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Overview – Introduction to Biochemistry | Lecturio
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標(biāo)題（采取USMLE標(biāo)題） （生理學(xué) 2級(jí) 中文4級(jí) 英文三級(jí)）
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Biochemistry
Biochemistry Basics
218 Overview – Introduction to Biochemistry
Describe biochemistry at a cellular level with regard to the history of the evolutionary process
Increasing scientific knowledge and improved technology has played significant roles in helping us to better understand the molecular basis of life. In this lecture I will go through a brief overview of the summary of our understanding and our perspective of living system, from ancient times up until today. Life is abundant on planet Earth and as far as we know in the universe that's the only place it exists, although likely it exists in other places as well. Life is diverse and life is widespread. From the deserts in Africa to the farmlands of America. Life has found niches in every land system on earth. In the sea we can look in the deep sea thermal vents, we can look in the top of the ocean and everywhere we look, we see aquatic life. In the air we see birds, we see insects, we see microbes that are floating around. Every available ecosystem on earth that we've examined is abundant with life.
01:02
Now human beings are people who organize and categorize things, and it's only natural therefore that we should be categorizing life systems as well. And one of the things that has happened in the organization of life systems is to create a hierarchical scheme. On the screen you can see one hierarchical scheme that is used to describe essentially every living organism on earth. Starting at the top with the most broad view and narrowing down as we go down through the names, domains of course relate to the very, very broad regions, relating to living systems. Kingdoms are a subdivision of that and phylum are a subdivision of the kingdoms, followed by class, order, family, genus and species. Now it's important to recognize that every life form on earth can be described by this hierarchical system.
01:54
Another system for organizing life is that's shown the screen based on evolutionary distance.
01:59
We think that all life on earth ultimately came from one primordial cell, and that one primordial cell evolved and gave rise to all the life forms that we see today. This plot shows as lines the evolutionary distance each living system is from that primordial cell and by extension how far each living system is evolutionarily from each of the other systems on the screen. On the lower left we can see bacteria. Bacteria of course are the single celled organisms that contain no organelles, they are very simple in their structure and they are very tiny. One of the ways people view bacterias as a bag of enzymes and nucleic acid and that's about what we find in bacteria. The archaeans are the more recently described types of life and they actually exist in some of the most inhospitable places on the planet.
02:53
Environments that other cells would find toxic, the archaeans find home. Like bacteria, they're very simple as well. The eukarya shown on the right include the multicellular organisms we see on eart. This includes the animals, the fungi, the plants and many other multicellular and a few unicellular forms as well. One unicellular form we see in the eukaryotes includes the yeast, makers of bread and ethanol. Now the eukaryotic cells differ from the prokaryotic cells and the archaeon cells in first of all generally being considerably larger than them and second of all, in containing specialized organelles, like the nucleus and like the mitochondrion. These specialized organelles play distinct functions in these cells that are distributed otherwise throughout the entire bacterial or archaean cell.
219 History – Introduction to Biochemistry
00:01 現(xiàn)在我們對生活的看法發(fā)生了很大變化 這些年來。可以追溯到文藝復(fù)興時(shí)期 人們對理解的興趣很大 通過了解解剖學(xué)來生活绿聘。所以解剖 變得很普遍岛啸，因?yàn)槿藗兏信d趣 理解活著意味著什么 通過了解器官或器官的功能 組織功能奕锌。因此，一種普遍的信念 已經(jīng)有成千上萬的人 多年實(shí)際上一直是 活力主義。生命主義說發(fā)生了什么 在活細(xì)胞中是活細(xì)胞所獨(dú)有的 并且無法在宇宙中的其他地方復(fù)制。 這個(gè)想法基本上被證明是錯(cuò)誤的 由屏幕上顯示的人弗里德里希 沃勒偎窘。 W?hler能夠使用普通 他可以制造尿素的化學(xué)反應(yīng) 已知是由生物體制造的， 在他被發(fā)現(xiàn)之前溜在，只有 使細(xì)胞成為可能陌知。非常感謝 發(fā)現(xiàn)活力，我們現(xiàn)在意識(shí)到 細(xì)胞發(fā)生的事情是一回事 那發(fā)生在宇宙的其余部分掖肋， 盡管可能以不同的方式仆葡。 現(xiàn)在，生命和分子的發(fā)現(xiàn) 生活的本質(zhì)完全取決于 在技術(shù)上志笼。第一次技術(shù)進(jìn)步 在幫助我們理解方面很重要 細(xì)胞是顯微鏡的發(fā)明沿盅。 安東·范·列文虎克（Anton Van Leeuwenhoek）在1650年代發(fā)明 第一個(gè)顯微鏡，他是第一個(gè) 曾經(jīng)見過單細(xì)胞生物的人纫溃， 他稱之為動(dòng)物的生物腰涧。他是 這些細(xì)胞非常吸引人。 羅伯特·胡克（Robert Hooke）在 Van Leeuwenhoek顯微鏡皇耗，能夠 做出一些非常有趣的發(fā)現(xiàn)南窗， 包括我們發(fā)揚(yáng)光大的東西 今天是生命的細(xì)胞基礎(chǔ)揍很。他的 在軟木塞上看到的軟木解剖圖 屏幕在此顯示單個(gè)單元格并提醒 我們郎楼，每個(gè)活細(xì)胞都來自以前 活細(xì)胞。到1850年代窒悔， 對分子很重要的分子 生活的基礎(chǔ)應(yīng)運(yùn)而生呜袁。弗里德里希·米歇爾 發(fā)現(xiàn)了一種在1850年代工作的化合物简珠， 他稱之為核子〗捉纾現(xiàn)在他很感興趣 在研究蛋白質(zhì)，但他所做的是 孤立核聋庵，當(dāng)他分離核 細(xì)胞膘融，他發(fā)現(xiàn)其中含有某種物質(zhì) 具有一些非常不尋常的特性。他 不知道這些屬性是什么祭玉，但是 他知道自己發(fā)現(xiàn)了一些新東西氧映， 他稱呼核子很重要。我們知道 當(dāng)然脱货，今天的核子是DNA岛都。奧古斯丁 和尚格里高·孟德爾（Gregor Mendel）很感興趣律姨，他當(dāng)時(shí) 與Miescher同時(shí)學(xué)習(xí)。 格雷戈?duì)枴っ系聽枺℅regor Mendel）對研究 一代人特質(zhì)的傳承 豌豆到另一代人臼疫，他做了 非常非常認(rèn)真的研究和他的研究 意識(shí)到有遺傳信息 從一代傳來的 到下一個(gè)择份。進(jìn)一步說，遺傳信息 具有他稱之為隱性的特性 和優(yōu)勢烫堤，我們與之相關(guān)的特質(zhì) 基因荣赶。孟德爾的作品基本上未被發(fā)現(xiàn) 大約30年，但當(dāng)它變成 被發(fā)現(xiàn)塔逃，它被揭示為 革命性的發(fā)現(xiàn)讯壶，當(dāng)然是它的時(shí)代。 到1930年代湾盗，分子基礎(chǔ)的思想 生活開始實(shí)現(xiàn)伏蚊。 著名物理學(xué)家ErwinSchr?dinger寫道 一本書叫做“生命是什么？”在他的書中 他提出了一個(gè)問題格粪，牢房不是 關(guān)于最根本的事情 生活躏吊。相反，他說分子基礎(chǔ) 分子內(nèi)生命的基礎(chǔ) 生命在于分子帐萎。在那些分子內(nèi) 我們可以找到所有可能發(fā)生的特征 在生物學(xué)上比伏。當(dāng)時(shí)他的想法很激進(jìn)津滞， 但實(shí)際上士鸥，它對許多人都有很大的影響 后來發(fā)現(xiàn)重大發(fā)現(xiàn)的人包括 沃森和克里克在發(fā)現(xiàn)DNA方面。 今天我們知道局齿，薛定ding基本上是 正確的澈段，就是生命有一個(gè)分子 基礎(chǔ)悠菜。艾利，麥克勞德和麥卡蒂在 1944年進(jìn)行了一系列 最終證明的實(shí)驗(yàn) 第一次败富，遺傳信息 在幾代人之間轉(zhuǎn)移 實(shí)際上悔醋，細(xì)胞數(shù)量是DNA。只有幾年 1953年下半年兽叮，沃森和克里克站在 巨人的肩膀芬骄，借用 Rosalind Franklin的數(shù)據(jù)，能夠顯示 DNA的結(jié)構(gòu)首次出現(xiàn)鹦聪。 美麗的雙螺旋分子账阻，具有互補(bǔ)性 內(nèi)部的基礎(chǔ)是一個(gè)啟示，因?yàn)?看到它泽本，人們很快意識(shí)到 鏈可以指定另一個(gè)的復(fù)制 股淘太。通過復(fù)制基因 信息可以相同地傳輸 從一個(gè)單元到下一代。的 中樞信條指出，DNA制造RNA琴儿，制造 蛋白質(zhì)段化，那是因?yàn)榉绞?信息在單元格中傳輸。 自從第一次出現(xiàn)以來我們就修改了中央教條 在60年代初期描述為合并 今天我們知道的有關(guān)RNA的其他一些信息 那時(shí)我們不知道造成。但是中央 教條及其轉(zhuǎn)移的描述 單元內(nèi)的信息對于 我們所做的一切显熏。我們是否在學(xué)習(xí) 基因組學(xué)，我們是否正在研究轉(zhuǎn)錄組學(xué) 或者我們是否正在研究代謝組學(xué)晒屎， 中央教條與今天一樣重要 首次描述時(shí)喘蟆。 現(xiàn)在結(jié)束本次演講，我想離開你 與結(jié)構(gòu)有關(guān)的一些想法 我之前提到的細(xì)菌 “對不起鼓鲁，我為所有 低度細(xì)菌蕴轨。你應(yīng)該很了解 在它們的微小內(nèi)部沒有細(xì)胞器 interia”
220Structure – Amino Acids
00:01 蛋白質(zhì)是制造蛋白質(zhì)的重要組成部分 生活可能。
建筑的多樣性 蛋白質(zhì)塊與其他大分子相比 為蛋白質(zhì)提供豐富多樣的 功能骇吭。在本講座中橙弱，我將討論 蛋白質(zhì)從結(jié)構(gòu)單元開始， 組成它們并分解它們的氨基酸 分為不同的組燥狰，必要的或不重要的 取決于他們是否可以 由有機(jī)體制成棘脐。我將討論基本 每個(gè)氨基的結(jié)構(gòu)和立體化學(xué) 酸以及每個(gè)氨基的側(cè)鏈如何 酸賦予它個(gè)性 它有。最后我給屬性 談?wù)摪被碾婋x 蛋白質(zhì)中發(fā)現(xiàn)的酸龙致。 蛋白質(zhì)蛀缝，我們可以說是主力軍 的細(xì)胞。他們執(zhí)行所有必不可少的 細(xì)胞需要存活的功能目代。這些 包括催化屈梁，反應(yīng)的催化 發(fā)生，預(yù)示著過程 細(xì)胞和有機(jī)體的一部分可以交流 細(xì)胞在生物的另一部分榛了。 蛋白質(zhì)的結(jié)構(gòu)在讶，例如纖維狀 在我們的頭發(fā)和指甲中發(fā)現(xiàn)蛋白質(zhì) 來自個(gè)人的有趣特征 蛋白分子。最后忽冻，蛋白質(zhì)非常 對于產(chǎn)生真朗，創(chuàng)造和 儲(chǔ)存能量此疹。地球上所有的蛋白質(zhì)都是 由約20個(gè)氨基酸組成僧诚。 20 氨基酸最常見于 地球上的生物。
已知的21位氨基酸 如硒代半胱氨酸蝗碎，在某些情況下 一些稀有蛋白質(zhì)湖笨。 氨基酸可以分為各種類別， 分類方案之一是除法 氨基酸分為必需基團(tuán)和非必需基團(tuán) 取決于生物體是否 可以在其細(xì)胞內(nèi)合成氨基酸蹦骑。 必需氨基酸是那些氨基酸 細(xì)胞需要在飲食中攝取慈省，因?yàn)?它本身無法做到。非必需氨基 氨基酸是細(xì)胞可以合成的氨基酸眠菇。 現(xiàn)在边败，將基本與否的分類 從一種生物到另一種生物的非必需 甚至隨著年齡的增長而變化 例如人類 成年后不同的必需氨基酸 比他們小時(shí)候 我們在蛋白質(zhì)中發(fā)現(xiàn)的氨基酸 叫α氨基酸袱衷，他們得到這個(gè) 名稱，
