Bio: Reproductive system Flashcards
Sperm need two things for max viability
really high levels of testosterone
Slightly cooler then body temp
The testes: male primary sex organ, have two jobs:
make sperm
make testosterone
_____ will become sperm and are stimulated by_____
_____ cells make testosterone and are stimulated by
spermatogonia
FSH
Leydig/interstitial cells make testosterone and are stimulated by LH
Sustentacular cells -> another name and function
Also called sertoili
Sustain sperm development, secrete nutrients, secrete ABP (androgen binding protein)
secrete inhibin -> inhibit FSH (It inhibits the synthesis and release of the follicle-stimulating hormone in the pituitary gland and reduces the hypothalamic LH - releasing hormone content)
Spermatogenesis:
When start and end? Describe process -> how many get after both cycles of meiosis?
After meiosis 1 get 2 secondary spermatocytes and at very end get 4 spermatids
Occurs daily from puberty to death
See diagram in packet
What is the epididymis?
What is spermeogenesis?
Urethra
Vas Deferens
Epididymis -> final place where sperm cells mature = spermeogenesis (final maturation step), coiled duct, 6 meters, secrete nutrients, giving sperm swimming ability
Urethra -> 20 cm long tube carries both urine and semen BUT not at the same time
Vas Deferens -> long muscular duct enter body cavity, connects epididymis to urethra (vasectomy -> Can disconnect and reconnect Vas deferens for sperm travel)
Why is semen basic? What is semen? What makes it?
Basicity important bc urine acidic that tube can be acidic and want to protect sperm cells so semen is basic to neutralize acidity left behind by urine so sperm cells can survive
Accessory glands make semen = nutritious (fructose), alkaline fluid
a) seminal vesicles (65% of total ejaculate volume)
b) prostate (30% total ejaculate volume)
c) Bulbourethral glands (4% total ejaculate volume, produce a highly alkaline mucus on arousal)
Sex chromosomes determine which duct system you develop
What is DHT?
What are Wolffian ducts vs Mullerian ducts?
DHT = testosterone
Wolffian ducts -> male system
Mullerian ducts -> female system
Sex chromosomes determine which duct system you develop
What is DHT?
What are Wolffian ducts vs Mullerian ducts?
How does the Wolffian system develop?
DHT = testosterone
Wolffian ducts -> male system
Mullerian ducts -> female system
In testes -> testosterone (DTH) causes secondary sex characteristics and wolffian ducts, and have mullerian inhibiting factor (MIF) and get regression of mullerian ducts
The SRY gene
Bar body
The SRY gene provides instructions for making a protein called the sex-determining region Y protein. This protein is involved in male sexual development, which is usually determined by the chromosomes an individual has
Bar body = get bc one of the X chromosomes randomly deactivates
When replicate bar body -> early blastocyst
vestibule
Greater vestibular glands
Mammary glands
female system: external genitalia
Vestibule = vaginal opening and urethral opening
Greater vestibular glands secrete alkaline mucus on arousal
Greater vestibular glands secrete alkaline mucus on arousal to help sperm
Mammary glands: single physiological function to produce milk to nurse an infant
Cervix (when non-fertile vs fertile)
endometrium
myometrium
Uterine Tubes
Cervix -> opening to uterus
non-fertile (most days of month) closed and sticky, acidic mucus
fertile (only a few days of month) open, thin, watery, alkaline mucus
Uterus: pregnancy develops here
- endometrium: layer into which a fertilized egg implants
- myometrium: smooth muscle wall of uterus, retain ability to rapidly divide
Uterine tubes: connect muscle wall of uterus, fallopian tubes
path that eggs takes to reach the uterus
cilliated to sweep the egg along
fertilization here
tubal ligation here
Cilia made of microtubules in eukaryotic cells, if have mutation in alpha tubulin so microtubules may not work properly and cilia can’t sweep egg along and egg can get stuck in falopian tube = ectopic surgery and can’t have baby
Tubal ligation -> to prevent egg from reaching uterus so no baby
Ovary and Oogenesis:
What does the ovary do?
What is the oogenesis process?
The ovary: makes ova, makes estrogen and progesterone
Oogenesis:
Prenatal Stage
Oogonia then by mitosis get many more oogonia then have activation to get primary oocytes and halt at prophase
*see diagram for rest
Oogenesis does not begin at puberty like for males
Not all get activated
5-6 selected to fininish meiosis part I
Dont let secondary oocytes do meta II, halt at meta II (in order to continue must get fertilized
Only choose 1 of ⅚
Monthy -> ⅚ finish meiosis 1 and the one that looks best gets ovulated and halted at meta II and only if that single one is fertilized will it go through meiosis II
The primary oocytes exist for decades! They were only made during prenatal stage! So during menopause, destroy eggs bc you are not fit to carry baby and these are super old primary oocytes!
What are the hormones starting from hypothalamus to signal to uterus?
Hypothalamus -> anterior pituitary -> FSH/LH -> ovary -> estrogen/progesterone -> uterus
Names phases of overian cycle
What day is important?
What is the positive and negative feedback like?
