{"id":4446,"date":"2019-06-24T12:41:53","date_gmt":"2019-06-24T12:41:53","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/4-7-passive-transport-3\/"},"modified":"2023-11-30T17:54:06","modified_gmt":"2023-11-30T17:54:06","slug":"4-7-passive-transport-3","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/4-7-passive-transport-3\/","title":{"raw":"4.7\u00a0Passive Transport","rendered":"4.7\u00a0Passive Transport"},"content":{"raw":"&nbsp;\r\n<div>\r\n\r\n[caption id=\"attachment_1650\" align=\"alignright\" width=\"403\"]<img class=\" wp-image-1650\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/windows-2-scaled.jpg\" alt=\"Image shows a photo of a living room with large windows. There is a leather armchair, coffee table, lamp and books. The walls have wood panelling.\" width=\"403\" height=\"504\" \/> Figure 4.7.1 Just as windows in a house let light in, the cell membrane lets certain substances into and out of the cell.[\/caption]\r\n<h1>Letting in the Light<\/h1>\r\n<\/div>\r\nLook at the big windows in this house (Figure 4.7.1). Imagine all the light they must let in on a sunny day. Now imagine living in a house that has walls without any windows or doors. Nothing could enter or leave. Or imagine living in a house with holes in the walls instead of windows and doors. Things could enter or leave, but you couldn\u2019t control what came in or went out. Only when a house has walls with windows and doors that can be opened or closed, can you control what enters or leaves. Windows and doors allow you to let in light and the family dog and keep out rain and bugs, for example.\r\n<div>\r\n<h1>Transport Across Membranes<\/h1>\r\n<\/div>\r\nIf a cell were a house, the\u00a0[pb_glossary id=\"5489\"]plasma membrane[\/pb_glossary]\u00a0would be walls with windows and doors. Moving things in and out of the cell is an important\u00a0function\u00a0of the\u00a0plasma membrane. It controls everything that enters and leaves the cell. There are two basic ways that substances can cross the plasma membrane: [pb_glossary id=\"5705\"]passive transport[\/pb_glossary] \u2014 which requires no\u00a0energy\u00a0expenditure\u00a0by\u00a0the cell \u2014 and\u00a0[pb_glossary id=\"5689\"]active transport[\/pb_glossary]\u00a0\u2014 which requires\u00a0[pb_glossary id=\"5753\"]energy[\/pb_glossary]\u00a0from the cell.\r\n<div>\r\n<h1>Transport Without\u00a0Energy\u00a0Expenditure\u00a0By The Cell<\/h1>\r\n<\/div>\r\n<strong>[pb_glossary id=\"5705\"]Passive transport[\/pb_glossary]<\/strong>\u00a0occurs when substances cross the [pb_glossary id=\"5489\"]plasma membrane[\/pb_glossary] without any input of energy from the cell. No energy is\u00a0required\u00a0because the substances are moving from an area where they have a higher\u00a0concentration\u00a0to an area where they have a lower concentration.\u00a0<strong>[pb_glossary id=\"5593\"]Concentration[\/pb_glossary]<\/strong>\u00a0refers to the number of particles of a substance per unit of volume. The more particles of a substance in a given volume, the higher the\u00a0concentration. A substance\u00a0<em>always<\/em>\u00a0moves from an area where it is more concentrated to an area where it is less concentrated.\r\n\r\nThere are several different types of passive transport, including simple\u00a0[pb_glossary id=\"1655\"]diffusion[\/pb_glossary],\u00a0[pb_glossary id=\"5663\"]osmosis[\/pb_glossary], and [pb_glossary id=\"5703\"]facilitated diffusion[\/pb_glossary]. Each type is described below.\r\n<h2>Simple\u00a0Diffusion<\/h2>\r\n<strong>[pb_glossary id=\"1655\"]Diffusion[\/pb_glossary]<\/strong> is the movement of a substance due to a difference in concentration. It happens without any help from other molecules. The substance simply moves from the area where it is more concentrated to the area where it is less concentrated. Picture someone spraying perfume in the corner of a room.\u00a0 Do the perfume molecules stay in the corner?\u00a0 No, they spread out, or diffuse throughout the room until they are evenly spread out.\u00a0 Figure 4.7.2 shows how diffusion works across a [pb_glossary id=\"5621\"]cell membrane[\/pb_glossary]. Substances that can squeeze between the lipid molecules in the plasma membrane by simple diffusion are generally very small, hydrophobic molecules, such as molecules of oxygen and carbon dioxide.\r\n\r\n[caption id=\"attachment_1659\" align=\"aligncenter\" width=\"759\"]<img class=\" wp-image-1659\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Diffusion-2.png\" alt=\"Image shows a diagram of the process of diffusion over time. The diagram shows three stages in time. In the first, all solutes are on one side of the plasma membrane. In the second stage, some of the solute has diffused through the plasma membrane, but there is still more on the first side. In the last stage, the molecules have diffused completely so that there are equal amounts on either side of the plasma membrane.\" width=\"759\" height=\"483\" \/> Figure 4.7.2 Molecules diffuse across a membrane from an area of higher concentration to an area of lower concentration until the concentration is the same on both sides of the membrane.