2-Minute Neuroscience: HPA Axis

In this video, I discuss the hypothalamic-pituitary-adrenal, or HPA, axis, which plays an important role in our stress response. I describe the components of the HPA axis (hypothalamus, pituitary gland, adrenal glands) and the hormones released by each of these structures during the stress response.

TRANSCRIPT:

Welcome to 2 minute neuroscience, where I explain neuroscience topics in 2 minutes or less. In this installment I will discuss the HPA axis.

The hypothalamic-pituitary-adrenal, or HPA, axis is best known for its role in our body’s reaction to stress. The HPA axis includes a group of hormone-secreting glands from the nervous and endocrine systems: the hypothalamus, pituitary gland, and adrenal glands. The hypothalamus is a small neuroendocrine structure situated just above the brainstem that controls the release of hormones from the pituitary gland, a hormone-secreting gland that sits just below the hypothalamus. The pituitary gland can release hormones into the bloodstream to reach a variety of targets. In the case of the HPA axis, hormones released from the pituitary gland travel down to the kidneys and influence the secretion of hormones from endocrine glands called the adrenal glands, which sit on top of the kidneys.

The primary function of the HPA axis is to regulate the stress response. When we experience something stressful, the hypothalamus releases a hormone called corticotropin-releasing hormone (or CRH). CRH signals the pituitary gland to secrete a hormone called adrenocorticotropic hormone, or ACTH into the bloodstream. ACTH travels down to the adrenal glands where it prompts the release of a hormone called cortisol from the cortex, or outer layer, of the adrenal glands. The release of cortisol causes a number of changes that help the body to deal with stress. For example, it helps to mobilize energy like glucose so the body has enough energy to cope with a prolonged stressor. When cortisol levels in the blood get high, this is sensed by receptors in areas of the brain like the hypothalamus and hippocampus, which leads to the shutting off of the stress response through what is known as a negative feedback mechanism.

References:

Tasker JG, Herman JP. Mechanisms of rapid glucocorticoid feedback inhibition of the hypothalamic-pituitary-adrenal axis. Stress. 2011 Jul;14(4):398-406. doi: 10.3109/10253890.2011.586446.

Thiel KJ, Dretsch MN. Basics of the Stress Response. In: Conrad CD, ed. The Handbook of Stress: Neuropsychological Effects on the Brain. Malden, MA: Wiley-Blackwell; 2011: 1-28.

Vedder H. Physiology of the Hypothalamic-Pituitary-Adrenocortical Axis. Neuroimmune Biology. 2007. Jul;7:17-31.

[llinda]

So i think of Hypothalamus as the director, Pituitary as the manager, and Adrenal as the staff. Director orders manager, and the manager walks to the employee office tells them to release cortisol. Never gonna forget again.

[KenDBerryMD]

The best 2 minute explanation of the HPA-axis I've ever seen!

[reyramos]

as a psych student, I was struggling to understand this in my Emotions class. This video just cleared up all confusion. THANK YOU

[avapilsen]

As a neuroscience undergrad, these videos are SO helpful. Thank you so much!

[Antoine_Fainthearted]

Didn't know I had a second nut sack in my brain, you learn something new everyday!

Edit: Thank you for the video.

[raginaldmars]

For a Biochemist Ph D - this is a true pleasure watching you doing this. Great Talent! Become a Prof. of Biochemistry!

[thickgall]

Love the video! Major help for my nursing exam on the endocrine system in 2 days

[lf]

I am French, and it's been two weeks I've been looking for this video! Thank you so much!

[razans]

The best video to explain HPA axis, thank you very much 😊

[gautamsain]

Nice video. How about making it 3 minutes so you could finish that last thought.

[KangarooOFgod]

Thank you very much for the knowledge about the hpa axis.❤

[JessentialLife]

This was perfect, clear and concise. Thank you!

[babyyodachelsea]

That was way simpler than I thought it was thank you so much!! ❤️❤️

[shubo]

Bro your two minutes videos are blessing for us students

[ethanboyd]

Haven't had time to read the papers but would I be wrong in assuming this negative feedback modulating the stress response of the hippocampus/hypothalamus is in part responsible for the so, ewhat spontaneous cessation of craving and drinking behaviors of opioids, alcohol, cocaine, and recently more?

[sharonamaya]

Big help! The best explanation I've seen! Thank you so much!

[Dreamer-ewzw]

@neuroscientifically Thank you very much for all of your Almost after three weeks.... Now there is a new life Have a nice day

[overcomer]

OK but how do we fix HP A-axis dysfunction and doesn't the thyroid tie in with this as well

[Tp]

Wow, I normally don't react or comment on videos, but your channel is greatly underappreciated! Thanks for the great videos!

[sergiosanchezpadilla]

Woah. Great job again man. I just got a bit lost the last 5 seconds but I will read the transcript to clarify :) THANKS BUDDY!!!