B8W2 Med Quiz

what cell types make up the corpus luteum

leftover theca + granulosa cells (after the egg is released)

Granulosa cells

• location in relation to egg

• male adjacent cell

• location in relation to egg- fixed to egg

• male adjacent cell- sertoli

Theca cell

• location in relation to egg

• male adjacent cell

• location in relation to egg- live around the egg/follicle

• male adjacent cell- leydig

too many theca cells can lead to an increase in what hormone

androgens

what hormones does the corpus luteum synthesize

progesterone + low levels of estradiol

timing in the ovarian cycle

• follicular phase: 0-14 days

• luteal phase: 15-28 days

timing in the endometrial cycle

• menses: 0-4 days

• proliferative phase: 5-14 days

• secretory phase: 15-28 days

what day does ovulation occur on

day 14

withdrawal of what hormone causes menstruation

progesterone

when is GnRH released or inhibited in response to progesterone levels (in comparison to estradiol)

• low progesterone- released

• high progesterone- inhibited

what effect does high estrogen have on FSH

it inhibits FSH

when does LH act on granulosa cells

during the luteal phase in preparation for ovulation (makes progesterone)

When does gametogenesis begin in males vs females

• males- during puberty

• females- during fetal life

What are the 6 hormones the placenta produces

• chorionic gonadotropin (hCG)

• placental lactogen (PL)

• ACTH-like protein

• PTH-related protein

• hypothalamic-like releasing hormones

• progesterone + estrogens

during fetal development, which organs does the placenta act as

• lungs

• GI tract

• liver

• kidneys

Internal female genitalia

• ovary

• fallopian tubes

• uterus

• vagina

external female genitalia

• clitoris (equal to penis)

• labia majora+ minora

• secretory glands(bartholin)

where is ovary cortex located and what does it develop

• cortex- outer

• responsible for developing follicles, corpus lutea and stroma

where is ovary medulla located + what does it develop

• medulla-inner

• develops blood vessels + stromal elements

role of fallopian tubes

• transport the ova from the ovary to uterus using cilia (beat egg towards uterus)

• fimbriae at the distal ends

3 parts of the uterus

• fundus

• corpus-endometrial lining

• cervix

menarche vs. thelarche vs. adrenarche

• menarche- beginning of menstrual cycle

• thelarche- breast development

• adrenarche- increase in adrenal androgen secretion around 6-8yrs old

how are gonadotropin levels during childhood

they are low (high sensitivity to feedback inhibition by steroids)

when GnRH becomes pulsatile how does the sensitivity of gonadotrophs to estrogen change

they sensitivity decreases (less inhibitory effect)

How does GnRH lead to a period

• increased pulsatility of GnRH causes LH surge, this marks initiation of 1st period (rise in LH and FSH levels produce androgen/estrogen that lead to period)

how often are gonadotrophins surging during our reproductive years

monthly

average age of puberty + what can delay it

• 9-10, but is decreasing in the US

• exercise + obesity can delay it

during the luteal + follicular phase what type of feedback is given by estrogen/progesterone

• luteal- negative feedback

• follicular- positive feedback

which cells can LH act on

theca (to make androgens a precursor for estradiol) + granulosa (FSH can only work on granulosa cells)

which cell types are estrogen + androgens made in

• estrogen- granulosa cells (bc they have aromatase)

• androgens- theca cells (bc they have 17 alpha hydroxylase)

What are the main roles of LH and FSH in female reproduction

• LH- progesterone synthesis

• FSH-estrogen synthesis

Primordial cells

• what are they

• when do they appear in the fetus

• when is a complete set made

• what % of follicles do they represent

• what are they- primary oocytes surrounded by single layer of pre-granulosa cells

• when do they appear in the fetus- 6 weeks

• when is a complete set made- 6 months after birth

• what % of follicles do they represent- 95%

how does the number of primordial cells change between birth + puberty

it decreases to 400,000 at puberty

growth stages of follicles

• primordial

• primary

• secondary (more granulosa layers, theca cells, make steroids bc of LH receptors)