[\/caption]\r\n\r\n<div>\r\n\r\n[caption id=\"attachment_1660\" align=\"alignright\" width=\"487\"]<img class=\" wp-image-1660\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Osmosis-2.jpg\" alt=\"Diagram shows a time lapse of the contents of a beaker. The beaker's contents are separated into two with a semi-permeable membrane. One the left side of the beaker, there is a solution with low amount of solutes. One the right side of the beaker, there is a solution with a high amount of solutes. The second half of the diagram shows the same beaker after time has passed. Since the solutes could not move through the semi-permeable membrane, the water (the solvent) has moved to the right side, leaving less solution on the left side, but equalizing the concentrations of the two sides.\" width=\"487\" height=\"233\" \/> Figure 4.7.3 Osmosis is a type of diffusion in which only water can cross the plasma membrane.[\/caption]\r\n<h2>Osmosis<\/h2>\r\n<\/div>\r\n<strong>[pb_glossary id=\"5663\"]Osmosis[\/pb_glossary]<\/strong>\u00a0is a special type of [pb_glossary id=\"1655\"]diffusion[\/pb_glossary] \u2014 the diffusion of\u00a0<em>water<\/em> molecules across a membrane. Like other molecules, water moves from an area of higher concentration to an area of lower concentration. Water moves in or out of a cell until its concentration is the same on both sides of the plasma membrane.\u00a0 In Figure 4.7.3, the dotted red line shows a semi-permeable membrane.\u00a0 In the first beaker, there is an uneven concentration of solutes on either side of the membrane, but the solute cannot cross \u2014 diffusion of the solute can't occur.\u00a0 In this case, water will move to even out the concentration as has happened on the beaker on the right side.\u00a0 The water levels are uneven, but the process of osmosis has evened out the concentration gradient.\r\n<h2>Facilitated Diffusion<\/h2>\r\nWater\u00a0and many other substances cannot simply diffuse across a membrane. [pb_glossary id=\"5677\"]Hydrophilic[\/pb_glossary] molecules, charged ions, and relatively large molecules (such as glucose) all need help with [pb_glossary id=\"1655\"]diffusion[\/pb_glossary].\u00a0This\u00a0help comes from special\u00a0proteins\u00a0in the membrane known as\u00a0[pb_glossary id=\"5493\"]<strong>transport<\/strong><strong>\u00a0<\/strong><strong>proteins<\/strong>[\/pb_glossary]. Diffusion with the help of transport\u00a0proteins\u00a0is called\u00a0<strong>[pb_glossary id=\"5703\"]facilitated diffusion[\/pb_glossary]<\/strong>. There are several types of transport proteins, including channel proteins and carrier proteins. Both are shown in Figure 4.7.4.\r\n<ul>\r\n \t<li><strong>Channel proteins<\/strong>\u00a0form pores (or tiny holes) in the membrane. This allows\u00a0water\u00a0molecules and small ions to pass through the membrane without coming into contact with the hydrophobic tails of the\u00a0lipid molecules in the interior of the membrane.<\/li>\r\n \t<li><strong>Carrier proteins<\/strong>\u00a0bind with specific ions or molecules. In doing so, they change shape. As carrier proteins change shape, they carry the ions or molecules across the membrane.<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_1662\" align=\"aligncenter\" width=\"685\"]<img class=\" wp-image-1662\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/facilitated_diffusion_in_cell_membrane-en.svg_-2.png\" alt=\"Image shows a diagram of a cell membrane with different types of transport proteins imbedded. There are protein channels which allow small hydrophilic ions or molecules through, and there are carrier proteins which bind with a particular ion of molecule, and then shape in such a way that it moves the ion or molecule across the plasma membrane,\" width=\"685\" height=\"299\" \/> Figure 4.7.4 Facilitated diffusion across a cell membrane. Channel proteins and carrier proteins help substances diffuse across a cell membrane. In this diagram, the channel and carrier proteins are helping substances move into the cell (from the extracellular space to the intracellular space).[\/caption]\r\n\r\n<div>\r\n<h1>Transport and\u00a0Homeostasis<\/h1>\r\n<\/div>\r\nFor a [pb_glossary id=\"5665\"]cell[\/pb_glossary] to function normally,\u00a0the inside of it must maintain a stable state. The concentrations of salts,\u00a0nutrients, and other substances must be kept within certain ranges. The state in which stable conditions are maintained inside a cell (or an entire organism) is called\u00a0<strong>[pb_glossary id=\"5761\"]homeostasis[\/pb_glossary]<\/strong>. Homeostasis requires constant adjustments, because conditions are always changing both inside and outside the cell. The transport of substances into and out of\u00a0cells\u00a0as described in this\u00a0section\u00a0plays an important role in homeostasis. By allowing the movement of substances into and out of\u00a0cells, transport keeps conditions within normal ranges inside the cells and throughout the organism as a whole.