{"id":1260,"date":"2020-06-19T11:31:25","date_gmt":"2020-06-19T15:31:25","guid":{"rendered":"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/?post_type=chapter&#038;p=1260"},"modified":"2020-08-17T19:59:09","modified_gmt":"2020-08-17T23:59:09","slug":"the-anatomy-of-pleasure-and-reproduction","status":"publish","type":"chapter","link":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/chapter\/the-anatomy-of-pleasure-and-reproduction\/","title":{"raw":"The Anatomy of Pleasure and Reproduction","rendered":"The Anatomy of Pleasure and Reproduction"},"content":{"raw":"<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.85pt\">Sexual anatomy is typically discussed only in terms of reproduction (see e.g., <a href=\"#_bookmark49\">King, 2015<\/a>). However, reproduction is only a (small) part of what drives us sexually (<a href=\"#_bookmark163\">Lucas &amp; Fox, 2018<\/a>). Full discussions of sexual anatomy also include the concept of pleasure. Thus, we will explore the sexual anatomies of females (see Figures 1a and 1b) and males (see Figure 2) in terms of their capabilities for both reproduction and pleasure.<\/p>\r\n\r\n<h2>Female Anatomy<\/h2>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.85pt\">Many people find female sexual anatomy curious, confusing, and mysterious. This may be because so much of it is internal (inside the body), or because\u2014historically\u2014women have been expected to be modest and secretive regarding their bodies.<\/p>\r\n&nbsp;\r\n<p class=\"import-Normal\" style=\"margin-left: 48.75pt\"><img src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image2-6.jpeg\" alt=\"image\" width=\"510.299737532808px\" height=\"299.6px\" class=\"aligncenter\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 48.75pt\"><a id=\"_bookmark142\"><\/a>Figure 1a: The Female\u2019s External Sex Organs. [Image: Open Stax College, https:\/\/goo.gl\/Hj59kX, CC BY 3.0,\u00a0https:\/\/goo.gl\/Dmg4Uu]<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.85pt\">Perhaps the most visible structure of female sexual anatomy is the vulva. The primary functions of the vulva are pleasure and protection. The <a href=\"#_bookmark160\"><strong>vulva<\/strong> <\/a>is composed of the female\u2019s <em>externalsex<\/em> <em>organs<\/em> (see Figure 1a). It includes many parts:<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;text-indent: 0pt\">the <a href=\"#_bookmark157\"><strong>labia<\/strong> <strong>majora<\/strong><\/a>\u2014the \u201clarge lips\u201d enclosing and protecting the female\u2019s internal sex organs;<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.9pt;text-indent: 0pt\">the <a href=\"#_bookmark157\"><strong>labia<\/strong> <strong>minora<\/strong><\/a>\u2014the\u201csmall lips\u201d surrounding and defining the openings of the vagina and urethra;\u00a0the minor and major <a href=\"#_bookmark160\"><strong>vestibular<\/strong> <strong>glands<\/strong> <strong>(VGs)<\/strong><\/a>.<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.85pt\">The minor VGs\u2014also called <strong>Skene's<\/strong> <strong>glands<\/strong> (not pictured), are on the wall of the vagina and are associated with female ejaculation, and mythologically associated with the G-Spot (<a href=\"#_bookmark49\">Kilchevsky<\/a><a href=\"#_bookmark49\"> <\/a><a href=\"#_bookmark49\">et<\/a><a href=\"#_bookmark49\"> <\/a><a href=\"#_bookmark49\">al.,<\/a><a href=\"#_bookmark49\"> <\/a><a href=\"#_bookmark49\">2012<\/a>; <a href=\"#_bookmark166\">Wickman, 2017<\/a>). The major VGs\u2014also called Bartholin's glands\u2014are located just to the left and right of the vagina and produce lubrication to aid in sexual intercourse. Most females\u2014especially postmenopausal females\u2014at some time in their lives report inadequate lubrication, which, in turn, leads to discomfort or pain during sexual intercourse (<a href=\"#_bookmark164\">Nappi<\/a><a href=\"#_bookmark164\"> <\/a><a href=\"#_bookmark164\">&amp;<\/a><a href=\"#_bookmark164\"> <\/a><a href=\"#_bookmark164\">Lachowsky<\/a><a href=\"#_bookmark164\">,<\/a><a href=\"#_bookmark164\"> <\/a><a href=\"#_bookmark164\">2009<\/a>). Extending foreplay and using commercial water-, silicone-, or oil-based personal lubricants are simple solutions to this common problem.