Sex

What factors is sex defined by?

Chromosomes, gonads, sex hormones, reproductive anatomy.

How are gonads different from other reproductive anatomy?

Their dev elopment depends on specific genes instead of hormone signaling.

SRY Gene

Gene on the Y chromosome that is responsible for triggering male-typical development.

Sexual Dimorphism

The differences between males and females of a species beyond their sex organs. Can arise form genetic and hormonal difference and from environmental influences.

What is responsible for sex differences in the brain?

Gene-environment interactions.

What does genome sequencing and analysis of brain activity tell us about a person?

Very little about a person’s behavior, skills, and intelligence.

Gametes

Reproductive cells produced by the gonads. Gametes only have one version of every chromosome including only one sex chromosome.

At the end of the first month of gestation what do embryo cells form?

Undifferentiated gonads. Mullerian system, and the Wolffian system.

What happens during the second month of gestation?

If the SRY gene is present the gonads develop into testes and if it is absent AND there are two X chromosomes, ovaries develop.

Androgens

Released by the testes and include testosterone (triggers development of internal reproductive anatomy) and dihydrotestosterone (triggers development of external reproductive anatomy).

Anti-Mullerian Hormone

Causes the Mullerian system to wither away.

What triggers development of female reproductive anatomy?

It is the default anatomy and the absence of anti-Mullerian signaling causes internal female reproductive anatomy to develop. The absense of androgen causes external anatomy to develop.

Turner Syndrome

Only one X chromosome without any gonads. Development occurs in the female-typical manner but are infertile and do not naturally undergo puberty.

Swyer Syndrome

Person with a Y chromosome with a not functioning SRY gene.

Persistent Mullerian Duct Syndrome

There is insufficient anti-Mullerian hormone signaling and people develop both male and female internal sex organs. They usually have functioning external male genitalia and are often fertile.

Androgen Insesitivity Syndrome

Caused by mutations in the adrogen receptor and result in incomplete or no masculinization of the body. External female genitalia develop without any internal sex organs in sever cases.

Kisspeptin

The key peptide that initiates puberty and signals the hypothalamus to trigger the release of GnRH.

GnRH

Stimulate pituitary to secrete two hormones (FSH and LH) which circulate in the blood and cause the gonads to release sex hormones.

What happens when a male has insufficient testosterone levels?

Required for males to be fertile.

Estrous Cycle

Animals broadcast when they are ovulating and fertile by changing their behavior and pheremones.

What happens when rats are castrated?

They show some female-typical behaviors and when injected with female sex hormones they often try to get other males to have sex with them.

Cognitive Adrenal Hyperplasia

The adrenal glands of females produce abnormally large amount of androgens resulting in partial masculinization of the body. Females have an increased chance of identifying as a straight man.

VMH

Plays an essential role in female sexual behavior and its size is regulated by testosterone. Located in the hypothalamus.

Medial Preoptic Area (mPOA)

Plays essential role inn male sexual behavior. There is a sexually dimorphic nucleus that is larger in males.

What signaling molecules are involved in pair bonding?

Vasopressin and oxytocin that are released in the blood as hormones and the brain as neuropeptides.

What happens to voles when vasopressin and oxytocin receptors are blocked?

Who they pair up with and when is influcned.