因?yàn)槭褂玫拿糠N氨基酸 蛋白質(zhì)中的特殊碳稱為 中間以綠色顯示的alpha碳 示意圖笑窜。所有20個(gè)氨基 可以以相同的示意圖繪制酸致燥。 現(xiàn)在我要去命名 通過這里，將幫助您更好 了解蛋白質(zhì)中的氨基酸排截。
每個(gè)Alpha碳都連接到Alpha 羧基嫌蚤，如下所示。而每個(gè)alpha 碳也連接到α胺上 這兩個(gè)給α氨基酸 名稱断傲。另外還附有阿爾法碳 您可以在此處看到氫氣的頂部 并在R組的左側(cè)R組是 是什么賦予了氨基酸特征 功能脱吱，形狀，結(jié)構(gòu)和特性认罩。
現(xiàn)在箱蝠，向您展示一個(gè)實(shí)際的氨基酸 我要在這里使用的方案 給你看半胱氨酸因此，如果我們看一下 右邊的組織方案是 在最后一張幻燈片上垦垂，與半胱氨酸進(jìn)行比較抡锈， 我們可以看到例如各種各樣的東西。 例如乔外，半胱氨酸具有α碳 如這里所見床三，一個(gè)α羧基，一個(gè) 在這種情況下杨幼，α胺和一個(gè)R基團(tuán) 含有巰基撇簿。在此圖中未顯示， 但存在于α碳上的是氫 高于α碳差购。 這是苯丙氨酸四瘫。例如苯丙氨酸 有一個(gè)α碳，一個(gè)α羧基 α胺欲逃，它有一個(gè)側(cè)鏈找蜜，在這個(gè) 盒子里有一個(gè)苯環(huán)。再次稳析，阿爾法 碳在其上方含有氫洗做。 因?yàn)榘柗ㄌ歼B接到四個(gè) 不同的基團(tuán)賦予了α碳 一些重要的屬性，需要了解彰居。 例如您在有機(jī)化學(xué)中學(xué)習(xí) 如果碳有四個(gè)不同的分子 附加到它有兩種方法 這些原子可以的三維空間 圍繞α碳進(jìn)行組織诚纸。 這顯示了例如糖D-甘油醛 和L-甘油醛，兩種不同形式 含有碳的糖 有四個(gè)不同的小組陈惰。 這就是所謂的不對稱碳畦徘， 在此處看到的綠色圓圈中顯示。 現(xiàn)在有四個(gè)不同的東西 由于這個(gè)原因，有兩種方法 他們可以組織起來井辆。我畫了 藍(lán)色和黃色箭頭顯示它如何 例如关筒，有兩個(gè)組織 這里。我們可以在左側(cè)的藍(lán)色箭頭下看到 灰色的球正向 觀眾杯缺，而后面的橙色球 正在伸出平委。在L異構(gòu)體中，這些 兩個(gè)位置顛倒了夺谁，我們看到橙色 球傳到前面和灰色球 向后移動(dòng)廉赔。 氨基酸也用D和L表示 用于糖。有趣的是匾鸥，幾乎 活細(xì)胞產(chǎn)生的所有氨基酸 在相同的配置中 L配置±現(xiàn)在，這很有趣 因?yàn)槿绻e個(gè)例子勿负，試管 然后您在測試中化學(xué)制造氨基酸 酶未產(chǎn)生的試管 一個(gè)單元格馏艾，您將得到50％D和50％L的混合物。 我們只獲得L的原因 在活細(xì)胞中是因?yàn)榛罴?xì)胞利用 產(chǎn)生氨基酸的酶奴愉，以及那些酶 具有三維的特定結(jié)構(gòu) 只能合成一個(gè) 存在兩種不同形式琅摩。 現(xiàn)在，這真的很有趣 和有用的锭硼，因?yàn)槲覀兛梢愿嬖V我們是否 分析氨基酸是否有混合物 D和L房资，或僅L，或僅D 問題檀头，因?yàn)橐环N偏向另一種偏見 會(huì)暗示它是由酶制成的轰异， 因此是由活細(xì)胞制成的。這是用 例如當(dāng)隕石落到地上 它們含有氨基酸和科學(xué)家 對理解非常感興趣暑始， 生物產(chǎn)生的那些氨基酸搭独，或 由自然化學(xué)產(chǎn)生。
Proteins are part and parcel of what makes life possible. The diversity of the building blocks of proteins compared to other macromolecules give proteins a rich and diverse array of functions. In this lecture I will talk about proteins starting with the building blocks, the amino acids that make them up and divide them into various groups, essential or nonessential depending upon whether or not they can be made by the organism. I'll discuss the basic structure and stereochemistry of each amino acid and how the side chains of each amino acid give it the individual characteristics that it have. Last I'll give the properties and talk about the ionization of the amino acids found in proteins. 00:41 Proteins, we can describe as the workhorses of the cell. They perform all the essential functions that cells need to stay alive. These include catalysis, catalyzing of the reactions that happen, signaling the process whereby cells and part of an organism can communicate with cells in another part of the organism. The structure of proteins such as the fibrous proteins found in our hair and our nails arises from interesting features within individual protein molecules. Last, proteins are very important for the generation, creation and storage of energy. All proteins on earth are comprised of about 20 amino acids. The 20 amino acids are most commonly found in every organism on earth. A 21st amino acid known as Selenocysteine, in some cases found in a few rare proteins. 01:36 Amino acids can be divided into various categories, one of the categorization schemes is divide amino acids into essential and nonessential groups, depending upon whether or not the organism can synthesize the amino acid within its cells. Essential amino acids are those amino acids that the cell needs to have in its diet because it can't make those itself. Nonessential amino acids are amino acids that cells can synthesize. Now, the categorization of essential versus nonessential varies from one organism to another and it even varies a little bit with the age of the organism, for example, humans have different essential amino acids as adults than they do as children. 02:23 Amino acids that are found in proteins we call alpha amino acids, and they get this name because every amino acid that's used in proteins has a special carbon call the alpha carbon seen here in green in the center of the schematic diagram. All 20 of the amino acids can be drawn in the same schematic scheme. Now there is nomenclature that I want to go through here that will help you to better understand the amino acids in the proteins. 02:51 Every alpha carbon is attached to an alpha carboxyl group, as shown here. And every alpha carbon is also attached to an alpha amine, these two giving the alpha amino acids their name. The alpha carbon is in addition attached on the top to a hydrogen as you can see here and on the left to an R group. The R group is what gives an amino acid its characteristic, functions, shape, structure and properties. 03:20 Now, to show you an actual amino acid according to the scheme that we're using here, I want to show you cysteine. So if we look at the organizational scheme on the right that was on the last slide and compare to cysteine, we can see for example the various things. 03:34 For example, cysteine has an alpha carbon as seen here, an alpha carboxyl group, an alpha amine and an R group that in this case contains a sulfhydryl. Not shown on this figure, but present on the alpha carbon is a hydrogen above the alpha carbon. 03:55 Here is phenylalanine. Phenylalanine for example, has an alpha carbon, an alpha carboxyl an alpha amine and it has a side chain and in this case contains a benzene ring. Again, the alpha carbon contains a hydrogen above it. 04:13 Because the alpha carbon is attached to four different groups it gives the alpha carbon some properties that are important to understand. You learned in organic chemistry for example that if a carbon has four different molecules attached to it, that there are two ways in three-dimensional space that those atoms can be organized around the alpha carbon. 04:36 This shows for example the sugar D-glyceraldehyde and L-glyceraldehyde, two different forms of a sugar that contain a carbon that have four different groups attached them. 04:46 This is known as an asymmetric carbon and it’s shown in the green circles seen here. 04:52 Now there are four different things attached to this and because of this, there's two ways that they can be organized. I've drawn the blue and the yellow arrows to show how it is that two groups, for example, are organized here. We can see under the blue arrow on the left that the gray ball is projecting towards the viewer whereas the orangish ball in the back is projecting away. In the L isomer, these two positions are reversed, we see the orange ball coming to the front and the gray ball moving to the back. 05:21 Amino acids also are designated by the D and L designation that are used for sugars. Interestingly, almost all of the amino acids made by living cells are in the same configuration, that of the L configuration. Now, this is interesting because if you take for example, a test tube and you make amino acids chemically in a test tube that are not being produced by the enzymes of a cell, you get a mixture of 50% D and 50% L. The reason that we get only L exclusively in living cells is because living cells use enzymes to make amino acids, and those enzymes have a three-dimensional specific structure that will only allow the synthesis of one of the two different forms being present. Now this turns out to be really interesting and useful because we can then tell if we analyze an amino acid whether it has a mixture of D and L, or only L, or only D for that matter, because a bias one way or the other would suggest it was made by an enzyme and therefore made by a living cell. This is used for example when meteorites fall to earth and they contain amino acids and scientists are very interested in understanding, were those amino acids produced biologically, or produced by natural chemistry.