<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.1pt\">The clitoris and vagina are considered parts of the vulva as well as internal sex organs (see Figure 1b). They are the most talked about organs in relation to their capacities for female pleasure\u00a0(e.g., <a href=\"#_bookmark49\">Jannini et al., 2012<\/a>). Most of the <a href=\"#_bookmark156\"><strong>clitoris<\/strong><\/a>, which is composed of 18 parts with an average overall excited length of about four inches, cannot be seen (<a href=\"#_bookmark6\">Ginger &amp; Yang, 2011<\/a>; <a href=\"#_bookmark164\">O'Connell et al., 2005<\/a>). The visible parts\u2014the glans and prepuce\u2014are located above the urethra and join the labia minora at its pinnacle. The clitoris is highly sensitive, composed of more than 8,000 sensory-nerve endings, and is associated with initiating orgasms; 90% of females can orgasm by clitoral stimulation alone (<a href=\"#_bookmark164\">O'Connell et al., 2005<\/a>; <a href=\"#_bookmark165\">Thompson, 2016<\/a>).<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.1pt\">The <a href=\"#_bookmark160\"><strong>vagina<\/strong><\/a>, also called the \u201cbirth canal,\u201d is a muscular canal that spans from the cervix to the introitus. It has an average overall excited length of about four and a half inches (<a href=\"#_bookmark164\">Masters &amp;<\/a> <a href=\"#_bookmark164\">Johnson, 1966<\/a>) and has two parts: First, there is the inner two-thirds (posterior wall)\u2014formed during the first trimester of pregnancy. Second, there is the outer one-third of the vagina (anterior wall). It is formed during the second trimester of pregnancy and is generally more sensitive than the inner portion, but dramatically less sensitive than the clitoris (<a href=\"#_bookmark48\">Hines, 2001<\/a>). Only between 10% and 30% of females achieve orgasms by vaginal stimulation alone (<a href=\"#_bookmark165\">Thompson, 2016<\/a>). At each end of the vagina are the <a href=\"#_bookmark156\"><strong>cervix<\/strong> <\/a>(the lower portion of the uterus) and the <a href=\"#_bookmark157\"><strong>introitus<\/strong> <\/a>(the vaginal opening to the outside of the body). The vagina acts as a transport mechanism for sperm cells coming in, and menstrual fluid and babies going out. A healthy vagina has a pH level of about four, which is acidic. When the pH level changes, often due to normal circumstances (e.g., menstruation, using tampons, sexual intercourse), it facilitates the reproduction of microorganisms that often cause vaginal odor and pain (<a href=\"#_bookmark15\">Anderson, Klink <\/a><a href=\"#_bookmark15\">&amp; Cohrssen, 2004<\/a>). This potential problem can be solved with over-the-counter vaginal gels or oral probiotics to maintain normal vaginal pH levels (<a href=\"#_bookmark165\">T<\/a><a href=\"#_bookmark165\">achedjiana<\/a><a href=\"#_bookmark165\"> <\/a><a href=\"#_bookmark165\">et<\/a><a href=\"#_bookmark165\"> <\/a><a href=\"#_bookmark165\">al.,<\/a><a href=\"#_bookmark165\"> <\/a><a href=\"#_bookmark165\">in<\/a><a href=\"#_bookmark165\"> <\/a><a href=\"#_bookmark165\">pr<\/a><a href=\"#_bookmark165\">ess<\/a>).<\/p>\r\n&nbsp;\r\n<p class=\"import-Normal\" style=\"margin-left: 60.95pt\"><img src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image3-1.png\" alt=\"image\" width=\"477.220052493438px\" height=\"284.619947506562px\" class=\"aligncenter\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 60.95pt\">Figure 1b: The Female\u2019s Internal Sex Organs. [Image: unknown, https:\/\/goo.gl\/5GMbCr, CC BY-SA\u00a03.0, https:\/\/goo.gl\/jidmcs]<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.85pt\"><a id=\"Male_Anatomy\"><\/a><a id=\"_bookmark144\"><\/a>The primary functions of the <em>internal<\/em> <em>se<\/em><em>x<\/em> <em>or<\/em><em>gans<\/em> of the female are to store, transport, and keep ovum cells (eggs) healthy; and produce hormones (see Figure 1b). These organs include:<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;text-indent: 0pt\">the <a href=\"#_bookmark160\"><strong>uterus<\/strong> <\/a>(or womb)\u2014where human development occurs until birth;<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.95pt;text-indent: 0pt\">the <a href=\"#_bookmark158\"><strong>ovaries<\/strong><\/a>\u2014the glands that house the ova (eggs; about two million; <a href=\"#_bookmark47\">Faddy et al., 1992<\/a>) and produce progesterone, estrogen, and small amounts of testosterone;\u00a0the <a href=\"#_bookmark157\"><strong>fallopian<\/strong> <strong>tubes<\/strong><\/a>\u2014where fertilization is most likely to occur. These tubes allow for <a href=\"#_bookmark158\"> <strong>ovulation<\/strong> <\/a>(about every 28 days), which is when ova travel from the ovaries to the uterus. If fertilization does not occur, <a href=\"#_bookmark157\"><strong>menstruation<\/strong> <\/a>begins. Menstruation, also known as a \u201cperiod,\u201d is the discharge of ova along with the lining of the uterus through the vagina, usually taking several days to complete.