3.1 - Girls vs Boys

Question 1

What are the components of the male reproductive system?

Answer 1

• Seminal vesicle
• Prostate gland
• Penis
• Testis
• Vas deferens
• Scrotum
• Urethra

Question 2

What are the components of the female reproductive system?

Answer 2

• Fallopian tubes
• Uterus
• Ovaries
• Cervix
• Vagina

Question 3

What is spermatogenesis?

Answer 3

Spermatogenesis is the production of sperm cells

Question 4

When does spermatogenesis begin?

Answer 4

Spermatogenesis begins at puberty and continues indefinitely

Question 5

What is oogenesis?

Answer 5

Oogenesis is the production of oocytes (ovum)

Question 6

When does oogenesis begin?

Answer 6

Oogenesis begins during fetal development, but pauses at prophase 1. It resumes each menstrual cycle, but doesn’t actually finish (this only happens when an egg is fertilized)

Question 7

What occurs during spermatogenesis?

Answer 7

In spermatogenesis, spermatogonia (immature sperm cells) perform mitosis to restock themselves

These cells then commit to meiosis (called primary spermatocytes). After meiosis I, they are secondary spermatocytes, which then become spermatids after meiosis II

Spermatids then develop into sperm cells by growing a tail and finally becoming spermatozoa

This entire process occurs in seminferous tubules

Question 8

What are the two types of cells which support spermatogenesis in the testes?

Answer 8

• Leydig (intersitital) cells
• Sertoli cells

Question 9

What are leydig (interstitial) cells?

Answer 9

Located between seminiferous tubules, leydig cells produce large amounts of testosterone, which stimulate spermatogenesis

Question 10

What are sertoli cells?

Answer 10

Located in the seminferous tubule, sertoli cells support growing spermatocytes, remove unnecessary waste, and help accumulate testosterone in the seminiferous tubules. They also produce certain hormones to send feedback to the brain about spermatogenesis

Question 11

How are spermatozoa released?

Answer 11

Spermatozoa are stored in the epididymis until ejaculation, at which point they leave through the vas deferens which merges into the urethra (which is also connected to the bladder)

Question 12

What 3 glands contribute to the solution that is released as semen?

Answer 12

• Seminal vesicle
• Prostate gland
• Bulbourethral (Cowper’s) gland

Question 13

What does the seminal vesicle do?

Answer 13

Produces 60% of the fluid in semen, largely containing fructose as fuel and helping counter the destructive environment of the vagina (which attempts to destroy sperm)

Question 14

What does the prostate gland do?

Answer 14

Produces a fluid to help sperm survive the vagina, but also which helps make semen less thick

Question 15

What does the bulbourethral (Cowper’s) gland do?

Answer 15

Produces a clear fluid prior to ejaculation to neutralize any urine in the urethra (i.e. preejaculate)

Question 16

What hormones are involved in spermatogenesis?

Answer 16

• GnRH (Gonadotropin releasing hormone)
• FSH (Follicle stimulating hormone)
• LH (Lutenizing hormone)
• Inhibin
• Testosterone

Question 17

How do hormones work in spermatogenesis?

Answer 17

• The hypothalamus produces GnRH, which travels to the pituitary gland and activates it
• The pituitary gland produces FSH and LH, which travels in the blood to the testes
• LH causes Leydig cells to produce testosterone
• FSH causes Sertoli cells to clump testosterone together and to produce Inhibin
• Inhibin and Testosterone travel back to the brain and reduce the production of GnRH and FSH/LH

Question 18

What occurs during the first stage of oogenesis?

Answer 18

1. During fetal development, oogonium (immature cells in the ovaries) perform mitosis.
2. After mitosis, they are called primary oocytes. Primary oocytes start meiosis I but stall in prophase I.
3. Meiosis is only resumed during a ~monthly menstrual/ovulation cycle, but pauses once again until fertilization at metaphase II

NOTE: Meiosis produces 2 cells; in oogenesis, one of the cells from meiosis I is large (secondary oocyte), but the other is small (a polar body) and is destroyed

Question 19

What occurs in oogenesis during the follicular & ovulation phases?

Answer 19

• About 5 eggs (primary oocytes) are chosen each cycle to continue growing.
• Each chosen egg is surrounded by cells called follicles, which help and promote egg development.
• One follicle is selected, and the others stop growing to support the chosen one.
• Two layers of cells form around the egg to guide it to the edge of the ovary.
• The egg is released from the ovary (ovulation) when it reaches the edge.
• The cells left behind after ovulation become a structure called corpus luteum, which produces hormones and stays in the ovary.
• Day 1-14
  ** 14 = Ovulation day

Question 20

What occurs in oogenesis during the luteal & menstrual phases?

Answer 20

• Hormones cause the lining of the uterus to thicken in earlier phases.
• After ovulation, the egg moves from the ovary through the Fallopian tubes, waiting to be fertilized.
• After ovulation, the corpus luteum signals the uterus to prepare for a potential fertilized egg by providing nutrients.
• The corpus luteum only lasts a few weeks. After that, if no fertilization occurs, menstruation starts as the uterine lining is released.
• If a fertilized egg arrives, it produces hormones that let the corpus luteum stick around instead of breaking down, preventing menstruation.
• Day 15-28
  ** Corpus luteum destroyed on day 26/27

Question 21

What hormones are involved in oogenesis?

Answer 21

• GnRH
• FSH
• LH
• Estrogen
• Progesterone

Question 22

How do hormones work in oogenesis?

Answer 22

-The hypothalamus sends a signal (GnRH) to the pituitary gland, telling it to produce FSH.
- FSH goes to the ovary and makes follicles grow. The main one produces estrogen.
- Estrogen tells the uterus lining to grow and tells the pituitary to stop making more FSH (to avoid more follicles).
- Estrogen then signals the pituitary to make LH, causing ovulation (egg release) and forming the corpus luteum.
- The corpus luteum releases progesterone, helping the uterus lining develop and stopping the pituitary from making more FSH (to prevent more follicles).