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Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,0:01\NVoiceover: Imagine you're in a movie theater.\N0:03\NYou're watching a really, really long movie.\N0:05\NAnd you've finished your entire bucket of popcorn.\N0:08\NYou've guzzled down a giant soda\N0:10\Nand all of a sudden, you have to pee.\N0:12\NAnd to make matters worse, you're watching a movie\N0:15\Nabout a whole bunch of people on a cruise ship\N0:17\Nthat hit an iceberg and so, there's a lot of water\N0:20\Nin this movie and you freak out because\N0:22\Nnow you have to get up and go to the bathroom.\N0:24\NBut then that should get you thinking,\N0:27\Nwell, how do my kidneys work?\N0:28\NHow is it that I can make all this pee\N0:30\Nthat I have got to get rid of?\N0:32\NWell in the next few videos, we're gonna\N0:33\Ntalk about how the kidneys work.\N0:35\NAnd I'll give a quick overview here\N0:36\Nbefore we delve more into the specifics.\N0:39\NAs you can see, the kidneys sit\N0:41\Nright here around your belly button.\N0:43\NThey're about the size of a fist and you've got two of them.\N0:47\NAnd they sit a little closer\N0:48\Nto the back, not really in the front.\N0:50\NSo the kidneys receive blood from the heart.\N0:52\NSo the heart goes on up here.\N0:56\NIt's also about the size of a fist.\N0:58\NAnd it pumps blood throughout the body.\N1:00\NYou know, you get some to your arms,\N1:03\Nyou have some that goes up to your brain,\N1:05\Nand you have this branch that comes down\N1:08\Nand it goes towards your legs, as well.\N1:10\NWell, what you can kind of see\N1:12\Nin the picture of the kidneys right here,\N1:14\Nis that they've got a little vessel right there\N1:16\Nso sure enough, there's some blood that comes\N1:18\Nfrom the heart into the kidneys.\N1:21\NBoth of your kidneys, then, are going to\N1:23\Nfilter the blood and release urine,\N1:26\Nwhich is just a collection of waste products\N1:28\Nthat your body wants to get rid of.\N1:30\NAnd the urine is gonna hang out\N1:32\Nin your bladder that sits about right here,\N1:34\Nuntil it's an appropriate time to go to the bathroom.\N1:37\NAnd that's kind of a broad overview.\N1:38\NBut let's go into a little more detail\N1:40\Nabout what the kidneys do.\N1:42\NSo I'm going to draw a box over here.\N1:45\NAnd this box is going to be what the kidneys do.\N1:50\NSo I'm going to give just a really simplistic\N1:53\Noverview of what the kidneys do.\N1:55\NAnd then in other videos, we'll go dive deeper into detail.\N1:59\NSo as I mentioned, each of your kidneys\N2:01\Ngets an oxygenated blood vessel,\N2:03\Nor an artery that goes to them.\N2:06\NAnd your arteries hold onto all the things in your blood.\N2:09\NThis can include things like your nutrients.\N2:11\NAnd so nutrients can be anything from say,\N2:15\Nyour electrolytes like your sodium ions.\N2:18\NThey can be things like your proteins or your\N2:21\Namino acids or even glucose, as well,\N2:24\Nthings that build your carbohydrates.\N2:26\NSo a lot of things that your body uses\N2:28\Nas the building blocks, or things that help\N2:30\Nother structures of your body work.\N2:33\NIn addition to your nutrients, you've also got\N2:35\Noxygen hanging out in your arterial blood.\N2:38\NAnd your arteries also contain waste products.\N2:41\NSo things your body has made through cellular respiration\N2:44\Nand all these other processes that we undergo\N2:47\Nthat we don't need anymore, that we want to get rid of.\N2:49\NAnd they can include things like urea and other\N2:52\Ntoxic compounds that we don't want to build up.\N2:54\NAnd at the same time, it can also include\N2:57\Nextra electrolytes, like sodium that we don't need.\N3:00\NBecause if we hold onto a lot of sodium chloride,\N3:02\Nwhich is just salt, we'll end up having high blood pressure.