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  • - [Instructor] What you see in these pictures,

  • this is a forward view of a transparent man

  • or a semitransparent man,

  • and this is a posterior, or back view

  • of a semitransparent woman.

  • But what these organs that are depicted,

  • these organs secrete molecules into the bloodstream,

  • and an organ that secretes things,

  • these are called glands,

  • and they secrete these molecules into the blood stream

  • that regulate other parts of the body,

  • things that might be quite far away from the organs,

  • the glands that actually do the secretion.

  • And so these molecules

  • that regulate other parts of the body,

  • these are called hormones.

  • And the word hormone comes from Greek hormōn,

  • which means to set in motion,

  • so one way to think about it, these are molecules

  • that set things in motion in other parts of the body,

  • and this is really to regulate the body function.

  • Now this entire system of glands is referred to

  • as the endocrine system, endo- referring to fact that

  • it's acting within the body, -crine originally comes

  • from Greek word to sift or to differentiate something

  • and it's a system of organs

  • or I guess you could say glands

  • that are secreting molecules,

  • these hormones into the bloodstream to regulate the body.

  • I'm not going to go in-depth

  • in all of these endocrine glands

  • but just to give you an appreciation of what they do

  • and what these hormones are all about,

  • we could list some of the more common ones

  • that you might hear about.

  • So for example, the thyroid gland produces thyroid hormone.

  • This is a version of thyroid hormone.

  • You see your carbons in the dark gray,

  • your hydrogens in the white.

  • You see your oxygens in the red, nitrogen in blue,

  • and these big atoms right over here, these are iodine,

  • and thyroid hormone plays an important role

  • in your metabolism.

  • In fact, if you have too much thyroid hormone,

  • that's a disorder called hyperthyroidism,

  • which would make your metabolism overactive.

  • Likewise, if you have too little thyroid hormone,

  • that's a disorder known as hypothyroidism,

  • in which case your metabolism isn't active enough.

  • You have hormones like adrenaline

  • that are released by the adrenal glands,

  • and that's where it gets the word adrenaline from.

  • It's often known as epinephrine,

  • and adrenaline, you might hear things like,

  • "Hey, so and so is an adrenaline junkie,"

  • which means they really like a thrill,

  • and adrenaline actually does play a role there.

  • It's involved in the fight-or-flight response,

  • where it'll increase your heart rate

  • and increase blood flow to the muscles.

  • And what's really interesting about all of these hormones

  • is they have so many impacts on the body

  • because they're released into the bloodstream

  • and to different cells they might do different things.

  • This right over here is a variation of estrogen,

  • which is produced primarily in females in the ovaries,

  • but it also exists in a male body

  • and it's associated with a lot of female bodily function,

  • but once again, not strictly female.

  • Estrogen also exists in males.

  • Similarly, you have testosterone,

  • which is associated with male function

  • but it also exists in females,

  • and it's primarily produced in men in the testes.

  • Thus the name testosterone,

  • but it can also be produced by the adrenal glands.

  • And women, it can be produced by the ovaries.

  • But you could also have a molecule like insulin

  • which you can see is much larger than the other hormones

  • that we have looked at.

  • It's produced in the pancreas

  • and it plays a super-important role

  • in how we process sugars and how we store fat

  • and scientists are constantly discovering new roles

  • for these various hormones.

  • Insulin in particular you might associate with diabetes.

  • People with Type 1 diabetes aren't able to produce

  • enough insulin to take the sugar out of their blood stream,

  • to have the cells absorb the sugar.

  • Insulin will bind to the surface of a cell

  • so that it will start taking in sugar

  • from the blood stream.

  • People with Type 2 diabetes, they have an insensitivity

  • to insulin, so they might have to take extra insulin

  • in order for their cells to take in the proper amount

  • of sugar.

  • But the big idea here is that the endocrine system,

  • although it might not be as obvious,

  • or it might not be as well known

  • as something like say the nervous system,

  • it plays a pivotal role in your body.

  • It helps regulate your body.

  • It helps keep it at the right temperature,

  • the right blood pressure,

  • your heart pumping at the right rate.

  • One way to think about this is

  • the notion of homeostasis, which is

  • derived from similar and staying the same.

  • So keeping your body at the right temperature

  • regardless of what the temperature is outside

  • or regardless of what your body is doing,

  • there's a whole series of roles that these hormones,

  • which are released by these endocrine glands

  • actually do.

- [Instructor] What you see in these pictures,

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B2 中上級

内分泌系の紹介 (Endocrine system introduction)

  • 15 1
    Amy.Lin に公開 2021 年 01 月 14 日
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