Term
| What is the pathway of blood through hypophysis? |
|
Definition
Ant: superior hypophyseal aa -> primary portal capillaries -> hypophyseal portal vv -> secondary portal capillaries -> hypophyseal vv
Post: inferior hypophyseal a -> hypophyseal v |
|
|
Term
Where are the cell bodies for the hypothalamo-hypophyseal tract?
What are their products? |
|
Definition
The supraoptic nuclei (SON) and Paraventricular nuclei (PVN) are located in the asal hypothalamus.
Their products are oxytocin and vasopressin (ADH) |
|
|
Term
| what is the path of the hypothalamo-hypophyseal tract? |
|
Definition
| The axons of the PVN and SON run through the infundibular stalk to the Pars Nervousa. Pituicytes are present here. Herring bodies can be visualized in the boutons of these axons. They are granules filled with oxytocin and ADH. |
|
|
Term
|
Definition
A binding protein found in the granules (herring bodies). It attaches to ADH and oxytocin.
|
|
|
Term
| What is the Function of ADH (vasopressin)? |
|
Definition
Acts on Renal collecting ducts and makes urine hypertonic. It relies on the osmoreceptors in the anterior hypothalamus for monitoring.
It also acts on vascular smooth mm causing contraction. |
|
|
Term
| What are the causes of Diabetes insipidus? |
|
Definition
Damage to the ant hypothalamus (irreversible)
Damage to the stalk (reversible) |
|
|
Term
Where is GH produced?
What are its effects? |
|
Definition
GH (somatorpin) produced in the somatotroph cells of the Ant pituatary, referred to as pars distalis. They are acidophilic cells (chromophils)
GH stimulates the liver and kidneys to recrete somatomedin -> body growth. |
|
|
Term
|
Definition
| Within the mammotrophs of the pars distalis (ant pit), they are acidophilic cells. |
|
|
Term
| Where are ACTH and LPH made? |
|
Definition
| In the corticotophic cells of the pars distalis (ant pit). They are basophilic cells |
|
|
Term
| Name the glycoprotein hormones made in the basophilic cells of the pars distalis (ant pit). |
|
Definition
TSH - made by the thyrotrophs
FSH/LH and ICSH - made by the gonadotrophs
|
|
|
Term
| What are the chromophobe cells of the pars distalis? |
|
Definition
| They are reserve stem cells and degranulated chromaphils. |
|
|
Term
| Describe the tubero-hypophyseal system: |
|
Definition
| The tuberal nuclei of the hypothalamus secretes stimulating/inhibitory factors in the primary portal capillaries, which travel to the pars distalis via the hypophyseal portal vv and to the secondary portal capillaries. They influence the release of hormones such as TSHRF, which stimulates TSH from thyrotrophs. |
|
|
Term
| How/when does the thyroid develop? |
|
Definition
At 24 days (4wks) the floor of the primitive pharynx grows downward into a thyroid diverticulum. The developing thyroid descends down the neck while still connected to the tongue by the thyroglossal duct, the opening in the tongue called the foramen cecum.
While descending the diverticulum bifurcates into two lobes. By the 7th wk, its at its final destination ant to the trachea. the two lobes are connected by the isthmus.
By the 20th wk TSH and thyroxine are produced. |
|
|
Term
| what is the pyramidal lobe? |
|
Definition
in half of the population the thyroglassal duct doenst atrophy... it attaches to the hyoid bone by fibrous mm tissue.
|
|
|
Term
| Review the blood supply and drainage of thyroid. |
|
Definition
Sup thyroid a (from ext coratid)
Inf thyroid a (from thyrocervical trunk)
Sup thyroid v (to int jugular)
middle thyroid v ( to int jug)
Inf thyroid v (brachiocephalic v) |
|
|
Term
| How are MIT and DIT made? |
|
Definition
monoiodotyrosin is made when a iodine radical is attached to the #3 position of a aryl ring of a tyrosil radical during the synthesis of a thyroglobulin molecule in the lumen.
DIT is made when another iodine radical is attached to the #5 position.
|
|
|
Term
|
Definition
TSH stimulates microvilli of follicular cells to extnd into lumen and take up colloid which has TG ( DIT and MIT), the TG droplets will be digested by lysosomes and released into the cytoplasm.
DIT + DIT = T4 + Alanine
MIT + DIT = T3 + Alanine
T3 and T4 will be secreted back into the blood vessel, and Iodine and the AAs will be recycled. |
|
|
Term
| Where does calcitonin come from? |
|
Definition
| Parafollicular cells of the thyroid |
|
|
Term
| What cells make up the parathyroid glands? |
|
Definition
Cheif cells - make PTH
Oxyphil cells - appear after 6yo, have more cytoplasm.
|
|
|