\N3:05\NSo our kidneys also help us maintain our\N3:08\Nblood pressure, as we'll talk about in other videos.\N3:10\NSo, this just kind of underlines\N3:12\Nthe point that if you have too much\N3:14\Nof your nutrients, they become waste products.\N3:16\NAnd so, your kidneys help to make sure you don't\N3:19\Nbuild too much of this good stuff here.\N3:21\NSo this is all the stuff you've got hanging out\N3:24\Nin the artery that's coming over to your kidney, right here.\N3:27\NAnd as you might recall, whenever you have\N3:29\Nan artery coming into an organ or a part of your body,\N3:32\Nthere should be a vein that takes the blood away\N3:36\Nfrom it that's going to return it to the heart.\N3:39\NSo this is your vein, right here.\N3:41\NAnd so the job of the kidneys then, is to make it so that\N3:45\Nthe nutrients you had in your arterial blood\N3:48\Nare collected and maintained when we get to the vein.\N3:51\NSo we want to hold on to our nutrients, right here.\N3:53\NSo I'll just write "nutrients".\N3:55\NAnd it stands for all the stuff that I\N3:57\Ngave examples for on the left side here.\N3:59\NAnd the kidneys, like every organ\N4:01\Nin the body, need oxygen to do well.\N4:03\NSo you'll have the oxygen go through the kidneys\N4:05\Nand some of it will make it out.\N4:07\NSome of it will be used by the kidneys.\N4:09\NBecause that's how we can maintain some of the tissue.\N4:12\NAnd so when we get to the other side,\N4:14\Nwhere the vein is, we'll have less oxygen.\N4:16\NSo I'll write it really tiny right here to show\N4:18\Nthat there's much less oxygen in your venous blood\N4:21\Nthan there was in your arterial blood.\N4:23\NAnd finally, the kidneys want to take all the\N4:25\Nwaste products your arterial blood brought\N4:27\Nto the kidney and hold on to it, make it so that\N4:31\Nthis stuff does not end up in the venous outflow.\N4:34\NAnd by collecting these waste products,\N4:36\Nthe kidneys will effectively produce your urine.\N4:40\NNow, you might notice in this picture\N4:42\Nthat I am missing something.\N4:44\NWhat connects the artery to the vein?\N4:46\NWell actually what goes on here\N4:48\Nis part of what makes the kidney so special.\N4:50\NAnd it answers the "how".\N4:52\NHow is it that the kidneys are able to do this?\N4:55\NHow is it that the kidneys can help us\N4:57\Nmaintain our nutrients in our body\N4:59\Nwhile getting rid of waste into urine?\N5:01\NWell, the kidney is special\N5:04\Nbecause it's got two capillary beds.\N5:07\NI think you might have heard\N5:09\Nwhat a capillary is before, alright?\N5:11\NA capillary bed is just something that\N5:14\Nconnects the artery and the vein.\N5:16\NIt's where you can have oxygen flow out.\N5:18\NYou can have nutrients flow in.\N5:20\NSo the way I'll draw it is that you've got one\N5:23\Ncapillary bed, right here, connecting your\N5:24\Nartery to your vein, like that.\N5:27\NAnd you've got another one down here connecting those two.\N5:31\NAnd so these guys work together to deliver oxygen\N5:36\Nto the kidney's tissue and, at the same time,\N5:39\Nrecollect these nutrients so that the vein can\N5:42\Ntake these nutrients elsewhere in the body for use.\N5:45\NAnd these capillary beds have two fancy names.\N5:47\NThe first one is called the vasa recta.\N5:52\NThe vasa recta.\N5:53\NAnd that's mainly to give oxygen to the kidneys.\N5:57\NThe other set of capillaries are\N5:59\Ncalled peritubular capillaries.\N6:04\NPeritubular capillaries, and we'll talk way more\N6:07\Ninto detail about these peritubular capillaries.\N6:10\NAnd these are the guys that are mainly\N6:13\Ngoing to be responsible for collecting\N6:15\Nnutrients that our kidneys will filter.\N6:18\NAnd we'll talk more about that\N6:20\Nprocess in the next few videos.