Chapter 5: sex hormones

Question 1

Sex glands / gonads

Answer 1

Glands are organs that make substances (like hormones or fluids). The sex glands / gonads are the testes in men and the ovaries in women.

Question 2

Pituitary gland

Answer 2

Regulate the testes and the ovaries. Is controlled by the hypothalamus.

Question 3

What are the sex hormones in males?

Answer 3

• Testosterone: produced by the testes. Stimulates secondary sex characteristics, sperm production and muscles and bone growth.
• FSH: follicle stimulating hormone. Controls sperm production.
• LH: luteinizing hormone. Controls testosterone production.
• GnRH: gonadotropin releasing hormone. Regulates LH levels.

Question 4

Negative feedback loop of testosterone

Answer 4

The hypothalamus, pituitary glands and the testes operate in e negative feedback loop to maintain constant levels of testosterone.

Question 5

Inhibin (in men)

Answer 5

A hormone produced by the testes that regulates FSH levels. Could be a male contraceptive, because it suppresses FSH and sperm production.

Question 6

What are the sex hormones in females?

Answer 6

• Estrogen: induces changes in puberty.
• Progesterone: prepares the endometrium for an egg.

Question 7

Inhibin (in women)

Answer 7

A hormone produced by the ovaries, inhibits FSH and regulates the menstrual cycle.

Question 8

Oxytocin

Answer 8

Stimulates the ejection of milk and contraction of the uterus. Promotes bonding and is stimulated by affectionate touching.

Question 9

Klinefelters syndrome (XXY)

Answer 9

A man with an extra X chromosome. Causes smaller testes, low testosterone production and no sperm production.

Question 10

Intersex condition / disorder of sex development (DSD)

Answer 10

When the reproductive structures are partly male and partly female, or are incomplete.

Question 11

Congenital adrenal hyperplasia

Answer 11

A genetic female develops ovaries, but later starts developing external male organs due to an overproduction of androgens.

Question 12

Androgen insensitivity syndrome

Answer 12

A genetic male is insensitive to testosterone and has the external appearance of a female.

Question 13

Percentage of body fat hypothesis

Answer 13

During puberty, the percentage of body fat increases in females. The menarche starts when this percentages rises to a certain level. This explains why the menstruation can stop due to anorexia.

Question 14

Adrenal glands

Answer 14

Produce androgens that stimulate the growth of pubic hair and female sex drive.

Question 15

Changes in sex hormones during puberty (in women)

Answer 15

The hypothalamus starts releasing GnRH → increases FSH → stimulates estrogen → stimulates breast growth and the growth of the uterus and vagina.

Question 16

Changes in sex hormones during puberty (in men)

Answer 16

Increased production of LH and FSH → LH stimulates testosterone production→ enlargement of the testes –→ more testosterone → more rapid growth.

Question 17

Estrous cycle

Answer 17

Cycle which dogs and horses have. Involves non/slight bleeding, ovulation occurs during this, animals only engage in sexual behaviour during this.

Question 18

Phases of the menstrual cycle

Answer 18

1. Follicular phase: estrogen stimulation the endometrium to thicken.
2. Ovulation
3. Luteal phase: progesterone stimulates nourishing substances for the egg. If the egg is nog fertilised estrogen levels drop and the menstruation starts.
4. Menstruation: a shedding of the inner lining of the uterus.

Question 19

Menstrual problems

Answer 19

• Dysmenorrhea: very painful menstruation due to contraction of the muscles in the uterus.
• Endometriosis: when the endometrium grows in a place other than the uterus.
• Primary amenorrhea: the absence of menstruation before the age of 18.
• Secondary amenorrhea: the absence of menstruation, but having had at least one period.

Question 20

Premenstrual syndrome (PMS)

Answer 20

Severe physical and psychological problems that occur before the menstruation.

Question 21

Premenstrual dysphoric disorder (PMDD)

Answer 21

Symptoms include feeling sad or hopeless, tense or anxious, tearfulness, irritability, difficulty concentrating and changes in appetite.

Question 22

Dopamine

Answer 22

More dopamine increases sexual desire and less dopamine decreases this.