\r\n\r\nWatch this video \"Cell Transport,\" by the Amoeba Sisters:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=Ptmlvtei8hw\r\n<p style=\"text-align: center;\">Cell Transport with the Amoeba Sisters, 2016.<\/p>\r\n\r\n<div class=\"textbox textbox--key-takeaways\"><header class=\"textbox__header\">\r\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">4.7 Summary<\/span><\/h1>\r\n&nbsp;\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<ul>\r\n \t<li>Controlling the movement of\u00a0things in and out of the cell is an important\u00a0function\u00a0of the [pb_glossary id=\"5489\"]plasma membrane[\/pb_glossary]. There are two basic ways that substances can cross the plasma membrane: [pb_glossary id=\"5705\"]passive transport[\/pb_glossary] \u2014 which requires no energy expenditure by the cell \u2014 and\u00a0[pb_glossary id=\"5689\"]active transport[\/pb_glossary]\u00a0\u2014 which requires energy.<\/li>\r\n \t<li>No energy is needed from the cell for passive transport because it occurs when substances move naturally from an area of higher concentration to an area of lower concentration.<\/li>\r\n \t<li>Simple [pb_glossary id=\"1655\"]diffusion[\/pb_glossary] is the movement of a substance due to differences in concentration. It happens without any help from other molecules. This is how very small, [pb_glossary id=\"5675\"]hydrophobic[\/pb_glossary] molecules (such as oxygen and carbon dioxide) enter and leave the cell.<\/li>\r\n \t<li>[pb_glossary id=\"5663\"]Osmosis[\/pb_glossary] is the diffusion of water molecules across a membrane. Water moves in or out of a cell by osmosis until its concentration is the same on both sides of the plasma membrane.<\/li>\r\n \t<li>[pb_glossary id=\"5703\"]Facilitated diffusion[\/pb_glossary] is the movement of a substance across a membrane due to differences in concentration, but it only occurs with the help of transport proteins (such as channel proteins or carrier proteins) in the membrane. This is how large or [pb_glossary id=\"5677\"]hydrophilic[\/pb_glossary] molecules and charged ions enter and leave the cell.<\/li>\r\n \t<li>Processes of passive transport play important roles in [pb_glossary id=\"5761\"]homeostasis[\/pb_glossary]. By\u00a0allowing the movement of\u00a0substances into and out of the cell, they keep conditions within normal ranges inside the cell and the organism as a whole.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\r\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">4.7 Review Questions<\/span><\/h1>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<ol>\r\n \t<li>What is the main difference between passive and active transport?<\/li>\r\n \t<li>Summarize three different ways that passive transport can occur. Give an example of a substance that is transported in each way.<\/li>\r\n \t<li>Explain how transport across the plasma membrane is related to homeostasis of the cell.<\/li>\r\n \t<li>In general, why can\u00a0only very small, hydrophobic molecules cross the\u00a0cell membrane\u00a0by simple diffusion?<\/li>\r\n \t<li>Explain how facilitated diffusion assists with osmosis in\u00a0cells. Define osmosis and facilitated diffusion in your answer.<\/li>\r\n \t<li>Imagine a hypothetical cell with a higher concentration of glucose inside the cell than outside. Answer the following questions about this cell, assuming all transport across the membrane is passive, not active.\r\n<ul>\r\n \t<li>Can the glucose simply diffuse across the\u00a0cell membrane? Why or why not?<\/li>\r\n \t<li>Assuming that there are glucose transport proteins in the cell membrane, which way would glucose flow \u2014 into or out of the cell? Explain your answer.<\/li>\r\n \t<li>If the concentration of glucose was equal inside and outside of the cell, do you think there would be a net flow of glucose across the cell membrane in one direction or the other? Explain your answer.<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>What are the similarities and differences between channel proteins and carrier proteins?<\/li>\r\n \t<li>[h5p id=\"474\"]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">4.7 Explore More<\/span><\/h1>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=L-osEc07vMs&amp;t=31s\r\n<p style=\"text-align: center;\">Osmosis and Water Potential, Amoeba Sisters, 2018.<\/p>\r\nhttps:\/\/www.youtube.com\/watch?v=AcrqIxt8am8\r\n<p style=\"text-align: center;\">Structure Of The Cell Membrane - Active and Passive Transport, Professor Dave Explains, 2016.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<h2>Attributions<\/h2>\r\n<strong>Figure 4.7.1<\/strong>\r\n\r\n<a href=\"https:\/\/unsplash.com\/photos\/EbivdbB83Y0\" rel=\"cc:attributionURL\">Windows\/ The Oyster Suite in Eureka, CA<\/a> by <a href=\"https:\/\/unsplash.com\/@drewcoffman\">Drew Coffman<\/a> on <a href=\"https:\/\/unsplash.com\/\">Unsplash<\/a> is used under the <a class=\"ICezk _2GAZm _2WvKc\" href=\"https:\/\/unsplash.com\/license\">Unsplash License<\/a> https:\/\/unsplash.com\/license).