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Dentistry Biological Science > The Menstrual Cycle > Flashcards

The Menstrual Cycle Flashcards

1
Q

What is the main affect on the periodontal tissue during puberty?

A

Increased gingival inflammation

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2
Q

In females, when does reproductive potential start and end?

A

Puberty

Menopause

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3
Q

Where does reproductive control start?

A

Pre-optic part of the hypothalamus

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4
Q

Explain the mechanism behind the release of LH and FSH

A

Gonadotrophin-releasing hormone (GnRH) neurones.
GnRH released from nerve terminals into blood vessels.
Hormone travels down portal vessels.
GnRH stimulates release of LH and FSH from gonadotroph cells in the anterior pituitary into the circulation.

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5
Q

What is the function of LH and FSH?F

A 
FSH = stimulates growth of the ovarian follicles 
LH = stimulates production of steroid hormones and ovulation
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6
Q

What are the two main roles of the ovaries?

A
  1. Production of oocytes (egg cells)

2. Production and release of steroid hormones

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7
Q

What are all steroid hormones generated from?

A

Cholesterol

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8
Q

What are the two key points about steroid hormones?

A
  • They pass through cell membranes (lipophilic) to act on intracellular receptors
  • Receptor activation leads to changes in gene transcription
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9
Q

What are oestrogens?
What is the naturally occurring one in pregnant women?
What are they synthesised and released from?

A
  • They are steroid hormones that function as the primary female reproductive hormone.
  • Oestradiol
  • From androgens and released from ovaries
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10
Q

What are progestagens?

What are they involved in?

A

They are steroid hormones derived from the same precursor as testosterone and oestrogen.
They are involved in the menstrual cycle and pregnancy.

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11
Q

Explain how the oocytes are stimulated

A

GnRH is released and goes to anterior pituitary to stimulate it to produce LH and FHS. These stimulate the ovaries to stimulate oocytes. They also cause the ovaries to release hormones into wider circulation.
LH and FSH have a negative feedback affect.

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12
Q

How do men and women differ in reproduction?

A
  • Men have continuous reproduction but women stops
  • Steroid hormones in males can be affected by the environment but womens can’t
  • Mens hormone levels are relatively stable but females change over the cycle
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13
Q

Give the number of eggs:

  1. Before birth
  2. At birth
  3. Puberty
  4. Menopause
A
  1. 7 million eggs
  2. 2 million eggs
  3. 0.4million eggs
  4. <1000 eggs
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14
Q

What is found scattered throughout ovaries?

What form are they in?

A

Ovarian follicles

Inactive

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15
Q

What are the 3 phases of the ovarian cycle?

What days are each of these?

A

Follicular phase: Days 1-10
A follicle grows in preparation for ovulation
The growing follicle releases oestradiol
Ovulatory phase: Days 11-14
High oestradiol causes the LH surge
Ovulation
Luteal phase: Days 14-28
• Remains of the follicle release progesterone – Corpus Luteum
This phase prepares for possible fertilisation.

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16
Q

Give details on the follicular phase

A

FSH causes follicles to grow.
(Not known as to when individual follicles are known when to be stimulated and growth. A few primordial follicles respond to FSH in each cycle).

Primordial follicle = immature dormant oocytes, surrounded by flat granulosa cells.
Changes to a mature follicle = dependant on FSH to grow, competition for limited FSH means that only one follicle is left by day 10. As the follicle grows, the theca cell and granulosa cells release oestradiol in response to LH.

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17
Q

What is the antrum?

A

Fluid filled sac around the outside of the follicle.

18
Q

What are the two layers which surround each oocyte?

A

Each oocyte is surrounded by many layers of granulosa cells. These granulosa cells are surrounded by a well vascularised thecal cell layer.

Granulosa cells secrete the fluid that accumulates in the extracellular space. The spaces coalesce (come together) to form the antrum.

In the mature Graafian follicle, a cluster of granulosa cells called the cumulus oophorus surround the accentrically-located oocyte.

19
Q

What does LH and FSH do to the follicle?

A

LH = stimulates the theca cells to produce androgens

FSH = stimulates growth of granulosa cells

20
Q

What happens to androgens in the follicle?

A

Androgens are main male reproductive hormone.
LH stimulates theca cells to produce androgens but we do not want a lot of this in females. The androgens are absorbed by the granulose cells in centre of the follicle and converted into oestrogen.
Oestrogen is then released into wider circulation.

21
Q

What happens during the follicular phase?

A

FSH causes follicles to grow.
LH stimulates hormone production from the growing follicles.
As the follicles grow, oestradiol levels increase.

22
Q

What happens during ovulatory phase?

A

Normally oestradiol have a negative feedback effect on LH release.
But during ovulation, oestradiol stimulates LH causing the LH surge.
The LH surge triggers ovulation.

Oestrogen normally has a negative feedback affects and inhibits LH and FSH.
Oestrogen can have a positive feedback affect when levels are high enough (changes from - to + feedback affect).
Oestrogen is high stimulates LH which then the Lh stimulates osteogen. The two cause each other to keep increasing. Spike in LH release is the trigger for ovulation.

23
Q

What happens after the release of the oocyte?

A

The follicle then collapses and the remaining granulosa and theca cells differentiate to become luteal cells, gaining the ability to secrete large quantities of progesterone.
The reputed follicles becomes the corpus leteum.

