L3 - HPA Axis

Question 1

two types of cells that make up the thyroid gland

Answer 1

follicles and C cells (parafollicular cells)

Question 2

what makes up a follicle consist of?

Answer 2

1. Many follicular cells lined up on the outside of the cell.
2. Colloid is in the inside of the cell and is the lumen component of the cell.

Question 3

where is the thyroid gland located?

Answer 3

at the lower part of your neck and right above/sitting in front of the trachea

Question 4

Production of thyroid hormone

Answer 4

Follicular cells produce thyroglobulin (protein) which is secreted via exocytosis into the colloid.
Meanwhile iodide is brought from the blood into the follicular cell via the NIS transporter (sodium-iodide symporter).
Iodide is transported from the follicular cell and into the colloid (lumen) via Pendrin (transporter).
In the lumen, iodide is converted into iodine by thyroperoxidase (enzyme).
Iodine attaches to the tyrosine rings of the thyroglobulin. Either one or two iodine can attach to each of the tyrosine rings. If it has one iodine attached it is called MIT (monoiodotyrosine) and two iodines attached is called DIT (diiodotyrosine). These tyrosine molecules join together - DIT + MIT = T3, and DIT + DIT = T4. This is an attached cell (T3 and T4).
The thyroglobulin then gets up in the follicular cells via proteolysis into T3 and T4 components and is secreted into bloodstream

Question 5

How do pancreatic beta cells work?

Answer 5

insulin is present in the vesicles of the beta cells. in order for vesicles to be released from the cell, there needs to be rises in intracellular calcium ions.
potassium is naturally always leaking out of the pancreatic beta cells via simple diffusion establishing a more negative charge inside the cell via potassium-ATP gated channel.
glucose enters the pancreatic beta cell via GLUT2 transporter and is converted to ATP.
this build up of ATP will block the ATP-gated potassium channel, causing increase of potassium inside the cell, and therefore depolarization
this activates voltage-gated calcium channels allowing calcium to flow into the cell
calcium will bind to calcium-receptor on insulin containing vesicles causing release of vesicle components via exocytosis into the portal venous blood

Question 6

HPA axis

Answer 6

involved in our body’s reaction to stress