\r\n\r\n<strong>Figure 4.7.2<\/strong>\r\n\r\n<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Scheme_simple_diffusion_in_cell_membrane-en.svg\" rel=\"cc:attributionURL\">Diffusion\/ Scheme simple diffusion in cell membrane <\/a>\u00a0by Mariana Ruiz Villarreal [<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LadyofHats\">LadyofHats]<\/a> is released into the <a class=\"extiw\" title=\"w:en:public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:public_domain\">public domain <\/a>(https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\n<strong>Figure 4.7.3<\/strong>\r\n\r\n<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:0307_Osmosis_cleaned.jpg\" rel=\"cc:attributionURL\">Osmosis<\/a> by <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/3-1-the-cell-membrane\">OpenStax<\/a> on Wikimedia Commons is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\">CC BY 3.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/3.0) license.\r\n\r\n<strong>Figure 4.7.4<\/strong>\r\n\r\n<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Scheme_facilitated_diffusion_in_cell_membrane-en.svg\" rel=\"cc:attributionURL\">Scheme facilitated diffusion in cell membrane<\/a> by Mariana Ruiz Villarreal [<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LadyofHats\">LadyofHats]<\/a> is released into the <a class=\"extiw\" title=\"w:en:public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:public_domain\">public domain <\/a>(https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n<h2>References<\/h2>\r\n<p class=\"hanging-indent\">Amoeba Sisters. (2016, June 24). Cell transport. YouTube. https:\/\/www.youtube.com\/watch?v=Ptmlvtei8hw&amp;feature=youtu.be<\/p>\r\n<p class=\"hanging-indent\">Amoeba Sisters. (2018, June 27). Osmosis and water potential. YouTube.\u00a0 https:\/\/www.youtube.com\/watch?v=L-osEc07vMs&amp;feature=youtu.be<\/p>\r\n<p class=\"hanging-indent\">Betts, J. G., Young, K.A., Wise, J.A., Johnson, E., Poe, B., Kruse, D.H., Korol, O., Johnson, J.E., Womble, M., DeSaix, P. (2013, April 25). Figure 3.7 Osmosis [digital image]. In <em>Anatomy and Physiology<\/em>. OpenStax. https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/3-1-the-cell-membrane<\/p>\r\n<p class=\"hanging-indent\">Professor Dave Explains. (2016, September 5). Structure of the cell membrane - Active and passive transport. https:\/\/www.youtube.com\/watch?v=AcrqIxt8am8&amp;feature=youtu.be<\/p>\r\n&nbsp;\r\n\r\n&nbsp;","rendered":"<p>&nbsp;<\/p>\n<div>\n<figure id=\"attachment_1650\" aria-describedby=\"caption-attachment-1650\" style=\"width: 403px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-1650\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/windows-2-scaled.jpg\" alt=\"Image shows a photo of a living room with large windows. There is a leather armchair, coffee table, lamp and books. The walls have wood panelling.\" width=\"403\" height=\"504\" \/><figcaption id=\"caption-attachment-1650\" class=\"wp-caption-text\">Figure 4.7.1 Just as windows in a house let light in, the cell membrane lets certain substances into and out of the cell.<\/figcaption><\/figure>\n<h1>Letting in the Light<\/h1>\n<\/div>\n<p>Look at the big windows in this house (Figure 4.7.1). Imagine all the light they must let in on a sunny day. Now imagine living in a house that has walls without any windows or doors. Nothing could enter or leave. Or imagine living in a house with holes in the walls instead of windows and doors. Things could enter or leave, but you couldn\u2019t control what came in or went out. Only when a house has walls with windows and doors that can be opened or closed, can you control what enters or leaves. Windows and doors allow you to let in light and the family dog and keep out rain and bugs, for example.<\/p>\n<div>\n<h1>Transport Across Membranes<\/h1>\n<\/div>\n<p>If a cell were a house, the\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5489\">plasma membrane<\/a>\u00a0would be walls with windows and doors. Moving things in and out of the cell is an important\u00a0function\u00a0of the\u00a0plasma membrane. It controls everything that enters and leaves the cell. There are two basic ways that substances can cross the plasma membrane: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5705\">passive transport<\/a> \u2014 which requires no\u00a0energy\u00a0expenditure\u00a0by\u00a0the cell \u2014 and\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5689\">active transport<\/a>\u00a0\u2014 which requires\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5753\">energy<\/a>\u00a0from the cell.<\/p>\n<div>\n<h1>Transport Without\u00a0Energy\u00a0Expenditure\u00a0By The Cell<\/h1>\n<\/div>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5705\">Passive transport<\/a><\/strong>\u00a0occurs when substances cross the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5489\">plasma membrane<\/a> without any input of energy from the cell. No energy is\u00a0required\u00a0because the substances are moving from an area where they have a higher\u00a0concentration\u00a0to an area where they have a lower concentration.