module 9 Flashcards
the method by which organisms make offspring
reproduction
Two basic methods of reproduction
- Asexual reproduction
- Sexual reproduction
Genetic sex determination consists of what chromosome configuration?
XX or an XY sex chromosome configuration
Genes from two individuals are combined in new ways to generate variety in offspring.
Sexual reproduction
XX genetic configuration
female anatomy
Why is variety in offspring desirable?
increases the odds of offspring surviving
XY genetic configuration
male anatomy
(T/F) germ cells or gametes (eggs and sperm) each have half the genetic information that a regular cell of that species of organism has
TRUE
True or False:
all embryos are inherently female and female is the default condition
True
In sexual reproduction, what process do germ cells or gametes (eggs and sperm) use to produce a new cell that has the full complement of genetic material for that species of organism.
Fertilization
how does one become male or female?
determined by the hormones that an embryo is exposed to early in development.
True or false
your genes determine whether you make ovaries or testes and then the hormones made by those organs determine the internal and external reproductive anatomy.
True
All embryos have structures that can either become the _______ or the testes.
ovaries
sexual reproduction introduces a lot of variety into these new cells because of what 3 processes?
- crossing over during meiosis
- independent assortment
- random fertilization
At about ___ weeks of development, if the embryo has a Y chromosome, the SRY (sex determining region of the Y chromosome) gene causes these structures to become _____.
- 6 weeks
- testes
How many chromosomes do humans have?
46 (23 pairs)
Testes form _____ cells that start to secrete _______ such as testosterone and _____ cells that start to secrete MIF/MIS (Mullerian inhibiting factor/substance).
- Leydig
- androgens
3.sertoli
Does the mom or dad determine a person’s genetic sex?
the dad
When eggs and sperm fuse during fertilization, the only thing that the sperm adds is what?
50% of nuclear DNA
what do ovaries secrete?
estrogen
All embryos have the capability to produce how many internal ductwork systems? name them
2 ductwork systems.
- Mullerian ducts
- Wolfian ducts
the Mullerian ducts become the ________ internal anatomy and the Wolfian ducts become the _____ internal anatomy.
- female
- male
How many of the chromosomes that come from your mom and your dad are autosomal chromosomes?
44 autosomal chromosomes
MIF/MIS causes which ducts to regress?
Mullerian ducts
testosterone causes the Wolfian ducts to become what 4 structures?
- epididymis
- vas deferens
- seminal vesicles.
define autosomal chromosomes
chromosomes that determine your general characteristics as a human such as eye color, nose shape, personality, etc.
what promotes the development of the penis and scrotum?
testosterone
True or false
a system that contains MIF/MIS and testosterone will develop into a female and a system without testosterone will develop into a male.
false,
contains MIF/MIS and testosterone will develop into a male
system without testosterone will develop into a female.
how many chromosomes are sex chromosomes?
two (one from mom, one from dad)
what aids in the development of secondary sexual characteristics such as male body type, thicker skin, deeper voice, and specific pattern of hair growth on the body.
testosterone
Dads can give an X or Y chromosome but Moms can only give an X chromosome (T/F)
TRUE
estrogen promotes female secondary sexual characteristics such as what?
- body type (wider hips, higher fat percentage, breasts)
- thinner skin.
external genitalia become the penis and scrotum in the 1. (presence OR absence?) of androgens such as testosterone and become the clitoris and labia in the
2. (presence OR absence?) of androgens.
- presence
- absence
True or false
Wolfian ducts which become the male internal reproductive structures persist in the presence of androgens and regress without androgens. Mullerian ducts which become the female internal genitalia regress in the presence of MIF/MIS and persist in the absence of MIF/MIS.
true
basic pathway for sperm movement out of the male reproductive tract
Seminiferous tubules
V
epididymis in the testes
V
through the vas deferens
V
into urethra
V
through penis
V
out of body
where does the basic pathway of egg movement through the female reproductive tract start and what is produced there?
at the ovaries where eggs are produced.
Eggs are released from the ovaries directly into what in females?
abdominal cavity
What structure gently wafts over the surface of the ovary and create a negative pressure which helps to pull the ovum into the uterine tube (Fallopian tube).
fimbrae
where are spermatozoa cells made
seminiferous tubules
If fertilization occurs, it usually occurs in which tube?
uterine tube
Where are testes located and what develops there?
in the scrotum where sperm develop
If the egg is fertilized it travels down the uterine tube to the uterus where ____________ into the endometrial lining of the uterus occurs.
implantation
If the egg is not fertilized, it then travels through the ______ into the vagina and out the body of the female.
cervix
Why are the testes located outside the abdominal cavity of the male in the scrotum?
the optimal temp for sperm development is about 3 degrees cooler than body temperature.
folds or ridges in the surface of the vagina that help keep sperm from being pushed backwards by the negative fluid flow through the female system to increase the chances that the sperm actually reach the egg in the uterine tube.
feature of the vagina: washboard surface
Fill in the blank about testes
Each testicle is about 1.______ long and 2.______ in diameter with septa that partition the organ into about 3.____ lobules. ____to 4. ______seminiferous tubules are found within each lobule.
