Sex Behavior
Overview
An In-dept Introduction to Male and Female Sex Behavior
Edited by: Gina Marie Hazzard, Catey Kelly, Christina Enodien, and Ryan Lietz
Male Sex Behavior - Blayre Walters:
Masculinization of the Brain and Male Behavior
Objectives:
- Learn the term Sexual Dimorphic Behaviors and how it relates to male sex behavior
- Understand the male hormones involved in sex behavior and their unique functions
Sexual dimorphic behaviors refer to the differences in behavior between males and females of a species. (Lopez-Ojeda & Hurley, 2021). In many species, including humans, these differences are the result of sexual differentiation in the brain during development. Sexual differentiation is the process by which the brain becomes male or female in response to hormonal signals during critical periods of development. Sex hormones, such as testosterone and estrogen, play a crucial role in this process. For example, testosterone is responsible for the development of male-typical behaviors such as aggression, mating behavior, and territoriality, while estrogen is associated with female-typical behaviors such as nurturing and caregiving. The exact mechanisms by which these hormones influence brain development are still being studied, but we know that they have significant effects on the structure and function of the brain regions involved in sexual behavior (Lopez-Ojeda & Hurley, 2021). Understanding the role of sex hormones in sexual differentiation and sexual dimorphic behaviors is becoming more crucial in today’s environment to understand the development of topics like gender identity.
Hormones such as testosterone and estrogen have different effects on the brain, with testosterone being associated with more dominant and aggressive behaviors in males, while estrogen is associated with more nurturing and caregiving behaviors in females. Testosterone is the primary male hormone that regulates sex behavior in the brain. It is produced in the testes and adrenal glands and is responsible for the development of male secondary sexual characteristics, including increased muscle mass, body hair growth, and deepening of the voice (Anders et al., 2015). Testosterone also affects the brain regions that are involved in sexual behavior. Research has shown that testosterone can modulate the activity of the amygdala, hypothalamus, and prefrontal cortex, which are all involved in the regulation of sex behavior. For example, testosterone has been shown to increase the activity of the amygdala, which is involved in the processing of sexual stimuli and the initiation of sexual behavior (Anders et al., 2015). Testosterone increases the activity of the hypothalamus, which regulates the release of hormones involved in sex behavior. Research has shown that testosterone levels are positively correlated with sexual desire and arousal in males, and studies have found that men with higher levels of testosterone are more likely to engage in sexual activity and report a higher frequency of sexual thoughts and fantasies. Testosterone also plays a role in the regulation of erectile function, as it enhances the response of the penis to sexual stimuli. Although estrogen is typically regarded as a female hormone, it also plays a crucial role in male sex behavior. Estrogen is produced in small amounts in the testes, and even the brain, where it is converted from testosterone by the aromatase enzyme (Cooke et al., 2017) . Estrogen receptors are present in various brain regions that are involved in the regulation of sex behavior, including the hypothalamus, amygdala, and prefrontal cortex. Research has shown that estrogen can modulate the activity of these brain regions, leading to changes in male sex behavior. For example, estrogen has been shown to increase sexual motivation and decrease anxiety in male rats (Cooke et al., 2017). In humans, studies have found that estrogen can enhance the responsiveness of the penis to sexual stimuli and improve erectile function. Progesterone is another hormone that is typically associated with female reproductive function but also plays a role in male sex behavior by acting on similar regions of the brain. For example, progesterone has been shown to decrease sexual motivation and increase anxiety in male rats. In humans, studies have found that progesterone can reduce sexual desire and arousal.
Male hormones such as testosterone, estrogen, and progesterone play a crucial role in the regulation of sex behavior in the brain. Testosterone is the primary male hormone that regulates sexual desire, arousal, and erectile function. Estrogen also plays a role in male sex behavior, enhancing sexual responsiveness and reducing anxiety, while progesterone can have a negative impact on male sex behavior, reducing sexual desire and increasing anxiety. The interplay between these hormones and their effects on the brain regions involved in sex behavior is complex and still not fully understood. Understanding these relationships is important to understanding more complex male sex behaviors and functions as it relates to the brain.
ASSESSMENT QUESTIONS:
- What do sexual dimorphic behaviors refer to?
- Differences in behavior between males and females of the SAME species
- Differences in behavior between males and females of a DIFFERENT species
- Similarities in behavior between males and females of the SAME species
- Similarities in behavior between males and females of DIFFERENT species
- Testosterone is responsible for..?
- modulating mainly the effects of dopaminergic and serotoninergic systems on sexual function
- Being an important role in the normal sexual and reproductive development in women
- regulating sex drive (libido), bone mass, fat distribution, muscle mass and strength, and the production of red blood cells and sperm
- Helping men think logically
- What is the role of the amygdala regarding sex behavior?
- The amygdala is responsible for sexual differentiation in the brain during development
- The amygdala is involved in sexual arousal due to the fear and safety emotions
- The amygdala is in small amounts in the testes and is converted from testosterone by the aromatase enzyme.
- What is the role of estrogen in male sex behavior?
- To modulate the activity of brain regions, leading to changes in male sex behavior
- It is primary male hormone that regulates sexual desire, arousal, and erectile function
- It is responsible for the development of male-typical behaviors such as aggression, mating behavior, and territoriality
- It stimulates breast development and milk production in women
- What animal are most studies conducted on for neuroscience research?