\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5593\">Concentration<\/a><\/strong>\u00a0refers to the number of particles of a substance per unit of volume. The more particles of a substance in a given volume, the higher the\u00a0concentration. A substance\u00a0<em>always<\/em>\u00a0moves from an area where it is more concentrated to an area where it is less concentrated.<\/p>\n<p>There are several different types of passive transport, including simple\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_1655\">diffusion<\/a>,\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5663\">osmosis<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5703\">facilitated diffusion<\/a>. Each type is described below.<\/p>\n<h2>Simple\u00a0Diffusion<\/h2>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_1655\">Diffusion<\/a><\/strong> is the movement of a substance due to a difference in concentration. It happens without any help from other molecules. The substance simply moves from the area where it is more concentrated to the area where it is less concentrated. Picture someone spraying perfume in the corner of a room.\u00a0 Do the perfume molecules stay in the corner?\u00a0 No, they spread out, or diffuse throughout the room until they are evenly spread out.\u00a0 Figure 4.7.2 shows how diffusion works across a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5621\">cell membrane<\/a>. Substances that can squeeze between the lipid molecules in the plasma membrane by simple diffusion are generally very small, hydrophobic molecules, such as molecules of oxygen and carbon dioxide.<\/p>\n<figure id=\"attachment_1659\" aria-describedby=\"caption-attachment-1659\" style=\"width: 759px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-1659\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Diffusion-2.png\" alt=\"Image shows a diagram of the process of diffusion over time. The diagram shows three stages in time. In the first, all solutes are on one side of the plasma membrane. In the second stage, some of the solute has diffused through the plasma membrane, but there is still more on the first side. In the last stage, the molecules have diffused completely so that there are equal amounts on either side of the plasma membrane.\" width=\"759\" height=\"483\" \/><figcaption id=\"caption-attachment-1659\" class=\"wp-caption-text\">Figure 4.7.2 Molecules diffuse across a membrane from an area of higher concentration to an area of lower concentration until the concentration is the same on both sides of the membrane.<\/figcaption><\/figure>\n<div>\n<figure id=\"attachment_1660\" aria-describedby=\"caption-attachment-1660\" style=\"width: 487px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-1660\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Osmosis-2.jpg\" alt=\"Diagram shows a time lapse of the contents of a beaker. The beaker's contents are separated into two with a semi-permeable membrane. One the left side of the beaker, there is a solution with low amount of solutes. One the right side of the beaker, there is a solution with a high amount of solutes. The second half of the diagram shows the same beaker after time has passed. Since the solutes could not move through the semi-permeable membrane, the water (the solvent) has moved to the right side, leaving less solution on the left side, but equalizing the concentrations of the two sides.\" width=\"487\" height=\"233\" \/><figcaption id=\"caption-attachment-1660\" class=\"wp-caption-text\">Figure 4.7.3 Osmosis is a type of diffusion in which only water can cross the plasma membrane.<\/figcaption><\/figure>\n<h2>Osmosis<\/h2>\n<\/div>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5663\">Osmosis<\/a><\/strong>\u00a0is a special type of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_1655\">diffusion<\/a> \u2014 the diffusion of\u00a0<em>water<\/em> molecules across a membrane. Like other molecules, water moves from an area of higher concentration to an area of lower concentration. Water moves in or out of a cell until its concentration is the same on both sides of the plasma membrane.\u00a0 In Figure 4.7.3, the dotted red line shows a semi-permeable membrane.\u00a0 In the first beaker, there is an uneven concentration of solutes on either side of the membrane, but the solute cannot cross \u2014 diffusion of the solute can&#8217;t occur.\u00a0 In this case, water will move to even out the concentration as has happened on the beaker on the right side.\u00a0 The water levels are uneven, but the process of osmosis has evened out the concentration gradient.<\/p>\n<h2>Facilitated Diffusion<\/h2>\n<p>Water\u00a0and many other substances cannot simply diffuse across a membrane. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5677\">Hydrophilic<\/a> molecules, charged ions, and relatively large molecules (such as glucose) all need help with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_1655\">diffusion<\/a>.\u00a0This\u00a0help comes from special\u00a0proteins\u00a0in the membrane known as\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5493\"><strong>transport<\/strong><strong>\u00a0<\/strong><strong>proteins<\/strong><\/a>. Diffusion with the help of transport\u00a0proteins\u00a0is called\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5703\">facilitated diffusion<\/a><\/strong>. There are several types of transport proteins, including channel proteins and carrier proteins. Both are shown in Figure 4.7.4.