R-group Categories – Amino Acids
Explain the categories of the R-groups of amino acids and cite examples
由自然化學(xué)產(chǎn)生廊镜。 現(xiàn)在還有其他組織氨基酸的方法 酸和我們組織的方式之一 氨基酸是由它們的R基團(tuán)決定的牙肝。
在這個(gè) 例如，我們可以看到分類方案 具有R基團(tuán)的氨基酸是什么 我們形容為疏水的嗤朴，這意味著它們 不喜歡與水結(jié)合配椭。這包括 色氨酸的芳香氨基酸，苯丙氨酸 和酪氨酸播赁。
它還包括氨基酸 具有脂族側(cè)鏈颂郎，例如蛋氨酸 異亮氨酸吼渡，亮氨酸容为，纈氨酸，甘氨酸，丙氨酸 和脯氨酸坎背。
另一組氨基酸 R基團(tuán)是那些親水的替劈， 那就是他們有能力結(jié)合 與水結(jié)合并與水結(jié)合。在這個(gè)類別中 我們有含有羥基的氨基酸 側(cè)鏈中的組得滤；這包括 絲氨酸陨献，蘇氨酸和酪氨酸。現(xiàn)在你會(huì) 注意酪氨酸已經(jīng)分為兩組 這些群體不是互相排斥的 當(dāng)您觀看和閱讀不同的作者時(shí)懂更， 您會(huì)看到作者將放置氨基酸 根據(jù)他們自己的感知在不同的群體中 化學(xué)眨业。 在親水條件下的第二類是 含有巰基，意味著它們含有 與氫連接的硫沮协。只有 該類別中的一種氨基酸龄捡，以及 那半胱氨酸。羧酰胺或羧酰胺 也叫氨基酸天冬酰胺 和谷氨酰胺慷暂。離子氨基酸是那些 在生理pH下將具有 加號(hào)或減號(hào)聘殖。這些包括 羧酸鹽，是天冬氨酸和 谷氨酸行瑞。羧酸鹽，當(dāng)它們 電離將帶負(fù)電荷氧吐。 生理pH值的胺含有額外的 質(zhì)子和額外的質(zhì)子使這些 胺帶正電荷心剥，胺當(dāng)然 包括賴氨酸，組氨酸和精氨酸役听。 現(xiàn)在我說過一些氨基酸 不只一個(gè)類別，而且這些也不是唯一的 無論如何锐涯，我再次提醒您 氨基酸的分類方式確實(shí)有所不同。 我現(xiàn)在想做的是 描述每個(gè)氨基酸和點(diǎn)
00:00 produced by natural chemistry. 00:01 Now there's other ways of organizing amino acids and one of the ways that we can organize amino acids is by their R groups. In this classification scheme we can see for example amino acids that have R groups that are what we describe as hydrophobic, meaning that they don't like to associate with water. This includes the aromatic amino acids of tryptophan, phenylalanine and tyrosine. It also includes amino acids that have aliphatic side chains, such as methionine, isoleucine, leucine, valine, glycine, alanine and proline. Another grouping of amino acids by R group are those that are hydrophilic, that is that they have an ability to bond with and associate with water. In this category we have the amino acids that contain hydroxyl groups in their side chain; this includes serine, threonine and tyrosine. Now you'll notice that tyrosine has been in two groups and these groups are not mutually exclusive and as you watch and read different authors, you'll see that authors will place amino acids in different groups based on their own perceived chemistries. 01:05 A second category when under hydrophilic is sulfhydryl containing, meaning that they contain a sulfur attached to a hydrogen. There's only one amino acid that's in this category, and that cysteine. The carboxyamides or carboxamides as they are also called, are amino acids asparagine and glutamine. The ionic amino acids are those that at physiological pH will have either a plus or a minus charge. These include the carboxylates, which are aspartic acid and glutamic acid. The carboxylates, when they ionize will have a negative charge. 01:45 The amines at physiological pH contain an extra proton and this extra proton gives these amines a positive charge, the amines of course include lysine, histidine and arginine. 01:57 Now as I said some amino acids appear in more than one category and these aren't exclusive in any way, and again I remind you that authors do differ in how they categorize amino acids. 02:06 What I would like to do now is go through and describe each of the amino acids and point
Which order set of the three amino acids named below are listed in this order: Hydrophobic, Hydrophilic, Ionic?
Arginine, Tyrosine, Asparagine Serine, Glutamine, Proline Histidine, Threonine, Phenylalanine Leucine, Cysteine, Lysine
Hydrophobic R-groups – Amino Acids
Explain the different biochemical categories of hydrophobic amino acids Describe the salient features of all hydrophobic amino acids Define hydrophobic amino acids and cite examples
00:00 我現(xiàn)在想做的是 描述每個(gè)氨基酸和點(diǎn) 適當(dāng)?shù)刂赋鏊鼈兊囊恍╋@著特征系馆。 氨基酸的芳香族基團(tuán)包括 酪氨酸涎永，色氨酸和苯丙氨酸∠畚ⅲ現(xiàn)在捧挺， 我已經(jīng)在酪氨酸上標(biāo)明了位置 α羧基宏所，α胺和 alpha碳，并再次提醒您 氫在上方投射莫换，但未顯示 在這張圖片中霞玄。酪氨酸被指出具有羥基 基團(tuán)連接在苯環(huán)的末端骤铃。
色氨酸以氨基酸聞名 具有最大的R基團(tuán)，包含苯 環(huán)連接到另一個(gè)五元環(huán) 如您所見】谰纾現(xiàn)在這個(gè)很大的笨重 色氨酸的人群往往是 限制蛋白質(zhì)內(nèi)的空間惰爬。 龐大的R基團(tuán)可能導(dǎo)致蛋白質(zhì) 必須扭轉(zhuǎn)和適應(yīng) 結(jié)果是更大的結(jié)構(gòu)。
苯丙氨酸 有一個(gè)簡單的苯環(huán)惫企。 現(xiàn)在我在這張幻燈片上所做的就是 在生理pH下標(biāo)記撕瞧， 出現(xiàn)在每個(gè)分子上。您會(huì)在 在每種情況下狞尔，α羧基為負(fù) 充電丛版，因?yàn)樗チ艘粋€(gè)質(zhì)子。每一個(gè) 情況下偏序，α胺帶正電荷 因?yàn)樗Ａ袅速|(zhì)子页畦。 pKa 的α羧基大約是2 生理pH當(dāng)然約為7.4。的 α胺基團(tuán)的pKa約為9研儒， 因此豫缨，由于這個(gè)原因，α胺保留了 質(zhì)子和α羧基已經(jīng)丟失 它的質(zhì)子《硕洌現(xiàn)在關(guān)于酪氨酸的注釋 是酪氨酸末端的羥基 可以在高pH下電離好芭，該pH高于 但是是生理范圍的。 我想要的第二組氨基酸 談?wù)摰氖悄切?含有脂族R基團(tuán)逸月。在這種情況下 在每個(gè)綠色方塊中再次標(biāo)記 每個(gè)氨基中包含的R基團(tuán) 酸栓撞。以甘氨酸為例，我們 看到甘氨酸有一個(gè)不尋常的R基團(tuán)碗硬， 它只含有氫瓤湘。因此，甘氨酸 具有自然界中最小的R基團(tuán) 蛋白質(zhì)中存在氨基酸恩尾，但是因?yàn)?它包含一個(gè)R基團(tuán)氫弛说，它也 包含附著在 α碳，這意味著只有三個(gè) 附著在阿爾法碳上的不同東西 甘氨酸翰意。因此木人，甘氨酸是 僅存在于20種氨基酸中 沒有立體化學(xué)的蛋白質(zhì)。
下一個(gè)感興趣的氨基酸是 脯氨酸冀偶。您可以看到脯氨酸具有R 從α碳開始的基團(tuán)醒第，但是 它也會(huì)回來并與 如您所見，α胺形成了五個(gè)成員 環(huán)〗現(xiàn)在稠曼，此連接有兩點(diǎn)限制 R組脯氨酸旋轉(zhuǎn)的能力。 如果您看一下所有其他的R組 所有其他蛋白質(zhì)客年，您會(huì)看到它們 只有一個(gè)鍵霞幅，可以自由旋轉(zhuǎn)漠吻。 脯氨酸受第二鍵約束 它是由α氨基組成的 結(jié)果，脯氨酸不能旋轉(zhuǎn) 它的R基團(tuán)司恳，意味著脯氨酸 較不靈活的氨基酸⊥灸耍現(xiàn)在有一些 實(shí)際發(fā)生彎曲的含義 在蛋白質(zhì)中，我們將在后面描述扔傅。
