Pregnancy and the reproductive system

Question 1

Define gonads and gametogenesis

Answer 1

• Gonads: organs that produce gametes (eggs or sperm)

* Gametogenesis: the generation of gametes

Question 2

State the characteristics that develop with the onset of puberty

Answer 2

Female
• Deposition of fat, predominantly in breasts and hips
• Breast development
• Broadening of the pelvis and growth of axillary and pubic hair

Male
• Increased larynx size and deepening of the voice
• Increased muscular development
• Growth of facial, axillary, and pubic hair, and increased growth of body hair

Question 3

State the components female reproductive system and their functions

Answer 3

• Vagina: Allows discharge of menstrual flow
• Cervix: Pathway of menstrual flow and sperms and parturition
• Uterus: Receives fertilised ovum or sheds superficial layer (menstruation)
• Endometrium: the mucous membrane that lines the uterus
• Fallopian tubes: Transport the ovum
• Ovaries: Produce hormones (oestrogen, progesterone)

Question 4

State the components of the male reproductive system and their functions

Answer 4

• Penis and urethra: Conveys urine and seminal fluid
• Scrotum: Encloses and protects the testes
• Testes Produce sperm and hormone (testosterone)
• Vas deferens: Store and convey spermatozoa
• Epididymis: Store sperm
Prostate gland: Secrete an alkaline fluid that helps neutralise acidity of sperm

Question 5

Understand the endocrine control of reproductive system

Answer 5

• During puberty the hypothalamus produces gonadotropin-releasing hormone (GnRH)
• The GnRH stimulates the anterior pituitary to produce the follicle simulating hormone (FSH) and luteinizing hormone (LH)
• FSH: stimulates gamete production (eggs maturation in females), (sperm in males)
• LH: stimulates production of hormones by the gonads (oestrogens and progesterone’s in females) (testosterone in males)

Question 6

List the functions of testosterone and which organ it is secreted by

Answer 6

Secreted by:
Testes

Functions:
• Testes: Produce sperm
• Other body tissues: Enable development of secondary sexual characteristics

Question 7

List the functions of oestrogen and which organ it is secreted by

Answer 7

Secreted by:
Ovaries

Function:
• Uterus: Proliferation of endometrial cells
• Mammary glands: Development of the mammary glands (ducts)
• Anterior pituitary & hypothalamus - Before ovulation, increased LH & FSH secretion. After ovulation, decreased LH & FSH secretion
• Other tissues: Enable development of secondary sexual characteristics

Question 8

List the functions of progesterone and which organ it is secreted by

Answer 8

Secreted by:
Ovaries

Functions:
• Uterus: growth of endometrial cells and secretion of fluid from uterine glands
• Mammary glands: Development of the mammary glands (ducts)
• Anterior pituitary & hypothalamus - Before ovulation, increased LH & FSH secretion. After ovulation, decreased LH & FSH secretion
• Other tissues: Enable development of secondary sexual characteristics

Question 9

List the functions of the human chorionic condition hormone and which organ it is secreted by

Answer 9

Secreted by:
Placenta

Functions
• Ovaries: increase progesterone secretion

Question 10

Briefly describe the follicular stage of the menstrual cycle

Answer 10

• This phase starts when the period starts and ends when ovulation starts
• It involves the release of the follicle stimulating hormone which causes the ovaries to prepare for ovulation
• Follicles are fluid filled sacs containing eggs. During the menstrual cycle, there are multiple follicles at varying stages of development
• This follicle produces oestrogen as it grows

Question 11

Briefly describe the proliferative stage of the menstrual cycle

Answer 11

• After the uterus lining is shed, the uterus responds to the oestrogen produced by the follicles to rebuild the lining
• The endometrium becomes thicker to prepare a place for a potential fertilized egg to implant and grow

Question 12

Briefly describe the ovulation stage of the menstrual cycle

Answer 12

• When the largest follicle produces high enough levels of oestrogen, it signals the brain to increase its levels of the luteinizing hormone
• Luteinizing hormone stimulates egg release (ovulation)
• Largest follicle will be the one to be released during ovulation

Question 13

Briefly describe the luteal stage of the menstrual cycle

Answer 13

• After ovulation the follicle that contained the egg transforms into something called acorpus luteumand begins to produce progesterone as well as oestrogen
• Progesterone levels peak, and these changes are associated with common premenstrual symptoms
• If an egg is fertilized, progesterone from the corpus luteum supports the early pregnancy
• No fertilization = corpus luteum starts breaking down, resulting in a drop in estrogen and progesterone levels. This causes menstruation