- Cats
- Rats
- Cows
- Birds
- What are the three hormones that play a vital role in understanding male sex behavior?
- Testosterone, Estrogen, Prolactin
- Estrogen, Androgen, Testosterone
- Progesterone, Prolactin, Testosterone
- Testosterone, Estrogen, Progesterone
PICTURES/VIDEOS
Sexual Behavior and the Brain - start at 0:25 - 7:12
Hormones and Sexual Behavior - start at 7:59 - 9:48
Ejaculation - Skyler Murphy:
Objectives:
- Learn about the physiology of the two phases of ejaculation- emission and expulsion
- Understand the symptoms and causes of two of the most common ejaculation dysfunctions- premature ejaculation and delayed ejaculation
Male ejaculation is defined as the forceful ejection of seminal fluid by men at the end of coitus from their urethral meatus (Coolen et al., 2004). While it is typically associated with orgasm, the two are not one and the same, as ejaculation is considered a spinal reflex while orgasm is a purely cerebral process. Ejaculation is controlled by multiple systems, including the sympathetic and parasympathetic nervous system as well as a spinal control center called the spinal ejaculation generator (Son, Jeong, & Jang, 2022). Ejaculation occurs in two phases- emission and expulsion. The emission phase begins with physical or erotic stimulation of the male genitals, which sends sensory input to the spinal ejaculation generator, triggering both the sympathetic and parasympathetic nervous system (Coolen et al., 2004). Once these systems are triggered, the sympathetic nervous system releases norepinephrine and the parasympathetic nervous system releases acetylcholine. The release of these neurotransmitters causes secretion of the seminal fluids from epithelial cells and sex glands. The fluid then moves to the posterior urethra, where once the fluid reaches this point, ejaculation becomes unavoidable (Coolen et al., 2004). The next stage of ejaculation is expulsion, at which point semen leaves the male due to rhythmic contractions of the bulbocavernosus and the ischiocavernosus muscles. Semen is ejaculated during the second contraction of the bulbocavernosus muscle in conjunction with multiple contractions of the ischiocavernosus muscle. This is thought to be because of a delay between the first contraction and filling of the upper part of the prostatic urethra. It was found that most of the semen was expelled after 5 or 6 contractions but in the majority of men contractions continued, which is thought to ensure that all semen enters the female (Gerstenberg, Levin, & Wagner, 1990). Once a man ejaculates, he enters a refractory period that can last from several minutes to several hours where he is unable to ejaculate again.
There are several disorders that are connected to ejaculatory dysfunction, two of the most common ones being premature ejaculation and delayed ejaculation. Premature ejaculation is described as ejaculation occurring within 1 minute after the start of sexual intercourse, and occurs in about 20-30% of men (Fiala et al., 2021). There are both physiological and psychological factors that can contribute to premature ejaculation. Physiologically, premature ejaculation can be caused by abnormalities of the afferent-efferent reflex pathway via the communications between different systems active in the reflex process as well as increased sensitivity of the glans penis (Porst and Burri, 2017). It can also be caused by Diabetes Mellitus, obesity, metabolic syndrome, and genetic and urological factors (Son, Jeong, & Jang, 2022). Psychologically, it’s often linked to anxiety, stress, depression, history of sexual suppression or sexual abuse, as well as having a poor body image. The activity of the sympathetic nervous system increases when a person has anxiety, and since it plays such an important role in the phases of ejaculation, it is very common for a person with anxiety to ejaculate quicker since their sympathetic nervous system is already in a heightened state (Son, Jeong, & Jang, 2022). Furthermore, high cortisol levels that are associated with increased stress in a person's life have also been linked to premature ejaculation, indicating that psychoneuroendocrinological interactions may play a significant role in the epidemiology of premature ejaculation (Fiala et al., 2021). These issues often require psychological intervention from a licensed therapist, and people who undergo counseling either alone or with their partner have seen improvements in the incidence of premature ejaculation.
The other most common ejaculatory disorder is delayed ejaculation, which is defined as a marked delay or absence of ejaculation after sufficient sexual stimulation (Son, Jeong, & Jang, 2022). There have been difficulties in defining delayed ejaculation since ejaculation and orgasm often occur in tandem even though ejaculation is a reflex process and orgasm is a purely cerebral process (Abdel-Hamid and Ali, 2018). Similarly to premature ejaculation, there are both psychological and physiological causes of delayed ejaculation, and these factors can often work together to make ejaculation, with a partner especially, very hard to achieve. Some psychological factors include insufficient mental stimulation, which often points to underlying conflicts either within themselves or within their relationship with their chosen partner (Abdel-Hamid and Ali, 2018). Unusual masturbation patterns or fantasies can also contribute to delayed ejaculation. Men who masturbate frequently often find they have trouble ejaculating with a partner since they are used to specific durations, pressures, and speeds that may not be able to be replicated by a partner. Furthermore, men may have specific fantasies that a partner may be unable or unwilling to recreate, preventing men from being properly mentally stimulated to achieve ejaculation (Son, Jeong, & Jang, 2022). Physiologically, age has been linked to decreased penile sensitivity, slower bulbocavernosus reflexes, and reduced spinal stimulation (Abdel-Hamid and Ali, 2018). Certain drugs, such as selective serotonin reuptake inhibitors have been linked to the inability to ejaculate, and have been seen to increase the likelihood of this phenomenon by up to seven times. Overall, there are a multitude of factors that can cause both premature ejaculation and delayed ejaculation that can interact with each other, and new studies are constantly being completed to try and understand the causes of these sexual dysfunctions as well as possible treatments for them.
