BIO 123 - Midterm 2 (FINAL VERSION)

A. A. Berthold

 The father of modern-day Endocrinology who was the first person to discover hormones.

* The way he realized that hormones were present in the bloodstream was by observing chickens. Specifically, he was curious why roosters had male-typical behaviors and anatomy.
* He conducted an experiment where he removed the testes from a baby rooster. He found that their comb and wattles were small, they had no interest in hens, weak crow, and listless fight behavior.
* What was revolutionary about this experiment was that by putting the testis back into the body, he knew that it was impossible that these changes couldn’t have been controlled by the nervous system, which is the alternative to a chemical signal like hormones.
* When the testis was put back into the body, blood vessels grew into it, and so he knew that the testes had to be secreting some chemical signal into the blood.
* Many years later that chemical signal was discovered and named testosterone.
* The idea that testes caused something was believed for centuries before Berthold, but he confirmed that it was a chemical messenger.

Testosterone

* Present in all vertebrates, both male and female
* Sometimes it’s called a male-typical hormone because it’s responsible for male physical characteristics.
* Also leads to the development of behavioral male characteristics.
* Causes roosters’ male physical characteristics, calling, mating, and running. Running tends to make their meat more stringy. If you castrate a male chick the meat will be juicier.

Calvin and Grace Coolidge - 30th President of the United States who had a biological phenomenon named after him

* He was visiting a chicken farm, on a tour separately from his wife. His wife came to the chicken yard and noticed that the male rooster was mounting and having sex with female after female. She told the guide to tell president Coolidge. The guide told Coolidge and he then asked him said to tell Grace.

The Coolidge Effect

* The presence of multiple females stimulates sex drive in males and does so in part by stimulating the release of testosterone which causes them to want to mate and call and so on.

Eunuch

a man who has been castrated, especially (in the past) one employed to guard the women's living areas in an Asian court

Castrati

young Italian boys with beautiful opera voices who were castrated before puberty so that testosterone would not cause their voices to deepen.

**Estracycle**

When females are receptive or when they can get pregnant

**Monoestrous**

Animals like wolves have one time period per year in which females are receptive and in which females can get pregnant. Only for a few days once per year can Monoestrous mammals mate.

**Seasonal Polyestrous**

Animals that have a certain season in the year where they mate multiple times. Certain rodents and chickens fit this example. Estracycle is one egg per day.

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**Monthly Estrous (Menstrual)**

When a human female ovulates one egg per month. Is receptive to males all month long, but can only get pregnant for a short period of time once per month.

**No Estrous**

Rabbits, females are always receptive and always able to get pregnant. That’s why they say “breeding like rabbits.”

**Gonadotropins**

* The brain releases hormones into the bloodstream called Gonadotropins, there are two (LH, FSH).
* Stimulatory hormones, also present in males
* They stimulate the testes to make **Sex Steroids** (Estrogen, Progesterone, and Testosterone)

 **Sex Steroids**

* (Estrogen, Progesterone, and Testosterone)
* Sex Steroids inhibit the release of Gonadotropins from the brain to the sex organs
* This is called negative feedback inhibition, where gonadotropins are released, which stimulates the production of sex steroids, and those sex steroids inhibit the production of more gonadotropins. This is like a thermostat in that it keeps the hormones at a constant level.

Anabolic Steroids:

*  Men who take a lot of steroids (testosterone), which goes to their brain and inhibit the production of gonadotropins, effectively preventing them from producing their own testosterone. This is reversible however, if they stop taking the steroids

The Menstrual Cycle

 the same negative feedback inhibition cycle applies here as well. 28-day cycle of hormones and menstruation

Day 1 - 4:

Menstruation first occurs when the lining of the uterus leaves the body, becoming less thick. The levels of estrogen and Progesterone are still pretty low at this point.