1.5 cm long
2. 3 cm in diameter
3. 250 lobules.
4. one to four
What occurs in the ovaries and begins during the first trimester (before birth) during development in human females?
oogenesis
What cells undergo mitosis to produce more oogonia and primary oocytes up until the 20th week of development.?
oogonia cells
sperm development occurs transversely from the outside of the tube to the inside of the tube. (T/F)
TRUE
True OR false
At the 20th week of development, a female has all the primary oogonia that she will ever have ( ~4 million).
true
what causes oogonia in a female to drop from 4 million to 1million?
cells are eliminated by apoptosis
Large cells that extend from the lumen of the tube out to the periphery.
Sertoli cells
After primary oocytes are formed, they begin ______ but stop right before the first division (meiosis I) and enter a stage of “meiotic arrest” until the ___________ of that egg cell occurs.
- meiosis
- ovulation
Name at least 3 functions of Sertoli cells
- barrier to chemicals to promote sperm development
- nourishing sperm
- secreting luminal fluid and androgen binding protein
- stimulating sperm differentiation and proliferation
- secreting inhibin which inhibits FSH secretion
- secreting paracrine agents that influence Leydig cells
- phagocytosing defective sperm
- secreting MIF/MIS.
T OR F
When ovulation occurs, the first meiotic division also occurs which results in a cell ready to undergo meiosis II and a polar body that contains only the extra chromosomes.
True
Define spermatogonia
Cells on the outside edge of the seminiferous tubules that give rise to sperm. (Diploid 46 chromosomes)
T or F
The resulting cell will NOT finish meiosis II if fertilization occurs.
False,
it will FINISH meiosis II if fertilization occurs
When the sperm binds to the egg, a polar body will be ejected with the excess genetic material. If fertilization never occurs, then the egg will pass out of the body without completing _________.
meiosis
At puberty some spermatogonia undergo _______ and _______to become primary spermatocytes which are still diploid cells.
- mitosis
- differentiation
how often does the hypothalamus release GnRH which travels to the anterior pituitary gland and triggers the release of FSH and LH.
every 1.5-2 hours
HORMONES IN MALES
FSH —-> 1.______ cells in the testes to trigger spermatogenesis (along with testosterone) and trigger the release of inhibin. Inhibin ——->2. _________ pituitary to inhibit the release of FSH in a 3.________ feedback loop. 4. __ __ travels to the Leydig cells to trigger the release of testosterone which travels to various target tissues to maintain secondary sexual characteristics, promote sex drive, and promote spermatogenesis. 5.___________ travels back to the anterior pituitary to inhibit the release of FSH and LH and back to the 6.__________ to inhibit the release of GnRH in a negative feedback loop.
- Sertoli
- anterior
- negative
- LH
- testosterone
- hypothalamus
HORMONES IN FEMALES
FSH —-> 1.__________ cells in the ovaries to trigger the release of inhibin.
2._______ —-> anterior pituitary to inhibit the release of 3. __ __ __ in a negative feedback loop. LH travels to the 4._____ cells to trigger the release of androgens which get converted to 5. ________. In low levels, estrogens travel to the _______ _______ to inhibit the release of LH and back to the hypothalamus to inhibit the release of GnRH in a _________ feedback loop.
- granulosa
- inhibin
- FSH
- theca
- estrogens
- anterior pituitary
- negative
For each cell that becomes a primary spermatocyte after mitosis, how many cells remains a spermatogonia.
one
What begins meiosis?
primary spermatocytes
What are cells produced after meiosis I called?
secondary spermatocytes
What are spermatids?
the cells produced after meiosis II
At each stage of division, the maturing cells are pushed further from the lumen of the tube. (T/F)
FALSE, they are pushed closer to the lumen of the tube
Why do spermatids undergo further differentiation?
to become mature sperm or spermatozoa
How long is the epididymis ?
4-5 meters long for storage
When sperm arrive at the epididymis what happens?
they are unable to fertilize an egg cell so they must undergo “capacitation” to become motile and mature.
The seminal vesicles add a fluid that contains _________which provides ________ for the ________ cells and accounts for about _________% of the fluid in semen.