Pictures:
"File:Diagram showing the parts of the penis CRUK 333.svg" by Cancer Research UK is licensed under CC BY-SA 4.0.
Video on ejaculation:
https://www.youtube.com/watch?v=wd3gE9qgdos&ab_channel=EKGScience
EKG Science. (2021, September 7). Erection & Ejaculation | Male Reproductive System [Video]. YouTube. https://www.youtube.com/watch?v=wd3gE9qgdos
Assessment Questions:
A patient is found to have high cortisol levels in their yearly blood-work, what is the sexual dysfunction that they likely have as a result of these high cortisol levels?
- Performance anxiety
- Delayed ejaculation
- Premature ejaculation
- Retrograde ejaculation
What could be a way to test the importance of the bulbocavernosus muscle in the role it plays in ejaculation?
- Remove the ischiocavernosus muscle
- Electrically stimulate the bulbocavernosus muscle and see what effect it has on ejaculation
- Inhibit bulbocavernosus muscle movement and observe what effect it has on ejaculation
- Numb the penis and observe what effect it has on ejaculation
- Both B and C
Male Sexual desire - Karla Deleon:
Objectives:
- Students will be able to define sexual desire.
- Students will be familiar with regions of the brain and its contributions.
- Students will be able to define HSDD and its factors.
Sexual desire is defined as the subjective psychological status to initiate and maintain human sexual behavior, triggered by internal and/or external stimuli. Sexual desire can be described through drive, motivation and wish, in relation to the three biopsychosocial components of biological, psychological, and social factors. The drive is associated with the biological aspect (anatomically and neuroendocrine system), motivation is associated with the psychological aspect (mental being and state), and wish is associated with the social or cultural aspect. There are many regions of the brain that are critical to the proper functioning of sexual desire within the male body. One of the key regions is the amygdala which is a structure found in the limbic system and is most commonly associated with emotion. The amygdala is responsible for emotional regulation when stimuli of any kind are presented. The hypothalamus is another key region which has control over the pituitary gland, thus being able to release hormones from the body. The thalamus is known as the body’s information relay station, where information from the senses are processed through the thalamus before it is interpreted. In this case, erotic stimuli that comes from the spinal cord is passed through here. The thalamus also plays a part in sexual preference and choosing a partner. Structures such as these set off autonomic responses such as heart rate, blood pressure, and increase in breathing, and are crucial to male erection and ejaculation.
Much like the regular function and increase of sexual desire, there can also be a decrease. When a male experiences a low sexual desire, they have what is called Hypoactive Sexual Desire Disorder (HSSD), where there is a lack of sexual fantasies and the desire to perform sexual activity. Age, depression, and illness are several factors that can contribute to sexual dysfunction.
Video: NBC News. (2018, July 26). Your Brain Wants You To Have Sex. Here’s How That Works. | Better | NBC News [Video]. YouTube. https://www.youtube.com/watch?v=4DJ0F-UFF4g
"File:Figure 35 03 06.jpg" by CNX OpenStax is licensed under CC BY 4.0.
ASSESSMENT QUESTIONS:
- When a male experiences an erection or ejaculation, which system is responsible for the increase in heart rate and breathing?
- Peripheral nervous system
- Autonomic nervous system
- Nervous system
- Somatic nervous system
- Which of the following are signs of a male being diagnosed with Hypoactive Sexual Desire Disorder (HSDD)?
- Decrease in testosterone levels
- High sex drive
- Anxiety
- A & C
Male arousal:
Objectives:
- Student will be able to define male sexual arousal
- Student will be able to identify hormones that are produced under the brain activity which enact with the male sexual arousal
- Student will be able to define how to identify the sexual arousal in various ways
The Endothermic behavior of the male arousal can be viewed in two pathways: the hormonal and the physical pathway. Under the hormone pathway, testosterone plays a central role in male sexual arousal. In terms of nonseasonal mammals, which are animals that do not perform reproduction under seasonal conditions, testosterone is low before puberty and higher after puberty, and an identical phenomenon is found in male sexual behavior. In terms of the seasonal mammals, which are animals that perform reproduction under seasonal conditions, testosterone is low during winter and higher during summer and an identical phenomenon is found under male sexual behavior (Alsian Demier, 2016). Furthermore, the research that tested the effect of injection of testosterone versus placebo has shown an increase in male-typical sexual arousal among castrated males. However, the effect of testosterone on male arousal only applies to the minimum level of required testosterone and after that level, the improvement of male sexual behavior is not detected (Carani, C. 1990). In fact, the identical experiment that injected testosterone and a placebo has given a stark increase among castrated males but a basal level of deviance among the hypogonadal males. This indicates that testosterone is an important factor in male sexual arousal yet not the only hormone that enacts to promote sexual arousal. The effect of testosterone is not limited to itself. In the male body, testosterone aromatizes itself to estradiol, another hormone that is essential for modulating male libido and penis erectile. Furthermore, testosterone can also be chemically synthesized to dihydro-T (DHT). This hormone activates the androgen receptor among the male which is needed for sexual differentiation during fetal development and changes in males during puberty. Furthermore, the hormone is also necessary for maintaining a sex drive in men which leads to higher sexual arousal(A. Sansone, 2021).