• tertiary (requires FSH, has antrum, gap junctions, desmosomes, granulosa cells differentiate)

• graafian- dominant follicle

secretion of what from graafian follicles triggers LH surges

estrogen (E2)

What does follicular development require

• FSH

• Estrogen (E2)

• LH

during childhood what does follicular development lead to

atresia

which follicle types undergo atresia

all except graafian

where are ovarian and endometrial cycles occuring

• ovarian- in the ovaries

• endometrial- in the uterus

Follicular phase

• how long it lasts

• follicle development stages

• what type of feedback from estrogen

• how long it lasts- 14 days

• follicle development stages- primordial into graafian follicle

• what type of feedback from estrogen- initially negative feedback on LH + FSH, but switches to positive and increases FSH+ LH around day 14

Luteal phase

• follicle development stages:

• what type of feedback are estrogen and progesterone exerting

• follicle development stages- graafian follicle turns into corpus luteum

• what type of feedback are estrogen and progesterone exerting- negative feedback to decrease FSH+LH release

what hormones does luteal cells secrete

estrogen + progesterone

what happens if egg is not fertilized

• corpus luteum will degrade

• decrease in estrogen + progesterone

does the luteal phase allow other follicles to develop

no, it inhibits follicles from developing + sustains uterine lining

what is occurring during the menstrual phase

• oocyte is not fertilized (no pregnancy)

• degeneration of corpus luteum (CL)

• drop in estrogen + progesterone secretion

proliferative phase

• what is happening to the endometrium

• estrogen levels

• what is happening to the endometrium- its thickening

• estrogen levels- high, but decrease after ovulation (in response to progesterone)

secretory phase

• what does the endometrium develop

• what causes the endometrium to slough off

• what is the layer left behind after menstruation

• which hormone is dominant

• what does the endometrium develop- secretory glands

• what causes the endometrium to slough off- decreased estrogen + progesterone

• what is the layer left behind after menstruation- zona basalis

• which hormone is dominant- progesterone

what halts the proliferative phase

production of 17 beta HSD from progesterone

when is the effective implantation window

day 16-19 (lasts 3-4 days)

role of estrogen in female reproduction

• positive + negative feedback on FSH/LH secretion

• causes maturation + maintenance of fallopian tubes, uterus, cervix, vagina

• causes development of female secondary sex characteristics at puberty

• causes thelarche

• upregulates estrogen, LH and progesterone receptors

role of progesterone in female reproduction

• negative feedback on LH/FSH during luteal phase

• increases secretory activity of uterus during luteal phase

• maintains endometrial lining during pregnancy

• decreases uterine contraction

4 stages of the female sex act

• excitation- parasympathetic

• plateau

• orgasm- myotonic(muscle contraction)+ sympathetic

• resolution- no refractory period

Menopause

• what is it

• average age

• what is it- termination of reproductive functions

• average age- 51 years

what causes menopause

• progressive loss of ovarian follicular units

• ovarian steroid levels fall + gonadotropin levels rise

• high FSH +LH, low estrogen, progesterone and inhibin

how many germ cells do women start with

6-7 million at 20 weeks (only a few primary by menopause)

how does GnRH levels change during puberty

they increase which leads to rise in FSH + LH (increasing gonadal steroid production)

what are the “triggers” for the start of puberty

• increased set point of hypothalamus + pituitary for gonadal steroid negative feedback (increased set point=increase circulating steroids)

what effect does estrogen have on progesterone receptors

estrogen increases the amt of progesterone receptors on uterine lining during secretory phase

Summary of events in the menstrual cycle (8 things)