接下來的三個(gè)氨基酸異亮氨酸耍共，纈氨酸 和亮氨酸在包含R基團(tuán)方面相似 含有碳和氫，主要是 如您所見铅鲤，對它們進(jìn)行了重新排列划提。 此處顯示的最后一個(gè)氨基酸是蛋氨酸枫弟， 蛋氨酸很有趣邢享，因?yàn)榈鞍彼?含有硫。這是僅有的兩個(gè)氨基之一 含硫的酸淡诗，硫是 可以連接到兩個(gè)不同的碳上 請參閱此處的分組骇塘。那個(gè)附件 兩種不同的碳意味著硫 在蛋氨酸中是非常沒有反應(yīng)的，不會(huì) 做很多韩容，這與硫相反 我們將在半胱氨酸中看到款违。 現(xiàn)在，如果我們看一下生理上的收費(fèi) pH群凶，我們可以看到這些氨基酸都不存在 有電離的R基團(tuán)插爹，就像我們看到的 在α胺具有正電荷之前 每種情況下，α羧基為負(fù) 收費(fèi)请梢。這些氨基酸各自在生理上 pH值為零赠尾。 接下來的兩個(gè)氨基酸是被離子化的氨基酸， 并且它們的R基團(tuán)中含有羧基 組毅弧。它們包括天冬氨酸气嫁，如圖所示 左邊是谷氨酸， 對够坐。這兩個(gè)氨基酸實(shí)際上是 彼此相同寸宵，除了 谷氨酸含有額外的碳 與天冬氨酸相比。在生理上 pH在這里我們看到R基團(tuán)離子化元咙， 這是因?yàn)閷τ谶@些 兩個(gè)氨基酸的pKa值約為4梯影， 表示在生理pH為7的情況下 羧基上的質(zhì)子丟失了 使分子帶有凈負(fù)電荷 在R組。每個(gè)的總費(fèi)用 這些氨基酸在生理上 pH為-1庶香。
00:00 What I would like to do now is go through and describe each of the amino acids and point out some salient features of them as appropriate. The aromatic group of amino acids includes tyrosine, tryptophan and phenylalanine. Now, I've marked on the tyrosine, the locations of the alpha carboxyl, the alpha amine and the alpha carbon, and remind you again that the hydrogen is projecting above but not shown in this image. Tyrosine is noted has a hydroxyl group attached to the end of benzene ring. Tryptophan is notable for being an amino acid that has the largest R group, contains a benzene ring attached to another five-member ring as you can see here. Now this very large bulky group that's on tryptophan, tends to be a limitation in terms of space within a protein. The bulky R group can cause the protein to have to twist and turn, and accommodate that larger structure as a result. Phenylalanine has a simple benzene ring. 01:03 Now what I've also done on this slide is I've marked at physiological pH, the charges that appear on each molecule. You'll see that in each case the alpha carboxyl has a negative charge because it has lost a proton. In each case, the alpha amine has a positive charge because it is retaining a proton. The pKa of the alpha carboxyl group is about 2, physiological pH of course is about 7.4. The pKa of the alpha amine group is about 9, so for this reason the alpha amine retains the proton and the alpha carboxyl has lost its proton. Now one note about tyrosine and that is that the hydroxyl at the end of tyrosine can ionize at a high pH, this pH is above that of the physiological range however. 01:52 The second group of amino acids that I want to talk about are those that contain aliphatic R groups. In this case I've marked again in the green squares each of the R groups as they are contained in each amino acid. Focusing on glycine for example, we see glycine has an unusual R group, and that it only contains a hydrogen. Glycine therefore has the smallest R group of any of the naturally occurring amino acids in proteins, but because it contains an R group hydrogen and it also contains the hydrogen that's attached to the alpha carbon, it means that there're only three different things attached to the alpha carbon of glycine. For this reason glycine is the only amino acid of the 20 that's found in proteins that does not have a stereochemistry. 02:44 The next amino acid that is of interest is proline. You can see the proline has an R group that goes off of the alpha carbon, but it also comes back around and connects with the alpha amine as you can see forming a five-member ring. Now this connection at two points limits the ability of the R group of proline to rotate. If you look at all of the other R groups of all of the other proteins, you'll see they only have a single bond and can freely rotate. 03:14 Proline is constrained by the second bond that it's making with the alpha amino group and as a consequence, proline cannot rotate its R group, meaning that proline is a much more inflexible amino acid. Now this has some implications for bending that actually happens within proteins as we will describe later. 03:35 The next three amino acids isoleucine, valine and leucine are similar in containing R groups that have carbons and hydrogens and mainly rearrangements of those as you can see. 03:49 The last amino acid as shown here is methionine, and methionine is of interest because methionine contains sulfur. It's one of only two amino acids that contain sulfur and the sulfur is attached to two different carbons as you can see in the grouping here. That attachment to two different carbons means that the sulfur in methionine is very unreactive and doesn't do much, this is in contrast to the sulfur that we will see in cysteine. 04:16 Now, if we look at the charges at physiological pH, we can see that none of these amino acids have R groups that ionize and like we saw before the alpha amine has a plus charge in each case and the alpha carboxyl has a negative charge. Each of these amino acids at physiological pH would have a charge of zero. 04:39 The next two amino acids are those that are ionized, and they contain in their R groups, carboxyl groups. They include aspartic acid, shown on the left and glutamic acid, shown on the right. These two amino acids are virtually identical to each other with the exception that glutamic acid contains one extra carbon compared to aspartic acid. At physiological pH we see here that the R group ionizes, and this is because that the R group for these two amino acids has a pKa value of about 4, meaning that at a physiological pH of 7, the proton on the carboxyl group is lost, leaving the molecule with a net negative charge on the R group. The overall charge of each of these amino acids at physiological pH is -1.