<\/p>\r\n\r\n<h2>Male Anatomy<\/h2>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.85pt\">The most prominent <em>e<\/em><em>xternal<\/em> <em>se<\/em><em>x<\/em> <em>or<\/em><em>gan<\/em> for the male is the <a href=\"#_bookmark158\"><strong>penis<\/strong><\/a>. The penis\u2019s main functions are initiating orgasm, and transporting semen and urine from the body. On average, a flaccid penis is about three and a half inches in length, whereas an erect penis is about five inches (<a href=\"#_bookmark166\">Veale et al., 2015<\/a>; <a href=\"#_bookmark166\">Wessells, Lue &amp; McAninch, 1996<\/a>).<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 62.2pt\"><img src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image4.png\" alt=\"image\" width=\"469.200839895013px\" height=\"306px\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 62.2pt\">Figure 2: The Male\u2019s Internal and External Sex Organs. [Image: unknown, https:\/\/goo.gl\/9kUDCN,\u00a0CC BY-SA 3.0, https:\/\/goo.gl\/jidmcs]<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.85pt\"><a id=\"Sex_on_the_Brain\"><\/a><a id=\"_bookmark145\"><\/a>If you want to know the length of a particular male\u2019s erect penis, you\u2019ll have to actually see it\u2014because there are <em>no<\/em> reliable correlations between the length of an erect penis and (a) the length of a flaccid penis, (b) the lengths of other body parts\u2014including feet, hands, forearms, and overall height\u2014or (c) race and ethnicity (<a href=\"#_bookmark165\">Shah &amp; Christopher, 2002<\/a>; <a href=\"#_bookmark165\">Siminoski &amp; Bain, 1993<\/a>; <a href=\"#_bookmark166\">Veale et al., 2015<\/a>; <a href=\"#_bookmark166\">Wessells,<\/a> <a href=\"#_bookmark166\">Lue &amp; McAninch, 1996<\/a>). The penis has three parts: the root, shaft, and glans. <a href=\"#_bookmark157\"><strong>Foreskin<\/strong> <\/a>covers the glans, or head of the penis, except in circumcised males. The <a href=\"#_bookmark157\"><strong>glans<\/strong> <strong>penis<\/strong> <\/a>is highly sensitive, composed of more than 4,000 sensory-nerve endings, and associated with initiating orgasms (<a href=\"#_bookmark48\">Halata<\/a><a href=\"#_bookmark48\">,<\/a><a href=\"#_bookmark48\"> <\/a><a href=\"#_bookmark48\">1997<\/a>). Lastly, it has the urethral opening that allows semen and urine to exit the body.<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.85pt\">In addition to the penis, there are other male external sex organs that have two primary functions: producing hormones and sperm cells. The <a href=\"#_bookmark159\"><strong>scrotum<\/strong> <\/a>is the sac of skin behind and below the penis containing the testicles. The <a href=\"#_bookmark160\"><strong>testicles<\/strong> <\/a>(or testes) are the glands that produce testosterone, progesterone, small amounts of estrogen, and sperm cells.<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.85pt\">Many people are surprised to learn that males also have <em>internal<\/em> <em>se<\/em><em>x<\/em> <em>or<\/em><em>gans<\/em>. The primary functions of male internal sex organs are transporting sperm cells, keeping sperm cells healthy, and producing <a href=\"#_bookmark159\"><strong>semen<\/strong><\/a>\u2014the fluid in which sperm cells are transported. The male\u2019s internal sex organs include:<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.9pt;text-indent: 0pt\">the <a href=\"#_bookmark156\"><strong>epididymis<\/strong><\/a>, which is a twisted duct that matures, stores, and transports sperm cells into the vas deferens;<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.9pt;text-indent: 0pt\">the <a href=\"#_bookmark160\"><strong>vas<\/strong> <strong>deferens<\/strong><\/a>\u2014a muscular tube that transports mature sperm to the urethra, except in males who have had a <a href=\"#_bookmark160\"><strong>vasectomy<\/strong><\/a>;\u00a0the <a href=\"#_bookmark159\"><strong>seminal<\/strong> <strong>vesicles<\/strong><\/a>\u2014glands that provide energy for sperm cells to move. This energy is in the form of sugar (fructose) and it composes about 75% of the semen. Sperm cells only compose about 1% of the semen (<a href=\"#_bookmark164\">Owen &amp; Katz, 2005<\/a>);<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.9pt;text-indent: 0pt\">the <a href=\"#_bookmark158\"><strong>prostate<\/strong> <strong>gland<\/strong><\/a>, which provides additional fluid to the semen that nourishes the sperm cells; and the <strong>Cowper's<\/strong> <strong>glands<\/strong>, which produce a fluid that lubricates the urethra and neutralizes any acidity due to urine;\u00a0the <a href=\"#_bookmark160\"><strong>urethra<\/strong><\/a>\u2014the tube that carries urine and semen outside of the body.