
What’s a symptom of an underactive parathyroid (hypocalcaemia)?
Tetany (pins and needles), muscle spasm, confusion and cardiac dysrhythmia
The adrenal is separated into the medulla and cortex, what are the 3 zones of the cortex and what are they for?
Zona Glomerulosa (androgens)
Zona Fasciculata (cortisol)
Zona Reticularis (aldosterone)
Steroid hormone synthesis is complicated. They’re originally generated from cholesterol, what are the 4 end paths?
Cortisol
Corticosterone
Aldosterone
Androstenedione
What is cortisol for?
Stress response (slow releasing, in fight or flight it would be adrenaline), releases glucose by Glycolysis and maintains blood pressure
What’s an adrenal cortex disease?
Addison’s Disease - Adrrnal insufficiency (cortisol & aldosterone)
What does the adrenal medulla do?
Synthesises catecholamines being adrenaline and noradrenaline (stress hormones)
What are adrenal hormones stimulated by?
CNS and SNS
What type of pathway is the adrenal pathway?
It’s a neuronal afferent pathway with an endocrine efferent pathway