24
Q

What happens during luteal phase?

A

The follicle becomes the corpus luteum and released oestriadiol and progesterone to prepare for pregnancy.
If the cell is not fertilised the corpus luteum degenerates.

The cycle then starts again.

25
Q

What phase is the only one where oestrogen can have a positive effect?

A

The ovulatory phase.

26
Q

Explain what the hypothalamic-pituitary gonadal axis does in 1)follicular phase 2)ovulatory phase 3)luteal phase

A

1) FSH causes follicle growth, increased oestradiol release as follicle grows
2) High oestradiol switches to a positive feedback effect. LH surge in response to positive feedback causes ovulation
3) The follicle collapses forming the corpus luteum and releasing oestradiol and progesterone.

27
Q

Give some information on the uterus during the menstrual cycle

A

The uterus also changes across the ovarian cycle.
Series of changes in the endometrium in response to changes in hormone levels.
The uterus lining thickens through the cycle in preparation for pregnancy. During the luteal phase the endometrium becomes dependent on progesterone. (thickest during luteal phase).
End of luteal phase, progesterone levels fall, uterus lining then breaks down during a period (menstruation).

28
Q

What actually causes the uterus to degenerate?

A

Corpus Leutum degenerates, progesterone secretion stops, uterus lining shed (menstruation).

29
Q

What happens if the egg does get fertilised?

A

Progesterone secretion continues, uterus lining and implants embryo survives.
Implantation causes hCG (human Chorionic gonadotrophin) secretion which stimulus the corpus leteum to survive.

30
Q

What are the 6 functions of the placenta?

A
  1. Gas exchange
  2. Nutrient transfer
  3. Excretion
  4. Immune protection
  5. Drug transfer and metabolism
  6. Hormone synthesis
31
Q

What hormones does the placenta secrete?

Give the examples and the pattern of growth of it

A

Both steroid and protein hormones.

Human Chorionic Gonadotrophin (hCG) - increases and then decreases to flatten out at a lower level

Progesterone - increases throughout

Oestrogens - increases but lower than progesterone

32
Q

What tooth effects can pregnancy cause?

What symptoms of pregnancy cause this?

A

Pregnancy gingivitis, pregnancy granuloma, increased tooth mobility.

Salivary changes (flow, minerals, buffer).
Acid increase (due to morning sickness, dietary changes, oesophageal reflux)
33
Q

Explain hormone secretion at parturition

A

• During pregnancy: high levels of placental oestrogen sensitise the uterus to oxytocin.
• Just before birth: the maternal hypothalamus stimulates the posterior pituitary to secrete oxytocin, which increases uterine contractions.
The uterine endometrium also secretes prostaglandins, which aid in uterine contractions.
• After birth: Oestrogen and progesterone decrease when placenta expelled.

34
Q

What are advantages of breast feeding?

A
  • Rapid establishment of infant-mother bond
  • Protects against malnutrition and environmental factors
  • Low cost food with minimal danger of contamination
  • Maternal immunoglobulin to infant
  • Ovulation is delayed by frequent suckling, spacing births (prevents a pregnancy from occurring too early)
35
Q

Explain hormone secretion and lactation during:

  • pregnancy
  • after birth
  • suckling
A
  • During pregnancy: oestrogen and progesterone increase fat and connective tissue in mammary glands, but not milk production.
  • After birth: hypothalamus stimulates the anterior pituitary to secrete prolactin, which stimulates milk production (but not milk ejection).
  • Suckling: stimulates the nerves in nipples → hypothalamus → posterior pituitary secretes oxytocin, which stimulates the milk ejection reflex
36
Q

How does suckling stimulate milk production?

A

Inhibiting dopamine secretion.
This increases the release of prolactin in the anterior pituitary.
Sucking communicates back to hypothalamus but to the oxytocin neurones. This causes the release of oxytocin into the blood from the posterior pituitary to decrease LH and FSH release.

37
Q

What happens after the menopause to the reproductive system?

A

No follicles, no oocytes, no oestradiol, oestrogen-deficency state

38
Q

Give 6 symptoms of the menopause

A
  1. Atrophic conditions (reproductive organs, skin)
  2. Osteoporosis
  3. Vasomotor symptoms (hot flushes, unstable blood pressure)
  4. Atherosclerosis and cardiovascular disease
  5. Emotional changes (nervousness, insomnia, depression, impairment of memory, tiredness, frigidity)
  6. Weight Gain
39
Q

What are clinical changes in the periodontal tissues during menopause and postmenopause?

A
  • Reduction in epithlial keratinisation
  • A reduction in salivary gland flow
  • Drying of oral tissues
  • Redness and abnormal paleness of gingival tissues
  • Bleeding on probing and brushing
40
Q

What are the take home messages from this lecture?

A
  • Female reproductive hormones and ovulation are cyclical.
  • The reproductive cycle is controlled by interactions between the ovarian follicles and the hypothalamus and pituitary.
  • During pregnancy the placenta secretes high levels of many hormones into the body of the mother.
  • Lactation is regulated by changing hormone levels.
  • The menopause marks the end of female reproductive function, with corresponding loss of steroid hormones.
  • The changing hormone levels involved in all of these female reproductive states can have major effects on the body – including the teeth and periodontal tissues.

Dentistry Biological Science (88 decks)

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