Chapter 8 Hormones + Sex Flashcards

Question

What is the relationship between hormones and human sexual behaviour?

Answer 1

Hormones play a permissive role only, they have to be there to stimulate sexual interest but they are not the main contributor to sexual behaviour. How other hormones (beyond testosterone) affect sexual behaviour is still unclear.

Answer 2

In animals pheromones allow for communication about information like identity, sexual attractiveness and receptivity, and status. They can influence the behaviour of others. In humans there may be some communication but it is very different than in animals and, although the obvious function would be to enhance reproduction, how it does so is unclear. Example pheromones may result in the synchronization of menstrual cycles in woman living in close proximity but there is no clear reproductive benefit from this.

Answer 3

the process by which individuals develop male or female sex characteristics and behaviours.

Answer 4

The default path of development is for the indifferent gonads to develop into ovaries. The external cells of the indifferent gonads will proliferate. If there is a Y chromosome, there is a sex determining region (the SRY gene). This encodes proteins that direct the internal core cells of the indifferent cell to proliferate, developing the indifferent gonads into testes.

Answer 5

The early fetus has a 1. ) genital bump that differentiates into either the clitoris or the penis (if exposed to testosterone) 2. ) Wolffian Duct: If exposed to testosterone, this system develops into the epididymis, vas deferens, and seminal vesicles. If not exposed to testosterone, than it degenerates. 3. the Mulllerian Ducts: if exposed to anti-mullerian hormone, it degenerates; if not exposed to AMH, it develops into oviducts (fallopian tubes) uterus, and inner vagina.

Answer 6

Testosterone is not strong enough to masculinize all structures in the body but it can be converted into a more potent androgen called dihydrotestosterone (DHT) by the 5-alpha-enzyme. DHT masculinizes the external genitalia to form the penis, prostrate gland, and scrotum. Without any androgens, a labia and fully formed clitoris develop.

Answer 7

A syndrome in which the individual is born with a single X chromosome and no other chromosome. Because there is no SRY gene, the individual has a largely feminized system. The wolffian system degenerates and the mullerian system remains. The external genitalia form into labia and clitoris. The ovaries are underdeveloped but recognizable. Individuals with Turner's syndrome often have consistent physical markers such as : - a short stature, - low hairline - fold of skin on neck - small finger nails - brown spots on the skin - distinct eye shape - cardiac issues - poor breast development - elbow deformities

Answer 8

When a female fetus (XX) is exposed to higher than normal levels of androgens due to overactive adrenal glands. They do not have the SRY gene nor enough testosterone to fully masculinize however. This results in an intersex appearance where the phallus will be intermediate between a penis and clitoris and the skin folds will be intermediate between a scrotum and labia. The individual will have ovaries and NOT testes due to a lack of the SRY gene however. This means that even if the genitalia are more masculine in form, the scrotum will be empty.

Answer 9

The androgen receptor gene is mutated resultign in malfunctioning androgen receptors. The individual has XY chromosomes and will develop normal testes BUT - depsite the testes producing testosterone, the body is insensitive to it and so the wollfian system degenerates. - the testes produce AMH so the mullerian system also degenerates. - being unable to detect testosterone, the individual develops a labia and clitoris and breasts (at puberty) - they do not mensturate (no uterus or ovaries) - they look and behave like woman (despite having XY)

Answer 10

Guevedoces means having a genetic mutation that disables the 5-alpha-reductase enzyme, preventing testosterone from turning into dihydrotestosterone. A lack of DHT means that the individual will develop normal testes and internal male reproductive systems but will have unmasculinized external genitalia that give the appearence of a clitoris and labia without the vaginal opening. At puberty, there is a enough testosterone to compensate for the lack of DHT and the external genitalia will develop into a scrotum and penis. In an area of the Dominic Republic, this condition is relatively common. For the first half of their lives, the individuals will present as female and then at puberty will change their presentation to male.

Answer 11

- The two are so closely tied that it is difficult (arguably impossible) to pull it apart. It is clear that it is more than simply having an XX or XY that makes someone a man or woman. For example, individuals with Turner's syndrome (who only have 1 X) reliably identify as woman as do women with androgen insensitivity (who actually have XY. We cannot reliably point to hormones as the determiner either. For example. it is not simply having testosterone that makes someone male (consider individuals with Guevedoces, they have testosterone all their life but begin with identifying as female) Likewise, woman with Congenital Adrenal Hyperplasia still identify as woman despite having higher than normal exposure to androgens however they do demonstrate some more male-typical behaviour, they are often described as tom-boys, tend to demonstrate male cognitive skills, and are more likely to be sexually attracted to females. So while hormones are not the only factor, they do obviously play a role. But again, we cannot disregard the role that socialization plays. For example, do those with Guevedoces transition from female to male during puberty because of hormonal changes that affect their physical body and presentation or is it because such a transition is not only culturally accepted but also encouraged? Are the male typical behaivours seen in AIS due to socialization exaggerating such behaviours. (e.g. growing up being called a tom-boy could affect how individuals present themselves)

Answer 12

Testosterone is aromatized (converted into estrogen in the cells of the brain via the enzyme aromatase). This means that it is actually estrogen that masculinizes the brain. Woman do not have a masculinized brain because an alpha-fetoprotein sequesters the estrogen, preventing from entering the brain.

Answer 13

In Rats, two main areas display sexual dimorphism. - the preoptic area of the hypothalamus is larger in rats exposed to testosterone during development. i the spinal nucleus of the bulbocavernosus (SNB). These nerves inervate the muscles at the base of the penis/clitoris. before birth, male and female rats have an equal number of nerves here. After birth, most SNB cells die off in female rats. In humans, females will still have SNB nerves but not as many as their male counterparts.

Answer 14

In rats, grooming by the mother can affect sexual differentiation. Males pups who are groomed more have larger SNB regions than pups who are groomed less. Female pups who are groomed more have more higher estrogen and oxytocin sensitivity which tends to make them more responsive mothers themselves.