3 - Biology

Question 1

Define the term hormone.

Answer 1

• A hormone (Greek roots: “to set in motion”) is any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour
  → Essentially, they are messengers that tell the body organs and tissues what to do
  → they all have many roles (which is why a lot of medication has secondary effects)

Question 2

What is the role of endocrine glands?

Answer 2

• Endocrine glands secrete hormones and are important to development of the sexes:
  → Releasing hormones are produced by the hypothalamus to stimulate the pituitary gland which produces tropic hormones to stimulate the gonads, i.e., ovaries and testes

Question 3

What is the role of the gonads?

Answer 3

• The gonads secrete steroidal hormones which are heavily involved in reproductive functioning (reproduction is their main role):
  → Androgens—most common is testosterone
  → Estrogens—most common is estradiol
  → Progestins—most common is progesterone
  → Males and females produce all three but in differing proportions

Question 4

What are the elements/characteristics of heredity?

Answer 4

• The basic building block of the nature perspective is the gene
  → Genes are specific sequence of nucleotides and are recipes for making proteins
  → Proteins make up the structure of the cell and let it function; They’re the building blocks and machines of cells
  → Genes are the blueprints that let our bodies build those blocks and machines
  → Genes are DNA sequences
  → DNA is looped up into clumps called chromosomes

Question 5

What is the role of chromosomes in sexual differentiation?

Answer 5

• Normally: In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females: “sex chromosomes”
  → Males – XY
  → Females – XX
  → the Y chromosome is shorter (not a full copy), which makes males more vulnerable to certain problems relating to those genes

Question 6

Differentiate the concepts of mitosis and meiosis.

Answer 6

• Mitosis: All cells, except those used in sexual reproduction, are created by mitosis
  –> Defined as the cell’s nucleus making an exact copy of all the chromosomes and splitting into 2 new cells
• Meiosis: Cells used in sexual reproduction are created by meiosis
  –> Gametes (sperm or ovaries) are formed in meiosis

Question 7

What are gametes?

Answer 7

• By definition: a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote
• Also known as: Sperm and Egg cells
  → The egg (or ovum) carries an X sex chromosome
  → The sperm carries the second sex chromosome, which can be an X or a Y
  → Sex of the zygote is determined by the sperm
• The rest of our cells, the somatic cells, are diploid: They carry two copies of each chromosome to form the 23 chromosome pairs

Question 8

What is a chromosomal abnormality?

Answer 8

• A chromosomal abnormality occurs when a child inherits too many or two few chromosomes
  → most of these will end in a miscarriage
• Some gametes do not divide evenly when they are forming. Therefore, some cells have more than 46 chromosomes. In fact, it is believed that close to half of all zygotes have an odd number of chromosomes. Most of these zygotes fail to develop and are spontaneously aborted by the mother’s body.
• One of the most common chromosomal abnormalities is on pair 21
  → Trisomy 21 or Down syndrome occurs when there are three rather than two 21st chromosomes

Question 9

When the abnormality is on ___ pair the result is a sex-linked chromosomal abnormality

Answer 9

23rd

Question 10

What is sexual dimorphism?

Answer 10

Beginning at conception:
- The genetic stage
→ Sex chromosomes (the X’s and Y’s)
- The gonadal stage
→ Reproductive organs
- The hormonal stage
→ Prenatally and pubertally
→ there are a lot of stages which show how men and women are different from each other
- Internal and external genitalia
→ develop differentially (difference in timing)
→ allows for the possibility of errors in developing either the male or female patterns

Question 11

How does Turner syndrome display in chromosomes?

Answer 11

X0 – Missing Y or X chromosome

Question 12

What is Turner syndrome (it’s characteristics in a person)?

Answer 12

• Appear female at birth
  → Infants can have swollen hands and feet at birth possible: high palate, low ears, flat feet, droopy eyelids
• Shorter than average – can be treated with hormones near puberty to give them a second growth spurt
• No functioning ovaries – can still carry a pregnancy but need an egg donor (and a ton of medical help)
  → it’s not advised but can happen
• Higher risk for certain medical conditions
  → UTIs, kidney issues, hypothyroidism, celiac disease, obesity, hearty abnormalities

Question 13

How does Klinefelter syndrome display in chromosomes?

Answer 13

XXY

Question 14

What is Klinefelter syndrome (its characteristics in a person)?