Day 4 - 14:

Estrogen levels start to rise pretty rapidly. The growth of tissue in the uterus lining is caused by the increase in estrogen. The estrogen is made by the ovaries, and as the estrogen levels rise the lining of the uterus begins to build back up. The egg is released from the ovaries at about day 14, during ovulation, and at this point, the estrogen levels slowly decline until the next cycle but the Progesterone levels spike and maintain from days 14 - 28

Day 14 - 28:

The lining is maintained by progesterone so that if a woman has sex and her egg is fertilized, it can attach to the uterine wall. After day 28 the next cycle begins. If pregnancy occurs, Progesterone levels stay high, otherwise, it dips down until the next cycle and the lining breaks down again.

**Birth Control Pill**

* Consists of progesterone, and sometimes other hormones.
* By adding progesterone, you block the production of gonadotropins, which means that you don't produce estrogen.
* Without estrogen, the uterus lining never builds up, there is no ovulation.

**“The Shot” (Depo-Provera) & “The Implant” (Implanon)**

both are progesterone-based hormonal contraception. They slow-release progesterone so that you do not ovulate, but even if you did, the uterine lining wouldn’t be thick enough anyway. Because progesterone levels never drop, the woman never has her period.

**Chemical Castration:**

* Progesterone shots reduce a man’s testosterone production and testosterone blood levels, and is called chemical castration. Is reversible, but is effectively stopping the production of testosterone. 
* Second-offense sex offenders are sometimes chemically castrated to reduce their urges. It’s very controversial where this actually works, but is still used in some cases.

**“The Morning After Pill” (Plan B**) **(contraceptive)**

*  Only prevents pregnancy when taken before fertilization of the ovum has occurred.
* A high dose of progesterone (contraception means against conception, meaning that it prevents pregnancy)
* Is not the same as getting an abortion because if a woman had already ovulated she would get pregnant anyway.

**“The Abortion Pill” (Mifeprex) (abortifacient):**

*  **is an abortifacient, it actually causes abortion in the first 7 weeks.**
* **The abortion pill actually has a progesterone blocker, preventing progesterone from binding to its receptor.**
* **While progesterone levels don’t change, progesterone cannot signal to the cells.**
* **Progesterone helps to maintain the uterine lining, so if its ability to do that is blocked, then the uterine lining will be shed, and the embryo with it.**
* **This is approved in the US for the first 7 weeks of pregnancy with a doctor's prescription**

Effectiveness of female birth control: Most effective

* implants, vasectomies, female sterilization, and IUDs.

Effectiveness of female birth control: Mostly effective

* Injectables, pills, LAM (Lactation amenorrhea method). Breastfeeding constantly during the first six months 

Effectiveness of female birth control: Somewhat effective

condoms, diaphragm, fertility-awareness-based methods

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Effectiveness of female birth control: Not very effective

Withdrawal, spermicide

Male birth control:

* Pill and Gel: progesterone and testosterone
* Nonsurgical vasectomy: injects a polymer into the vas deferens to block sperm

As long as progesterone is high

menstruation will not occur and the fetus develops. This is because progesterone functions to maintain the uterine lining, which the fertilized egg implants into.

Home pregnancy tests detect

embryonic gonadotropins in urine. Blood tests as well.

The implanted embryo secretes

embryonic gonadotropin (HCG), which acts just like the gonadotropin from the brain (LH, FSH), and it causes the ovaries to continue making progesterone.

Gestation Period

40 weeks total is gestation.

Order from fertilization to birth

Fertilization between sperm and egg lead to a fertilized egg, cleavage then occurs, where the egg divides into the Blastula/Blastocyst, then the Gastrula, and then the early first trimester, first trimester, second trimester, and lastly newborn.

* What causes childbirth?

* It’s caused by an interesting cascade of events that culminates in the release of oxytocin, which stimulates the muscles in the uterus to start contracting. Oxytocin positively stimulates contractions in the uterus to help squeeze and push the baby out.
* The woman will start timing her contractions because as her labor progresses the contractions become closer and closer together. While this is happening, the cervical canal at the bottom of the uterus begins to dilate. Once she’s about 10cm dilated and oxytocin continues to do its thing, then she’ll be ready to push.
* There is a positive feedback loop where oxytocin causes an increase in further oxytocin, which causes an increase until the contractions get so strong that the baby is born.

