Endocrine Flashcards
What is the approx diameter of the fenestration vessels in the adrenal glands?
7 micrometers - just large enough to allow RBC through
Where does the Medulla of the adrenal glands receive blood supply from internally?
First from the capillaries and sinusoids of cortex
Second from arterioles passing from the capsule to the medulla
The neurosectrory cells of the medulla show a difference in colour staining to the rest, what is this called?
Vulpian reaction
In the islets - what is the most common cell type at 70%?
Beta cells
The blood supply through the pancreas passes through the endocrine then into exocrine cells - how does this influence exocrine?
The exocrine will receive relatively high concentrations of the hormones released. If hormones of insulin are high this then may influence the uptake/ synthesis of exocrine pancreatic enzymes.
What used to synthesis the cholesterol into progesterone?
Pregnenolone
Where are Chief cells found and what do they secrete?
Parathyroid
PTH
What maintains the homeostasis of calcitonin?
PTH
Where is calcitonin secreted from?
Parafolicular cells of the thyroid
What controls the synthesis and break down of thyroglobulin?
Thyroid stimulating hormone
Where does the thyroid develop from, and what type of tissue is it?
thyroglossal duct from the floor of the pharaynx
endodermal
What organelle is thyroglobulin produced in?
R.E.R
What are the cells that produce TSH and what do they stain?
Thyrotrophs - basophilic
What are the acidophils of the pituitary?
Somatotrophs
Lactotrophs
What are the basophilics of the pituitary?
Corticotroph
Gonadotrophs
Thyrotrophs
What is the marker of thyroid downgrowth on the back of the tongue?
Foramen Caecum
What is the name of the transporter that brings Iodide into the follicular cells?
Sodium Iodide symporter
What are the hormones T3 and T4 secreted out the follicular cell by?
Mono-Carboxylate transporter
What is the main transporter of thyroid hormones?
Thyroxine binding globulin
Outline the hypothalamic pituitary axis:
hypothalamus: Thyroid releasing hormone
Thyrotropes: thyroid stimulating hormone
What breaks down T4 into T3?
5’Deiodination by 1 deiodinase
What receptor responds to Thyroid stimulating hormone?
Thyrotropin Receptor
What does Ca2+ bind to in the enterocyte? and where it is stored?
Calbindin
In the rough E.R
Why does there need to be adjustments for albumin when measuring Ca2+
Off the Ca2+ in the blood 47% of is in free ionised form.
However we can only measure the total Ca2+
therefore - if low albumin we need to take this into account as the level of free Ca2+ may not actually be down
How does Vit D help with absorption of Ca2+?
Increases Calbindin and Ca2+/ATPase activity
Why if a patient has low Mg2+ may it affect calcium levels?
Mg2+ is essential for normal PTH release. as such if calcium levels are low and PTH needs to be released it may not be correctly.
What cells produce calcitonin?
Parafollicular cells
What’s the enzyme that converts 25OHD into 1,25OHD? and where is it found?
1-alpha hyroxylase.
In the PCT of kidneys
Where does the medulla of the adrenal gland develop from and what germ cell layer?
Neural crest cells
Ectoderm
Where does the cortex of the adrenal gland develop from?
Primitive mesothelium
Mesoderm
The capsule of the adrenal is surrounding by what?
Perinephric fat
Whats unique the medullary vein in the adrenal medulla?
sporadic layering of smooth muscle
What controls CRH?
Environmental factors:
- stress
- illness
- time of day - morning its most
The Steroid receptor family is made up of sub-units, what are they and what do they do?
A/B - control gene expression
C - DNA binding
D - Hinge points that control movement to the gene
E - Ligand binding
F - C terminal
Does cortisol cause break down of glycogen?
No - it may even promote synthesis of it
What does cortisol do to insulin?
Supresses its release
What kind of receptor does ACTH bind to? and how does it work?
G -protein - promotes cAMP levels causing Ca2+
this up-regulates the enzymes needed for hormone production
What receptor is Angiotensin II on the adrenal glands?
G - protein - increases Phospholipase C
What kind of receptor is Thyroid stimulating receptor?
G - protein. Adenly cyclase cAMP levels
Where are the islet cells more numerous in the pancreas?
Body and tail