The arousal is exacted with higher blood pressure is released around the genitalia during the sexual arousal in the male. However, the classification of sexual arousal is into three categories: central arousal, which involves neurobiological events within the central nervous system (CNS); peripheral non-genital arousal, (examples are salivary secretion, skin vasodilatation and feeling of warmth, nipple erection, heart rate, and blood pressure increase), and general neuromuscular tension alteration like a genital erection in male (Levin, R. J. 1994). While the vast research in the past has focused solely on the 3rd category- a genital erection, the other two factors are also key aspects to determining sexual arousal and what stimulates them.
Historically, male erections were the sole basis of measurement for male sexual arousal. However, through technological development, recent studies were able to identify a different way to calculate sexual arousal for males: breathing as a chemical marker for sexual arousal. The participants of 12 females and 12 males were randomly selected to 3 different 10-minute long film clips: sports film( positive- nonsexual), horror film (negative- nonsexual), and erotic film(sexual)(Wang, N. 2022). Then the measured VOC/ CO2 levels along with genital arousal and temperature with respect to each movie. This setting was made to measure the exile of chemical elements in relation to sexual arousal. By measuring VOC and CO2 rates in 3 different genres of films, it validated breathing as a tool for the indicator of sexual arousal. Exhaled breath VOCs showed variation in concentration: males exhibited significantly lower CO2, C2H4O2, and C6H6O breath levels, respectively, for the sex clip compared to the other two clips. (Along with the deviance in the breathing, there were genital responses and temperature variation) (Wang, N. 2022).
Assessment Questions
- Which hormone does not function directly in a male arousal?
- Testosterone
- Estradiol
- DHT
- Estrogen
- Which factors can we measure to identify male arousal through their breathing?
- VOC
- CO2
- C2H4O2
- H2
- Which animals would have the highest testosterone level?
- Male Seasonal mammal under apt season
- Female seasonal mammal under apt season
- Male Seasonal mammal
- Female non-seasonal mammal
- Male Seasonal mammal under inapt season
Picture:
Artoria2e5, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons
Female Sex Behavior
Aubrey Strause, Grecia Reyes Santos, and Skyler Martinez
Female Reproductive Anatomy - Gina Marie Hazzard
Objectives:
- Learn about the main functions of the female reproductive system
- Learn about the external genitalia
- Learn about the internal genitalia
The main functions of the female reproductive system are reproduction, sexual intercourse, and produces sex hormones that maintain the menstrual cycle. The main function of the female external genitals is to protect the internal parts from infection and to allow sperm to enter for reproductive purposes. Vulva is the collective name for all the external genitals. People often mistake “vagina” as the entirety of the female reproductive system, but the vagina is its own structure within the system. In the vulva or external genitals there are six main parts: the labia majora, labia minora, clitoris, vaginal opening, hymen, and the urethra (The National Institute for Occupational Safety and Health (NIOSH), 2022).
The labia majora encloses and protects the other external reproductive organs. During puberty, hair growth occurs on the skin of the labia majora for protective purposes. The labia minora has a variety of different shapes and sizes. The labia minora lies within the labia majora and surrounds the opening of the vagina and urethra. The vaginal opening allows menstrual blood and babies to exit the body. Inside of the vaginal opening lies the hymen, which is a piece of tissue that covers part of the vaginal opening as a remnant of fetal development. Slightly above the vaginal opening is the urethra, where bodily fluids such as urine are excreted (Cleveland Clinic, 2022). Lastly is the clitoris, which is above the urethra and where the two labia minora meet. It is a small, sensitive protrusion of nerves that is covered by a fold of skin called the prepuce. The clitoris has both reproductive and pleasurable functions, as its stimulation results in sexual stimulation that helps to increase blood flow and lubrication within the vagina (Levin, 2020).
The internal genitalia of the female reproductive system have the main role of sexual activity and reproduction. There are five main components: the vagina, cervix, uterus, ovaries, and fallopian tubes. The vagina is the muscular canal that joins the cervix to the outside of the body. It widens during childbirth and can shrink back to its original size. It is lined with mucous membranes for protection and reproductive purposes. The cervix is the opening that allows sperm to enter the body and menstrual blood to exit the uterus. During childbirth, the cervix also dilates to facilitate pushing the infant out. The uterus is the organ that houses the fertilized egg and eventually a fetus during pregnancy. The uterus has two parts: the cervix and the corpus. The corpus is the larger part that expands during the course of pregnancy and the cervix is the barrier between the corpus and the vagina. The ovaries are small, oval-shaped glands that are on both sides of the uterus. The ovaries produce eggs (ovum) and hormones. The fallopian tubes are the narrow tubes that connect the uterus to the ovaries. They are the pathway for ovum to travel from the ovaries into the uterus, where fertilization of the egg occurs. Some women who become pregnant may have an ectopic pregnancy, where the embryo does not implant in the uterus, and most often implants in the fallopian tubes. These pregnancies are not viable as the fallopian tubes cannot expand with the expansion of the fetus, and can result in maternal mortality at a rate of 5-10% (Mullaney et al., 2023).