**Labor Induction:**

* pitocin is an oxytocin injection that is sometimes administered to help speed up labor.

**Epidural Anesthesia:**

A catheter is put through the spinal cord which allows injection of anesthetic via the epidural needle. Some dull the pain from the waist down to more easily push while others completely block the pain, called spinal blocks, which is done more in a cesarian section.

Early dilation

* Baby’s head engaged, widest dimension is along left-right axis.

Late dilation

*  Baby’s head rotates so widest dimension is in anteroposterior axis. Dilation nearly complete.

Expulsion

Baby’s head extends as it is delivered

Placental stage

* After baby is delivered, the placenta detaches and is removed.

Women with narrower hips have a harder time with childbirth, but this is made easier by

Fontanels and Episiotomy

**Fontanels**

* When a baby is born, the skull bones are not fused together, instead each piece called a fontanel, is connected via. cartilage. This makes the baby’s skull much more flexible and easier to squeeze through the birth canal. The fontanels will eventually fuse and the head will become normal.

**Episiotomy**

a slight incision below the vagina which is very controversial. Some physicians say it helps prevent tearing and guides the place where the injury will occur to a less serious place. Others say there’s no need for an episiotomy.

**The Afterbirth (Delivering the Placenta)**

after the baby is delivered, the placenta comes out. The umbilical cord is connected to the placenta. While the ovaries make most of the progesterone at the beginning of a pregnancy, eventually the placenta takes over and makes most during the later stages.

The Placenta:

* Nutrient, waste, and gas exchange
* Makes hormones
* Makes hormones important for pregnancy and childbirth
* “Cloaks” mother’s immune system: To prevent the mother’s immune system from killing the baby’s cells.

Umbilical cord:

The belly button is basically a scar where the umbilical cord used to attach.

Nuchal Cord (Very serious)

* The baby’s umbilical cord wraps around its neck and can suffocate it. In general, physicians are able to move the baby around inside the uterus to remove the chord from around its neck, but if not, the baby will be delivered via c-section.

Breech (Somewhat serious)

* Most babies are born head first, but if a baby is facing feet first it can be a big problem because when babies try to come out feet first, the infant's head can be caught in the birth canal, and that can threaten a safe delivery. Sometimes it works okay, but generally risky.

Placenta Previa (The most serious

* Occurs when the placenta blocks the cervical canal. If nothing is done, the baby’s head will push against the placenta and rupture, causing both the mother and the baby to bleed to death. If a placenta previa is found on an ultrasound, the doctor will do a C-section.

Cesarean Section

* When the mother’s abdomen is cut open to rapidly remove the baby. This is an emergency surgery, although it can sometimes be done as a pre-scheduled surgery. Usually, the mother is awake and there is no general anesthesia but instead a spinal block (epidural). There’s usually a sheet in front of her so she can't see but she feels some pressure.

Some countries in Africa underuse c-sections.

(Nearly 1 in 3 U.S. babies delivered by C-section.

Many people are choosing elective c-sections to

avoid the pain of vaginal birth, to avoid stretching out their vagina, and to avoid having an episiotomy

Babies delivered by Caesarean section are at a higher risk of

asthma and allergies.

When a baby goes through the vagina it’s exposed to

certain kinds of bacteria that colonize the baby’s gut and help it to digest food.

C-section Risk Factors

* Researchers found significant differences in the gut bacteria found in infants born surgically and naturally
* Exclusively bottle-fed babies also had significant differences in their gut bacteria
* Previous research found children born surgically are at double the risk of obesity in childhood
* C-sections increase the risk of autism by 23%
* Antibiotics or C-section can increase likelihood of childhood obesity because it changes the kind of gut bacteria that the child is born with, leading to different dietary choices.