<\/p>\r\n\r\n<h2>Sex on the Brain<\/h2>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.9pt\">At first glance\u2014or touch for that matter\u2014the clitoris and penis are the parts of our anatomies that seem to bring the most pleasure. However, these two organs pale in comparison to our central\u00a0nervous system\u2019s capacity for pleasure. Extensive regions of the brain and brainstem are activated when a person experiences pleasure, including: the insula, temporal cortex, limbic system, nucleus accumbens, basal ganglia, superior parietal cortex, dorsolateral prefrontal cortex, and cerebellum (see Figure 3, <a href=\"#_bookmark164\">Ortigue et al., 2007<\/a>). <a href=\"#_bookmark158\"> <strong>Neuroimaging<\/strong> <strong>techniques<\/strong> <\/a>show that these regions of the brain are active when patients have spontaneous orgasms involving no direct stimulation of the skin (e.g., <a href=\"#_bookmark47\">Fadul et<\/a> <a href=\"#_bookmark47\">al., 2005<\/a>) and when experimental participants self-stimulate erogenous zones (e.g., <a href=\"#_bookmark163\">Komisaruk<\/a> <a href=\"#_bookmark163\">et al., 2011<\/a>). <a href=\"#_bookmark156\"><strong>Erogenous<\/strong> <strong>zones<\/strong> <\/a>are sensitive areas of skin that are connected, via the nervous system, to the somatosensory cortex in the brain.<\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.85pt\"><img src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image5-4.jpeg\" alt=\"image\" width=\"298.266666666667px\" height=\"242.2px\" class=\"aligncenter\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.85pt\">Figure 3: Some of the many regions of the brain and brainstem activated during pleasure experiences. [Image: Frank Gaillard, https:\/\/goo.gl\/yCKuQ2, CC-BY-SA 3.0. Identifying marks\u00a0added]<\/p>\r\n<p class=\"import-BodyText\" style=\"margin-left: 5.95pt;margin-right: 5.95pt\"><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 6pt\"><img src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image6-5.jpeg\" alt=\"image\" width=\"303.880209973753px\" height=\"369.909921259843px\" class=\"aligncenter\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 6pt\">Figure 4: Erogenous Zones Mapped on the Somatosensory Cortex.<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.1pt\"><br style=\"clear: both\" \/>The <a href=\"#_bookmark160\"><strong>somatosensory<\/strong> <strong>cortex<\/strong> <\/a>(SC) is the part of the brain primarily responsible for processing sensory information from the skin. The more sensitive an area of your skin is (e.g., your lips), the larger the corresponding area of the SC will be; the less sensitive an area of your skin is (e.g., your trunk), the smaller the corresponding area of the SC will be (see Figure 4, <a href=\"#_bookmark165\">Penfield &amp;<\/a> <a href=\"#_bookmark165\">Boldrey, 1937<\/a>). When a sensitive area of a person\u2019s body is touched, it is typically interpreted by the brain in one of three ways: \u201c<em>That<\/em> <em>tickles!<\/em>\u201d \u201c<em>That<\/em> <em>hurts!<\/em>\u201d or, \u201c<em>That\u2026you<\/em> <em>need<\/em> <em>to<\/em> <em>do<\/em><em> again!<\/em>\u201d Thus, the more sensitive areas of our bodies have greater potential to evoke pleasure. A study by Nummenmaa and his colleagues (<a href=\"#_bookmark164\">2016<\/a>) used a unique method to test this hypothesis. The Nummenmaa research team showed experimental participants images of same- and opposite-sex bodies.<\/p>\r\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.85pt\">They then asked the participants to color the regions of the body that, when touched, they or members of the opposite sex would experience as sexually arousing while masturbating or having sex with a partner. Nummenmaa found the expected \u201chotspot\u201d erogenous zones around the external sex organs, breasts, and anus, but also reported areas of the skin beyond these hotspots: \u201c[T]actile stimulation of practically all bodily regions trigger sexual arousal\u2026.\u201d Moreover, he concluded, \u201c[H]aving sex with a partner\u2026\u201d\u2014beyond the hotspots\u2014\u201c\u2026reflects the role of touching in the maintenance of\u2026pair bonds.\u201d<\/p>","rendered":"<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.85pt\">Sexual anatomy is typically discussed only in terms of reproduction (see e.g., <a href=\"#_bookmark49\">King, 2015<\/a>). However, reproduction is only a (small) part of what drives us sexually (<a href=\"#_bookmark163\">Lucas &amp; Fox, 2018<\/a>). Full discussions of sexual anatomy also include the concept of pleasure. Thus, we will explore the sexual anatomies of females (see Figures 1a and 1b) and males (see Figure 2) in terms of their capabilities for both reproduction and pleasure.