Exam 4 - Reproductive Flashcards
How is the egg swept up at the end of the fallopian tube
by cilia
How does the egg move through the fallopian tube
muscular contractions and the cilia
How long does it take from when the sperm enter the uterus to get the the fallopian tubes? Why?
30 minutes because the uterine muscles propel them
What is capacitation
when chemicals in the woman’s body alter the sperm to make them able to fertilize the egg
How long can sperm stay in the oviduct before fertilization
several days (1-2 wk)
Where does fertilization occur
In the oviduct
T or F Protein’s from the sperm’s cap must hook up precisely with proteins on the surface of the zona pellucida
true
How do the sperm get through the zona pellucida
they shed their outer coating releasing enzymes that allow them to enter
how many fertilized eggs do not result in viable embryos
over 50%
What happens to the zona pellucida once one sperm enters
It locks out all other sperm
When does the egg complete meiosis
After fertilization
How long until the first mitosis (post fertilization)
24 hours
After the first mitosis, how often do the cells divide
every few hours
How do you get identical twins
if the tiny group of dividing cells splits into two groups
How many days after fertilization does the blastocyst leave the zona pellucida? How?
6 days after fertilization it releases enzymes to break out
How is the blastocyst not destroyed?
It releases chemicals to suppress the mothers immune system
Where does the blastocyst go?
It becomes embedded in the endometrium
Why does morning sickness occur? Does everyone get it?
the changing hormones associated with pregnancy can cause it in some women
What is gastulation
the development of three germ layers
What do the three layers of the developing embryo become
Lower - lungs, liver, lining digestive tract (endoderm)
Middle - bone, blood, heart, and skeletal muscles (mesoderm)
Outer - CNS, skin and hair (ecotoderm)
When is it considered a fetus?
2 months after fertilization when all the organ systems are in place
T or F Maternal and fetal blood mix
False
T or F The heart works early in development
True
What do bones begin as?
Cartilage (from mesoderm/middle layer)
When does myelination begin occuring
6th month of gestation
How much does the mother’s blood volume increase?
50%
How much does the cervix open at birth?
4 inches
Before modern medicine, what was the common outcome of birth?
Death for the mother and the infant
T or F The human brain is bigger than that of primates, and the human pelvis is smaller than primates
True
Name the gonads for each sex and what is produced by each
Female - Ovary - ovum; steroid hormones: estrogen and progesterone
Male - testis - sprem; steroid hormone: testosterone
State what SRY stands for, where it is found, when and where it is expressed and what it do
Sex Determining Region found on the Y chromosome and expressed in the gonad for a few weeks only to cause the cells of the gonads to differentiate into male parts
State the functions of the different testicular cells during development and the role of the hormones those cells produce directly and indirectly
Setroli cells: secrete Mullerian-inhibiting substance (MIS) that causes the mullerian ducts to regress
Leydig cells: secrete testosterone which…
1) causes wolfian ducts to differentiate into the epididymes, seminal vesicle, ducti diferentia, and the ejaculatory duct
2) is converted to dihydrotestosterone that stimulates the development of the penis, scrotum, and prostate
State what happens during development if the SRY gene is not expressed
The gonads develop into ovaries w/o sertoli and leydig cells
Absence of MIS - mullerion ducts transform to uterus, fallopian tubes, and the inner vagina
Absence of testosterone: wolffian ducts regress (8wks) and deveop outer vagina, female external genitalia
What is the default sex
female
Describe the mechanism and effect of testicular feminization
It is when the SRY gene is present but the receptors for testosterone are non-functional so wolffian ducts regress and external develops into female anatomy
Not known until puberty when menstruation does not occur
State how long spermatogenesis usually takes and general process
64 days
spermatogonium (2n 2x) —> primary spermatocyte (2n 2x) —> secondary spermatocyte (n 2x) —> spermatid (n x) –> sperm (n x)
Describe the anatomy of a sperm cell
Head - contains nucleus, small cytoplasm & acrosome (has enzymes to digest thru zona pellucida of ovum)
Midpiece: contains mitochondria to make ATP to drive mvmt of flagella
Tail/flagellum
State how many sperm cells are made per day
30,000,000 or 30 mil
Describe the role of the Sertoli cell in spermatogenesis, include what is made by the Sertoli cell and the mechanism and function of the blood-testis barrier
Sertoli cells run b/t the basement membrane of seminif tub and lumen and have very tight junc to prtect developing sperm from any molecules from blood
1) spermatogonia start at top and move as they develop towards lumen
2) sertoli cells secrete fluid in lumen to drive flow of sperm into epididymis
3) sertoli cells secrete androgen binding proteins to keep concentration of testosterone high in lumen
4) secrete inhibin involved in feedback regulation of pituitary gland
5) can phagositize defective sperm
Describe how sperm is moved from the seminiferous tubules to the epididymis
Sperm moves by fluid pressure to the epididymis: filtration of plasma across sertoli cells into lumen drive sperm into epidid
State the role of the epididymis in the male reproductive system
Absorb lots of fluid to concentrate the sperm and mature them as the move thru (use contraction of smooth muscle to drive flow out, but store it until ejaculation)
Describe the steps of penile erection
Purpose: to make the penis rigid so that it can penetrate the vagina
Initiated by (2 ways)
1a) Descending CNS pathways triggered by thoughts, emotions and sensory inputs such as smell
1b) Input from penis mechanoreceptors
2) Increase activity of neurons that release NO
3) Decrease activity of adrenergic symp neurons that release norepine
4) dilation of penis arterioles
5) penile erection
6) compression of veins (positive feedback on erection)
Define emission and ejaculation and describe the mechanisms
Emission (epi to urethra): Dependent on symp activation of smooth muscle (nor on alpha 1) in vas deferens, epi and ejaculatory ducts to cause peristaltic contraction. Nor on alpha 1 also causes seminal vesicle, prostate and bulbourethral to secrete glycogen and prostaglandins