Lactation

* As mammals, we are defined as mammals by lactation, where we feed our young milk produced by the mammary glands.
* Underneath the fat in breasts are mammary glands which produce milk.
* Breast milk is different than cow milk as it's mostly water, 88.1%.
* In Babies, Breastfeeding is associated with a lower risk of many diseases. Part of this is because human breast milk contains substances that are important in stimulating the baby’s immune system.
* Women who breastfeed have less breast cancer.
* Also better for the planet, no methane emissions like there are when drinking cow’s milk.

**Biological “Assigned” Sex:**

anatomical, physiological and genetic characteristics associated with being male or female

**Gender Identity:**

psychological sense of being male or female. May match biological sex, those people are called cisgender and if not, those people are called transgender.

**Sexual Orientation (=Attraction):**

enduring (excludes experimentation) pattern of attraction to people

**Sexual Behavior:**

people you actually have sex with

**Our current understanding of sex and gender and how they’re all related is called:**

**The Gender Unicorn**

**The Gender Unicorn:**

Gender Identity: female/woman/girl, male/man/boy

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Gender Expression: feminine/masculine/other

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Sex Assigned at Birth: Female, male or other/interex

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Physically Attracted to: Women, Men, Other Gender(s)

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Emotionally Attracted to: Women, Men, Other Gender(s)

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**Gender Identity in Humans:**

very little we know about this scientifically

*Nature vs. Nurture:*

is gender caused by something permanent or biological or is this learned by being brought up a certain way? It’s not one or the other and is extremely complicated and can be different from person to person.

David Reimer

One of two twin boys. When he was a young boy he had a botched circumcision that ruined his penis. His family decided to surgically change his sex to a girl and condition him as a girl. When he found out he was born male all hell broke loose. When he started to hit puberty and felt uncomfortable in his body, he changed his sex back to male.

John Money

Believed that gender identity was totally based on nurture. He was very wrong.

**Gender-Diverse Cultures**:

There are many cultures that have long recognized that there is more than just male and female.

**The Hijra**

a group of transgender people in South Asia including India. They are usually men who are transgendered females who sometimes change their sex to females via surgery. They are known as the third gender. The word hijra is sometimes seen as derogatory but these people are also revered. Many of them work as sex workers and experience high rates of sex crimes.

**Sexual Behavior in Animals**

We can’t say what an animal is attracted to, only what they have sex with. In animals, behavior and orientation are conflated whereas in humans they are not. Homosexuality in animals is extremely common.

Sexual variation is

normal

**Why do animals exhibit same-sex sexual behavior?:** \n

**Assertion of Dominance**

Dominant male asserts dominance over a subordinate male

**Why do animals exhibit same-sex sexual behavior:**

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**Prisoner Effect**

when limited to only other men, animals and men may have sex with each other when usually they would not.

**Why do animals exhibit same-sex sexual behavior?:**

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**Social Glue**

bottlenosed dolphins have sex with each other because it creates bonds and may reduce tension and conflict or it may facilitate reconciliation after conflict

**Why do animals exhibit same-sex sexual behavior?:**

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**Practicing**

Maybe they’re just practicing sex for when they have actual females to mate

**Anything But Sexual**

Two male orangutans regularly mouthed the penis of the other on a reciprocal basis. This behavior, however, may be nutritively rather than sexually motivated.

**“Discourse of Deviance”**

Scientists using pejorative adjectives to describe homosexuality - strange, bizarre, aberrant, deviant, abnormal.

**Human Sexual Behavior vs Orientation:**

people may not act on their orientation

**Homosexual:**

has sex with people of the same assigned sex

**Heterosexual:**

has sex with people of the opposite assigned sex

**Bisexual:**

has sex with people of either the same or opposite assigned sex

**Pansexual:**

has sex with anyone regardless of sex

**Kinsey Scale of Sexual Behavior - named after Alfred Kinsey**

0 - 6 from exclusively heterosexual to homosexual. He concluded that as many as “10 percent of the males are more or less exclusively homosexual…for at least three years between the ages of 16 and 55. He’s looking at sexual behavior, not orientation.