<\/p>\n<h2>Female Anatomy<\/h2>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.85pt\">Many people find female sexual anatomy curious, confusing, and mysterious. This may be because so much of it is internal (inside the body), or because\u2014historically\u2014women have been expected to be modest and secretive regarding their bodies.<\/p>\n<p>&nbsp;<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 48.75pt\"><img decoding=\"async\" src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image2-6.jpeg\" alt=\"image\" width=\"510.299737532808px\" height=\"299.6px\" class=\"aligncenter\" \/><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 48.75pt\"><a id=\"_bookmark142\"><\/a>Figure 1a: The Female\u2019s External Sex Organs. [Image: Open Stax College, https:\/\/goo.gl\/Hj59kX, CC BY 3.0,\u00a0https:\/\/goo.gl\/Dmg4Uu]<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.85pt\">Perhaps the most visible structure of female sexual anatomy is the vulva. The primary functions of the vulva are pleasure and protection. The <a href=\"#_bookmark160\"><strong>vulva<\/strong> <\/a>is composed of the female\u2019s <em>externalsex<\/em> <em>organs<\/em> (see Figure 1a). It includes many parts:<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;text-indent: 0pt\">the <a href=\"#_bookmark157\"><strong>labia<\/strong> <strong>majora<\/strong><\/a>\u2014the \u201clarge lips\u201d enclosing and protecting the female\u2019s internal sex organs;<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.9pt;text-indent: 0pt\">the <a href=\"#_bookmark157\"><strong>labia<\/strong> <strong>minora<\/strong><\/a>\u2014the\u201csmall lips\u201d surrounding and defining the openings of the vagina and urethra;\u00a0the minor and major <a href=\"#_bookmark160\"><strong>vestibular<\/strong> <strong>glands<\/strong> <strong>(VGs)<\/strong><\/a>.<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.85pt\">The minor VGs\u2014also called <strong>Skene&#8217;s<\/strong> <strong>glands<\/strong> (not pictured), are on the wall of the vagina and are associated with female ejaculation, and mythologically associated with the G-Spot (<a href=\"#_bookmark49\">Kilchevsky<\/a><a href=\"#_bookmark49\"> <\/a><a href=\"#_bookmark49\">et<\/a><a href=\"#_bookmark49\"> <\/a><a href=\"#_bookmark49\">al.,<\/a><a href=\"#_bookmark49\"> <\/a><a href=\"#_bookmark49\">2012<\/a>; <a href=\"#_bookmark166\">Wickman, 2017<\/a>). The major VGs\u2014also called Bartholin&#8217;s glands\u2014are located just to the left and right of the vagina and produce lubrication to aid in sexual intercourse. Most females\u2014especially postmenopausal females\u2014at some time in their lives report inadequate lubrication, which, in turn, leads to discomfort or pain during sexual intercourse (<a href=\"#_bookmark164\">Nappi<\/a><a href=\"#_bookmark164\"> <\/a><a href=\"#_bookmark164\">&amp;<\/a><a href=\"#_bookmark164\"> <\/a><a href=\"#_bookmark164\">Lachowsky<\/a><a href=\"#_bookmark164\">,<\/a><a href=\"#_bookmark164\"> <\/a><a href=\"#_bookmark164\">2009<\/a>). Extending foreplay and using commercial water-, silicone-, or oil-based personal lubricants are simple solutions to this common problem.<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.1pt\">The clitoris and vagina are considered parts of the vulva as well as internal sex organs (see Figure 1b). They are the most talked about organs in relation to their capacities for female pleasure\u00a0(e.g., <a href=\"#_bookmark49\">Jannini et al., 2012<\/a>). Most of the <a href=\"#_bookmark156\"><strong>clitoris<\/strong><\/a>, which is composed of 18 parts with an average overall excited length of about four inches, cannot be seen (<a href=\"#_bookmark6\">Ginger &amp; Yang, 2011<\/a>; <a href=\"#_bookmark164\">O&#8217;Connell et al., 2005<\/a>). The visible parts\u2014the glans and prepuce\u2014are located above the urethra and join the labia minora at its pinnacle. The clitoris is highly sensitive, composed of more than 8,000 sensory-nerve endings, and is associated with initiating orgasms; 90% of females can orgasm by clitoral stimulation alone (<a href=\"#_bookmark164\">O&#8217;Connell et al., 2005<\/a>; <a href=\"#_bookmark165\">Thompson, 2016<\/a>).