Endocrine System Flashcards
What are endocrine and exocrine glands?
Collection of secretory epithelial cells
What are the differences between exocrine and endocrine glands?
Exocrine have ducts and secrete onto a surface
Endocrine dont have ducts and secrete into bloodstream
Give examples of exocrine glands
Sebaceous glands
What shape is the pituitary gland?
Oval
Where is the pituitary gland found?
Attached to the underside of the brain (hypothalamus)
In the sella turcica of the sphenoid bone
What attaches the pituitary gland to the hypothalamus?
Infundibulum/ pituitary stalk
Name some secretions from the pituitary
Prolactin, growth hormone, thyroid stimulating hormone, gonadotropin, adrenocorticotropic hormone
What is prolactins function and target organ?
Milk production - mammary glands
What is growth hormones function and target organ?
Stimulates growth, cell reproduction and cell regeneration - musculoskeletal system
What is thyroid- stimulating hormone function and target organ?
Stimulates thyroid to produce thyroxine and triiodothyronine - thyroid gland (….obviously)
What is adrenocorticotropic hormone function and target organ?
Increases production and release of cortisol by the cortex of the adrenal gland
What is gonadotropins function and target organ?
LH triggers ovulation/ stimulates testosterone production
FSH regulates the development, growth, pubertal maturation and reproductive processes of the body
- gonads
How common is hypopituitarism?
Super rare
What are the majority of hypopituitarism cases caused by?
Tumours
What are the symptoms of hypopituitarism?
Small stature Fertility issues Temperature regulation issues Fatigue Inability to produce breast milk
What does the thyroid gland secrete?
thyroxine, triiodothyronine and thyrocalcitonin
What do thyroxine and triiodothyronine do?
Increase metabolic activity
What does thyrocalcitonin do?
Lowers levels of blood calcium and promotes bone formation
Where is the thyroid gland?
C5-T1
What forms the thyroid gland?
Two lateral lobes and a central isthmus (also sometimes pyramidal lobe)
Where does the thyroid gland develop?
Oral cavity
What was the pyramidal lobe?
Remnant of the thyroglossal duct
Where does the superior thyroid artery come from?
External carotid
Where does the inferior thyroid artery come from?
Thyrocervical trunk (comes from subclavian artery)
Where do the superior and middle thyroid veins drain into?
Internal jugular
Where do the inferior thyroid veins drain into?
Brachiocephalic veins
What muscles cover the thyroid gland?
Omohyoid, sternothyroid and sternohyoid muscles
What shape are the parathyroid glands?
Ovoid
How big are the parathyroid glands?
5mm
How many parathyroid glands do you have?
4 - 2 superior and 2 inferior
Where are the superior parathyroid glands found?
Middle of the posterior border of the thyroid
Where are the parathyroid glands found?
Posterior surface of the thyroid gland
What is the function of the parathyroid glands?
Secrete parathyroid hormone
What does the parathyroid hormone do?
Stimulates osteoclastic activity in bones, stimulates reabsorption of calcium in kidney and absorption from small intestine
What is the parathyroid hormone controlled by?
Blood calcium levels
What is osteoclastic activity in bones?
Mobilise bone calcium and increase calcium in blood
What type of feedback is the parathyroid hormone controlled by?
Negative feedback loop
When is hyperparathyroidism usually diagnosed?
After a routine blood test
How do you treat hypoparathyroidism?
Oral calcium and vitamin D analogues
What is the earliest endocrine organ to develop?
Thyroid gland
How does the thyroid gland develop?
Endodermal thickening in the midline of the pharynx that becomes a diverticulum —> thyroid gland
What is the diverticulum that eventually forms the thyroid gland called?
Thyroglossal duct
What is it called if not all of the thyroglossal duct disappears?
Pyramidal lobe
What remains of the thyroglossal duct can you see in the oral cavity?
A pit at the back of the tongue- foramen caecum
What happens if the thyroglossal duct doesnt close?
Mucus secretions from the oral cavity can run down and form a cyst that can become infected
What is the pancreas?
Lobular, elongated, glandular organ
Where does the pancreas sit?
Epigastric region and upper left quadrant
Is the pancreas an endocrine or an exocrine organ?
Both
What do pancreatic secretions contain?
Enzymes capable of hydrolysing fats, proteins and carbs
What collects the secretions in the pancreas?
Main bile duct of the pancreas
What part of the pancreas does the accessory duct drain?
Upper part of the head
What do hormones secreted by the pancreas help?
Maintain sugar and salt balance
What % of pancreas is made up of endocrine cells?
5
What are the clusters of endocrine cells in the pancreas called?
Pancreatic islets or islets of langerhans
Where are the suprarenal/adrenal glands found?
Upper poles of kidneys
How is the right suprarenal gland shaped?
Pyramid shaped
What shape is the left adrenal gland?
Crescent
What are the sections of the adrenal gland?
Cortex and medulla
Why is the right adrenal gland much harder to access?
Really close to the IVC
What hormones do the ovaries produce?
Oestrogen and progesterone
Where do the ovaries lie?
Within the broad ligament
What hormone do the testes produce?
Testosterone
What suspends the testes in the scrotum?
Spermatic cord
What makes up the spermatic cord?
Ductus deferens, testicular artery, testicular veins and more
What muscle do the walls of the scrotum contain?
Dartos muscle
What do the testicular veins form?
Pampiniform plexus around the outside of the spermatic cord
What is the function of the pampiniform plexus?
Cool incoming arterial blood
What is the thymus’ function?
Stimulates maturation of T lymphocytes
What does the thymus secrete?
Thymosin
How many lobes make up the thymus?
2
When is the thymus a thing in development?
Enlarges during childhood and atrophies after puberty
What is the main secretion of the pineal gland?
Melatonin
What is melatonin important in?
Circadian rhythm
What shape are the pineal glands?
Pine cone shaped
What can happen to the pineal glands in middle age?
Become calcified
Where is the pineal gland?
Related to the midbrain and attached via a stalk
What is the pineal gland important in?
Sight
What other functions (not sight) is the pineal gland believed to play a role in?
Sexual development, seasonal breeding and hibernation in animals
What have pineal tumours been linked to?
Early puberty
When does the pineal gland shrink?
Puberty
What separates the anterior and posterior triangles of the neck?
Sternoclaidomastoid muscle
Where does the sternoclaidomastoid muscle attach?
Sternum, clavicle and mastoid process
Where is the mastoid process?
Lumpy bit behind ear
What is the posterior triangle of the neck bound by?
Anterior border of trapezius, posterior border of the sternoclaidomastoid and the superior border of the clavicle
What is the anterior triangle bound by?
Anterior border of the sternoclaidomastoid, midline and the inferior border of the mandible
Where do right and left ovarian veins drain into?
Right- into IVC
Left- into left renal vein
What branches come off the coeliac trunk?
Splenic artery, left gastric and hepatic
What happens if the recurrent laryngeal nerve is injured during thyroid surgery?
Vocal cord paralysis and hoarse voice