"Human female inner genitalia" by Sciencia58 is marked with CC0 1.0.
Assessment Questions:
- What is the collective name for all the female external genitalia?
- Uterus
- Vagina
- Cervix
- Vulva
- What is the main function of the external genitalia?
- Maintaining the menstrual cycle
- Sexual activity and reproduction
- Protection of internal genitalia
- None of the above
- What is the primary function of the internal genitalia?
- Sexual activity and reproduction
- Dilation for childbirth
- Maintaining hormones
- Production of ovum and hormones
Function of Female-Typical Hormones During Fetal and Sexual Development
Objectives:
- Understand the roles of hormones in fetal and pubescent development
- Distinguish between the functions of estrogen and progesterone
- Understand certain consequences women may face with unbalanced hormones
Before diving into the roles of estrogen and progesterone in the development of biological females, it is important to understand that there are no male or female sex-specific hormones. While androgens such as testosterone and dihydrotestosterone are associated with the development of male-typical behaviors and estrogens such as estrogen and progesterone are associated with female-typical behaviors, they are only correlated with these behaviors. This is why it is important to remember that correlation does not always mean causation, as you will see later in this section.
The sex of the embryo is determined at conception, but it is not until six weeks into the pregnancy where signs of gonadal differentiation will be visible. At this point in time, if the SRY gene is suppressed and the embryo is female (XX), then the ovaries will start to form. They will primarily produce estrogen and progesterone, which feminizes the brain and allows for the stimulation of estrogen receptors that will be needed during puberty. The ovaries also produce slight amounts of testosterone which is important for inhibiting the development of internal male genitalia aka the wolffian ducts. The lack of testosterone also allows for the development of external female genitalia which consists of the clitoris and labia. The ovaries also do not produce mullerian inhibiting hormones unlike male testis, which promotes the development of the mullerian ducts which consist of the fallopian tubes, uterus and cervix. So while estrogens are not actively present in physical sexual differentiation, it is the lack of androgens produced by the ovaries that result in the female characteristics of the embryo and allow for the feminization of the brain (N. Simon, Personal Communication, Feb 2, 2024).
After birth, the ovaries will stay quiescent, or dormant, until puberty. Once menses starts, the ovaries will actively produce the estrogens estradiol (E2) and progesterone (P). The ovarian hormones promote the development of secondary sex characteristics, such as breasts, body and facial hair, uterine lining, and body fat distribution. Normally, the body is able to regulate itself when it comes to these hormones, but in certain cases that does not happen, which leads to the development of certain disorders. In the uterus, estrogen is important for the maintenance of the mucous membrane, the thickness of the vaginal lining, and the act of self-lubrication for sexual intercourse (Lee et al., 2012). When estrogen levels are elevated, certain health risks can occur such as irregular periods and reproductive problems. When estrogen levels are too low, delayed puberty may occur or possibly not at all, which is known as primary amenorrhea. Women also have the risk of preventing timely sexual development, which can lead to low levels of sexual desire and painful sex. In regards to progesterone, the levels naturally rise after ovulation to prepare the uterus for pregnancy by triggering the vaginal lining to thicken in order to accept a fertilized egg. Progesterone also inhibits muscle contractions from occurring in the uterus so as to not reject an egg. Low levels of progesterone can impact the regularity of periods, and if the levels of progesterone remain high, then it can indicate pregnancy.
"Mullerian duct development" by Devinka98 is licensed under CC BY-SA 4.0.
Assessment Questions
- What instances can drastically change a woman’s hormone levels? Select all that apply.
- Puberty
- Disease
- Pregnancy
- Muscle contractions
2. Delayed sexual development is due to ___ ______ levels which can cause _____ ___.
- Low progesterone, normal sex
- High progesterone, painful sex
- Low estrogen, painful sex
- High estrogen, normal sex
Menstrual Cycle
Objectives:
- Learn about the three stages of the menstrual cycle
- Learn how a pregnancy or menstrual period comes to be through a monthly cycle
- Learn about menstrual cycle related disorders
Women that are of reproductive age, typically between the ages of 11 to 16 years old, experience cycles of hormonal activity that occur at approximately every 28 days. With each cycle, the body prepares itself for a potential pregnancy. In the ovaries at the time of puberty in a normal, healthy female are approximately 300,000 eggs. In preparation of a pregnancy, an egg moves down the fallopian tube, where it has the chance of becoming fertilized if a sperm reaches the egg. Regardless of whether or not sperm reaches the egg, it will eventually move its way into the uterus where implantation can occur. If the egg is fertilized, then the egg will attach itself to the uterine wall and develop into a fetus. In the instance when a pregnancy does not occur, then the uterine lining sheds, resulting in menstruation or a “period” (Cleveland Clinic, 2022).