1. FSH↑- follicular growth + estradiol secretion

2. Estradiol↑-proliferative growth of endometrium, inhibits FSH, stimulate LH surge

3. LH surge +smaller increase in FSH (ovulation + CL formation)

4. corpus luteum secretes progesterone + estradiol

5. estradiol+ progesterone ↑- inhibits FSH+ LH, secretory phase

6. corpus luteum degenerates if fertilization/implantation don’t occur

7. estradiol↓ + progesterone ↓- result in menstrual flow

8. estradiol ↓- FSH ↑ + cycle begins again

what effect does continuous GnRH have on LH/FSH levels

decreases LH/FSH (shutting down reproductive system)

How does birth control work

• continuous secretion of synthetic estrogen/progesterone

• blocks LH surge + ovulation + FSH needed for follicle development

• mimics negative feedback of estrogen + progesterone

What contributes to the nucleus vs cytoplasm

• nucleus- sperm + egg equally

• cytoplasm- oocyte

where does energy from sperm motility come from

fructose in seminal vesicles

steps of fertilization

1. sperm cells weave past follicular cells + binds to zona pellucida and interacts with ZP3

2. increased Ca2+ causes acrosomal reaction that allows sperm to exocytose its acrosomal contents (hydrolytic enzymes) into zona pellucida

3. hydrolytic enzymes dissolve the zona pellucida + the tail pushes the sperm head towards the oocyte membrane

4. microvilli of the oocyte surround the sperm head, fuse + allow its contents into the oocyte

5. increased Ca2+ in the oocyte causes a cortical reaction hardening the zona pellucida (preventing another sperm from entering)

6. increase Ca2+ also causes completion of the oocytes 2nd meiotic division forming the 2nd polar body and a pronucleus

7. the sperm head enlarges + becomes the male pronucleus

8. the male + female pronuclei fuse together

Post-fertilization

• what happens to the embryo

• what happens to the inner cell mass

• what happens to the trophoblasts

• what happens to the embryo- it divides multiple times during its path to the uterus and becomes blastocyst

• what happens to the inner cell mass- becomes the embryo proper

• what happens to the trophoblasts- becomes the placenta (inner- cytotrophoblast + out-syncytiotrophoblast aka multinucleated cell)

steps of implantation (4)

1. hatching- zona pellucida of the blastocyst degenerates

2. apposition

3. adhesion- interaction between trophoblasts + uterine epithelial cells

4. invasion- blastocysts penetrate through epithelial layer via syncytiotrophoblast

placentation

• what do syncytiotrophoblasts invade

• where do lacunae form

• what do lacunae fuse with

• what do fetal blood vessels form from

• what is the role of intervillous space

• what do syncytiotrophoblasts invade- maternal blood vessels + kill and replace maternal endothelial cells

• where do lacunae form- within syncytiotrtophoblasts

• what do lacunae fuse with- maternal blood vessels to form intervillous space full of blood

• what do fetal blood vessels form from- tertiary chorionic villi

• what is the role of intervillous space- surrounds fetal vessels to supply gas/nutrients to fetus from mother

what prevents maternal blood from mixing w fetal blood

syncytiotrophoblast/placental barrier

when does the placenta develop

around 14 days post fertilization

what is the role of the placenta

• creates hormones essential for growth/development of fetus

• prevents mixing of maternal/fetal blood

• nutrient exchange

Non-placenta counterparts + source

• hCG

• hPL

• ACT-like protein

• PTH-related protein

• hypothalamic-like releasing hormones

• progesterone/estrogens

• hCG- LH+ pituitary

• hPL- Gh, hPRL+ pituitary

• ACT-like protein: ACTH+ pituitary

• PTH-related protein: PTH+ pituitary

• hypothalamic-like releasing hormones: GnRH, TRH,CRH, somatostatin + hypothalamus

• progesterone/estrogens- ovary

insulin resistance during pregnancy

• competition for food w baby so mother increases insulin following meals

• if it takes longer for mother to take up glucose=more food for fetus (hPL acts on moms prolactin receptors to increase insulin resistance)