Question 14

Briefly describe the secretory stage of the menstrual cycle

Answer 14

• Endometrium prepares to either support pregnancy or break down for menstruation
• The endometrium secretes prostaglandins that cause changes to other cells nearby, “PGF2α” and “PGE2”.
• They cause the uterine muscle to contract/ cramp which helps trigger the period
• If a pregnancy occurs, prostaglandin production is inhibited
• If pregnancy does not occur, the corpus luteum stops producing oestrogen and progesterone
• The drop in hormones, along with the effects of the prostaglandins, cause the blood vessels to constrict and tissue of the endometrium to break

Question 15

Explain the process of fertilisation

Answer 15

• When a sperm reaches and fuses with the egg, it must capacitate: their membranes must become fragile and release hydrolytic enzymes
• The first sperm to make contact with the eggs membrane will capacitate and its will move into the cytoplasm of the egg
• The eggs nucleus and sperms nucleus fuse
• Meanwhile, the egg releases cortical granules into the extracellularly space to prevent the entry of other sperm

Question 16

Appreciate the sex determination and differentiation

Answer 16

• The sperm decides the genetic sex: the presence of the Y chromosome = male
• The presence of the SRY gene the Y chromosome causes the development of the testes in males

Question 17

Discuss how oral contraceptives work

Answer 17

• The pill: Synthetic versions of oestrogen and progesterone
• Mini pill: Synthetic version of progesterone only, used by patients who cannot take oestrogen
• Prevent ovulation by maintaining more consistent hormone levels
• Without a peak in estrogen, the ovary doesn’t get the signal to release an egg
• Causes thickened cervical mucus so the sperm cannot reach the egg

Question 18

Understand the oral implications of contraceptives

Answer 18

• Can exacerbate inflammatory status
• Tendency toward gingival bleeding, gingival enlargement
• Dry socket after extraction
• Interact with antibiotics

Question 19

Explain the positive feedback control using parturition as an example

Answer 19

• The first contractions of labour push the baby toward the cervix
• The cervix contains stretch-sensitive nerve cells that monitor the degree of stretching
• These nerve cells send messages to the brain, which in turn causes the posterior pituitary to release oxytocin
• Oxytocin causes stronger contractions of the smooth muscles in of the uterus, pushing the baby further down the birth canal
• This causes even greater stretching of the cervix

Question 20

Explain the positive feedback control using lactation as an example

Answer 20

• During pregnancy oestrogen and progesterone, and other placental hormones inhibit prolactin-mediated milk
• It is not until the placenta is expelled that this inhibition is lifted
• The suckling action of an infant causes the brain to receive sensory input from the areola
• The brain releases prolactin, which leads to milk production; more suckling leads to more prolactin, which in turn leads to more lactation.
• Oxytocin stimulates myoepithelial cells to squeeze milk from the alveoli so it can eventually discharge through the nipple pores

Question 21

List the oral changes during pregnancy

Answer 21

• Gingivitis and periodontitis: Hormones
• Swollen red gums that bleed easily: blood supply
• Pyogenic granuloma: caused by increased progesterone in combination with local irritants/bacteria
• Caries: food craving, frequent snacks and sweets
• Erosion: Morning sickness
• Prevention: rinse immediately, smear toothpaste over teeth, don’t brush immediately

Question 22

List the oral changes during menopause

Answer 22

• Burning mouth syndrome
• Xerostomia
• Mucosal changes (menopausal gingivostomatitis)
• Abnormal pale dry or shiny erythematous appearance
• Pyogenic granuloma
• Trigeminal neuralgia
• Osteoporosis and periodontitis
• Eating disorders and caries

Question 23

Discuss the precautions when managing a pregnant patient

Answer 23

• Dental treatment in the 2nd trimester is the safest time
• Be aware of drugs which could cross the placenta
• N2O is not recommended for pain management (birth defects)
• Avoid supine hypotensive syndrome in the 3rd trimester
• Dental X-ray can be taken at anytime BUT use of a lead drape is recommended

Question 24

Understand the physiological effects of pregnancy

Answer 24

• Hormones increases in human chorionic gonadotropin, oestrogen, progesterone to maintain pregnancy
• Metabolic adaptations in pregnancy: increased metabolic rate, increased oxygen consumption, decreased insulin sensitivity
• Cardiovascular adaptations: increased blood volume, changes in blood pressure, cardiac output and haematocrit
• Respiratory changes in pregnancy: structural changes, increase in alveolar ventilation
• Renal changes in pregnancy: increase in renin, angiotensin II and aldosterone, increased filtration, increased water and sodium retention