Answer 14

• The extra chromosome gives extra instructions for the body to follow
• Male internal and external genitalia
• Small testes and penis, usually sterile
• Taller than average stature, wider hips
• Longer legs, shorter torso and broader hips compared with other boys
• Absent, delayed or incomplete puberty
• After puberty, less muscle and less facial and body hair compared with other teens
• Enlarged breast tissue (gynecomastia)

Question 15

True or false: Within the first 6 weeks of development, no difference exists between male and female embryos

Answer 15

True:
→ Same internal reproductive system
→ Thus, the capability of developing according to either the male or female pattern, regardless of chromosomal pattern
→ Initially, male and female external genitalia are identical

Question 16

What is the Wolffian system?

Answer 16

In the development of male and female physiology in utero, has the capacity to develop according to the male pattern, but is not yet

Question 17

What is the Mullerian system^

Answer 17

In the development of male and female physiology in utero, has the capacity to develop according to the female pattern, but is not yet

Question 18

Explain some factors of the reproductive organs of males en embryo.

Answer 18

• Presence of androgens
• Prompts development of Wolffian system
• Secretion of Mullerian-inhibiting substance (causes the Mullerian system to degenerate)
• Gonads develop into testes

Question 19

Explain some factors of the reproductive organs of females en embryo.

Answer 19

• Absence of androgens
• Allows the Müllerian system to develop
• The Wolffian system degenerates
• Gonads develop into ovaries
• the default is the female system, if there’s a problem with androgens, the body will end up looking female

Question 20

Differentiate primary sexual characteristics and secondary sexual characteristics.

Answer 20

These both come out during puberty
- Primary sexual characteristics
→ Maturity of sexual organs
→ Reproductive maturity
- Secondary sexual characteristics
→ Physical features that reflect sexual maturity but are not involved directly in reproduction

Question 21

What is LH or Luteinizing hormone?

Answer 21

→ Causes follicle to rupture and release ovum
→ Maturation of sperm

Question 22

What is FSH or Follicle stimulating hormone?

Answer 22

→ Stimulates follicles to mature an ovum
→ Involved in sperm production

Question 23

What do LH and FSH have in common?

Answer 23

• men and women both have these hormones but in varying amounts
• Released by Pituitary
• Stimulate gonads to increase production of estrogens and androgens
• Results in maturation of the genitals
• Produces menstrual cycle

Question 24

How does the nervous system vary in gender?

Answer 24

• Brain size differs with sex, but the proportion is similar to differences in body size
  → so there’s no actual difference in brain size when taking this into account
• Cerebral hemispheres differ in function
  → Lateralization of function occurs
  → women have improved lateralization of the brain, but researchers still are unsure what it means
• Gender differences in brain structures are small compared to other individual differences

Question 25

What is the sexually dimorphic nucleus?

Answer 25

• In the hypothalamus
• The most prominent brain difference between men and women
• 2.5 times larger in men than in women
• Its function in humans is not understood
  → since it’s in the hypothalamus, it’s difficult to understand what may happen if there’s a problem with it because the hypothalamus is crucial for brain function; thus if there’s a lesion in the SDN, there’s likely one in another part of the hypothalamus

Question 26

What is the role of the spinal nucleus of the bulbocavernosus?

Answer 26

• Involved in ejaculation in men
• Involved in vaginal contractions in women
• 25% larger in men

Question 27

Where are the potential sex differences in brain structure situated?

Answer 27

• Sexually dimorphic nucleus
• Spinal nucleus of the bulbocavernosus

Question 28

According to a study done examining differences in the brains of cisgendered and transgender people, what were the results?

Answer 28

• The brains of transgender women ranged between cisgender men and cisgender women (albeit still closer to cisgender men), and the differences to both cisgender men and to cisgender women were significant (p = 0.016 and p < 0.001, respectively). These findings add support to the notion that the underlying brain anatomy in transgender people is shifted away from their biological sex towards their gender identity
• In a graph: While cisgender men find themselves higher up on the scale, leaning towards masculinity, and cisgender women find themselves lower on the scale, leaning towards femininity, transgender women find themselves in the middle

Question 29

Name the 4 problems related to prenatal hormone exposure.

Answer 29

1) Congenital adrenal hyperplasia
2) Androgen insensitivity syndrome
3) Intersexuality
4) 5-alpha-reductase deficiency

Question 30

What is congenital adrenal hyperplasia?

Answer 30

• Problem related the prenatal hormone exposure
• Caused by an increase in androgen production
• For XY males, typically few problems occur
• For XX females, causes masculinization of external Genitalia
  → can be born intersex

Question 31

What is androgen insensitivity syndrome?