• Gestational diabetes results if mother can’t produce enough insulin to lower blood sugar

how do the following parameters change during pregnancy

• blood volume

• RBC mass

• arterial pressure

• weight

• breast size

• cardiac output

• blood volume- increase by 30%

• RBC mass- increase

• arterial pressure- decrease (progesterone/estrogen vasodilate)

• weight- increase

• breast size- double

• cardiac output- increase by 30% (contributes to mild HTN + can lead to pre-eclampsia)

how does the fetus increase blood delivery

by increasing maternal blood pressure

hCG

• what produces it

• what does it do

• what produces it- trophoblasts (trophoblast proliferation increases hCG)

• what does it do- prevents regression/death of corpus luteum(maintains progesterone release to maintain uterine lining)

Luteal placental shift

• at around 8 weeks the corpus luteum degrades + hCG decreases+ slight decrease in progesterone

• the placenta takes over progesterone production and levels go back up

fetoplacental unit

• maternal cholesterol is converted to progesterone in placenta

• fetal DHAS is converted into estrogen in the placenta (via aromatase)

• fetal DHAS is also transported to liver to become 16OH DHAS

• fetal 16OH-DHAS gets transported to the placenta to form estriol

Quiescence- stage 0

• uterus is relaxed + insensitive to uterotonins (prostaglandins/oxytocin)

• braxton-hicks contractions occur at the end of pregnancy (weak + irregular)

• steady progesterone (inhibits uterine contractions)

Transformation/activation-stage 1

• switch to estrogen (begin to activate expression of uterotonins)

• myometrium becomes more contractile via increase expression of CAPs

• cervix expresses enzymes that break down collagen matric to facilitate dilation

Active labor-stage 2

• forceful + rhythmic contractions associated w dilated

• increased levels of prostaglandins(PGF2a + oxytocin)

• increased myometrial cell interconnectivity

• increased myometrial responsiveness to PGs + oxytocin

involution-stage 3

• oxytocin causes sustained + forceful myometrial contractions after uterine contents are expelled

lactation (let down reflex)

• suckling leads to oxytocin release from hypothalamus followed by post pit

• inhibition of dopamine release to promote prolactin(PRL) secretion

• oxytocin travels to myoepithelial cells in breast to release milk

circulation pathways in the fetus

• placenta

• ductus venosus- directs blood from left umbilical vein to inferior vena cava (oxygenated blood can bypass liver)

• foramen ovale- shunts oxygenated blood from right to left atrium

• ductus arteriosus- directs blood from pulmonary artery to aorta to by pass fetal lungs

what happens to these fetal circulation pathways at birth

ducts close + placenta is removed

how do the following values change after birth

• vascular resistance

• blood flow

• arterial pressure

• vascular resistance- decrease

• blood flow- increase

• arterial pressure- decrease

what triggers first breath

• mild hypoxia/hypercapnia + tactile stimuli and cold skin

how do left atrial vs right atrial pressures change in newborns

• left increases bc of increased systemic resistance

• right decreases bc of decreases flow from closed ductus arteriosus (decreases venous return)

signals from the pituitary control what 3 things in ovarian follicle

• formation of antral/graafian follicles

• resumption of meiosis

• ovulation

how does high levels of estrogen affect gonadotrophs sensitivity to GnRH

it enhances sensitivity

what is the climacteric

the transition period from being reproductive to non-reproductive (pre-menopausal)

tonic vs Gn regulated growth phases

• tonic-class 1-4

• Gn regulated- class 5-8

what 2 hormones causes maternal blood sugar to remain high after a meal

• placental lactogen(PL)

• GH

what is the role of RU486

a progesterone antagonist that induced labor +delivery

2 main evolutionary developments in humans

• bipedalism(2 feet walking)

• encephalization (big brains)

what effect does cortisol have on surfactant

it increases surfactant production