<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.1pt\">The <a href=\"#_bookmark160\"><strong>vagina<\/strong><\/a>, also called the \u201cbirth canal,\u201d is a muscular canal that spans from the cervix to the introitus. It has an average overall excited length of about four and a half inches (<a href=\"#_bookmark164\">Masters &amp;<\/a> <a href=\"#_bookmark164\">Johnson, 1966<\/a>) and has two parts: First, there is the inner two-thirds (posterior wall)\u2014formed during the first trimester of pregnancy. Second, there is the outer one-third of the vagina (anterior wall). It is formed during the second trimester of pregnancy and is generally more sensitive than the inner portion, but dramatically less sensitive than the clitoris (<a href=\"#_bookmark48\">Hines, 2001<\/a>). Only between 10% and 30% of females achieve orgasms by vaginal stimulation alone (<a href=\"#_bookmark165\">Thompson, 2016<\/a>). At each end of the vagina are the <a href=\"#_bookmark156\"><strong>cervix<\/strong> <\/a>(the lower portion of the uterus) and the <a href=\"#_bookmark157\"><strong>introitus<\/strong> <\/a>(the vaginal opening to the outside of the body). The vagina acts as a transport mechanism for sperm cells coming in, and menstrual fluid and babies going out. A healthy vagina has a pH level of about four, which is acidic. When the pH level changes, often due to normal circumstances (e.g., menstruation, using tampons, sexual intercourse), it facilitates the reproduction of microorganisms that often cause vaginal odor and pain (<a href=\"#_bookmark15\">Anderson, Klink <\/a><a href=\"#_bookmark15\">&amp; Cohrssen, 2004<\/a>). This potential problem can be solved with over-the-counter vaginal gels or oral probiotics to maintain normal vaginal pH levels (<a href=\"#_bookmark165\">T<\/a><a href=\"#_bookmark165\">achedjiana<\/a><a href=\"#_bookmark165\"> <\/a><a href=\"#_bookmark165\">et<\/a><a href=\"#_bookmark165\"> <\/a><a href=\"#_bookmark165\">al.,<\/a><a href=\"#_bookmark165\"> <\/a><a href=\"#_bookmark165\">in<\/a><a href=\"#_bookmark165\"> <\/a><a href=\"#_bookmark165\">pr<\/a><a href=\"#_bookmark165\">ess<\/a>).<\/p>\n<p>&nbsp;<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 60.95pt\"><img decoding=\"async\" src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image3-1.png\" alt=\"image\" width=\"477.220052493438px\" height=\"284.619947506562px\" class=\"aligncenter\" \/><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 60.95pt\">Figure 1b: The Female\u2019s Internal Sex Organs. [Image: unknown, https:\/\/goo.gl\/5GMbCr, CC BY-SA\u00a03.0, https:\/\/goo.gl\/jidmcs]<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.85pt\"><a id=\"Male_Anatomy\"><\/a><a id=\"_bookmark144\"><\/a>The primary functions of the <em>internal<\/em> <em>se<\/em><em>x<\/em> <em>or<\/em><em>gans<\/em> of the female are to store, transport, and keep ovum cells (eggs) healthy; and produce hormones (see Figure 1b). These organs include:<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;text-indent: 0pt\">the <a href=\"#_bookmark160\"><strong>uterus<\/strong> <\/a>(or womb)\u2014where human development occurs until birth;<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.95pt;text-indent: 0pt\">the <a href=\"#_bookmark158\"><strong>ovaries<\/strong><\/a>\u2014the glands that house the ova (eggs; about two million; <a href=\"#_bookmark47\">Faddy et al., 1992<\/a>) and produce progesterone, estrogen, and small amounts of testosterone;\u00a0the <a href=\"#_bookmark157\"><strong>fallopian<\/strong> <strong>tubes<\/strong><\/a>\u2014where fertilization is most likely to occur. These tubes allow for <a href=\"#_bookmark158\"> <strong>ovulation<\/strong> <\/a>(about every 28 days), which is when ova travel from the ovaries to the uterus. If fertilization does not occur, <a href=\"#_bookmark157\"><strong>menstruation<\/strong> <\/a>begins. Menstruation, also known as a \u201cperiod,\u201d is the discharge of ova along with the lining of the uterus through the vagina, usually taking several days to complete.<\/p>\n<h2>Male Anatomy<\/h2>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.85pt\">The most prominent <em>e<\/em><em>xternal<\/em> <em>se<\/em><em>x<\/em> <em>or<\/em><em>gan<\/em> for the male is the <a href=\"#_bookmark158\"><strong>penis<\/strong><\/a>. The penis\u2019s main functions are initiating orgasm, and transporting semen and urine from the body. On average, a flaccid penis is about three and a half inches in length, whereas an erect penis is about five inches (<a href=\"#_bookmark166\">Veale et al., 2015<\/a>; <a href=\"#_bookmark166\">Wessells, Lue &amp; McAninch, 1996<\/a>).