<\/p>\n<ul>\n<li><strong>Channel proteins<\/strong>\u00a0form pores (or tiny holes) in the membrane. This allows\u00a0water\u00a0molecules and small ions to pass through the membrane without coming into contact with the hydrophobic tails of the\u00a0lipid molecules in the interior of the membrane.<\/li>\n<li><strong>Carrier proteins<\/strong>\u00a0bind with specific ions or molecules. In doing so, they change shape. As carrier proteins change shape, they carry the ions or molecules across the membrane.<\/li>\n<\/ul>\n<figure id=\"attachment_1662\" aria-describedby=\"caption-attachment-1662\" style=\"width: 685px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-1662\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/facilitated_diffusion_in_cell_membrane-en.svg_-2.png\" alt=\"Image shows a diagram of a cell membrane with different types of transport proteins imbedded. There are protein channels which allow small hydrophilic ions or molecules through, and there are carrier proteins which bind with a particular ion of molecule, and then shape in such a way that it moves the ion or molecule across the plasma membrane,\" width=\"685\" height=\"299\" \/><figcaption id=\"caption-attachment-1662\" class=\"wp-caption-text\">Figure 4.7.4 Facilitated diffusion across a cell membrane. Channel proteins and carrier proteins help substances diffuse across a cell membrane. In this diagram, the channel and carrier proteins are helping substances move into the cell (from the extracellular space to the intracellular space).<\/figcaption><\/figure>\n<div>\n<h1>Transport and\u00a0Homeostasis<\/h1>\n<\/div>\n<p>For a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5665\">cell<\/a> to function normally,\u00a0the inside of it must maintain a stable state. The concentrations of salts,\u00a0nutrients, and other substances must be kept within certain ranges. The state in which stable conditions are maintained inside a cell (or an entire organism) is called\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5761\">homeostasis<\/a><\/strong>. Homeostasis requires constant adjustments, because conditions are always changing both inside and outside the cell. The transport of substances into and out of\u00a0cells\u00a0as described in this\u00a0section\u00a0plays an important role in homeostasis. By allowing the movement of substances into and out of\u00a0cells, transport keeps conditions within normal ranges inside the cells and throughout the organism as a whole.<\/p>\n<p>Watch this video &#8220;Cell Transport,&#8221; by the Amoeba Sisters:<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Cell Transport\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/Ptmlvtei8hw?feature=oembed&#38;rel=0&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p style=\"text-align: center;\">Cell Transport with the Amoeba Sisters, 2016.<\/p>\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">4.7 Summary<\/span><\/h1>\n<p>&nbsp;<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Controlling the movement of\u00a0things in and out of the cell is an important\u00a0function\u00a0of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5489\">plasma membrane<\/a>. There are two basic ways that substances can cross the plasma membrane: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5705\">passive transport<\/a> \u2014 which requires no energy expenditure by the cell \u2014 and\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5689\">active transport<\/a>\u00a0\u2014 which requires energy.<\/li>\n<li>No energy is needed from the cell for passive transport because it occurs when substances move naturally from an area of higher concentration to an area of lower concentration.<\/li>\n<li>Simple <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_1655\">diffusion<\/a> is the movement of a substance due to differences in concentration. It happens without any help from other molecules. This is how very small, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5675\">hydrophobic<\/a> molecules (such as oxygen and carbon dioxide) enter and leave the cell.<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5663\">Osmosis<\/a> is the diffusion of water molecules across a membrane. Water moves in or out of a cell by osmosis until its concentration is the same on both sides of the plasma membrane.<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5703\">Facilitated diffusion<\/a> is the movement of a substance across a membrane due to differences in concentration, but it only occurs with the help of transport proteins (such as channel proteins or carrier proteins) in the membrane. This is how large or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5677\">hydrophilic<\/a> molecules and charged ions enter and leave the cell.