Endocrine System Flashcards
What type of glands and tissues make up the endocrine system?
Ductless
What is the function of the endocrine system?
To secrete hormones directly into the bloodstream
These hormones then regulate the metabolic activities of different organs and tissues of the body in order to maintain homeostasis
What system does the endocrine system work in conjunction with? Which system exerts a slower more diffuse response?
Autonomic nervous system
Endocrine system
What structure coordinates the autonomic and endocrine system?
Hypothalamus of the brain
List the seven main endocrine organs
Pituitary Gland
Hypothalamus
Thyroid Gland
Parathyroid Gland
Adrenal Gland
Pancreas
Testes/Ovaries
What is the name given to the depression in the skull where the pituitary gland sits?
Hypophyseal fossa (sella)
In what cranial bone does the pituitary gland sit in?
Sphenoid bone
What air sinus has a close relation to the pituitary gland and hypothalamus? Where is it located in relation?
Sphenoid air sinus
Inferiorly
What other two structures lie in close relation to the pituitary gland and hypothalamus?
Optic chiasm
Thalamus
Where is the optic chiasm located in relation to the pituitary gland?
It lies superior to the pituitary gland
Where is the thalamus located in relation to the hypothalamus?
It lies inferior (anterior on cross section) to the hypothalamus
What clinical feature tends to arise when the pituitary gland enlarges? Why?
Bitemporal hemianopia
An enlargement of the pituitary gland impinges on the crossing fibres of the optic chiasm
What is bitemporal hemianopia?
A condition in which vision is missing in the outer half of both eyes
Which structure connects the pituitary gland to the hypothalamus?
The pituitary stalk
What three lobes make up the pituitary gland?
Anterior lobe
Intermediate lobe
Posterior lobe
What two other terms are used to refer to the anterior lobe of the pituitary gland?
Pars anterior
Adenohypophysis
What two other terms are used to refer to the posterior lobe of the pituitary gland?
Pars nervosa
Neurohypophysis
What other term is used to refer to the intermediate lobe of the pituitary gland?
Pars intermedia
What does the anterior lobe of the pituitary gland develop from?
Brachial arches
What does the posterior lobe of the pituitary gland develop from?
It is a continuation of the hypothalamus and pituitary stalk
What ventricle of the brain lies superior to the pituitary gland?
Third ventricle
What structure is connected to the posterior lobe of the pituitary gland?
Mamillary bodies
Which lobe of the pituitary gland is larger?
Anterior lobe
What pituitary gland lobe is glandular and secretes several hormones? How many hormones does it secrete?
Anterior lobe
Seven
What pituitary gland lobe is neuroendocrine and secretes several neurohormones?
Posterior lobe
What two neurohormones are secreted by the posterior lobe of the pituitary gland?
Oxytocin
Vasopressin (ADH)
What colour does the anterior pituitary lobe stain with a H&E stain?
Dark pink
What colour does the posterior pituitary lobe stain with a H&E stain?
Light pink
What three cells make up the pituitary gland?
Acidophilic
Basophilic
Chromophobic
What colour do acidophilic cells stain with a H&E stain?
Pink
What colour do basophilic cells stain with a H&E stain?
Light purple
What colour do chromophobic cells stain with a H&E stain?
Pale
What additional cell makes up the posterior pituitary lobe?
Non-myelinated axons
Where are the cell bodies of the posterior pituitary lobe axons located?
Hypothalamus
What are the two classifications of acidophil cells?
Somatrophs
Mammotrophs
What hormone do somatrophs produce? What is the target organ of this hormone?
GH
Chondrocytes, which are located within the epiphyseal growth plate
What hormone do mammotrophs produce? What is the target organ of this hormone?
Prolactin
Mammary gland
What are the three classifications of basophil cells?
Corticotrophs
Thyrotrophs
Gonadotrophs
What two hormones do corticotrophs produce? What is the target organ of each hormone?
ACTH - Adrenal gland
MSH - Melanocytes
What hormone do thyrotrophs produce? What is the target organ of this hormone?
TSH
Thyroid gland
What two hormones do gonadotrophs produce? What is the target organ of this hormone?
FSH - Sex organs
LH - Sex organs
What two arteries supply the hypothalamus and the pituitary gland? What are these arteries a branch of?
Superior hypophyseal artery
Inferior hypophyseal artery
Internal carotid artery
What does the superior hypophyseal artery supply?
The hypothalamus
Before this artery enters into the hypothalamus, it breaks up into the hypophysial portal system. These capillaries then supply the anterior pituitary lobe
What does the inferior hypophyseal artery supply?
The posterior pituitary lobe
How does the hypothalamus communicate with the anterior pituitary?
