L3 Nuts and Bolts Flashcards
Where is the pituitary gland located?
sella turcica of sphenoid bone
Two parts of the pituitary gland
Adenohypophysis - glandular part - outpouching of ectoderm of oral cavity - Rathkes pouch
TSH FSH LH
Neurohypophysis - neural part- down growth from diencephalon of brain
oxytocin and ADH
Blood circulation to pituitary gland
2 Main blood vessels
superior hypophyseal supplies median reminence and upper part of stalk
Inferior hypophyseal supplies the neurohypophysis and lower part of stalk
Arteries supplying the median em and stalk end as capillary plexuses
the capillary plexuses in median eminence and stalk ending are drained by portal veins which pass to ant lobe of pit. veins then form a secondary cap plexus.
this allows route for neurosecretory substances released from the hypothalamus to reach to ant lobe.
How is activity of the pituitary gland controlled?
recieves signals from hypothalamus to control its hormone release. from both the adeno and neuro
Describe the structure of the thyroid gland
bilobed gland in the neck
2 lateral lobes connected by isthmus that courses anterior to the trachea
derrived from endoderm
Blood supply to thyroid gland
supply by superior and inferior thyroid arteries
sup - from ex carotid
inf - from subclavian
Drainage - veins
drain from plexus into IJV and BCV
Parathyroid glands
4
2 sup 2 inf
located posterior aspect of thyroid - capsule
Where are parathyroid glands derived from?
from cells originating from 3/4th pharnygeal pouches - migrate caudally with the thymus
Why must you preserve the parathyroid glands during thyroidectomy?
PTH regulates calcium and phosphate homeostasis
if removed, blood calcium levels fall resulting in muscles including resp muscles and laryngeal go into tetanic contraction leading to death
VAN - parathyroid glands
V - sup middle and inf thyroid
A - primarily inf thyroid but also superior
N - middle and cervical ganglions
where are adrenal glands located?
superior pole of kidneys
retroperitoneal
T12
where do cortex and medulla of adrenal glands originate from?
cortex - mesoderm
medulla - from neural crest cells
Adrenal glands - medulla
secretory cells of medulla - chromaffin cells derived from same embryonic tissue as symp ganlgia
the medulla is regarded as modified symp ganglion (ANS)
secrete adrenaline and smaller amounts of nor
Blood supply to adrenal glands?
sup middle and inf suprarenal arteries
Why do hormones produced by corticol cells influence activity of cells in the medulla? eg - cortisol mediates mediates NA conversion to adrenaline
Because medullary arteries pass through cortex to supply the medulla so recieves blood from 2 sources
