Exam #4: Female Reproductive Physiology I Flashcards Preview

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Flashcards in Exam #4: Female Reproductive Physiology I Deck (37):
1

What are the general functions of the ovaries?

- Principal female reproductive organ
- Estrogen and progesterone production (steroidegenesis)
- Storage and release of the ovum (oogenesis)

2

What are the hypothalamic peptide hormones?

GnRH
Oxytocin

GnRH= gonadotropin releasing hormone

3

What are the pituitary peptide hormones?

FSH
LH
Prolactin

4

What is the ovarian peptide hormone?

Inhibin

5

What are the ovarian steroid hormones?

Estradiol
Progesterone
Androstenedione
Testosterone

6

Review the synthesis of peptide hormones.

- 3-200 aa
- Synthesized as an inactive pre-prohormone
- Post-translational processing
- Stored in vesicles

7

List the important characteristics of peptide hormones.

- Circulate free
- Bind cell surface receptors i.e. NOT going to cross the membrane
- Hydrophilic i.e. water soluble
- Release is Ca++ dependent

8

What are the typical receptors for peptide hormones? Review the mechanisms that occur following binding of a peptide hormone with these receptors.

1) RTK
- Transmembrane receptor
- Intrinsic enzymatic activity
- Bind hydrophilic hormones

2) GPRC
- Transmembrane receptor
- Couple to G proteins
- Bind hydrophilic hormones

9

Review the synthesis of steroid hormones. What is the general sequence in synthesis of the steroid hormones?

- Steroid hormones are derived from cholesterol
- Sequence:
1) Progesterone
2) Androgen
3) Estrogen

10

List the important characteristics of steroid hormones.

- Lipophilic
- Circulate bound to plasma proteins
- Cross membranes
- Intracellular receptors that regulate gene transcription

*NOT stored in vesicles

11

Why is protein binding in circulation important in regards to the metabolism of hormones?

- Binding to a plasma protein protects against degradation and INCREASES the half-life
- Half-life free<< Half-life bound

12

What are the two principal sites of degradation of hormones?

1) Site of action
2) Liver

*Note that steroid hormones will be conjugated in the liver to make them more water soluble for excretion

13

What are the effects of estrogen on the uterus?

1) Proliferation of the endometrial stroma*****
2) Development of endometrial glands
3) Increased size of the uterus

14

What are the effects of estrogen on the ovaries & vagina?

Increase in size

15

What is the effect of estrogen on bone?

Inhibition of osteoclast activity that inhibits bone resorption and stimulates bone growth

16

What is the effect of estrogen on cervical mucous?

Estrogen makes cervical mucus thin & stringy, which provides channels that guide sperm

*****Note that this is OPPOSITE the effects of PROGESTERONE*****

17

What are the effects of progesterone on the uterus?

1) Promotes secretory changes of the endometrium & of the uterus i.e. getting the endometrium ready for implantation
2) Decreases frequency & intensity of uterine contractions
3) Decreases prostaglandin production

18

What is the effect of progesterone on cervical mucous? What hormone is this effect opposite to?

Production of a thick & tacky mucous that has an increased viscosity

*Progesterone containing contraceptives increase viscosity of cervical mucous to prevent sperm from reaching egg

19

Outline the process of oogenesis.

N/A

20

When does the female have the highest number of potential oocytes?

Birth

21

What is the difference between mitosis and meiosis?

Mitosis= 1x DNA replication & 1x splitting into two daughter cells

Meiosis= 1x DNA replication with 2x rounds of division

22

What is the difference between a primary oocyte and a secondary oocyte?

Primary=immature egg arrested until the reproductive years
- Diploid
- Arrested in meiosis I

Secondary= immature egg that is selected to continue meiosis in reproductive years
- Haploid
- End of meiosis II

23

How does meiosis differ between males and females?

Males= 4 sperm i.e. 4 gametes

Females= 1 gamete i.e. loss of 3 "polar bodies"
- Get a secondary oocyte and a polar body after meiosis I in the female
- Meiosis II yields 3x polar bodies and one gamete

*This is referred to as "chromosomal wastage"

24

What is the primoridal follicle?

This is the primary oocyte PLUS a layer of granulosa cells that surround it

25

What important hormone is secreted by the primordial follicle?

Oocyte-maturation inhibiting factor

*Regulates meiotic events

26

What is the primary follicle?

Proliferation of the granulosa cells surrounding the primary oocyte has occured, and now there is a mass of granulosa cells surrounding the primary oocyte
- Happens in the reproductive years

27

Outline & diagram the hypothalamic-pituitary-gonadal (HPG) axis.

1) Hypothalamus
- GnRH
2) Anterior Pituitary
- FSH
- LH
3) Gonads i.e. ovaries
- Estrogen
- Progesterone
- Inhibins

*Note that these steroid hormones function in a "long-loop" negative & positive feedback, primarily at the level of the anterior pituitary

28

What is the average duration of the female reproductive cycle?

28 days

29

What major events occur during the female monthly sexual cycle.

- Fluctuations in hormones
- Follicle maturation
- Endometrial lining of the uterus develops in preparation for fertilization & then is shed if NOT fertilized

30

What is the difference between the Follicular & Luteal Phases of the sexual cycle?

Follicular= Day 1
- Follicle development
- Endometrial proliferation
- Ovulation

Luteal= After ovulation
- Corpus Luteum forms
- Endometrial differentiation
- Menses if fertilization does NOT occur

31

Describe the release of GnRH from the hypothalamus.

Released in a pulsatile fashion
- Pulse duration= 5-25 min
- Frequency= Q1-2 hours

*****This stimulates the ant. pit. to release FSH & LH ; thus, throughout the different phases of the cycle there are pusatile changes in FSH & LH

32

What is the net effect of estrogen feedback in the follicular phase?

Negative feedback on hypothalamus and anterior pituitary

****Note that this is NOT a complete shut-down; it is more just holding things in check

33

When does the effect of estrogen feedback change? What are the relative levels of estrogen at this point?

Mid-cycle

*****Estrogen levels have peaked at this point

34

What is the net effect of estrogen feedback mid-cycle?

Positive i.e. increases FSH & LH, resulting in a surge of these gonadotropins mid-cycle

35

What is the net effect of estrogen & progesterone feedback in the luteal phase? Which predominates?

Negative feedback that is now PRIMARILY mediated by PROGESTERONE

*****Note that now this is more of a "shutting off"

36

What is the role of the inhibins in the female montly cycle?

Inhibition of the HPG axis

37

When do inhibins exert their effects? Which inhibins predominate throughout the different phases of the female monthly sexual cycle?

1) Follicular phase= Inhibin B that mostly regulates FSH secretion

2) Just after ovulation= Inhibin B turns off FSH secretion after ovulation

3) Luteal phase= Inhibin A is secreted by the CL and inhibits LH & FSH, decreasing ovarian steroid production

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