The first phase of the menstrual cycle is the follicular phase, which generally starts on the first day of a period. During this phase, two hormones are released from the anterior pituitary gland in the brain and travel to the ovaries: follicle stimulating hormone (FSH) and luteinizing hormone (LH). The presence of FSH and LH trigger the release of estradiol. However at the low levels that estradiol begins at in this phase, it inhibits further production of LH. FSH stimulation is slightly regulated, but enough of the hormone remains to stimulate the growth of approximately 18 eggs in the ovaries. The shell that surrounds the egg is known as the follicle. Gradually one follicle will become dominant and continue to mature, which results in the rest of the follicles dying. At the same time as the follicle grows, estradiol levels will continue to increase until around day 12 of the menstrual cycle. Thus the ovulatory phase will begin as the follicle phase ends.
The increase in estradiol levels occur as a result of the self-stimulation that estradiol is able to accomplish. The presence of estradiol stimulates the estrogen receptors in the ovarian follicle. The estradiol is then able to bind to the receptors, stimulating more estradiol to be released. This continues to repeat itself until enough estrogen has built up within the follicle triggering a spike in LH production. Approximately five days prior to the LH spike, vaginal discharge may be experienced as the mucus is released to assist in sperm projection to the egg. Once the spike occurs, the dominant follicle will release the egg from the ovary and send it to the fallopian tube, transitioning to the luteal phase.
In the luteal phase, the empty follicle will become the corpus luteum, which releases estrogen and progesterone into the system. Progesterone is the dominant hormone during this time as it prepares the uterus for egg implantation, as well as inhibits the production of LH and FSH once more. If the egg has managed to become fertilized, then it will attach to the uterine wall and progesterone levels will remain high. If the egg was not fertilized, then it will dissolve in the uterus, and the lining that had formed will shed. Now the period, or menses, has started.
Generally, periods last between two to seven days. However, this varies amongst women depending on a variety of factors. These factors include: age, weight, diet, and even medication. Younger women tend to experience longer, more regulated cycles whereas middle aged women may start to experience irregular periods as they near the age of menopause, which marks the end of one's period as a result of aging. While younger women tend to have regulated cycles, there are instances where that is not the case. Conditions where there are irregularities amongst periods and behavior are known as menstrual cycle related disorders.
Examples of such disorders include:
- Polymenorrhea
- Diagnosis when a woman experiences periods more frequently or irregularly during cycles of <21 days.
- Oligomenorrhea
- Diagnosis when a woman experiences periods very infrequently and irregularly during cycles of >42 days.
- Primary Amenorrhea
- Diagnosis when a woman does not experience menstruation by 15.5 years of age.
- Primary Dysmenorrhea (PD)
- Extreme and intense throbbing experienced in the uterus before and leading into menstruation.
- Premenstrual Symptoms (PMS)
- Describes a wide range of symptoms including food cravings, fatigue, mood swings, irritability, etc that occur 5-7 days before menstruation.
- Premenstrual Dysphoric Disorder (PMDD)
- Differs from PMS in severity and duration. Women suffer from severe depressive symptoms up to two weeks before and during menstruation.
While the cause of these disorders are not clear, they can be extremely debilitating in the lives of women. There are treatment options that can be discussed with medical professionals such as hormonal birth control to prevent periods, making changes in lifestyle and diet, anti-pain medication such as ibuprofen, and depending on the severity of the case, antidepressants taken in the weeks leading up to the period to improve quality of life (N. Simon, personal communication, Feb 27, 2024).
"Hormone levels during the human menstrual cycle" by C. F. Draper K. Duisters, B.Weger, A. Chakrabarti1, A. C. Harms, L. Brennan, T. Hankemeier, L.Goulet, T. Konz, F. P. Martin, S. Moco & J. van derGreef is licensed under CC BY-SA 4.0.
Assessment Questions:
- In the Follicular Phase, which two hormones are released that trigger an increase in estrogen?
- Progesterone and Testosterone
- Follicle Stimulating Hormone and Progesterone
- Follicle Stimulating Hormone and Luteinizing Hormone
- Luteinizing Hormone and Progesterone
- During the Ovulatory Phase there is a surge of Luteinizing Hormone. What process results from this surge?
- Menstrual period
- Implantation
- Increase of cervical mucus
- Ovulation
- During the Luteal Phase, what occurs if the egg is not fertilized?
- Uterine lining is shed, beginning of the period
- The embryo will implant in the uterine lining
- Cervical mucus will increase
- None of the above
Olfactory Sensitivity
Objectives:
- Understand what the basic aspects of what the olfactory system is used for
- Be able to identify what olfactory sensitivity is
- Understand how olfactory sensitivity affects a woman’s sex life
Olfactory sensitivity is a sensation that occurs when olfactory receptors in the nose are stimulated by specific chemicals. Olfactory systems consist of things we are able to smell. The olfactory system also contributes to social behavior in humans and has an impact on how we choose specific mates. Specific odors, like androgen-odors, induce sexual arousal because olfactory perception leads to hypothalamic activation. These androgen-odors are otherwise known as pheromones. Olfactory perception is the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form. In a study done by Johanna Bendas, Thomas Hummel and Llona Croy there was an investigation of the relationship between olfactory function and its effect on sexual behavior using healthy individuals. The researchers hypothesized that higher olfactory function would be associated with higher levels of sexual desire, sexual experience and sexual performance. Odor sensitivity correlated positively with sexual experience. Participants with high olfactory sensitivity reported higher pleasantness of sexual activities (Bendas et al., 2018). Women with high olfactory sensitivity reported a higher frequency of orgasms during sex.
