Endocrine - Key Concepts - Reproductive Physiology Flashcards
The reproductive system is composed of…
gonads and external genitalia
What are the two main functions of the gonads?
Production of gametes and production of hormone
Production of reproductive hormones is reglated by…
the hypothalamic-pituitary-gonadal axis
The seminiferous tubules contain…
Sertoli cells
developing sperm cells
Define
Spermatogenesis
the progression of sperm cells from spermatogonia through the processes of meiosis and spermiogenesis to form mature spermatozoa
_ and _ are required for normal sperm production
Testosterone and FSH
Only Sertoli cells express _ and _
Androgen receptor
FSH receptor
These hormones regulate spermatogenesis indirectly thru actions on S cel
Sertoli cells produce ____, which negatively feeds back on _ .
Inhibin
Pituitary FSH production
Functions of the Sertoli cells include:
production of ABP
production of fluid
creation of the blood testis barrier
production of inhibin
Leydig cells are _ cells that reside _.
Stromal cells
outside the seminiferous tubules
Leydig cells respond to _ by producing _.
Leydig cells respond to LH by producing Testosterone.
Define
Testosterone
What is it? What is it converted to?
Active androgen
Converted peripherally to DHT or to estradiol
Leydig cells are regulated by…
hypothalamic - pituitary - testicular axis
What is the hypothalamus-pituitary-testicular axis?
Hypothalamus produces GnRH → stimulates pituitary gonadotropes → secrete LH and FSH → Testosterone, DHT, and estradiol negatively feedback at the pituitary and hypothalamus → inhibit LH more than FSH
Inhibin selectively inhibits…
FSH
The male reproductive tract includes…
tubal structures (epididymis, vas deferens, and urethra)
accessory sex glands (seminal vesicles, prostate, bulbourethral)
penis
Seminal fluid is produced in the…
seminal vesicles
prostate
What is the purpose of seminal fluid?
nourish, buffer, and protects sperm
Penile erection involves…
complex neurovascular response leading to engagment of the erectile tissue
penis and shaft fill with blood
_ is the functional unit of the ovary?
The follicle
Follicles contain _ and _ cells that surround the _.
Granulousa
Theca
primary oocyte
Primary oocyte remains in the _ until _.
Primary oocyte remains in the first meiotic prophase until just before ovulation.
The menstrual cycle refers to an approximately 28 day cycle that is driven bby the following ovarian events:
Development of one large antral follicle to a preovulatory follicle (Follicular phase), ovulation, and formation and death of a corpus luteum of mensturation (luteal phase)
How do the ovarian and uterine cycles relate?
Follicular Phase = menses and proliferative phase
Luteal Phase = secretory phase
Ovary ; uterine
How many follicles make it through the entire cycle?
One dominant follicle is selected per menstrual cycle
How is the dominant follicle chosen?
usually the largest follicle with the most FSH receptors
During the menstrual cycle:
High levels of _ occur around midcycle
What do they do?
Estradiol
Exert positive feedback on gonadotropin secretion
The positive feedback exerted on gonadotropin secretion by high estradiol around midcycle induces _.
the LH, and smaller FSH, surge
The midcycle gonadotropin surge induces:
- Meiotic maturation of primary oocyte to secondary oocyte paused at metaphase of the second miotic division
- Breakdown of the ovarian and follicular wall for ovulation
- Differentiation of remaining follicular cells into corpus luteum
The corpus luteum produces…
high levels of progesterone, estradiol, and inhibin
What happens to the corpus luteum if pregnancy does not occur?
The corpus luteum will die in 14 days
Luteal phase
What is the function of the fallopian tubes?
Capture the egg and transport it toward the uterus
What is the function of estrogen in egg transport?
promotes transport
What is the function of progesterone in egg transport?
inhibits transport
Define
Endometrium
Uterine mucosa
normal site of embryonic implantation
What happens to the endometrium during the menstrual cycle?
The mucosa is increaded in thickness in preparation for implantation and is sloughed away if no pregnancy occurs
What occurs during the mid to late follicular phase (days 6-14)?
The ovary produces estradiol, which induces all cells of the endometrium to proliferate
Proliferative phase
What occurs during the luteal phase (days 16-28)?
Production of progesterone
Progesterone produced during the luteal phase…
Progrsterone stimulates secetion from the uterine glands
Secretory phase
What happens if pregnancy doesnt occur?
Corpus luteum dies
Progesterone production ceases
Uterine endometrium is sloughed
Menses - follicular phase - days 1-5
What is the cervix?
Lower portion of the uterus
What happens to cervical mucous during midcycle?
In response to estrogen, cervical mucous promotes entry of sperm into the uterus
What happens to cervical mucous during the luteal phase?
In response to progesterone, cervical mucous becomes thick and poses a barrier to entry of sperm and microbes into the uterus
Where does fertilization occur? What happens?
Fallopian tube
Penetration of the oocyte by sperm
Pregnancy hormones can induce what major changes in maternal physiology?
An increase in insulin resistance
Increase in fatty acid use by the mother
Development of mammary glands
Mammary gland development is promoted by…
estrogen
progesterone
placental lactogen
maternal pituitary prolactin
Maternal pituitary prolactin secretion is stimulated by…
Placental estrogens
Define
Oxytocin
What is it? What does it do?
Pituitary hormone
Promotes contraction of certain smooth muscles, including myometrial contractions during labor and myopeithelial contractions in the breasts that lead to let-down of milk in response to suckling
Menopause results from…
Exhaustion of the ovarian reserve
Menopause is characterized by…
low ovarian hormone
Elevated gonadotropin levels