The hypothalamus releases ‘releasing hormones’ into the bloodstream. These hormones enter the anterior pituitary via the pituitary stalk to stimulate the production of other hormones
How does the hypothalamus communicate with the posterior pituitary?
The supraoptic and paraventricular nuclei in the hypothalamus secrete neurohormones which then travel down axons. They then terminate in the posterior pituitary lobe
Describe venous drainage of the pituitary gland and hypothalamus
They drain via hypophysial veins into the cavernous sinus
What structure is located anteriorly to the thyroid gland?
Larynx
What structure is located inferiorly to the thyroid gland?
Trachea
At what vertebral level is the thyroid gland located?
Between C5 and T1
What two structures is the thyroid gland located between?
Circoid cartilage
6th tracheal ring
What is the isthmus of the thyroid gland?
The bridge of tissue which connects the two lobes of the thyroid gland
Where does the isthmus lie opposite to?
The 2nd and 4th tracheal rings
What two strap muscles overlie the thyroid gland?
Sternothyroid muscle
Sternohyoid muscle
What two nerves supply the vocal cords of the larynx?
Recurrent laryngeal nerve
Superior laryngeal nerve
Where does the recurrent laryngeal nerve run between?
Trachea
Oesophagus
Where does the superior laryngeal nerve run between?
Superficial pharyngeal constrictor
Inferior pharyngeal constrictor
What is the superior laryngeal nerve a branch of?
The vagus nerve
What two arteries supply the thyroid gland?
Superior thyroid artery
Inferior thyroid artery
What is the superior thyroid artery a branch of?
Common carotid artery
What is the inferior thyroid artery a branch of?
Subclavian artery
What three veins drain the thyroid gland?
Superior thyroid vein
Middle thyroid vein
Inferior thyroid vein
What vein does the superior thyroid vein drain into?
Internal jugular vein
What vein does the middle thyroid vein drain into?
Internal jugular vein
What vein does the inferior thyroid vein drain into?
Braciocephalic vein
Where are hormones stored in the thyroid gland?
The cavities of follicles
What type of cells line the thyroid gland follicles?
Simple, cuboidal, non-stratified epithelial cells
What are thyroid hormones bound to when they are stored within the thyroid gland? What is this collective structure referred to as?
Glycoproteins
Colloid
What colour do colloids stain on an H&E stain?
Light pink
What type of cells are c-cells in the thyroid gland?
Neuroendocrine cells
What is another name for c-cells?
Parafollicular cells
What hormone do c-cells secrete?
Calcitonin
What are the three hormones secreted by the thyroid gland?
T3
T4
Calcitonin
Where are the parathyroid glands located?
They lie on the lateral aspect of the posterior surface of each thyroid lobe, external to the thyroid fibrous capsule
How many parathyroid glands are there?
Four
What separates the parathyroid glands from the thyroid gland?
Thin fibrous capsule
What level are the superior parathyroid gland located?
The inferior border of the circoid cartilage
What level are the inferior parathyroid gland located?
The inferior poles of the thyroid
What artery supplies the parathyroid glands?
Inferior thyroid arteries
What two veins drains the parathyroid glands? What vein do these veins drain into?
Superior thyroid veins
Middle thyroid veins
Internal jugular vein
What two cells make up the parathyroid gland?
Chief cells
Oxyphil cells
What cells mainly make up the parathyroid gland and stain darker on an H&E stain?
Chief cells
What hormone is secreted by the parathyroid gland?
Parathyroid hormone (PTH)
What is the function of PTH?
It removes calcium from bone and releases it into blood
What is another name for the adrenal glands?
Suprarenal glands
Where are the adrenal glands located?
At the upper pole of each kidney
How are the adrenal glands separated from the kidney?
Fat and capsule
How are the adrenal glands peritonised?
Retroperitoneal
What are the two components of the adrenal glands?
Outer cortex
Inner medulla
What embryological structure does the cortex of the adrenal gland arise from?
Mesodermal epithelium
What embryological structure does the medulla of the adrenal gland arise from?
Neuroectoderm
What three arteries supply the adrenal gland?
Superior suprarenal arteries
Middle suprarenal arteries
Inferior suprarenal arteries
What arteries give rise to the superior suprarenal arteries?
Inferior phrenic arteries
What artery give rise to the middle suprarenal arteries?
Aorta
What arteries give rise to the inferior suprarenal arteries?
Renal arteries
What vein drains the adrenal glands?
Suprarenal vein
How many suprarenal veins are there?
One
What does the suprarenal vein drain into on the right side?
Inferior vena cava
What does the suprarenal vein drain into on the left side?
Left renal vein, which then drains into the inferior vena cava
What are the three zones of the adrenal gland cortex?