Assessment Questions
- High levels of olfactory sensitivity in woman can correlate to which of the following
- Higher frequency of orgasms compared to women with lower levels of olfactory sensitivity.
- Lower frequency of orgasms compared to women with higher levels of olfactory sensitivity
- Higher levels of estrogen
- Higher levels of progesterone
2. Which of the following would be considered a part of the olfactory system?
- Nose
- Mouth
- Eyes
- Ears
Abstinence, Sexual Activity, and Quality of Life
(Catherine Kelly)
Objectives:
- Understand the relationship between quality of life and sexual activity in those sexually active
- Be able to discuss the practice of abstaining from sex along with potential motivators for doing so
Abstinence is the behavioral practice of refraining from sexual activities with oneself or with partners. Abstinence levels have been historically higher in females than males, and over the last 100 years, the percentage of women practicing abstinence has decreased significantly (Wang 2014), but abstinence is still a notable sexually-related behavior worth discussing. There are a variety of sociocultural motivators for one’s decision to be abstinent. In a study exploring abstinence in relation to HIV transmission in South Africa, researchers sought to examine the reasoning participants in the study had for abstaining. While the practice of abstinence is mostly associated as a cultural and behavioral response to sexuality, common abstinence motivators that were observed for individual participants included conservatism, religiosity, as well as the desire to prevent consequences of unsafe sexual behavior, including pregnancy and the risk of contracting sexually transmitted diseases (Mokwena & Morabe 2016). It is important to note that abstinence cannot be interchanged with the term “asexual”. Asexuality is the clinical absence of sexual attraction or desire, whereas abstinence is the conscious choice not to take part in sexual activity, despite having normal sexual attraction and sex drive.
While there appears to be little notable correlation between abstinence and quality of life, studies have displayed evidence that sexual satisfaction plays a large part in quality of life for large populations of both sexually active male and female individuals (Flynn et. al 2016). Obviously, results from studies where people are asked to report how they feel about a particular behavior are subjective, and we cannot conclude that every abstinent person is experiencing poorer quality of life due to not participating in sexual behavior. However, knowing that sexual behavior does have a significant positive effect on the quality of life of sexually active people is valuable knowledge that can be considered when healthcare professionals evaluate patients overall health and wellbeing. Engaging in or refraining from sexual activities alone is not the determinant of quality of life, but rather the combination of one’s beliefs, experiences, environment, physical and psychological health, and medical predispositions.
Assessment Questions:
- Which of the following have been observed as recurring abstinence motivators? (Select Two)
- Higher education
- Avoidance of negative consequences of sexual activity
- Religiosity and personal beliefs
- Open discussion of sex in communities
2. True or false: there is notable correlation between abstinence and quality of life.
- True
- False
Sexual Attraction and Hormones
(Catherine Kelly)
Objectives:
- To understand the basics of categorization of female human sexual motivation
- Be able to discuss how hormonal changes and/or menstruation influences sexual motivation
Sexual motivation for females can be better understood through the endocrinology of sexual attraction. The brain's hypothalamus influences the production of the hormones testosterone and estrogen which are the major chemical substances that influence our sexual attraction and behavior. High levels of these hormones are known to be associated with high sex drive in women, so in cases of low sexual motivation, women can often be treated by being prescribed these hormones (Cappelletti & Wallen 2016). Contrary to popular belief, there are no male and female specific hormones. Rather, the role that hormones like estrogen and testosterone play are different in males and females. Hormones work in conjunction with neurotransmitters to obtain the physical sensations associated with sexual attraction and pleasure. The neurotransmitters most closely associated with sexual experience are dopamine and norepinephrine (Field, 2023). The dopamine pathway and its relation to sexual arousal and behavior has been very well studied, and there is ample evidence suggesting that it plays an important role in arousal, desire, and even orgasm (Meisel & Been 1970).
The female menstrual cycle also has a significant impact on sexual arousal and behavior, as hormone levels fluctuate significantly throughout the cycle. Ovarian hormones and anterior pituitary hormones are the most important hormones that change throughout a menstrual cycle. These changes in hormones are associated with different levels of sexual motivation. Sexual motivation and behavior is reported to be at its highest during the follicular phase leading up to ovulation. Drive declines significantly after ovulation in the luteal phase (Shirazi et. al 2018). This makes sense, as after ovulation, there is less chance of pregnancy as the egg prepares to be shed with the lining of the uterus after not being fertilized. Evolution of the menstrual cycle and hormonal changes have made sure that high sex drive aligns with the highest probability of conception to increase the chances of becoming pregnant.
Assessment Questions:
- Which of the following are primary neurotransmitters released during sexual attraction? (Circle two)
- Acetylcholine
- Norepinephrine
- Dopamine
- GABA
- Which phase of the menstrual cycle is associated with high levels of Progesterone?
- Luteal
- Follicular
- Ovulation
- Menstruation
- True or false: estrogen is exclusively a female hormone.