Ejaculation: urethra out
Describe the male hypothalamic-pituitary-gonadal axis
Hypo Release GnRH
GnRH to ant pituitary (every 90 min)
Stim release FSH and LH
FSH - sertoli cells - stim spermatogenisis and secrete inhibin (neg feed on release FSH)
LH - leydig cells - testosterone (neg feedback LH and GnRH) - repro tract and other organs respond
State the effects of testosterone in the male (6 places)
Skin: growth facial and body hair; baldness w/ genetic disposition
Male sex organs: sperm production, prostate growth, erectile function
Muscle: increase size and strength
Bone: maintain bone density
Marrow: RBC production (thru kidney function)
Brain: increase labido/sex drive
State two hormones that can be made from testosterone in the male and state what enzymes do the conversion
Dihydrotestosterone (by 5 alpha-reductase)
Estradiol (aromatase) - primary estrogen of males
1) released by sertoli cells that convert test to est which is necessary for cell fun
2) receptors in smooth muscle tract for it
3) fun in bone marrow for long bone growth
4) some neurons in brain that infuence repro behaviours
Is female gamete production and release cyclical?
Yes
State the average length of the menstrual cycle
28 days
State what happens on day 1 of the menstrual cycle
Start of menses/pituitary hormone will increase to cause 10-25 follicles to start growing
State the functions of the ovary (5)
1) oogenesis
2) site of development and maturation of the oocyte
3) expulsion of oocyte
4) makes sex steroids (progest and estradiol)
5) produces inhibin
State where in the ovary the oocytes mature and where hormones are produced
The ovaries mature in the follicle and the hormones are produced in the different tissues of the follicle
State when mitotic oogenesis occurs
Mitotic oogenesis occurs at about 7 months gestation as a fetus
State how many eggs are present in the ovaries at birth and what stage the eggs are in
2-4 million per ovary and they are in meoitic arrest in phase I
Define meiotic arrest and say when it occurs (that is what stage of meiosis)
Meiotic arrest is where the cell is stopped from further division or continuation of development and it occurs in prophase I of meiosis
State when the first meiotic cell division is completed in the female
The first meiotic cell division is completed in the female about every 28 days; just before ovulation occurs
Describe the generation of polar bodies and when you get them
Polar bodies are due to the unequal division of organelles and cytoplasm during meiosis
Describe follicular development and the role of granulosa cells and theca cells
Primordial follicle (w/prim oocyte): simple squamous granulosa cells that have the potential to secrete est, prog and inhibin, but only if theca cells
Primary follicle (w/prim oocyte): cuboidal granulosa cells and stratified 2-4 layers Start secreting glycoprotein to form gel around oocyte (zona pellucida - important for sperm to bind and enter and has projections to communicate w/developing egg) --> second division occurs just before ovulation
Secondary follicle (w/sec oocyte & 1st polar): theca interna and externa (secrete androgens and allow for granulosa cells to secrete)
Follicle matures and as approach ovulation 4 things occur so that it can be expelled
What happens to the maturing follicle as it approaches ovulation (4)
1) corona radiata and oocyte detach from rest of cumulus mass
2) migrates to edge of ovary and granulosa cells secrete enxmes to break trhu theca and expose antrum of follicle to surface of ovary
3) Gran cells release prostaglandins to stim smooth muscle like cells to push oocyte an corona radiata to surface of ovary
4) OOcyte w/zona pellucida and radiata expelled
Describe the zona pellucida and what its importance is
Zona pellucida surrounds the developing oocyte and it is gel-like which is important for sperm binding. Also has pores
Describe how granulocytes communicate with the developing egg
Granulocytes have projections that enter pores of zona to deliver messages to egg about development and to provide nutrients for maintenance and growth
State when during the lifetime and menstrual cycle you could find the different stages of follicular development
Cells proliferate into primary follicles at any point in life. Secondary follicles come after puberty
State approximately how many follicles start to develop passed the early secondary stage during each menstrual cycle and state what happens to those which do not become dominate
About 10-25 follicles;
those that do not become dominant degenerate/experience atresia
State how many eggs are present in the ovaries at puberty and how many are ovulated
At puberty there are about 200,000 to 400,000 and only about 400 are ovulated
State what happens to generate fraternal twins
Fraternal twins is when two secondary follicles are at a similar stage of growth when the pituitary hormones increase, so both will be expelled from the ovary
Describe what happens to the follicle after ovulation including what the cells secrete
Secrete increased amounts of progesterone and inhibin and can make estrogen
State how long the corpus luteum survives without fertilization
It can survive up to 10 days because of the high levels of LH that are present
State the two ovarian phases of the menstrual cycle
Follicular stage (1-14) and Luteal stage (14-28) assuming that ovulation is day 14 Follicular stage is more variable
What happens on the different days of the mesntrual cycle in the ovary
Follicular Stage (1-14)
1-7:
1: pituitary hormones increase to cause 10-25 follicles grow
7: one follicle dominant, others degenerate
7-14: mature dom follicle
Luteal stage (14-28) 3-4 days pre menses: corpus luteum secretes enzymes & w/o fert, it degenerates and leads to menses
Once degenerated, pituitary hormone increases and cycle starts again
State what cells make the different hormones in the ovary and how these cells are similar to testicular cells
Granulocytes: estrogen, inhibin, and little progesterone (like sertoli cells, support and nourish developing gamete and respond to FSH)
Theca: androgens and little progesterone (like leydig cells, make androgens, respond to LH)
Luteal: estrogen and large progesterone
Pituitary: LH and FSH (same as in males)
Describe the events of the menstrual cycle as far as hormone release, follicle/corpus lutuem development, ovulation, and uterine changes. Include all specifics discussed in class.