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 62.2pt\"><img decoding=\"async\" src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image4.png\" alt=\"image\" width=\"469.200839895013px\" height=\"306px\" \/><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 62.2pt\">Figure 2: The Male\u2019s Internal and External Sex Organs. [Image: unknown, https:\/\/goo.gl\/9kUDCN,\u00a0CC BY-SA 3.0, https:\/\/goo.gl\/jidmcs]<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.85pt\"><a id=\"Sex_on_the_Brain\"><\/a><a id=\"_bookmark145\"><\/a>If you want to know the length of a particular male\u2019s erect penis, you\u2019ll have to actually see it\u2014because there are <em>no<\/em> reliable correlations between the length of an erect penis and (a) the length of a flaccid penis, (b) the lengths of other body parts\u2014including feet, hands, forearms, and overall height\u2014or (c) race and ethnicity (<a href=\"#_bookmark165\">Shah &amp; Christopher, 2002<\/a>; <a href=\"#_bookmark165\">Siminoski &amp; Bain, 1993<\/a>; <a href=\"#_bookmark166\">Veale et al., 2015<\/a>; <a href=\"#_bookmark166\">Wessells,<\/a> <a href=\"#_bookmark166\">Lue &amp; McAninch, 1996<\/a>). The penis has three parts: the root, shaft, and glans. <a href=\"#_bookmark157\"><strong>Foreskin<\/strong> <\/a>covers the glans, or head of the penis, except in circumcised males. The <a href=\"#_bookmark157\"><strong>glans<\/strong> <strong>penis<\/strong> <\/a>is highly sensitive, composed of more than 4,000 sensory-nerve endings, and associated with initiating orgasms (<a href=\"#_bookmark48\">Halata<\/a><a href=\"#_bookmark48\">,<\/a><a href=\"#_bookmark48\"> <\/a><a href=\"#_bookmark48\">1997<\/a>). Lastly, it has the urethral opening that allows semen and urine to exit the body.<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.85pt\">In addition to the penis, there are other male external sex organs that have two primary functions: producing hormones and sperm cells. The <a href=\"#_bookmark159\"><strong>scrotum<\/strong> <\/a>is the sac of skin behind and below the penis containing the testicles. The <a href=\"#_bookmark160\"><strong>testicles<\/strong> <\/a>(or testes) are the glands that produce testosterone, progesterone, small amounts of estrogen, and sperm cells.<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.85pt\">Many people are surprised to learn that males also have <em>internal<\/em> <em>se<\/em><em>x<\/em> <em>or<\/em><em>gans<\/em>. The primary functions of male internal sex organs are transporting sperm cells, keeping sperm cells healthy, and producing <a href=\"#_bookmark159\"><strong>semen<\/strong><\/a>\u2014the fluid in which sperm cells are transported. The male\u2019s internal sex organs include:<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.9pt;text-indent: 0pt\">the <a href=\"#_bookmark156\"><strong>epididymis<\/strong><\/a>, which is a twisted duct that matures, stores, and transports sperm cells into the vas deferens;<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.9pt;text-indent: 0pt\">the <a href=\"#_bookmark160\"><strong>vas<\/strong> <strong>deferens<\/strong><\/a>\u2014a muscular tube that transports mature sperm to the urethra, except in males who have had a <a href=\"#_bookmark160\"><strong>vasectomy<\/strong><\/a>;\u00a0the <a href=\"#_bookmark159\"><strong>seminal<\/strong> <strong>vesicles<\/strong><\/a>\u2014glands that provide energy for sperm cells to move. This energy is in the form of sugar (fructose) and it composes about 75% of the semen. Sperm cells only compose about 1% of the semen (<a href=\"#_bookmark164\">Owen &amp; Katz, 2005<\/a>);<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 5pt;margin-right: 5.9pt;text-indent: 0pt\">the <a href=\"#_bookmark158\"><strong>prostate<\/strong> <strong>gland<\/strong><\/a>, which provides additional fluid to the semen that nourishes the sperm cells; and the <strong>Cowper&#8217;s<\/strong> <strong>glands<\/strong>, which produce a fluid that lubricates the urethra and neutralizes any acidity due to urine;\u00a0the <a href=\"#_bookmark160\"><strong>urethra<\/strong><\/a>\u2014the tube that carries urine and semen outside of the body.<\/p>\n<h2>Sex on the Brain<\/h2>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.9pt\">At first glance\u2014or touch for that matter\u2014the clitoris and penis are the parts of our anatomies that seem to bring the most pleasure. However, these two organs pale in comparison to our central\u00a0nervous system\u2019s capacity for pleasure. Extensive regions of the brain and brainstem are activated when a person experiences pleasure, including: the insula, temporal cortex, limbic system, nucleus accumbens, basal ganglia, superior parietal cortex, dorsolateral prefrontal cortex, and cerebellum (see Figure 3, <a href=\"#_bookmark164\">Ortigue et al., 2007<\/a>). <a href=\"#_bookmark158\"> <strong>Neuroimaging<\/strong> <strong>techniques<\/strong> <\/a>show that these regions of the brain are active when patients have spontaneous orgasms involving no direct stimulation of the skin (e.g., <a href=\"#_bookmark47\">Fadul et<\/a> <a href=\"#_bookmark47\">al., 2005<\/a>) and when experimental participants self-stimulate erogenous zones (e.g., <a href=\"#_bookmark163\">Komisaruk<\/a> <a href=\"#_bookmark163\">et al., 2011<\/a>). <a href=\"#_bookmark156\"><strong>Erogenous<\/strong> <strong>zones<\/strong> <\/a>are sensitive areas of skin that are connected, via the nervous system, to the somatosensory cortex in the brain.