- True
- False
Sexual Excitement/Sexual Anxiety
(Catherine Kelly)
Objectives
- Be able to identify the different anatomical differences that arise from a woman being sexually excited
- Understand the difference between physical and psychological sexual stimulation
- Understand the different factors that can cause sexual inhibition and sexual avoidance
Female sex behavior is regulated by a sexual response cycle which consists of desire, excitement, orgasm and resolution. When a woman is sexually aroused, the process that occurs follows a predictable sequence of events.
Female sexual arousal can be initiated by either physical and/or psychological sexual stimulation. Common responses to physiological stimulation are vasocongestion, myotonia, vaginal dilation, and protrusion of the clitoris (Woodard, Diamond 2009). Other responses to sexual excitement can be an increased heart rate, increased blood pressure and higher respiration. Unlike men, when a woman is sexually excited, vaginal lubrication occurs. Although vaginal lubrication occurs as a response to being sexually excited, the amount of lubrication varies from person to person, and many women suffer from inability to self-lubricate. Psychologically, we refer to arousal as subjective arousal, which can be defined as “mental engagement during sexual activity” (Meston & Stanton 2019). Both subjective and genital arousal play key roles in sexual behavior, but the two are often regarded as separate entities that act in distinctly different ways.
https://commons.wikimedia.org/wiki/File:Female_genital.svg
Sexual anxiety can be thought of as anxiety related to engaging in sexual behavior, whereas sexual aversions are defined as “persistent or recurrent extreme aversion to, and avoidance of, all or almost all, genital contact with a sexual partner.” (Brotto 2010). The sexual aversion scale assesses sexual fears, sexual guilt, pregnancy, as well as sexual trauma. All of these factors can have an impact on one’s ability to become sexually excited and engage in sexual behavior. There are a range of psychological therapies available that aim to help people suffering from sexual anxiety or aversion work through their fears and concerns in order to have a healthier sex life, which can ultimatelt lead to overall better wellbeing.
5 Rare Sexual Disorders To Learn About
Check out this video for more information on rare sexual disorders!
Assessment Questions:
- Sexual anxiety can disrupt which of the following?
- Respiration
- Heart rate
- One’s ability to become sexually excited
- Puberty
2. What can cause sexual aversion to occur?
- Low olfactory sensitivity
- High olfactory sensitivity
- Sexual trauma
- A Bad diet
3. What is most likely to occur if a woman is sexually excited?
- Increased blood pressure
- Vaginal lubrication
- Increased body temperature
- Increased appetite
- Glossary
- Abstinence
- Acetylcholine
- Afferent-efferent reflex pathway
- Amygdala
- Androgen
- Aromatase enzyme
- Aromatize
- Bulbocavernosus muscle
- Celibacy
- Cerebral
- Cervix
- Clitoris
- Coitus
- Corpus
- Cortisol
- Diabetes mellitus
- Dihydro-T (DHT)
- Dopamine
- Ectopic pregnancy
- Emission
- Endocrinology
- Erectile Function
- Epithelial cells
- Estrogen
- Estradiol
- Expulsion
- External genitalia
- Fallopian tubes
- Fertilized egg
- Follicle
- Follicle stimulating hormone
- Follicular phase
- Glans penis
- Glands
- Hymen
- Hypoactive Sexual Desire Disorder (HSDD)
- Hypogonadal
- Hypothalamus
- Implantation
- Ischiocavernosus muscle
- Labia majora
- Labia minora
- Luteal phase
- Luteinizing hormone
- Masturbation
- Menopause
- Menstruation
- Metabolic syndrome
- Mullerian ducts
- Myotonia
- Neurotransmitters
- Norepinephrine
- Nonseasonal mammals
- Olfactory receptors
- Olfactory sensitivity
- Oligomenorrhea
- Orgasm
- Ovaries
- Ovulation
- Ovulatory phase
- Ovum
- Parasympathetic nervous system
- Pheromones
- Polymenorrhea
- Pregnancy
- Prefrontal cortex
- Premature ejaculation
- Premenstrual dysphoric disorder
- Premenstrual Symptoms
- Prepuce
- Primary amenorrhea
- Primary dysmenorrhea
- Progesterone
- Psychoneuroendocrinological interactions
- Puberty
- Quality of life
- Quiescent
- Receptors
- Refractory period
- Responses
- Seasonal mammals
- Selective serotonin reuptake inhibitors
- Seminal fluid
- Sexual activeness/frequency
- Sexual anxiety
- Sexual arousal
- Sexual attraction
- Sexual aversions
- Sexual behavior
- Sexual desires
- Sexual dysfunction
- Sexual motivation
- Sexual satisfaction
- Sexual stimuli
- Sexual stimulation
- Sexual trauma
- Sex glands
- Sex hormones
- Sexual development
- Sexual desire
- Sexual desire
- Sexual satisfaction
- Sexual avoidance
- Sexual fears
- Sexual activeness/frequency
- Sexual motivator
- Sexual satisfaction
- Sexual trauma
- Spinal ejaculation generator
- Spinal reflex
- Stimuli
- Testosterone
- Thalamus
- Urethra
- Urethral meatus
- Uterus
- Vagina
- Vaginal discharge
- Vaginal lubrication
- Vaginal opening
- Vaginal pulse amplitude
- Vasodilation
- VOC
- Vulva
- Wolffian ducts
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