DAYS 1-5/10
1-5/10:
1) LH increase at first and then constant
2) FSH increasing and stay fairly high - stim 10-25 fol to srat develop; required for them to get out of early secondary follicular stage
3) both go up here bc of neg feedback 3a) est and prog inhibit FSH and LH when high, but once low, disinhibit and start secrete again
3b) FSH stim increase by decrease others - act on granulosa cells to trigger prolif and secrete more fluid and produce estrogen
3c) LH acts on LH receptors of theca to cause take up chol to convert to androstenedione
4) FSH increase, LH increase, granulosa proliferate and make estrogens
Describe the events of the menstrual cycle as far as hormone release, follicle/corpus lutuem development, ovulation, and uterine changes. Include all specifics discussed in class.
DAYS 7-14
days 7-14:
1) FSH starting to fall, LH no change (fall bc neg feedback,e st increase bc FSH stim gran to prolif to make more est and inhibin)
2) At some level est, switch of pituitary and now pos feed back - LH surge
Peak of surge 12 hr pre ov, leads theca and granulosa to become luteal, prog up and est down, LH decrease, gran stim oocyte first meiotic division & digest thru wall of follicle, increase blood flow ovary so more fluid in antrum, produce progesterone and decrease estrogen
Follicle becomes corpus luteum
Describe the events of the menstrual cycle as far as hormone release, follicle/corpus lutuem development, ovulation, and uterine changes. Include all specifics discussed in class.
DAYS 14+
LH levels remain high during most
1) maintains corpus luteum 1-10 days
2) neg feedback of high est and prog cause LH (and fsh) to degenerate
1st 10 days - secrete large est and prog
If pregnant: placenta secrete gonadotropin which binds same receptors as LH so high levels maintained
Describe the production of estrogen by the ovary
Androgen from theca cells converted to androstenidione where it moves to granulosa cells to be converted into estrogen
Describe how a follicle can become dominate
Follicle becomes dominant because prior to signal from pituitary there are already primary follicles developed, so the more developed ones are then able to proliferate and change and develop quicker, becoming larger at the time and therefore dominant
Phases of the Uterus during menstruation
Menstrual (day 1-3/5): stratum func dying bc of decrease in est and prog @ end of luteal in ovary when corp lut degen; bleeding occurs to wash away dead tissue; thickness of endo decreases during menstrual phase
Proliferative (post menses to ov): estrogen stim the prolif of the funct endo; stim production of glands in endo and myo; est stimulates the progesterone receptors to be expressed in endo and myo (w/o progest its just in prep)
Secretory (post ov to menses): producing prog and est; endo stop proliferation and start secreting fluid filled w/glycogen and glycoproteins w/mucous like consistency good for eggs, plug for sperm
What does progesterone do in the uterus during the secretory phase?
Cause blood vessels to infiltrate the endometrium and myometrial quiescence (no contractions)
What does estrogen like w/ and w/o prog in the uterus?
w/o: cervix produces thin water mucus for sperm to easily swim thru
w/ mucous plug - eggs only viable 1st 24 hours so if sperm not already present, no fertilize
Uterine Flow Chart - hormones
1) degen of corpus luteum (bc LH levels decreased)
2) decreased progesterone and estrogen
3) increase prostaglandins in uterus
4) cause intesnse vasoconstriction of arterioles to functional endometrium
5) decrease O2 and nutrients
6) causes necrosis of func endo tissues
7) once dead, uterine arteries vasodilate
8) hemmoraging
9) pushes out sloughing endometrium
Uterine Flow chart (uterus)
1) degen of corpus luteum (bc LH levels have decreaed)
2) decrease prog and est
3) increase prostaglandins
4) causes myometrium to constrict to increase P in uterus to help bluk flow
5) sloughing endometrium propelled out
