Endocrinology | Pancreas: Glucagon Function

Ninja Nerds!

Join us for this two part lecture series where Professor Zach Murphy will be teaching you about the pancreas. During this lecture we discuss the hormone glucagon and its function to act upon the liver to stimulate glycogenolysis and increase blood glucose levels. We hope you enjoy this lecture and be sure to support us below!

Correction @ 7:16 I referred to CCK and secretin as Glucagon stimulators, but they are actually glucagon INHIBITORS due to being released during the fed state. CCK and secretin are insulin stimulators, as their action is to lower blood glucose levels. Thanks!

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[kmkim]

Regarding the relationship between low blood glucose and glucagon release... it looks confusing. But I guess the explanation by Ninja Nerd is the best at present moment. The link between low concentrations of glucose and depolarization of the cell membrane is still under debate. According to one of the hypotheses, they think ATP-dependent K+ channels (KATP) plays important roles as in beta cells but the downstream link seems to be not clear yet. At moderate inhibition of KATP (low glucose concentration), membrane is moderately depolarized to open Na+ channels, resulting in the opening of voltage-dependent calcium channels. At high glucose concentration, KATP is strongly inhibited and the membrane potential is strong enough to inactivate Na+ channels, and calcium channels cannot be activated. This is just one of the current hypothesis, and it is not still clear why this does not apply in the regulation of insulin secretion in beta cells.

[abraxadabra]

For anyone perplexed about the Ca Channels, I think the answer is : Voltage-activated calcium channels can be divided into two subgroups based on their activation threshold, low-voltage-activated (LVA) and high-voltage-activated (HVA).

[SkpperCS]

'I think Ill mention it for those students who want to learn a little more'

This means so much to me to hear. Thank you dearly.

[shreyadixit]

You are a god's gift to medical students. Thank you so much for sharing your knowledge with us. Really very grateful!

[supernovachampions]

I love how you added glucagons effect on the myocardium... useful in beta blocker and CCB overdose. Great review!

[rabiamaham]

You get all the concepts together and make them understandable in a very easy manner. Great work and thank u so much for all these videos

[miriamcampillo]

Hey ! I am studying Biotechnology and have some exams in a few weeks. I just wanted to tell you that your videos are incredibly well explained. I could just watch them for fun. Congratulations for all the work and effort and thank you very much :)

[loloonthelow]

the best teacher... i wish i could pay my med school tuition to this king

[isabear]

Thank you Ninja Nerd, this video was very helpful, and so was the Insulin one. For anyone else confused about the Ca channel part, I tried asking chatGPT whose answer made sense. Not sure how scientifically accurate it is though, but the logic tracks:

Both alpha and beta cells use ATP and KATP channels to sense glucose, but their responses diverge. In beta cells, high glucose increases ATP, closes KATP channels, depolarizes the membrane, opens L-type Ca²⁺ channels, and triggers insulin secretion—no need for Na⁺ spikes. In contrast, alpha cells rely on Na⁺-driven action potentials to activate P/Q-type Ca²⁺ channels for glucagon release. At high glucose, increased ATP also closes KATP in alpha cells, but this depolarizes the membrane just enough to inactivate Na⁺ channels, suppressing APs, reducing Ca²⁺ influx, and inhibiting glucagon secretion. Thus, while both cell types share similar glucose-sensing machinery, their ion channel dynamics and calcium dependencies lead to opposite functional outcomes.

[vatsalshah]

Comprehensive information provided here.
You make life really easy in just 25 minutes. And after this, reading through text book becomes a breeze.
Keep up the work and would love to see more topics covered.

[wardakashif]

i had my endocrine exam today and it went absoleutuly great, actually i aced it, thank u sooo much for all of these videos. this whole endocrine palylist was soo detailed yet so easy to understand.

[abraxadabra]

I appreciate the way you're enthusiastic about the things you explain - it makes the difference!! :D

[schuggy]

I am now a fan. You are becoming my favorite YouTube channel. I am so glad you exist as a person and you do what you do. Keep making these videos and I'll keep watching them. Look for a patreon donation coming your way.

[pristinepolido]

You're an angel. I'll marathon your videos as prep for my licensure exam!!

[safaaamehdar]

I hope you reach 10 million subscribers
Very well explained, You are amazing teacher !

Lucky to have you Ninja nerd ❤️

[shahbaz]

hello Dr. WE need more videos of yours. start a new series of videos on any system. please keep em coming. we really love and appreciate your work.

[ElectricKoolaid]

how did only 9.6k people like this video out of 337k views?! Zach is the best instructor on YT hands down

[YKSSN]

thank you for sticking through the whole process of making this video

[vinalkumar]

yes !! i did enjoy the video !! and thank you for keeping these for free us students to learn and always come back to!! Much appreciation from a fellow med student.

[bensonchangwe]

Thank you so much ninja nerd. You just made endocrine system easy to understand. ❤