Reproductive System

Question 1

What is a gonad?

Answer 1

An organ that produces gametes

Question 2

What makes up the male gonad?

Answer 2

Testis and epididymis

Question 3

Where are the testis found and what are they surrounded by?

Answer 3

In the scrotum (to keep cool)

Tunica vaginalis

Question 4

What route does the sperm take in the testis?

Answer 4

Sperm passes from the seminiferous tubules to the epidimysis

Question 5

Describe the structure of the scrotum

Answer 5

• Skin is rugose
• Has a midline raphe
• Contains dartos (smooth) muscle and is divided by a septum

Question 6

List the female genital organs

Answer 6

Ovary
Uterine Tube
Uterus
Fundus of uterus
Cervix
Vagina

Question 7

Where is the ovary located?

Answer 7

Lateral pelvic wall

Question 8

Where does ovulation occur?

Answer 8

In the peritoneal cavity, where the ovum is picked up by the fimbriated end of the uterine (/Fallopian) tube aka fimbrae

Question 9

What is ectopic pregnancy and why does it occur?

Answer 9

The egg is not picked up by the fimbrae and is embedded onto other parts of the abdomen

6 weeks into pregnancy, it grows big enough to damage the internal organs

Question 10

Where is the blood supply of the ovary coming from?

Answer 10

Its blood supply is linked to the back of the abdomen

Question 11

What is the function of the uterus?

Answer 11

A pelvic organ for implantation of the fertilised ovum and growth of the foetus

Question 12

How is the uterus tethered in place?

Answer 12

By supportive uterine ligaments - connecting the uterus and cervix to the sacrum, pubis and lateral pelvic walls

Question 13

What do female gonads produce and by what process?

Answer 13

Oocytes (eggs) by oogenesis

Question 14

What do male gonads produce and by what process?

Answer 14

Sperm by spermatogenesis

Question 15

What are the gonadal hormones involved in?

Answer 15

• Gamete production

- Supporting conception, pregnancy and lactation

Question 16

What controls gonads?

Answer 16

Hypothalamic-pituitary-gonadal axis

Question 17

What is the Hypothalamic-Pituitary-Gonadal axis made up of?

Answer 17

Hypothalamic signalling hormone and Pituitary hormones

Question 18

What is the Hypothalamic signalling hormone?

Answer 18

Gondadotropin-releasing hormone (GnRH) (peptide hormone)

Question 19

What are the Pituitary hormones?

Answer 19

• Luteinising hormone (LH)

- Follicle stimulating hormone (FSH)

Question 20

What happens when ovaries are targeted by LH and FSH?

Answer 20

An ovum is released monthly, and oestrogens/oestodiol and progestins/progesterone are secreted

Question 21

What are the main hypothalamic areas involved in ovarian control?

Answer 21

Preoptic nucleus and Supraoptic nucleus

Question 22

Describe the production of the peptide hormone GnRH

Answer 22

• Production is by Preoptic nucleus neurons and Supraoptic nucleus neurons
• Produced as prohormone, then modified to active form
• Secreted into hypophyseal portal system

Question 23

Describe the release of the peptide hormone GnRH (Gonadotropin-releasing hormone)

Answer 23

Release is pulsatile/not constant

• Requires less energy
• Does not desensitise target tissue receptors
• Stress can influence secretion (and therefore the menstrual cycle too)

Question 24

Describe the delivery of GnRH

Answer 24

Delivered via the hypophyseal portal circulation to the anterior pituitary gonadotropes; these then result in the production of FSH and LH, which target the gonads

Question 25

Summarise how the GnRH controls the ovaries

Answer 25

1. GnRH is produced from prohormones, made active, and is then secreted 2. GnRH is released by pulsations 3. GnRH is delivered to the anterior pituitary gonadotropes 4. Gonadotropes secrete FSH and LH 5. FSH and LH target the gonads

Question 26

Describe the follicles of the ovary

Answer 26

The ovary contains follicles of various stages (e.g. primordial, primary, secondary, tertiary, Graafian), but the most important is Graafian follicles in the endocrine ovaries Made up of the primary oocyte, antrum, theca cells and granulosa cells

Question 27

Describe the cells making up the Graafian follicle

Answer 27

Theca cells - Outer layer of cells - Can be externa or interna - Have LH receptors - Convert cholesterol into prenenolone, then produce the hormones androstenedione and testosterone Granulosa cells - Inner layer of cells - Have LH and FSH receptors - Convert cholesterol into prenenolone and activate aromatase, then produce androstenedione, testosterone and oestradiol (the oestrogen hormone)

Question 28

Describe the beginning and end of oogenesis

Answer 28

Starts in the embryo for females - Premordial germ cells (oogonia) increase in number, and many mature into oocytes At 20 weeks of pregnancy, oocyte numbers reach maximum numbers - from then on, oocyte numbers start declining until exhausted (menopause)

Question 29

What are the three main oestrogens?

Answer 29

- Oestradiol - Oestrone - Oestriol

Question 30

Describe the secretion/feedback regulation of oestrogens

Answer 30

Feedback shifts from -ve to +ve, then shifts back to -ve This is because: - Oestrogen levels increase - Results in upregulation of receptors (Eg. GnRH in anterior pituitary) - Results in increased production of LH and FSH prior to ovulation

Question 31

Describe progestins

Answer 31

- Progesterone - Produced in theca and granulosa cells - Has a short half-life in circulation (5 minutes) - Secretion regulation is intrinsically linked to oestrogen secretion

Question 32

Summarise up the hormonal behaviour of the reproductive system

Answer 32

Start of the ovarian cycles (takes 14 days) 1. Hypothalamus produces sex hormone GnRH about once a month 2. GnRH stimulates the anterior pituitary and the production of LH and FSH 3. FSH stimulates the growth of one single follicle 4. That follicle secretes its own oestrogen that simulates it even more to grow faster 5. The secretes oestrogen stimulates the anterior pituitary to secrete LH to finish the job 6. Oocyte matures and leaves the follicle 7. Damaged follicle becomes the corpus luteum and secretes progesterone to stop the secretion of FSH and LH