Which of the following is not an aromatic amino acid? (choose all that can apply) Tryptophan Methionine Phenylalanine Tyrosine
Which of the following is the simplest amino acid? Tryptophan Methionine Glycine Histidine Phenylalanine
Which of the following are sulfur-containing amino acids? (More than one correct answer) Glycine Methionine Proline Lysine Cysteine
如何注冊影子郵箱
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https://zhuanlan.zhihu.com/p/50177781
如何學(xué)習(xí) 生理生化
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生理學(xué)（中文）
01 總論
00:00 在這里救军，我們將討論生理學(xué)及其一般原理〔埔欤現(xiàn)在你可能在想 在這一點(diǎn)上，生理學(xué)到底是什么唱遭。因此戳寸，讓我們先解決這個(gè)問題。生理是 生命科學(xué)拷泽。生理學(xué)本質(zhì)上是相當(dāng)廣泛的疫鹊，旨在了解其機(jī)理 從基因和分子到細(xì)胞再到細(xì)胞 功能并最終融入整個(gè)身體的行為。另一件事是 與生理學(xué)相關(guān)的重要考慮因素是人體在正常條件下的工作方式司致。 為什么這很重要拆吆，是稍后我們要區(qū)分正常生理和 醫(yī)學(xué)生理學(xué)。生理幾乎用于您在日常生活中所做的一切脂矫，從是否 您正在散步或鍛煉枣耀，無論是閱讀還是觀看 特別的Lecturio講座。它幾乎完成了所有事情⊥ピ伲現(xiàn)在讓我們定義什么是 醫(yī)學(xué)生理學(xué)與常規(guī)生理學(xué)的區(qū)別捞奕。在醫(yī)學(xué)生理學(xué)中， 我最喜歡的報(bào)價(jià)是由一個(gè)調(diào)查小組完成的拄轻，該調(diào)查小組首先發(fā)現(xiàn)了動(dòng)脈 在這種情況下颅围，他們決定使用重癥監(jiān)護(hù)藥物 生理原則來照顧重病患者。因此恨搓，在醫(yī)學(xué)生理學(xué)上院促，我們將 更詳細(xì)地討論一些主題，并深入探討斧抱，因?yàn)樗鼈冊卺t(yī)學(xué)上更 相關(guān)的常拓。生理學(xué)中有一些主題，但是夺姑，我們將僅解釋概念墩邀，因此您 了解它是如何工作的，但我們不會(huì)以相同的方式進(jìn)行深入研究盏浙，因?yàn)樗?在醫(yī)學(xué)上很重要眉睹。好的，現(xiàn)在讓我們將這些主題放在一起废膘，然后通過 我們需要討論的各個(gè)領(lǐng)域或系統(tǒng)竹海。一般生理將是那些 經(jīng)歷身體的所有器官系統(tǒng)。神經(jīng)系統(tǒng)將是大腦丐黄，脊柱 繩索和神經(jīng)斋配，這些有助于控制和調(diào)節(jié)其他器官系統(tǒng) 其他器官系統(tǒng)包括肌肉骨骼系統(tǒng)。所以就肌肉系統(tǒng)而言 這就是肌肉的收縮，它們?nèi)绾卫瓌?dòng)骨骼杠桿艰争，這樣您就可以 走路坏瞄，走路，做日常生活的各種活動(dòng)甩卓。但是鸠匀，要做正常的活動(dòng) 你需要新陳代謝。為了進(jìn)行新陳代謝逾柿，我們需要有氧氣缀棍，這就是 呼吸系統(tǒng)起作用。在這里机错，呼吸系統(tǒng)在 環(huán)境爬范，進(jìn)入人體和肺部，您將能夠吸收氧氣并 您將能夠消除二氧化碳弱匪。您如何將氧氣吸收到體內(nèi)所有細(xì)胞周圍 涉及心血管系統(tǒng)青瀑。所以在這里，我們將有心臟在抽血×》ǎ現(xiàn)在就這樣 將血液泵送到全身狱窘，您需要擁有脈管系統(tǒng)或輸液管杜顺， 將血液輸送到整個(gè)身體财搁，每個(gè)細(xì)胞的擴(kuò)散距離都足夠近 接收氧氣。腎臟系統(tǒng)在血液過濾中非常重要躬络。 因此尖奔，就像呼吸系統(tǒng)正在添加物質(zhì)一樣，腎臟系統(tǒng)也會(huì)被去除 代謝過量或底物穷当。胃腸道系統(tǒng)很好提茁，因?yàn)樗梢蕴砑痈鞣N營養(yǎng)素 根據(jù)人體細(xì)胞的需要，例如葡萄糖馁菜。最后茴扁，內(nèi)分泌系統(tǒng)將 類似于神經(jīng)系統(tǒng)的調(diào)節(jié)系統(tǒng)中的另一種控制方法對我們有幫助 將所有各種器官系統(tǒng)整合到體內(nèi)。現(xiàn)在讓我們討論這些器官系統(tǒng) 以及它們?nèi)绾卧诹鞒虉D中相互聯(lián)系汪疮。在這里你可以看到身體是 在許多不同的層中進(jìn)行設(shè)置峭火。我們這里的頂層是肺，這是 當(dāng)然智嚷，二氧化碳將離開而氧氣將進(jìn)入卖丸。請注意，心臟是 一分為二盏道，心臟的右側(cè)將血液泵入肺部稍浆，我們的左側(cè) 心臟在整個(gè)系統(tǒng)中移動(dòng)血液。腎臟系統(tǒng)將位于第三位 梯級(jí)，這又是我們的過濾系統(tǒng)衅枫。在第二梯級(jí)嫁艇，我們有胃腸道 系統(tǒng)，它將再次成為血液吸收營養(yǎng)的地方 葡萄糖弦撩，蛋白質(zhì)裳仆，脂肪，然后可以傳遞到人體的所有細(xì)胞孤钦。終于在 最低的橫檔歧斟，我們有毛細(xì)血管床，這表示體內(nèi)的所有不同細(xì)胞 以及每個(gè)人將如何接受其中含有氧氣偏形，營養(yǎng)物質(zhì)的血液静袖，并且 過濾良好，因此可以進(jìn)行相應(yīng)的正晨∨ぃ活動(dòng) 系統(tǒng)队橙，無論是神經(jīng)系統(tǒng)，肌肉骨骼系統(tǒng)還是內(nèi)分泌系統(tǒng)萨惑。
02 穩(wěn)態(tài)
現(xiàn)在是我們需要按照中心原則進(jìn)行討論的過程捐康。中央 生理原理基本上是體內(nèi)平衡，但我們都需要在同一頁面上 穩(wěn)態(tài)實(shí)際上意味著庸蔼。這是生物系統(tǒng)維持的受控過程 在各種壓力或壓力下動(dòng)態(tài)但相對一致的內(nèi)部條件 由外部和內(nèi)部因素引起解总。有很多事情要考慮，所以讓我們談?wù)劙?通過這些過程中的每個(gè)過程姐仅，我們將了解這個(gè)定義是什么花枫。 首先要考慮的是身體的哪些變量對您足夠重要 真正規(guī)范他們。如果您想一想這幾秒鐘掏膏，其中一個(gè) 在我看來是葡萄糖劳翰。因此，您需要調(diào)節(jié)血液中的葡萄糖量馒疹，以便 最佳量被遞送到體內(nèi)的每個(gè)細(xì)胞佳簸。氧氣也是如此。 氧氣需要輸送到體內(nèi)的每個(gè)細(xì)胞颖变，需要進(jìn)行精確調(diào)節(jié)生均。 您如何確保身體各個(gè)部位獲得足夠的氧氣和葡萄糖？ 您需要有足夠的血壓或壓力才能將血液推到各個(gè)部位悼做。 這些是3個(gè)非常好的例子疯特。其他您可能尚未想到的 包括調(diào)節(jié)體溫，調(diào)節(jié)pH平衡等 我們需要調(diào)節(jié)的整數(shù)變量「刈撸現(xiàn)在债查，關(guān)于定義的另一件事是 認(rèn)為我們應(yīng)該多討論一些似乎矛盾的地方，因?yàn)閮烧叨际莿?dòng)態(tài)的 并保持一致邮破，這就是我們的意思。這不是一個(gè)特定的數(shù)字组题，而是 在醫(yī)學(xué)中很重要的一系列數(shù)字。例如抱冷，葡萄糖水平不 將是一個(gè)數(shù)字崔列，而是一個(gè)范圍。血壓不僅僅是我們的一個(gè)數(shù)字 而是一系列血壓之后旺遮，這就是動(dòng)態(tài)成分赵讯， 盡管我們必須始終將其保持在狹窄范圍內(nèi)。有哪些例子 可以改變體內(nèi)平衡的內(nèi)部因素耿眉？這主要涉及新陳代謝的變化边翼。因此，如果 您進(jìn)行類似運(yùn)動(dòng)的運(yùn)動(dòng)會(huì)增加新陳代謝鸣剪，而如果您 睡覺會(huì)使您的新陳代謝減少组底。這是一個(gè)內(nèi)部因素。外部因素是 幾乎沒有名字可言筐骇，這些都是來自外部環(huán)境的東西 影響身體债鸡。可能是外部铛纬，太陽或 從環(huán)境以及它如何影響我們的生理厌均。可能會(huì)很冷饺鹃，如何影響寒冷 我們的生理狀況莫秆，或者處于壓力狀態(tài)，您會(huì)感到害怕或制定了 戰(zhàn)斗或逃跑反應(yīng)悔详。這是另一個(gè)例子，我們現(xiàn)在需要處理的外部因素 在動(dòng)態(tài)但始終如一的范圍內(nèi)惹挟，但保持超調(diào)變量茄螃。另一件事 我們需要牢牢把握的動(dòng)態(tài)平衡是在什么水平上以及這個(gè)水平上 是一個(gè)組織層次。所以有原子连锯，這些原子形成分子归苍，然后形成更大的分子 分子，然后最終形成各種細(xì)胞成分运怖，例如線粒體拼弃， 也可能是其他局部類型的細(xì)胞器。最后摇展，我們有了單元吻氧。 該單元可能是我們真正需要維持的第一層組織 里面的環(huán)境，這就是任何內(nèi)部的穩(wěn)態(tài)環(huán)境 細(xì)胞。這調(diào)節(jié)著進(jìn)入細(xì)胞的物質(zhì)盯孙，調(diào)節(jié)著細(xì)胞質(zhì)的溶解 將由組成÷成現(xiàn)在，每個(gè)單獨(dú)的細(xì)胞被組合在一起形成一個(gè)組織振惰。 在組織水平上歌溉，我們也有穩(wěn)態(tài)調(diào)節(jié)作用，因此特定組織會(huì)調(diào)節(jié) 其中一些參數(shù)骑晶。器官系統(tǒng)還將調(diào)節(jié)體內(nèi)平衡規(guī)范痛垛。器官 系統(tǒng)共同調(diào)節(jié)人體的各種體內(nèi)平衡機(jī)制，例如血液和 最后桶蛔，我們有了需要調(diào)節(jié)的整個(gè)有機(jī)體榜晦。所以從細(xì)胞，組織 器官羽圃，器官系統(tǒng)級(jí)別乾胶，最后是整個(gè)有機(jī)體，所有這些都需要 個(gè)人層面和公司層面的動(dòng)態(tài)平衡朽寞。那怎么辦识窿？好一 調(diào)節(jié)體內(nèi)平衡需要考慮的事情是，這全都基于我們的遺傳學(xué)脑融。所以 您在每個(gè)細(xì)胞中都有DNA喻频，因此實(shí)際上細(xì)胞可以成為體內(nèi)的任何組織。 