<\/li>\n<li>Processes of passive transport play important roles in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4446_5761\">homeostasis<\/a>. By\u00a0allowing the movement of\u00a0substances into and out of the cell, they keep conditions within normal ranges inside the cell and the organism as a whole.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">4.7 Review Questions<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ol>\n<li>What is the main difference between passive and active transport?<\/li>\n<li>Summarize three different ways that passive transport can occur. Give an example of a substance that is transported in each way.<\/li>\n<li>Explain how transport across the plasma membrane is related to homeostasis of the cell.<\/li>\n<li>In general, why can\u00a0only very small, hydrophobic molecules cross the\u00a0cell membrane\u00a0by simple diffusion?<\/li>\n<li>Explain how facilitated diffusion assists with osmosis in\u00a0cells. Define osmosis and facilitated diffusion in your answer.<\/li>\n<li>Imagine a hypothetical cell with a higher concentration of glucose inside the cell than outside. Answer the following questions about this cell, assuming all transport across the membrane is passive, not active.\n<ul>\n<li>Can the glucose simply diffuse across the\u00a0cell membrane? Why or why not?<\/li>\n<li>Assuming that there are glucose transport proteins in the cell membrane, which way would glucose flow \u2014 into or out of the cell? Explain your answer.<\/li>\n<li>If the concentration of glucose was equal inside and outside of the cell, do you think there would be a net flow of glucose across the cell membrane in one direction or the other? Explain your answer.<\/li>\n<\/ul>\n<\/li>\n<li>What are the similarities and differences between channel proteins and carrier proteins?<\/li>\n<li>\n<div id=\"h5p-474\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-474\" class=\"h5p-iframe\" data-content-id=\"474\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Passive Transport\"><\/iframe><\/div>\n<\/div>\n<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">4.7 Explore More<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"Osmosis and Water Potential (Updated)\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/L-osEc07vMs?start=31&#38;feature=oembed\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p style=\"text-align: center;\">Osmosis and Water Potential, Amoeba Sisters, 2018.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-3\" title=\"Structure Of The Cell Membrane: Active and Passive Transport\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/AcrqIxt8am8?feature=oembed&#38;rel=0&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p style=\"text-align: center;\">Structure Of The Cell Membrane &#8211; Active and Passive Transport, Professor Dave Explains, 2016.<\/p>\n<\/div>\n<\/div>\n<h2>Attributions<\/h2>\n<p><strong>Figure 4.7.1<\/strong><\/p>\n<p><a href=\"https:\/\/unsplash.com\/photos\/EbivdbB83Y0\" rel=\"cc:attributionURL\">Windows\/ The Oyster Suite in Eureka, CA<\/a> by <a href=\"https:\/\/unsplash.com\/@drewcoffman\">Drew Coffman<\/a> on <a href=\"https:\/\/unsplash.com\/\">Unsplash<\/a> is used under the <a class=\"ICezk _2GAZm _2WvKc\" href=\"https:\/\/unsplash.com\/license\">Unsplash License<\/a> https:\/\/unsplash.com\/license).<\/p>\n<p><strong>Figure 4.7.2<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Scheme_simple_diffusion_in_cell_membrane-en.svg\" rel=\"cc:attributionURL\">Diffusion\/ Scheme simple diffusion in cell membrane <\/a>\u00a0by Mariana Ruiz Villarreal [<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LadyofHats\">LadyofHats]<\/a> is released into the <a class=\"extiw\" title=\"w:en:public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:public_domain\">public domain <\/a>(https:\/\/en.wikipedia.org\/wiki\/Public_domain).<\/p>\n<p><strong>Figure 4.7.3<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:0307_Osmosis_cleaned.jpg\" rel=\"cc:attributionURL\">Osmosis<\/a> by <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/3-1-the-cell-membrane\">OpenStax<\/a> on Wikimedia Commons is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\">CC BY 3.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/3.0) license.<\/p>\n<p><strong>Figure 4.7.4<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Scheme_facilitated_diffusion_in_cell_membrane-en.svg\" rel=\"cc:attributionURL\">Scheme facilitated diffusion in cell membrane<\/a> by Mariana Ruiz Villarreal [<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LadyofHats\">LadyofHats]<\/a> is released into the <a class=\"extiw\" title=\"w:en:public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:public_domain\">public domain <\/a>(https:\/\/en.wikipedia.org\/wiki\/Public_domain).<\/p>\n<h2>References<\/h2>\n<p class=\"hanging-indent\">Amoeba Sisters. (2016, June 24). Cell transport. YouTube. https:\/\/www.youtube.com\/watch?v=Ptmlvtei8hw&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">Amoeba Sisters. (2018, June 27). Osmosis and water potential. YouTube.