Endocrine path/ physiology Flashcards
What is the function of Calcitonin in the Kidneys
Increases excretion of calcium AND phosphate
What stimulates renin secretion
-reduction in extracellular fluid volume
-low BP
-sympathetic stimuli
eg: cardiac failure, hypotension, renal artery constriction, sodium depletion, hemorrhage, dehydration
What converts angiotensinogen to angiotensin I
Renin
What converts angiotensin I to angiotensin II
ACE (angiotensin converting enzyme)
What factors stimulate growth hormone secretion
Sleep
exercise
protein rich diet
circulating oestradiol
HYPOglycaemia
What factors inhibit growth hormone secretion
HYPERglycaemia
carb rich diet
free fatty acids
somatostatin
cortisol
How would you differentiate between a primary and secondary adrenal insufficiency
Presence of hyperpigmentation:
present= ACTH produced by pituitary= ACTH also acts as melanocyte stimulating hormone= primary insufficiency
absent= no ACTH produced by pituitary= secondary insufficiency
During embryological development, when does the thyroid gland first appear and where
Week 4
At the foramen caecum of the base of the tongue
Where is the final position of the thyroid gland and when does it reach this position
Thyroid travels along the thyroglossal duct to reach its final position at week 24
What is the communication between the initial and final positions of the thyroid gland called
Thyroglossal duct
What is the complication of I&D or untreated thyroglossal cyst
Fistula
What is a thyroglossal cyst
A cystic remnant of the thyroglossal duct
What are the actions of insulin
1- movement of glucose + potassium from blood into cells
2- glycogenesis (converts glucose to glycogen and stores in liver/ muscles)
3- lipogenesis (converts glucose to triglycerides and stores in liver/ adipose tissue)
Function of following hormones on glucose/ glycogen:
Glucagon
Cortisol
adrenaline
thyroxine
Glucagon- glycogenolysis, gluconeogenesis
Cortisol-glycogenesis, gluconeogenesis
adrenaline-glycogenolysis, gluconeogenesis
thyroxine-increased blood glucose
What are the structures present anterior to the thyroid gland
Pre-tracheal fascia
Infrahyoid muscles:
-sternothyroid
-sternohyoid
-omohyoid
At what level of the neck does the thyroid sit?
C5-T1
What fascia surrounds the thyroid
Pre-tracheal fascia
What nerves are found and where are they situated in relation to the thyroid
external and recurrent laryngeal nerves (medial to thyroid)
Arterial supply of thyroid
superior + inferior thyroid arteries
3-10% also have thyroid ima/ internal mammary arteries
Venous drainage of thyroid
superior
middle
inferior thyroid veins
Which veins supplying the thyroid drain into the internal jugular
superior + middle thyroid veins
Which veins supplying the thyroid drain into the subclavian vein
inferior thyroid vein
Where do the arteries supplying the thyroid originate from
superior thyroid = external carotid
inferior thyroid= thyrocervical trunk
Which nerve is in close proximity to the superior thyroid artery
external laryngeal nerve
Which nerve is in close proximity to the inferior thyroid artery
recurrent laryngeal nerve
In thyroidectomy for a well-differentiated thyroid carcinoma- what is the level of neck dissection carried out
Level 6 neck dissection
Which lymph nodes drain the thyroid
deep cervical
Where can the recurrent laryngeal nerve be found (_____ triangle) and describe its boundaries
Beahr’s triangle
superior= inferior thyroid artery
medial= trachea
lateral= common carotid artery
Describe the path of the recurrent laryngeal nerve
right:
hooks under the brachiocephalic trunk
travels in tracheo-oesophageal groove
goes under the thyroid gland inferiorly
left:
hooks under arch of aorta
travels in tracheo-oesophageal groove
goes under the thyroid gland inferiorly
What artery is related to the external laryngeal nerve
superior thyroid
Action of the recurrent and external laryngeal nerves
recurrent:
innervates ALL the instrinsic muscles of the larynx (EXCEPT cricothyroid)
-thyroarytenoids
-posterior cricoarytenoids
-lateral cricoarytenoids
-transverse arytenoid
-oblique arytenoid
external laryngeal:
-cricothyroid
What are the intrinsic muscles of the larynx
-thyroarytenoids
-posterior cricoarytenoids
-lateral cricoarytenoids
-transverse arytenoid
-oblique arytenoid
-cricothyroid
What are the extrinsic muscles of the larynx
supra + infrahyoid muscles
Name the suprahyoid muscles
geniohyoid
mylohyoid
digastric (sup/ inferior bellies)
stylohyoid
Name the infrahyoid muscles
thyrohyoid
sternohyoid
sternothyroid
omohyoid (2x bellies)
What are the 8 steps of thyroid hormone production
- active transport of iodine from blood into follicular cells
- Oxidation of iodine to iodide (I-) in follicular cells
- Iodide moves into to colloid and binds with the tyrosine+thyroglobulin molecule with the help of thyroid peroxidase
- depending on how many iodine bind to tyrosine+thyroglobulin molecule, MIT and DIT are made
- TSH from pituitary stimulates the movement of MIT/ DIT back into follicular cells via vacuoles BY PINOCYTOSIS
- lyzosomes/ proteases are released into these vacuoles and breakdown MIT/ DIT, alanine is produced as a byproduct
- thyroglobin is released back into colloid
- remaining T3/ T4 is released in the plasma
What are the hormones produced by the thyroid gland
Thyroxine T4
Triiodothyronine T3
calcitonin
What plasma proteins transport T3/4
Thyroid binding globulin (TBG)
Thyroid binding prealbumin (TBPA)
Albumin
At which point in the production of T3/4 does carbimazole/ PTU act
blocks oxidization of iodine to iodide
What is the structure of thyroid follicles
follicular cells are arranged around colloid and surrounding these clusters of follicular cells are capillaries
What hormone stimulates the secretion of testosterone
Luteinizing hormone from leydig cells (interstitial cells)
What cells produce the hormone that stimulates testosterone secretion
Basophilic gonadotrophs in the anterior pituitary
Function of FSH in men
Works with testosterone to make androgen binding protein (ABP)
ABP keeps testosterone levels high in the tubular fluid
What inhibits secretion of prolactin
Somatostatin
Dopamine
What factors increase prolactin secretion
Pregnancy
Stress response
What hormones increase following the stress response
Glucagon
cortisol
growth hormone
ADH/ vasopressin
prolactin (preg)
What happens to thyroid hormones and insulin in the stress response
Decreased levels of Insulin, T3, T4
In response to hyponatremia-what happens to renin levels
INCREASES
Effect of Growth hormone on glucose concentrations
increases glucose