Zona glomerulosa
Zona fasciculata
Zona reticularis
What is the outer zone of the adrenal gland?
Zona glomerulosa
What is the middle zone of the adrenal gland?
Zona fasciculata
What is the inner zone of the adrenal gland?
Zona reticulares
What cells are found within the adrenal medulla? What is their function?
Chromaffin cells
They secrete adrenalin and noradrenalin
What group of hormones does the zona glomerulosa produce? Name a hormone
Mineralcorticoids
Aldosterone
What group of hormones does the zona fasciculata produce? Name a hormone
Glucocorticosteroids
Cortisol
What group of hormones does the zona reticularis produce? Name a hormone
Androgens
Testosterone
How is the pancreas peritonised?
Retroperitonised - except tail
What is the pancreas connected to on the right hand side of the body?
Duodenum
What is the pancreas connected to on the left hand side of the body?
Spleen
Name the five sections of the pancreas
Head
Neck
Body
Tail
Uncinate process
What is the transpyloric plane?
An imaginary plane located at L1
What do the arteries of the pancreas derive from?
Splenic artery
Gastroduodenal artery
Superior mesenteric artery
What vein related to the pancreas is found at level of the transpyloric plane?
Splenic vein
What is the exocrine part of the pancreas?
The pancreatic acini
What is the endocrine part of the pancreas?
The Islets of Langerhans
What are the five types of cells found in the Islet of Langerhans?
Alpha cells
Beta cells
Delta cells
Pp cells
Epsilon cells
What do alpha cells of the Islet of Langerhan secrete?
Glucagon
What do beta cells of the Islet of Langerhan secrete?
Insulin
What do delta cells of the Islet of Langerhan secrete?
Somatostatin
What do Pp cells of the Islet of Langerhan secrete?
Pancreatic polypeptide
What do epsilon cells of the Islet of Langerhan secrete?
Ghrelin
What is another name for the pituitary stalk?
Infundibulum
How do we access the pituitary gland for surgical procedures?
Sphenoid air sinus
Which pituitary lobe is the mamillary body attached to?
Posterior
Which pituitary lobe is the optic chiasm attached to?
Anterior
Which large artery runs near the pituitary stalk?
Internal carotid artery
Which bone is closely located to the thyroid gland?
Hyoid bone
What does the aortic arch divide into on the right hand side?
Braciocephalic artery
What are the two divisions of the brachiocephalic trunk?
Right subclavian
Right common carotid
What does the aortic arch divide into on the left hand side?
Left subclavian
Left common carotid
Where does the sternohyoid muscle arise and attach to?
Sternum
Hyoid bone
Where does the sternothyroid muscle arise and attach to?
Sternum
Thyroid cartilage
Which compartment of the neck does the thyroid gland sit in?
Visceral compartment
Which artery lies anteriorly - superior thyroid artery or inferior thyroid artery?
Superior thyroid artery
Which artery lies posteriorly - superior thyroid artery or inferior thyroid artery?
Inferior thyroid artery
What are the two divisions of the superior laryngeal nerve?
External laryngeal nerve
Internal laryngeal nerve
Where membrane does the internal laryngeal nerve pass through?
Thyrohyoid membrane
Where is the external laryngeal nerve located?
On the surface of the thyroid gland
What is the function of the internal laryngeal nerve?
Sensory innervation to the epiglottis
What is the function of the external laryngeal nerve?
Sensory innervation to the circothyroid muscle
Which nerve is closely associated with the superior thyroid artery?
Superior laryngeal nerve
What happens if the external laryngeal nerve is accidentally ligated during superior thyroid artery ligation?
No sensory innervation to circothyroid muscle, so hoarse voice
What is the function of the recurrent laryngeal nerve?
Sensory innervation to the vocal cord muscles, except circothyroid muscle
What does the recurrent laryngeal nerve hook around on the left hand side?
Aortic arch
What does the recurrent laryngeal nerve hook around on the right hand side?
Subclavian artery
What happens if the recurrent laryngeal nerve is accidentally ligated during inferior thyroid artery ligation?
No sensory innervation to the vocal cord muscles, except circothyroid muscle
This means that the vocal cord on the affected side will be adducted
Stridor
Are the parathyroid glands visualised on specimens?
No
What vein follows the same drainage pattern as the suprarenal veins (left - renal, vein, right - IVC)?
Gonadal veins
Which vessels lie posterior to the pancreas?
Splenic artery
Between which two pancreas compartments does the SMA arise?
Neck and unicate process
Which organ lies anterior to the pancreas?
Stomach
What sac lies anterior to the pancreas?
Lesser sac of the stomach