**How many Americans are actually gay?**

About 10% of the human population is LGBTIQ.

Is sexual orientation a choice?

the overwhelming evidence shows that it is not a choice

Several (blank) have been identified as potentially being involved in sexual orientation

genes

Homosexuality can be (blank) (from twin/sibling studies)

heritable

**INAH (**Gay, straight, and the reason why (Simon Levay)) **-**

sexually dimorphic meaning that it has different shapes and sizes in males and females. The number of neurons is much higher in the INAH of men than in women. Higher INAH3 was associated with sexual behavior. The size of the INAH3 was much more similar to that of women. Part of the reason gay men are attracted to other men is because they have a similar sized INAH3 to women.

**LGBTQIA**

**L**esbian

**G**ay

**B**isexual

**T**ransgender

**Q**uestioning

**I**ntersexual

**A**sexual

**Pheromone**

Chemical signal that alters behavior or physiology of others

* Different from odor cues: receptors and brain regions are different. Their nerve connection to the brain is different than that of odor cues
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Flehmen Response

Animals develop different facial expressions for when they are detecting pheromones. Allows animals to detect pheromones

Vomeronasal Organ (VNO)

Resides underneath the nose and allows animals to process the pheromones.

* Delivers pheromone signals to the brain
* Different neuron pathway than olfactory signals
* Humans do not have a VNO, but we definitely use odor queues.

**Sex Pheromones:**

* Chemical signals that alter the sexual behavior of another individual
* Advertise species, fertility, receptivity, quality
* Moths are active at night, so visual queues are not that important but pheromones are. Trying to find another moth to mate with in the dark is hard but pheromones make it easier. Moth antennae detect pheromones; they are similar to the VNO in dogs, snakes, lizards, etc. The pheromones can travel up to 30 miles.
* When visual and auditory queues aren’t useful, pheromones are.

Traits of sex pheromones

* Travel slowly
* Last long
* Travel far

Male moths use their (blank) to produce pheromones. 

hair pencil

Pheromones can be used to deceive

Orchids have evolved a trick that attracts longhorn beetles by mimicking their pheromone blend into carrying its pollen and spreading it to other orchids. They have evolved multiple traits to mimic bugs into spreading their pollen/semen.

Why do male moths fall for this bolas spider?

*  Because most of the time the pheromone signal is real and missing out on a breeding opportunity is major
* Uses a pheromone-laced globule attached to her web to bait and capture male moths for food. She can use different pheromones based on the type of moth.

Pheromones Used to Detect Receptivity

Male giraffes use flehmen response by tasting the female’s urine to determine if they are ovulating and receptive.

Pheromones Can Prevent Inbreeding

Many animals have pheromone-producing glands in their cheek that otters use to inspect each other. Squirrels learn their own “scent”, and use it as a reference for how to react to others. They do the same kissing behavior as otters because they have the same pheromone-producing glands in their cheeks that they can use to determine if they are related to the squirrel they are interacting with.

**The Armpit Effect -**

* **The less related the other individual, the more the “scent” is investigated**
* **Cubes rubbed on strangers, some related more than others to the test animals**
* **Researchers examined how long test animals investigated the cubes**

What about inbreeding in humans? (incest): We can voluntarily avoid inbreeding but pheromones are less significant 

* Incest taboos exist more or less in different human cultures.
* In some places it’s illegal, in some places it’s not.
* In royal families, for example, hemophilia (can’t stop bleeding) became extremely common 
* Consanguineous union caused Charles II to be severely physically and sexually defective: he was very short, had a growth hormone deficiency, severe renal tubular acidosis, and so the bloodline ended with him.
* Engaged couple discovered they were brother and sister when their parents meet just before wedding
* The unnamed pair are expecting a child and had been together for five years
* On average, first cousin unions can produce children that have medical difficulties but isn’t necessarily true on average.