<\/p>\n<p class=\"import-Normal\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.85pt\"><img decoding=\"async\" src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image5-4.jpeg\" alt=\"image\" width=\"298.266666666667px\" height=\"242.2px\" class=\"aligncenter\" \/><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify;margin-left: 5.95pt;margin-right: 5.85pt\">Figure 3: Some of the many regions of the brain and brainstem activated during pleasure experiences. [Image: Frank Gaillard, https:\/\/goo.gl\/yCKuQ2, CC-BY-SA 3.0. Identifying marks\u00a0added]<\/p>\n<p class=\"import-BodyText\" style=\"margin-left: 5.95pt;margin-right: 5.95pt\">\n<p class=\"import-Normal\" style=\"margin-left: 6pt\"><img decoding=\"async\" src=\"http:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-content\/uploads\/sites\/17\/2018\/08\/image6-5.jpeg\" alt=\"image\" width=\"303.880209973753px\" height=\"369.909921259843px\" class=\"aligncenter\" \/><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 6pt\">Figure 4: Erogenous Zones Mapped on the Somatosensory Cortex.<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.1pt\"><br style=\"clear: both\" \/>The <a href=\"#_bookmark160\"><strong>somatosensory<\/strong> <strong>cortex<\/strong> <\/a>(SC) is the part of the brain primarily responsible for processing sensory information from the skin. The more sensitive an area of your skin is (e.g., your lips), the larger the corresponding area of the SC will be; the less sensitive an area of your skin is (e.g., your trunk), the smaller the corresponding area of the SC will be (see Figure 4, <a href=\"#_bookmark165\">Penfield &amp;<\/a> <a href=\"#_bookmark165\">Boldrey, 1937<\/a>). When a sensitive area of a person\u2019s body is touched, it is typically interpreted by the brain in one of three ways: \u201c<em>That<\/em> <em>tickles!<\/em>\u201d \u201c<em>That<\/em> <em>hurts!<\/em>\u201d or, \u201c<em>That\u2026you<\/em> <em>need<\/em> <em>to<\/em> <em>do<\/em><em> again!<\/em>\u201d Thus, the more sensitive areas of our bodies have greater potential to evoke pleasure. A study by Nummenmaa and his colleagues (<a href=\"#_bookmark164\">2016<\/a>) used a unique method to test this hypothesis. The Nummenmaa research team showed experimental participants images of same- and opposite-sex bodies.<\/p>\n<p class=\"import-BodyText\" style=\"text-align: justify;margin-left: 6pt;margin-right: 5.85pt\">They then asked the participants to color the regions of the body that, when touched, they or members of the opposite sex would experience as sexually arousing while masturbating or having sex with a partner. Nummenmaa found the expected \u201chotspot\u201d erogenous zones around the external sex organs, breasts, and anus, but also reported areas of the skin beyond these hotspots: \u201c[T]actile stimulation of practically all bodily regions trigger sexual arousal\u2026.\u201d Moreover, he concluded, \u201c[H]aving sex with a partner\u2026\u201d\u2014beyond the hotspots\u2014\u201c\u2026reflects the role of touching in the maintenance of\u2026pair bonds.\u201d<\/p>\n","protected":false},"author":23,"menu_order":5,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-1260","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":365,"_links":{"self":[{"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/pressbooks\/v2\/chapters\/1260","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/wp\/v2\/users\/23"}],"version-history":[{"count":3,"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/pressbooks\/v2\/chapters\/1260\/revisions"}],"predecessor-version":[{"id":1669,"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/pressbooks\/v2\/chapters\/1260\/revisions\/1669"}],"part":[{"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/pressbooks\/v2\/parts\/365"}],"metadata":[{"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/pressbooks\/v2\/chapters\/1260\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/wp\/v2\/media?parent=1260"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/pressbooks\/v2\/chapter-type?post=1260"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/wp\/v2\/contributor?post=1260"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.library.upei.ca\/upeiintropsychology\/wp-json\/wp\/v2\/license?post=1260"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}