恰好發(fā)生在當(dāng)前時(shí)間是細(xì)胞和組織肘迎。所以當(dāng)我們考慮 組織甥温，器官，器官系統(tǒng)和生物體妓布，我們必須始終意識(shí)到每個(gè)單獨(dú)的細(xì)胞 經(jīng)歷自身的動(dòng)態(tài)平衡姻蚓，以及如何相互調(diào)節(jié)動(dòng)態(tài)平衡 整個(gè)生物體的基本遺傳密碼 組織層次結(jié)構(gòu)。因此匣沼，讓我們將其重新組合成所有器官系統(tǒng)狰挡，然后 討論此過程如何以集成方式工作。所以請記住你有類似 頂部的神經(jīng)系統(tǒng)和底部的內(nèi)分泌系統(tǒng)有助于 整個(gè)生物體的調(diào)節(jié)释涛。肌肉骨骼加叁，呼吸，心血管唇撬，腎臟 和GI系統(tǒng)正在幫助進(jìn)行監(jiān)管它匕，并且某些監(jiān)管在 性質(zhì)意味著它是通過植物神經(jīng)系統(tǒng)誘發(fā)的，其中一些是 行為的窖认。因此豫柬，例如告希，如果天氣太熱，您可以做一些事情轮傍，例如坐在火中 和汗水來嘗試調(diào)節(jié)您的體溫暂雹，或者您可以簡單地起身去 更涼爽的環(huán)境。這些是行為和自主反應(yīng)之間的各種選擇 可用來維持體內(nèi)平衡的物質(zhì)创夜。我認(rèn)為動(dòng)態(tài)平衡的最后一個(gè)方面 最能幫助您思考的是使您能夠 適應(yīng)不同的環(huán)境或壓力杭跪。最好通過以下方式制定 考慮器官系統(tǒng)可能會(huì)做什么。因此驰吓，在幻燈片一側(cè)的示例中 這里您的血壓升高涧尿。因此，如果血壓升高檬贰，您需要 可以感覺到血壓上升的信號(hào)姑廉，然后再傳回心臟， 說“嘿翁涤，嘿桥言，壓力太大了】瘢”我們要么不得不放慢腳步 特別的心号阿。這可能會(huì)更加復(fù)雜，不僅僅是與擁有 壓力增加和心臟減慢鸳粉，而是多因素的扔涧。所以在這個(gè) 在下一個(gè)例子中，隨著平均動(dòng)脈血的增加届谈，我們將顯示相同的響應(yīng) 壓力感受器會(huì)感知到的血壓枯夜，這些都是壓力感受器 或壓力感受器。然后將其反饋到腦干艰山，在本例中為髓質(zhì)湖雹。的 然后，髓質(zhì)組織信息并將信號(hào)發(fā)送到心臟以及 血管程剥。內(nèi)心深處劝枣，它會(huì)發(fā)出一個(gè)信號(hào)，它應(yīng)該放慢速度织鲸，不應(yīng)該 跳得這么快，也不必灰心溪胶。最后對于血管搂擦，它會(huì)說 “嘿，你可以放松一點(diǎn)哗脖，你太緊張了瀑踢，血壓太高了扳还。 系統(tǒng)需要擴(kuò)張”，這種情況也會(huì)降低血壓橱夭。這會(huì)導(dǎo)致兩個(gè) 東西氨距，心動(dòng)過緩和血管舒張，并希望兩者結(jié)合就足夠了 將平均動(dòng)脈血壓降低到我們試圖調(diào)節(jié)的值棘劣。 同樣俏让，這是一個(gè)動(dòng)態(tài)的過程，但是我們正在尋找一個(gè)穩(wěn)定的范圍茬暇。
03 控制和調(diào)節(jié)
因此首昔，在這種情況下，我們將要調(diào)節(jié)一個(gè)變量糙俗。那個(gè)調(diào)節(jié)變量 有些東西會(huì)影響它勒奇。假設(shè)有一個(gè)外部壓力源，這將 導(dǎo)致您的調(diào)節(jié)變量發(fā)生變化巧骚。你需要做什么赊颠？你怎么知道 變量是否太高？您體內(nèi)需要安裝各種傳感器劈彪。就像我們 壓力升高時(shí)有壓力感受器竣蹦。所以你有一個(gè)傳感器，你可能有 多個(gè)傳感器都將收集由該法規(guī)生成的數(shù)據(jù) 變量》垭現(xiàn)在您有了傳感器來收集數(shù)據(jù)草添，它需要將其發(fā)送到某個(gè)地方 因?yàn)閭鞲衅鞅旧頍o法確定要做什么。因此它將數(shù)據(jù)發(fā)送到集成 系統(tǒng)扼仲，有時(shí)甚至是一個(gè)協(xié)調(diào)系統(tǒng)远寸，這將協(xié)調(diào)我們的響應(yīng) 調(diào)整變量發(fā)生的變化，然后將信號(hào)發(fā)送到 效應(yīng)器和這些效應(yīng)器將能夠改變或引起我們的改變 調(diào)節(jié)變量屠凶。因此驰后，我們擁有這四類插腳系統(tǒng) 變量，傳感器矗愧，積分器灶芝，協(xié)調(diào)中心和效應(yīng)器都在嘗試 確保我們的調(diào)節(jié)變量在一個(gè)內(nèi)部被協(xié)調(diào)或調(diào)節(jié)的各個(gè)方面 各種范圍。好吧唉韭，讓我們回到我們的內(nèi)心例子夜涕，嘗試進(jìn)一步梳理一下，如此 我們可以表示調(diào)節(jié)變量在哪里属愤，傳感器在哪里女器，在哪里 集成商和協(xié)調(diào)系統(tǒng)，以及我們的效應(yīng)器將要成為的住诸。所以我們將 看看下一張圖驾胆。因此涣澡，我們系統(tǒng)中用于控制動(dòng)脈血的傳感器 壓力將成為壓力感受器。現(xiàn)在有許多不同的壓力感受器 位于血管系統(tǒng)中的血液中或血液外部丧诺，而那些位于 頸動(dòng)脈竇入桂，它們在您的脖子上，主動(dòng)脈弓位于左上方 心室或血液排出的地方驳阎。這些將使我們能夠洞悉什么血液 壓力是抗愁，但是請注意，您到處都沒有壓力感受器 位于關(guān)鍵地點(diǎn)搞隐。那么為什么這是關(guān)鍵驹愚？好吧，就主動(dòng)脈弓而言劣纲， 在您將血液擠出到全身循環(huán)之后逢捺。所以你想知道什么 是心臟排出血液的壓力。另一個(gè)關(guān)鍵因素是 知道血液流到大腦非常重要癞季。所以你想擁有壓力感受器 在頸動(dòng)脈竇中能夠吸收進(jìn)入大腦的血壓劫瞳。那些是 將成為我們主要的受調(diào)節(jié)壓力感受器。它們通過各種顱神經(jīng)绷柒，迷走神經(jīng)發(fā)送 主動(dòng)脈弓為顱神經(jīng)X或舌咽或顱神經(jīng)IX為 頸動(dòng)脈竇志于。他們被送到哪里？他們被送到延髓废睦，這是我們的 整合中心伺绽。記住，當(dāng)我們整合某些東西時(shí)嗜湃，我們會(huì)抓住所有 信息奈应，這是由稱為NDS或核的特定腦干成分完成的 獨(dú)尾。這是我們的聚會(huì)場所购披。您可以想到它杖挣，例如火車站 所有的信息都回到中心位置，以便我們知道信息在哪里 來自刚陡，但僅僅是因?yàn)樾畔⒄诜祷爻透荆⒉灰欢ㄒ馕吨?我們知道該怎么做，所以我們需要一些地方筐乳，這是一個(gè)協(xié)調(diào)中心 那將能夠獲取所有這些信息歌殃，并讓我們決定如何處理它。所以在 以血壓為例蝙云，我們可能有三個(gè)主要位置或效應(yīng)器 完成挺份。因此，我們有一個(gè)心臟減速區(qū)贮懈，這在副交感神經(jīng) 系統(tǒng)匀泊。我們在交感神經(jīng)系統(tǒng)中有心臟加速器系統(tǒng)， 交感神經(jīng)系統(tǒng)中的血管收縮成分朵你。這些是我們所要做的 可以換各聘。那么，如果血壓下降怎么辦抡医？
副交感神經(jīng) 神經(jīng)系統(tǒng)將試圖減慢心臟的速度躲因。那你如何減慢 減速器？好吧忌傻，你將不得不抑制它大脉。因此，您正在禁止減速器水孩。 您還將向必須做的心臟部分發(fā)出積極信號(hào) 心率加快镰矿，這會(huì)增加您的心率。您將增加收縮力俘种。 您將增加發(fā)送到小動(dòng)脈的信號(hào)秤标，這些小動(dòng)脈是血管的一部分 引起血管收縮。您將增加對靜脈部分的信號(hào) 那也可以收縮宙刘。因此苍姜，在我們的示例中，我們向 竇房結(jié)來自交感神經(jīng)系統(tǒng)悬包，收縮力衙猪，小動(dòng)脈和靜脈。從 副交感神經(jīng)系統(tǒng)布近，來自減速區(qū)的信號(hào)為負(fù) 這將使我們能夠提高竇房結(jié)去極化率垫释。那么這是什么意思 所有這些不同方面？這意味著我們將增加心率吊输，增加 收縮力增加饶号，血管收縮增加，靜脈收縮增加 頸動(dòng)脈竇發(fā)送給我們的信號(hào)是血壓降低季蚂。 現(xiàn)在茫船，我們可以想到一些病理生理學(xué)實(shí)例，這些實(shí)例會(huì)影響這些 循環(huán)扭屁，我要指出的其中之一是動(dòng)脈粥樣硬化或其他成分 我們可以想到的是衰老算谈，因?yàn)檫@兩種都會(huì)使壓力感受器反應(yīng)變鈍 因?yàn)樗鼈円允寡鼙诟驳姆绞礁淖冄鼙凇Ｈ绻写?墻更硬料滥，發(fā)生的情況是它在響應(yīng)時(shí)不會(huì)擴(kuò)大或變大 血壓變化然眼。因此，如果血壓升高葵腹，它將拉伸血管高每。 如果它拉伸血管屿岂，就會(huì)影響或引起周圍神經(jīng)的變化 該血管，因此鲸匿，如果您有血管爷怀，并且您有正確的神經(jīng) 在它旁邊，當(dāng)它擴(kuò)張時(shí)带欢，它將推動(dòng)該神經(jīng)运授，并將信號(hào)轉(zhuǎn)換回 腦。在這種情況下乔煞，如果您的船只較硬吁朦，則通過的信息較少 僵硬的血管，因此您對反應(yīng)的反應(yīng)程度不同渡贾，因此可以更改 人在衰老或動(dòng)脈粥樣硬化中的壓力感受器反應(yīng)逗宜，這會(huì)影響您的 調(diào)節(jié)變量，例如動(dòng)脈血壓剥啤。
Physiology
Physiology – Introduction & Central Principles
1479.Introduction to Physiology
Define the field of physiology and identify its prominence in medicine Summarize the integrated organ systems approach of medical physiology
It's a science related to physics. The science that aims to understand the mechanisms of living systems, from the molecular to the complex structure of the body. A science that studies higher forms of life. The science that aims to understanding how the body gets sick. The science exclusively aimed at understanding how organs relate to each other.
