Anatomy of the endocrine system Flashcards
what are the names of the main endocrine organs in the body?
pineal gland
thymus
parathyroidglands
thyroid gland
adrenal glands
pancreas
placenta (during pregnancy)
ovaries
testes
the pituitary gland sits in a hollow in the skull
what is the hollow called and in what bone of the skull is it situated?
pituitary fossa/sella turcica
sphenoid bone
how is the optic chiasm related to the pituitary gland?
the optic chiasm is directly above the pituitary gland
clinical: enlargement of the pituitayr gland in disease often impinges on the crossing fibres of the optic chiasm
which fibres form the optic nerve, nasal or temporal, cross over to the opposite side at the chiasm?
what therefore would the resultant visual defect be due to pituitary gland enlargement?
nasal
loss of temporal vision - bitemporal hemianopia
a
mamillary body
b
pituitary stalk
c
posterior pituitary
d
hypothalamus
e
optic chiasm
f
pars intermedia
g
anterior pituitary
what is the larger of the two lobes of the pituitary gland?
anterior pituitary
which of the two lobes of the pituitary gland is glandular and manufactures numerous hormones?
anterior
what is the function of the posteiror pituitary?
stores and secretes two hormones made in the hypothalamus
does the anterior or posterior pituitary stain darker?
anterior - darker
posterior - pale
what cells are seen in the anterior pituitary and what colour do they stain?
acidophilic (stain pink)
basophilic (stain light purple)
chromophobic (dont take up much stain and therefore appear pale)
whata re the different classes of acidohpil?
somatotrophs
mammotrophs
what is the secretory product and target organ of somatotrophs?
GH
all tissues
what is the secretory product and target organ of mammotrophs?
prolactin
mammary gland
what are the different classes of basophil?
corticotrophs
tyhrotrophs
gonado-trophs
what is the secretory product and target organ of corticotrophs?
ACTH and MSH
adrenal gland and skin
what is the secretory product and target organ of thyrotrophs?
TSH
thyroid gland
what is the secretory product and target organ of gonado-trophs?
FSH and LH
Ovaries/Testes
what are the main secretory cells of the posterior pituitary?
neurosecretory ccells
magnocellular neurones
what hormones do the cells of the posterior pituitary secrete?
ADH
oxytocin
what is the blood supply of the hypothalamus?
branches of the ICA - the superior and inferior hypophysial arteries
the superior hyophysial artery enters into the substance of the hypothalamus before breaking up into capillaries (the hypophysial portal system). these capillaries then supply the anterior pituitary gland
the inferior hypophysial artery supplies the posterior pituitary gland
how does the hypothlamus communicate with the anterior pituitary?
special portal blood system - hypothalamus-hypophyseal
how does the hypothalamus communicate with the posteiror pituitary?
neurons - magnocellular
venous drainage is through what?
hypophysial veins into the cavernous sinus
where is the thyroid gland located?
in the neck anterior to the trachea and just inferior to the larynx
located between the level of C5 and T1 and between the thyroid cartilage and the 6th tracheal ring
the isthmus lies opposite the 2nd and 4th tracheal rings
what are the 3 strap muscles that overlie the thyroid gland?
sternohyoid
omohyoid (anterior belly)
sternothyroid
name the two nerves that supply the muscles of the vocal cords and describe their location in relation to the thyroid gland
- recurrent laryngeal nerve - tuns between trachea and oesophagus
- external laryngeal nerve (branch of the superior laryngeal nerve) - lies close to superior thyroid artery
form which major artery in the neck does the superior thyroid artery arise?
ECA
from which artery doe sthe inferior tyhroid artery arise?
subclavian artery
into which vein does the superior thyroid vein drain?
IJV
into which vein does the middle thyroid vein drain?
IJV
into which vein does the inferior thyroid vein drain?
brachiocephalic vein (left)
most lymph vessels form the thyroid gland drain into the ______ ________ group of lymph nodes
deep cervical
the hormones of the thyroid gland are stored in _______, surrounded by _______ cells. these make up a ______. within the cavity of the follicle, the hormone is bound to a __________ and is called as ______. during secretion the hormones is re-absorbed from the cavity, and then released into surrounding interstitial spaces
cavities
secretory
follicle
glycoprotein
colloid
what type of cell do you see lining the follicle?
follicular cells
simple cuboidal epithelial
what colour does the colloid stain (in a H&E stained slide)?
pink
what do clear/parafollicular/C cells secrete?
calcitonin
Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone
Secretion of this hormone is controlled directly by the blood’s calcium levels. When the levels start to increase, the body responds with increased calcitonin levels
what hormone does the thyroid gland secrete?
T3 - Triiodothyronine
T4 - thyroxine
the parathyroid glands lie on the _____ half of the ______ surface of each thyroid lobe, external to the thyroid fibrous capsule
most people have 4
they are seperated from the thyroid gland by a think ______ capsule
lateral
posterior
fibrous
where are the superior and inferior parathyroids situated?
the superior parathyroids are situated at the level of the inferior border of the cricoid cartilage
the inferior parathyroids are usually near the inferior poles of the thyroid, though their position is variable
what is arterial and venous drainage of the arathyroid glands?
arterial supply to both superior and inferior parathyroids is predominantly form the inferior thyroid arteries
venous drainage is via the veins draining the thyroids to the internal jugular veins
what types of cells are seen in the parathyroid?
cheif cells
oxyphil cells
cheif cells are mor enumerous and have a darker staining cytoplasm
what hormone is secreted by the parathyroid gland and what is the action of this hormone?
parathyroid hormone:
decreases phosphate
increases plasma calcium
what cells does parathyroid hormone act upon and what is their subsequent action?
stimulates osteoclasts to increase release of Ca2+
inhibit osteoblasts to reduce Ca2+ dpeosition in bone
increase Ca2+ reabsorption from kidney tubules
increase renal excretion of phosphate
stimulates kidney to synthesise calcitriol from vit D which promotes calcium absorption at the gut and kidney
are the adrenal glands retroperitoneal or intraperitoneal?
retroperitoneal
what are the two parts of the suprarenal glands and what do they develop from?
outer cortex - mesodermal epithelium
inner medulla - neuroectoderm
what is the blood supply of the adrenal glands?
suprarenal arteries that arise from the inferior phrenic arteries, the aorta and renal arteries
where does the superior, middle and inferior adrenal arteries come form?
superior - inferior phrenic
middle - aorta
inferior - renal arteries
there is only one suprarenal vein
into which vein does the suprarenal vein drain?
on right side - IVC
on left side - left renal or left inferior phrenic vein
what are the layers of the cortex?
zone glomerulosa (thin)
zona fasiculata (thick)
zone reticularis - immediatley adjacent to the medulla)
what does the medulla contain and secrete?
the medulla has large collections of large ovoid chromaffin cells which secrete adrenalin and noradrenalin
what are the 3 main hormone types secreted form each of the three zones?
zona glomerulosa - Mineralocorticoids - aldosterone
zona fasiculata - Glucocorticoids - cortisol
zona reticularis - androgens
(medulla - epinepharine and norepinepharine)
is the pancreas retroperitoneal or intraperitoneal?
retroperitoneal
a
hepatic artery
b
splenich artery
c
inferior mesenteric artery
d
superior mesenteric artery
differentiate the exocrine part of the pancreas (pacnreatic acini) form the endocrine part (Islets of Langerhans)
what type of cell types are found within the Islets of Langerhans and what do they secrete?
a - glucagon
b - insulin
delta - somatostatin