Answer 31

• A problem related to prenatal hormone exposure
• When the person’s cells do not respond to androgenic hormones (the flip side of congenital adrenal hyperplasia)
  → the androgen is sent out, but the body is insensitive to this message
• Clinically affects chromosomal (XY) males (XX females can also be androgen insensitive but usually do not have significant side effects)
• AIS has three degrees of genital masculinization:
  1) Complete androgen insensitivity syndrome (CAIS): is when the external genitalia are that of a normal female
  → CAIS is typically not identified until puberty
  → Fail to reach menarche: they have testes where the ovaries normally are, no uterus, and a shallow vagina (on average half as deep)
  → Outwardly female, except no pubic hair and sometimes no armpit hair
  → very typically girly girls and feminine, but during teenage years, menstruation doesn’t come through, often no uterus
  2) Mild androgen insensitivity syndrome (MAIS) is when the external genitalia are that of a normal male
  3) Partial androgen insensitivity syndrome (PAIS) is indicated when the external genitalia are partially, but not fully, masculinized

Question 32

What is intersexuality?

Answer 32

• A problem related to prenatal hormone exposure
• Replaced outdated term: hermaphrodite / hermaphroditism
• Occurs when an individual has both ovarian and testicular tissue but can also include other conditions, such as AIS
• Vagina and a micropenis, or no vagina and a micropenis, it’s a mix of both which differs from person to person
  → in the past, the doctors would simply choose a gender (typically female because it was easier) and have surgery to adjust but this caused a lot of problems later on in the kids life because often the doctor guessed the gender wrong

Question 33

What is 5-alpha-deficiency?

Answer 33

• A problem with prenatal hormone exposure
• Extremely rare
• Affects XY males
• Can appear female at birth, or have “ambiguous” genitals at birth, often raised female
• Develop according to male pattern during puberty and may adopt a male gender role in early adulthood

Question 34

What is premenstrual syndrome or PMS?

Answer 34

• Wide publicity but not a precise definition
  → Research improved over the years
  → Most has not carefully controlled for SOCIAL PRIMING
• Two well-controlled studies
  → Failed to find any evidence of PMS
  → Instead, PMDD (pre-menstrual dysmorphic disorder)
  → because hormone levels to change through the menstrual cycle

Question 35

How can testosterone be linked to aggression?

Answer 35

• A series of studies (Dabbs et al.) revealed complex relationships between testosterone level and antisocial (but not necessarily aggressive) behavior. Testosterone also affects women’s behavior; results show a complex pattern
  → […] the relationship between testosterone & aggression may be that aggression raises the level of testosterone rather than the other way around […]
• Aggressive behaviours tend to be very socialized, there are people who are naturally more aggressive but it can’t be explicitly linked to testosterone levels
  → in Western cultures, men are more likely to express their anger
• When feeling anger, the body does release more testosterone as well, so this makes it a bit more difficult to understand the link

Question 36

Explain the germinal period (weeks 1 - 2)

Answer 36

• Mitosis is a fragile process and fewer than one half of all zygotes survive beyond the first two weeks (Hall, 2004)
  → Some of the reasons for this include the egg and sperm do not join properly, thus their genetic material does not combine, there is too little or damaged genetic material, the zygote does not replicate, or the blastocyst does not implant into the uterine wall.
• If it implants in the fallopian tube it results in an ectopic pregnancy, which is not viable
  → this occurs when there is lining in the fallopian tube

Question 37

Explain the embryonic period (weeks 3 - 8)

Answer 37

• The head develops in the fourth week and the cells which will turn into the heart begin to show rhythmic contractions by the 6th week
• In the early stages of the embryonic period, gills and a tail are apparent; However, by the end of this stage they disappear, and the organism takes on a more human appearance
• Some organisms fail during the embryonic period, usually due to gross chromosomal abnormalities
• As in the case of the germinal period, often the mother does not yet know that she is pregnant which can lead to the embryo being exposed to dangerous environmental influences
  → p.ex: being in polluted air, around smoke or chemicals

Question 38

What is an embryo?

Answer 38

• Term given to the zygote once it is completely embedded in the uterine wall
  → at 3 weeks after conception, the fertilized egg is about 2 millimeters long and resembles a salamander

Question 39

Explain the fetal period (weeks 9 - 38)

Answer 39

• In month 3, the testes in a male fetus secrete androgens that cause development of a penis and scrotum
  → Females lack the hormone, and thus develop a vagina and labia as the “default human” structures
  → In androgen insensitive genetic males, the secreted hormone has no or little effect which leads to female or mixed genitalia