Answer: B
00:00 Here we are going to talk about physiology and its general principles. Now you may be thinking at this point, well, what exactly is physiology. So let's address that first. Physiology is the science of life. Physiology is fairly broad in nature and it aims to understand the mechanisms of living and this incurs all the way from the genetic and molecular to the cell and to cell function and eventually into integrated behavior of the whole body. The other thing that's important to think about with physiology is it is how the body works under normal conditions. 00:41 Why this is important is later we're going to differentiate between normal physiology and medical physiology. Physiology is used in almost everything you do in daily life from whether you're walking or exercising, whether you're reading or whether you're watching this particular Lecturio lecture. It's done in just about everything. So let's also now define what is medical physiology and difference from regular physiology. In medical physiology, one of the quotes that I like best is done by an investigative team that first discovered what an arterial blood gas is and in this case they decided that critical care medicine is basically applying physiological principles to the care of the seriously ill patient. So in medical physiology, we will talk about some topics in greater detail and drill those down because they are more medically relevant. There are some topics in physiology, however, we will just explain the concept so you understand how this works but we won't drill it down in the same way because it's less medically important. Okay, now let's bring these topics together and go through which are the various areas or systems that we need to discuss. General physiology will be those things that undergo through all organ systems in the body. The nervous system will be the brain, the spinal cord and the nerves and these help control and regulate the other organ systems and those other organ systems include the musculoskeletal system. So in terms of the muscular system this would be the contractions of muscles, how they pull on skeletal levers so that you can ambulate, walk, do the various activities of normal daily living. However, to do normal activities you need to have metabolism. For metabolism, we need to have oxygen and that's where the respiratory system comes into play. Here, the respiratory system exchanges air between the environment and into the body and to the lungs, you will be able to then absorb oxygen and you will be able to eliminate CO2. How you get that oxygen around to all the cells in the body involves the cardiovascular system. So here, we will have the heart pumping blood. Now as it pumps blood throughout the body you need to have a vasculature or a tube system so it delivers blood throughout the whole body and every cell is in close enough diffusional distance to receive that oxygen. The renal system is very important in undergoing filtration of the blood. 03:31 So like the respiratory system was adding substances, the renal system will be removing metabolic excesses or substrates. The GI system is nice in that it adds back various nutrients as needed for the cells in the body such as glucose. Finally, the endocrine system will be another one of those control in regulation systems similar to the nervous system that help us integrate all the various organ systems in the body. So now let's discuss these organ systems and how they relate to each other in more of a flow diagram. Here you can see the body is set up in a number of different layers. The top layer we have here is the lungs and this is of course where the carbon dioxide will leave and oxygen will enter. Notice that the heart is split into two, the right side of the heart pumping blood in to the lungs, we have the left side of the heart moving that blood throughout the system. The renal system will be on the third rung and that's again our filtration system. On the second rung we have the gastrointestinal system and that will be once again the spot in which blood will come to pick up nutrients like glucose, proteins, fats so that then can be delivered to all the cells of the body. Finally at the lowest rung we have the capillary beds and that is to denote all the different cells in the body and how each one of them will receive this blood that has oxygen in it, has nutrients in it and is well filtered and so that can correspond to do the normal activities that are needed for that system, whether it be the nervous system, the musculoskeletal system or the endocrine system.
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Log In subjected to; subjected to also subject to; subjecting to; subjects to Definition of subject to 1: affected by or possibly affected by (something) The firm is subject to state law. The schedule is tentative and subject to change. Clothing purchases over 500 fine. 2: likely to do, have, or suffer from (something) My cousin is subject to panic attacks. I'd rather not live in an area that is subject to flooding. 3: dependent on something else to happen or be true The sale of the property is subject to approval by the city council. All rooms are just $100 a night, subject to availability.
1480 Homeostasis: Definition & Level of Organization
Define homeostasis Name some important physiological variables that must be regulated within the body Recognize the dual dynamic and consistent elements of homeostasis Recognize the numerous internal and external factors that can challenge homeostasis Summarize the levels of organization at which homeostasis occurs, with a focus on the cell as the primary level of organization Recognize the genetic influence on homeostasis at a cellular level Summarize the negative feedback control mechanism involved in blood pressure homeostasis
1 What is homeostasis?
A process by which a biological system maintains a dynamic but consistently stable internal condition in the face of both internal or external pressures.
The control system for blood pressure.
The ability to regulate body fluids.
A static situation in the body.
The body’s internal milieu.
Answer:A
2 What variables in the body are important enough to be consistently regulated?
Urinary output, liver functions, digestion.
Respiratory rate.
Oxygen saturation, blood pressure, glucose, pH, body temperature.
Amount of red cells.
Blood flow in the muscles.
Answer:C 3 What is the meaning of “dynamic but relatively consistent state”?
A state maintained within a close range of values.
A situation that can be safely manipulated.
A state that may change widely but spontaneously returns to baseline.
A state that is fixed on one value.
A state that cannot be manipulated.
Answer: A
4 What inner factors can change homeostasis?
A salt load
Changes in metabolism
Exposure to the sun
Increasing water intake
A sugar load
Answer:B
5 Which is the lowest level of organization that needs homeostatic regulation in order to function properly? The whole body
Organs
The cell
Atoms
Molecules
Answer:C
6 What is the homeostasis mechanism most commonly seen in the body?
Neuromodulators
Signal molecules
Feedback mechanism
Hormones
Receptor binding
Answer:C
00:00 This is the process now that we need to discuss in terms of a central principle. The central principle of physiology is basically homeostasis but we all need to be on the same page of what homeostasis actually means. It is a regulated process by which a biological system maintains a dynamic but relatively consistent internal condition during various stresses or pressures incurred both from external and internal factors. That's a lot to think about so let's kind of deal through each of those processes a little bit more so we will understand what this definition is. 00:41 First thing to think about is what variables of the body are important enough for you to actually regulate them. If you think about this for a couple of seconds, one of them that comes to my mind is glucose. So you need to regulate the amount of glucose in the blood so that an optimal amount is delivered to each of the cells in the body. The same goes with oxygen. 01:09 Oxygen needs to be delivered to each cell in the body, it needs to be precisely regulated. 01:14 How do you make sure you get enough oxygen and glucose to the various spots in the body? You need to have enough blood pressure or pressure to push the blood to those various spots. 01:27 So those are 3 really good examples. Other ones that you might not have thought of yet include things like the regulation of body temperature, the regulation of pH balance are also integral variables that we need to regulate. Now, the other thing about the definition that I think we should discuss a little bit more that seems kinds of contradictory is that it's both a dynamic and consistent and what we mean by that. It's not going to be one particular number but rather a range of numbers that's going to be important in medicine. For example, a glucose level is not going to be one number but rather a range. Blood pressure is not just one number that we are after but rather a range of blood pressures and that is what is the dynamic component, although we have to consistently keep it within a narrow range. What are some examples of internal factors that can change homeostasis? This mainly involves changes in metabolism. So if you undergo something like exercise you have an increase in metabolism while if you are sleeping you have a decrease in metabolism. That's an internal factor. External factors are almost too great to even name, these are anything that will be from the external environment impacting the body. That can be something like heat generated from outside, from the sun or from the environment and how that impacts our physiology. It could be cold, how cold impacts our physiology or maybe in a stressful condition in which you are scared or you enacted the fight or flight response. That's another example, that external factor that we need to now deal with but maintain over regulated variables in a dynamic but consistent range. The other thing about homeostasis that we need to have a firm grasp on is at what level are we talking about and this level is a level of organization. So there are atoms and these form molecules which then form larger molecules and then finally form various cellular components like mitochondria in this case, it could be other local types of cellular organelles as well. Then finally we have the cell. 04:00 The cell is probably the first level of organization that we really need to maintain an environment in and this is the homeostatic environment of whatever is going to be within the cell. This is regulating what comes into the cell, it regulates what that cellular cytosol is going to be composed of. Now each individual cell though is combined together to form a tissue. 04:30 At the level of tissue, we also have a homeostatic regulation, so a particular tissue will regulate some of these parameters. Organ systems will also regulate a homeostatic norm. Organ systems together regulate the body's various homeostatic mechanism such as the blood and then finally we have the whole organism that needs to be regulated. So from the cell, tissue, organ, organ system level and finally the organism as a whole, all of these need to have homeostasis both at the individual level and the corporate level. So how is that done? Well one thing to think about with regulation of homeostasis is that it's all based upon our genetics. So you have DNA within each individual cell and so in fact a cell could become any tissue in the body. 05:31 It just so happens it is the cell and tissue that it is at the current time. So when we think about tissues, organ, organ system and organism, we have to always realize that each individual cell undergoes its own homeostasis and how that builds upon each other to regulate the homeostasis of the whole entire organism but the basic genetic code is in each cell of this overall hierarchy of organization. So let's bring it back together as all the organ systems and then discuss how this process works in an integrated fashion. So remember you have something like the nervous system at the top and the endocrine system at the bottom helping out with the regulation of the entire organism. The musculoskeletal, respiratory, cardiovascular, renal and GI systems are helping that regulation occur and some of the regulation is automatic in nature meaning that it's induced through the autonomic nervous system and some of it is behavioral. So for example if it's too hot out you can either do something like sit in the heat and sweat to try to regulate your body temperature or you can simply get up and go to a cooler environment. Those are the various choices between behavior and autonomic responses that are available to try to maintain homeostasis. The last aspect of homeostasis that I think will be most helpful to think about is what are the various components that allow you to regulate to a different environment or a different stressor. That can be best enacted by thinking about what an organ system might do. So in the example on the one side of your slide here you have an increase in blood pressure. So if blood pressure goes up, you need to have something to sense the blood pressure going up and then a signal coming back to the heart to say "Hey, hey that's too much pressure." We're going to either have to slow down that particular heart. This can be more complex to be not just one factor being involved with having an increase in pressure and a slowing down of the heart but rather be multifactorial. So in this next example we're going to show the same response with increase in mean arterial blood blood pressure that's going to be sensed by a pressure receptor and these are baroreceptors or pressure receptors. Then that is fed back to the brainstem, in this case the medulla. The medulla then organizes the information and sends the signal out both to the heart as well as the blood vessels. To the heart, it's going to send a signal that it should slow down, shouldn't beat so fast, it also doesn't have to be disheart. Finally for blood vessels, it's going to say "Hey you can relax a little bit, you're too tensed, there is too much blood pressure in the system you need to dilate" and this case that will also reduce blood pressure. This induces two things, a bradycardia and a vasodilation and hopefully those two in combination are enough to lower mean arterial blood pressure down to a value in which we are trying to regulate. 09:06 Again, this is a dynamic process but we're looking at a consistent range that we're looking for.
