Forgotten Physiology – The Endocrine System Part 1

If someone asked you to describe the endocrine system in three words and the words “What is that?” are all that come to mind then…yeah, you should check out these articles.

5899276_f260Ah yes, the endocrine system is one of my favorite misunderstood topics in biology (did you just get chills…me too). I’ll bet that if we gathered up all of the skeletons from America’s academic closet they would all be huddled around the endocrine system for warmth. Beneath his rough exterior of ten syllable physiological names the endocrine system is just a big ole softy. However, once you learn half of what this system is capable of you’ll be happy that you never leave home without it (which would be impossible and gross).

It will be difficult. There is an [EXPLETIVE] load of hormones and chemicals involved that you’ll need to commit to memory and unfortunately, your professors will want you to “apply your knowledge” on an exam, requiring you to magically posses an intimate understanding of the facts you’ll probably stay up all night on Coke and Doritos, force feeding your brain. So let us dive into the nuts and bolts of how this system works.

It’s all about the Glands

The endocrine system is a network of ductless glands (chemical secreting glands without the fancy side channels) that secrete chemical signals called hormones directly into the bloodstream. These hormone signals communicate with organs in our bodies on a cell to cell basis, like wickedly efficient chemical text messages.

“Hey liver cells, let’s lower the blood sugar later.” – Your BFF the Pancreas.

They will tell you that this change occurs gradually but when you consider just how many trillion cells there are in the body this is really an extraordinarily rapid process.

Some Basic Anatomy

There are about 6 glands that have been granted endocrine VIP status:

Pituitary AkA the Hypophysis(anterior & posterior) – which hangs out on the lower fore brain, riding shot gun with the hypothalamus just a few centimeters away from the spinal chord.

Thyroid – forms a mass over the trachea like a really ugly, trippie butterfly

Parathyroids – four tiny masses with each pair hitching a ride with either side of the thyroid

Adrenal glands (cortex & medulla) – you have two that ride piggie back on top of each kidney

Pancreas – parked along the lower curvature of the stomach just before it forms into the duodenum, essentially hanging along the sagging waistline of the digestive system

Gonads – general name that describes the testes in men and the ovaries in women which are located within the pelvic cavity, A.K.A the nether region, the land down under, cave of secrets, magic kingdom….yeah, well you get the idea.

The Pituitary Gland A.K.A Hypophysis

Whatever you do don’t confuse the hypophysis with the word hypothesis…seriously try not to think about how similar those two words sound.
As endocine glands go, the pituitary is like a sleek, sophisticated hybrid model. Your pituitary and hypothalamus form a neuroendocrine network of neurons and endocrine cells, granting the pituitary global access to other endocrine glands in the system. If the body were highschool the pituitary would be that trendy, oh so popular chick with everyone’s number programmed into her phone.
In many ways it is the brains of the endocrine system, sensing subtle changes in the body and signaling endocrine organs such as the thyroid or adrenal gland to produce hormones that allow the body to compensate for those changes. For example, if a decrease in blood sugar is detected by the hypothalamus the pituitary will produce a trophic hormone ACTH (adrenocorticotrophic hormone) which triggers the adrenal gland to secrete cortisol, which gradually increases the blood sugar. Trophic hormones signal the secretion of hormones by other endocrine organs. Since the pituitary is souped up with nifty neural connections it can pass notes fairly easily to all the cool kids in the class (endocrine target organs within the system) with an assortment of trophic hormones.

Pituitary Gland Top 5 Greatest Hits (Trophic hormones)

here’s a fun list of trophic hormones produced by the anterior pituitary and their functions

TSH (thyroid stimulating hormone) – stimulates the thyroid gland to secrete thyroid hormone which actively regulates metabolism….more on this later

ACTH (adrenocorticotrophic hormone) – stimulates adrenal cortex to release glucocorticoids, steroid hormones that regulate glucose

FSH (folicle stimulating hormone) – stimulates the maturation of eggs in females and the production of sperm cells in males

GH (growth hormone) – stimulates bone and muscle growth as well as the production of IGF (insulin like growth factor) produced primarily in the liver which triggers growth in many tissues. Plays a crucial role in growth and development in early childhood.

LH (Leutinizing hrmone) – induces ovulation in women and the secretion of testosterone in men…more on this later.

THe EnD..well for now…

Hey don’t worry, I’ve got way more to say about the endocrine system. It’s kind of a big topic so I’ve broken it down into a few articles for your convenience. Please keep reading and if I’ve made some incorrect or misleading points along the way let me know..but be nice. I’m sensitive 🙂 Stay classy and never stop learning.

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