Follicular phase (Day 1-13)-> develop follicle (oocyte + some supporting cells), triggered by FSH, secretes estrogen Ovulation (DAY 14) release oocyte + some supporting cells Triggered by LH surge Luteal phase (days 15-28) Follicle remnants become the corpus luteum triggered by LH surge secretes estrogen and progesterone to maintain the corpus luteum need LH
See diagram for feedback
Explain uterine cycle 3 phases
See diagram in packet
Describe levels of LH, FSH, estrogen and progesterone and levels of endometrium, and events of ovary in body through out menstrual cycle
See diagram and explanation in packet
What does blastula do?
How does birth control work?
Blastula -> makes hcG which acts like LH bc can maintain luteum so you will not menstruate
Birth control = estrogen and progesterone combo -> first 7 days pills dont do much but on day 7 get estrogen and progesterone (inhibtor of FSH and LH early on!) to inhibit ovulation so no pregnancy -> see yellow line below
acrosome
granulosa
Head of sperm
Acrosome in sperm is filled with digestive enzymes to eject at surface of granulosa so can enter cell
Better to be fashionably late bc other sperm cells dumped out their enzymes earlier to make a pathway through granulosa on outside of egg for a later sperm cell
What happens when a sperm enter egg? Where does it occur?
What implants in uterus? Describe the events/cell stages that lead to its creation
We want to prevent polyspermy, only 1 sperm
When 1 sperm enters -> egg cell depolarizes
This fertilization is in the fallopian tube
dikaryon (one cell, 2 nuclei) -> oocyte meiosis II -> egg releases 2nd polar body -> syngamy (egg and sperm nuclei fuse) -> zygote -> after 24 hours get 2-cell stage (ball of two cells) -> morula (solid ball of cells) -> Blastula implants in uterus
May take 2-4 days for blastula to get to and implant in uterus
Trophoblast?
Inner cell mass?
How does body prevent the lining from shedding with the implanted ____?
Implantation of blastula
Trophoblast -> secrete hCG to maintain the corpus luteum becomes the placenta in 3 months, secrete estrogen, progesterone, etc
Inner cell mass -> becomes embryo, umbilical cord, amniotic sac
To prevent shedding:
Trophoblast secrete hcG to maintain corpus luteum so that continue to produce hormone to keep lining intact and doesn’t shed with the egg
What does a pregnancy test look for?
Pregnancy test test hcG, 3 months don’t make hcG anymore bc trophoblast becomes placenta in 3 months
Where are stem cells found? What kind are they?
What can pluripotent stem cells become?
What is induction?
Embryonic stem cells (ESCs) derived from the inner cell mass of a blastocyst are pluripotent stem cells
Embryonic stem cells can be found in blastocyst
stem cells undifferentiated cells -> can become different types of specialized cells and can divide to produce more stem cells (immortal)
Pluripotent can make any cell except placenta
Induction = signaling by surrounding cells or artificial chemicals
Where are adult stem cells found?
Adult stem cells are found in bone marrow -> blood stem cells are multipotent cells: can become some, but not all, body cell types like red blood cells, platelets, white blood cell
What is a totipotent cell?
Totipotent cell = Zygote! Can be any body cell type and placenta!!
Where is telomerase found (what kind of cells)?
Telomerase only found in “immortal cells” to help cells divide a lot and once terminally differentiated they will silence telomerase
ex. cancer cells
What is gastrulation?
Neurulation and Organogenesis?
Endoderm
Mesoderm
Ectoderm
What kind of cells make up these germ layers
- Gastrulation -> first half (about 4 weeks) of embryonic stage -> form the 3 primary germ layers
These multipotent cells (more limited in what they can become)
Endoderm:
- lining of tissue
- gland tissues
- pancreas
- liver
- gland organs and inner linings
Mesoderm
- muscular system
- heart
- bones
- non gland organs
Ectoderm
- hair
- skin
- nails
- cornea
- nervous system (portion that pinches off neural plate/tube)
Neurulation and Organogenesis -> second half of embryonic stage
further develop nervous system plate/tube
Describe process of labor (pos or neg feedback? What ends the feedback? What are the 3 triggers of labor?
Pos feedback, external regulator = baby’s birth will end cycle bc no more stretch of cervix
Three triggers:
- placenta deteriorate
- uterus stretched
- baby’s head stretch the cervix
What changes occur in baby once born?
See diagram
Baby’s Changes
Baby in womb bypass lungs bc no air to breath anymore so need to close lung bypass
There is hole b/w right and left atria (pink hole called foramen ovale so could bypass lungs) and a vessel that connects the pulmonary artery and aorta (so bypass lung, this vessel called ductus arteriosis)
Once baby born, no more O2 from mom’s hemoglobin
The foramen closes fast and ductus arteriosis deteriorates
Close liver bypass (baby doesn’t need to break things down) -MCAT has never asked about this
Close umbilical vessels -> Umbilical vessel bring blood and transport O2 to baby, baby and mom circulation near to exchange, arteries close first and vein close second
Stop making fetal hemoglobin (stingy bc steal O2 from mom’s hemoglobin)
Changes in mother after labor?
See diagram
When she delivers placenta massive drop in estrogen and progesterone so increase prolactin and make milk (but not a true pos feedback)
As baby nurses the more oxytocin and the less baby nurses the less all these hormones made