1481 Control and Regulation
Describe the control and regulation of physiological variables via sensors, integrators, coordinating centers, and effectors Summarize the control system for arterial blood pressure and describe the sensors, integrator, coordinating centers, and effectors involved Explain how aging and atherosclerosis can affect the body’s ability to regulate arterial blood pressure
1 Which of the following receptors sense pressure? Neuroreceptors Metaboreceptors Thermoreceptors Baroreceptors Ergoreceptors
Answer:D
2 How is a given variable detected in the system for controlling arterial blood pressure? Sensing by one or multiple receptors Direct adaptation to stressors Local responses Stressors themselves Changes in the endothelium of blood vessels
Answer: A
3 Where do data collected by sensors go to maintain homeostasis? To arteries in the neck Back to the stressor To an integrator and coordinating center To the blood vessels where it was collected To veins in the neck
Answer:C
4 What is the function of an effector? To cause alterations in the integrator To cause alterations in the stressor To cause alterations in the sensors To cause alterations in the regulated variable To cause alterations in the coordinating center
Answer: D
5 A rise in blood pressure causes which of the following? Activation of baroreceptors that stimulate the activity of sympathetic neurons Activation of baroreceptors that inhibit the activity of neurons in the dorsal motor nucleus of the vagus and the nucleus ambiguous to influence heart rate Activation of baroreceptors that inhibit the activity of parasympathetic neurons Activation of baroreceptors that inhibit the activity of sympathetic neurons Increase of vasoconstrictive effects of sympathetic innervation on the peripheral blood vessels
Answer: D
6 A rapid drop in blood pressure causes which of the following? Decreased baroreceptor stimulation that increases the activity of sympathetic neurons Activation of baroreceptors that stimulate the activity of neurons in the dorsal motor nucleus of the vagus and the nucleus ambiguous that influence heart rate. Activation of baroreceptors that inhibit the activity of sympathetic neurons Activation of baroreceptors that stimulate the activity of parasympathetic neurons Decrease vasoconstrictive effects of sympathetic innervation on the peripheral blood vessels.
Answer: A
7 Which of the following is caused by aging and atherosclerosis? Delayed effector responses Dilation of the vessels Stiffening of the vessel walls Decreased effectiveness of the integrator and coordinating center Quicker effector responses
Answer: C
00:00 So in this case, we're going to have a variable that's regulated. That regulated variable, something will affect it. So let's say there is an external stressor out there and that's going to cause a change in your regulated variable. What you need to do? How do you know that variable is too high? You need to have various sensors in the body to pick that up. Just like we had baroreceptors when pressure was elevated. So you have a sensor and you may have multiple sensors that all are going to gather the data that is generated by this regulated variable. Now that you have the sensors garnering that data, it needs to send it somewhere because the sensor itself cannot determine what to do. So it sends the data to an integrated system or sometimes also a coordinating system and that is going to coordinate our response to that change that happened to our regulated variable and that signal is then sent to effectors and these effectors are going to be able to then change or cause an alteration in our regulated variable. So we have this four-kind of prong system where we have a regulated variable, sensors, an integrator and coordinating center and effectors all trying to do the various aspects of making sure our regulated variable is coordinated or regulated within a various range. Okay, let's go back to our heart example to try to tease this out further and so we can denote where our regulated variables are, where our sensors are, where our integrator and coordinating system are and what our effectors are going to be. So we will take a look at that in the next diagram. So our sensors in our system for controlling arterial blood pressure are going to be baroreceptors. Now there are a number of different baroreceptors located in the blood or just outside of the blood in the blood vessel system and those are in the carotid sinuses, they are here in your neck, your aortic arch which is just above the left ventricle or where the blood is pushed out. Those will allow us to give us insight into what blood pressure is but notice that you don't have baroreceptors everywhere, you just have them located in key spots. So why would this be key? Well in terms of the aortic arch, it's going to be right after you squeezed out the blood into the systemic circulation. So you want to know what is the pressure in which the heart is pushing out blood. The other key component to this is to know that the blood going to the brain is very important. So you'd want to have baroreceptors in the carotid sinuses to be able to pick up that blood pressure going to the brain. Those are going to be our main regulated baroreceptors. They are sent via various cranial nerves, vagus or cranial nerve X for the aortic arch and the glossopharyngeal or cranial nerve IX for the carotid sinuses. Where are they sent to? They are sent to the medulla and this is our integrating center. Remember when we integrate something, we are grabbing a hold of all the information and this is done from a specific brainstem component called the NDS or the nucleus tractus solitarus. This is our gathering area. You can think of it something like the train depot, all the information is coming back to a central location so that we know where the information is coming from but just because the information is coming back doesn't necessarily mean that we know what to do with it so we need to have some place and this is a coordinating center that is going to be able to take all these information and let us decide what to do with it. So in a blood pressure example, we have three main places or effectors that we might be able to accomplish. So we have a cardiac decelerator region and this is in the parasympathetic nervous system. We have a cardiac accelerator system in the sympathetic nervous system and a vasoconstrictor component in the sympathetic nervous system. These are the things which we can change. So what happens if you have an decrease in blood pressure? The parasympathetic nervous system is going to try to slow down the heart. So how do you slow down a decelerator? Well you're going to have to inhibit it. So you're inhibiting the decelerator. 04:51 You're also going to be giving a positive signal to the portions of the heart that have to do with heart rate and that increases your heart rate. You're going to increase your contractility. 05:07 You're going to increase the signal sent to your arterioles which are part of your blood vessels that cause vasoconstriction. You're going to increase the signal to the portions of the veins that can also venoconstrict. So in our example here, we have an increased signal to the sinoatrial node from the sympathetic nervous system, contractility, arterioles and veins. From the parasympathetic nervous system, we have a negative signal from the decelerator region which will allow us to increase the sinoatrial node depolarization rate. So what does this mean all these different aspects? It means we're going to get an increase in heart rate, an increase in contractility, an increase in vasoconstriction, increase in venoconstriction in response to the signal that was sent to us from the carotid sinuses and that was a decrease in blood pressure. 06:06 Now, there are pathophysiology examples that we can think of that will affect these regulated loops and one of the ones that I will just point out is atherosclerosis or another component that we could think of is aging because both of these can blunt baroreceptor responses because they change the vessel walls in such ways that the vessel walls are stiffer. If a vessel wall is stiffer, what happens is it doesn't distend as much or become bigger in responses to changes in blood pressure. So if blood pressure goes up, it should stretch the blood vessel. 06:45 If it stretches the blood vessel, it impacts or enacts changes in the nerve that's right around that blood vessel and therefore if you have a blood vessel and you have the nerve that's right next to it, as it distends it pushes on that nerve and will transduce the signal back to the brain. In this case if you have a stiffer vessel, less information travels through a stiff vessel and therefore you don't respond to the same extent and so you can change your person's baroreceptor responses in aging or in atherosclerosis and that impacts your ability to regulate a variable such as arterial blood pressure.