\u00a0 https:\/\/www.youtube.com\/watch?v=L-osEc07vMs&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">Betts, J. G., Young, K.A., Wise, J.A., Johnson, E., Poe, B., Kruse, D.H., Korol, O., Johnson, J.E., Womble, M., DeSaix, P. (2013, April 25). Figure 3.7 Osmosis [digital image]. In <em>Anatomy and Physiology<\/em>. OpenStax. https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/3-1-the-cell-membrane<\/p>\n<p class=\"hanging-indent\">Professor Dave Explains. (2016, September 5). Structure of the cell membrane &#8211; Active and passive transport. https:\/\/www.youtube.com\/watch?v=AcrqIxt8am8&amp;feature=youtu.be<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_4446_5489\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5489\"><div tabindex=\"-1\"><p>A semi-permeable lipid bilayer that separates the interior of all cells from their surroundings.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5705\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5705\"><div tabindex=\"-1\"><p>a type of movement of substances across the cell membrane which does not require energy because the substances are moving with the concentration gradient (from high to low concentration).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5689\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5689\"><div tabindex=\"-1\"><p>The movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5753\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5753\"><div tabindex=\"-1\"><p>The ability to do work.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5593\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5593\"><div tabindex=\"-1\"><p>The amount of particles of a substance in a given amount of solution.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_1655\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_1655\"><div tabindex=\"-1\"><p>Image shows the pathway of events in the activation of T Cells.   This includes: 1) T Cells are activated when they encounter a foreign antigen on an MHC from an antigen-presenting cell.  2) Cytokines help the T cell to mature. Some T Cells become helper T cells and continue to produce cytokines.  3) Some T Cells become Killer T Cells and search out and destroy infected or cancerous cells.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5663\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5663\"><div tabindex=\"-1\"><p>The movement of water or other solvent through a plasma membrane from a region of low solute concentration to a region of high solute concentration.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5703\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5703\"><div tabindex=\"-1\"><p>The passive movement of molecules across the cell membrane with the aid of a membrane protein.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5621\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5621\"><div tabindex=\"-1\"><p>The semipermeable membrane surrounding the cytoplasm of a cell.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5677\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5677\"><div tabindex=\"-1\"><p>Attracted to water.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5493\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5493\"><div tabindex=\"-1\"><p>A membrane protein involved in the movement of ions, small molecules, or macromolecules, such as another protein, across a biological membrane.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5665\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5665\"><div tabindex=\"-1\"><p>The smallest unit of life, consisting of at least a membrane, cytoplasm, and genetic material.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5761\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5761\"><div tabindex=\"-1\"><p>The ability of an organism to maintain constant internal conditions despite external changes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4446_5675\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4446_5675\"><div tabindex=\"-1\"><p>Repelled by water.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":32,"menu_order":7,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":"cc-by-nc"},"chapter-type":[48],"contributor":[],"license":[55],"class_list":["post-4446","chapter","type-chapter","status-publish","hentry","chapter-type-numberless","license-cc-by-nc"],"part":4404,"_links":{"self":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters\/4446","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/users\/32"}],"version-history":[{"count":4,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters\/4446\/revisions"}],"predecessor-version":[{"id":6384,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters\/4446\/revisions\/6384"}],"part":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/parts\/4404"}],"metadata":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters\/4446\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/media?parent=4446"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapter-type?post=4446"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/contributor?post=4446"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/license?post=4446"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}