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MCAT > Bio: Reproductive system > Flashcards

Bio: Reproductive system Flashcards

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MCAT flashcards
1
Q

Sperm need two things for max viability

A

really high levels of testosterone

Slightly cooler then body temp

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2
Q

The testes: male primary sex organ, have two jobs:

A

make sperm

make testosterone

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3
Q

_____ will become sperm and are stimulated by_____

_____ cells make testosterone and are stimulated by

A

spermatogonia
FSH

Leydig/interstitial cells make testosterone and are stimulated by LH

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4
Q

Sustentacular cells -> another name and function

A

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)

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5
Q

Spermatogenesis:

When start and end? Describe process -> how many get after both cycles of meiosis?

A

After meiosis 1 get 2 secondary spermatocytes and at very end get 4 spermatids
Occurs daily from puberty to death
See diagram in packet

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6
Q

What is the epididymis?
What is spermeogenesis?
Urethra
Vas Deferens

A

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)

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7
Q

Why is semen basic? What is semen? What makes it?

A

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)

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8
Q

Sex chromosomes determine which duct system you develop
What is DHT?
What are Wolffian ducts vs Mullerian ducts?

A

DHT = testosterone
Wolffian ducts -> male system
Mullerian ducts -> female system

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9
Q

Sex chromosomes determine which duct system you develop
What is DHT?
What are Wolffian ducts vs Mullerian ducts?
How does the Wolffian system develop?

A

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

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10
Q

The SRY gene

Bar body

A

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

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11
Q

vestibule
Greater vestibular glands
Mammary glands

A

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

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12
Q

Cervix (when non-fertile vs fertile)

endometrium
myometrium

Uterine Tubes

A

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

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13
Q

Ovary and Oogenesis:
What does the ovary do?
What is the oogenesis process?

A

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!

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14
Q

What are the hormones starting from hypothalamus to signal to uterus?

A

Hypothalamus -> anterior pituitary -> FSH/LH -> ovary -> estrogen/progesterone -> uterus

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15
Q

Names phases of overian cycle
What day is important?
What is the positive and negative feedback like?

A 
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

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16
Q

Explain uterine cycle 3 phases

A

See diagram in packet

17
Q

Describe levels of LH, FSH, estrogen and progesterone and levels of endometrium, and events of ovary in body through out menstrual cycle

A

See diagram and explanation in packet

18
Q

What does blastula do?

How does birth control work?

A

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

19
Q

acrosome

granulosa

A

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

20
Q

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

A

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

21
Q

Trophoblast?
Inner cell mass?

How does body prevent the lining from shedding with the implanted ____?

A

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

22
Q

What does a pregnancy test look for?

A

Pregnancy test test hcG, 3 months don’t make hcG anymore bc trophoblast becomes placenta in 3 months

23
Q

Where are stem cells found? What kind are they?
What can pluripotent stem cells become?
What is induction?

A

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

24
Q

Where are adult stem cells found?

A

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

25
Q

What is a totipotent cell?

A

Totipotent cell = Zygote! Can be any body cell type and placenta!!

26
Q

Where is telomerase found (what kind of cells)?

A

Telomerase only found in “immortal cells” to help cells divide a lot and once terminally differentiated they will silence telomerase
ex. cancer cells

27
Q

What is gastrulation?
Neurulation and Organogenesis?

Endoderm
Mesoderm
Ectoderm

What kind of cells make up these germ layers

A
  1. 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

28
Q

Describe process of labor (pos or neg feedback? What ends the feedback? What are the 3 triggers of labor?

A

Pos feedback, external regulator = baby’s birth will end cycle bc no more stretch of cervix

Three triggers:

  1. placenta deteriorate
  2. uterus stretched
  3. baby’s head stretch the cervix
29
Q

What changes occur in baby once born?

A

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)

30
Q

Changes in mother after labor?

A

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

MCAT (36 decks)

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