- fructose
- energy
- sperm
- 45-80%
What do clotting enzymes help with?
helps the semen clot after ejaculation
what keeps sperm from being washed downstream out of the female reproductive tract before fertilization has had a chance to occur?
fibrin coagulum
What 3 events must occur to effectively transfer semen to the female reproductive tract?
- erection
- emission
- ejaculation
when vasodilation of the arterioles that lead into the spongy tissues of the penis occurs so that more blood flows into the tissues of the penis
Erection
What is the neurotransmitter responsible for the vasodilation and increased blood flow to the penis?
Nitric oxide
When does emission occur?
when semen begins to move into the urethra
What occurs when peristaltic contractions of the tubular system, contractions of the seminal vesicles and prostrate gland, and contractions of the muscles at the base of the penis occur to force the semen out the tip of the urethra.
ejaculation
Erection is under parasympathetic control and emission and ejaculation are under sympathetic control. (T/F)
TRUE
- What is the volume of semen in a single ejaculation?
- What is the normal range for numbers of sperm cells in each milliliter of semen?
- 1.5 ml - 5.0 ml
- 40 -250 million
Flow of the Movement of sperm cells during fertilization
Vagina > cervix > uterus > uterine tubes
By the time the sperm reach the uterine tubes, how many have survived to enter each uterine tube?
only 100
If a secondary oocyte is present in the tube, the sperm cells will surround it and start tunneling through the corona radiata and the zona pellucida surrounding the egg using their digestive enzymes in their acrosomes. (T/F)
TRUE
What happens when the first sperm cell reaches the egg and binds to the surface?
chemical changes occur in the zona pellucida that keep other sperm from entering.
When fertilization occurs, the secondary _______finishes _________and ejects the polar body. The ___________from the egg and sperm join and development begins.
- oocyte
- meiosis
3.chromosome
Secondary oocytes can only live from ____-___ hours after ovulation, but sperm cells can live from ___-____ days within the female body.
4- 24 hours
3-7 days
fertilization can occur only if intercourse occurs within the 6 days leading up to ovulation and the one day following ovulation. (T/F)
TRUE
As the fertilized egg (zygote) travels down the uterine tube towards the uterus, what occurs?
cleavage (division by mitosis) begins to form an embryo.
what do estrogens promote in females?
the development of an egg cell.
Within how many days of fertilization does the embryo usually arrive?
4 days
In females, as the egg cell starts to develop, it starts secreting its own ________ which means that the levels get higher in the system.
estrogen
By the time implantation occurs, the embryo has been converted into ________ with an inner mass of cells which will become the ______and an outer layer of cells which will become the __________.
- blastocysts
- fetus
- placenta
(females) When estrogen levels are high, estrogen triggers the anterior pituitary to start releasing more LH in a __________ feedback loop which causes an LH surge in the system.
positive
(females) The LH surge triggers what and the release of what?
triggers ovulation and the release of the egg
What begins when the fetus has developed into a size that starts to stretch the uterine walls in such a way as to resemble a muscle contraction?
Labor
Is this an example of a negative or positive feedback loop?
stretches on the uterus cause a signal to be sent to the hypothalamus that triggers a signal to be sent to the posterior pituitary to release oxytocin. Oxytocin travels to the uterus and amplifies contractions which send a signal that causes even more oxytocin to be released. In addition, prostaglandins are released from the uterus which also aid in muscle contraction.
Positive feedback loop
When the egg is removed from the system, estrogen levels _________ again and the system goes back to being under the control of a ________ feedback loop.
decrease (fall to “low” level again)
negative
changes in hormone level can be tracked during what?
the monthly reproductive cycle in females.
(females) ______________ levels stay high after the release of the egg from the ovary at ovulation around the 14th or 15th day of the cycle.
progesterone
(females) The follicle from which the egg came scars over to form what?
corpus luteum.
For approximately two weeks after ovulation, the corpus luteum continues to secrete ___________ to maintain the endometrial lining of the uterus in case of a possible pregnancy. If fertilization does not occur, then the corpus luteum slowly __________ its activity until progesterone levels fall enough that they can no longer maintain the _________ lining. When that occurs, the lining is shed (first day of the menstrual period) and the process starts over again.
- progesterone
- decreases
- endometrial
If fertilization does occur, then the conceptus immediately begins to secrete
1. _ _ _ (human chorionic gonadotropin). This is the pregnancy hormone detected by home pregnancy tests. hCG keeps the 2.______ luteum active and secreting progesterone until about the 12th to 14th week of pregnancy which maintains the endometrial lining so a normal pregnancy can occur. When the 3. _________ is developed around the 12th-14th week of pregnancy, it takes over secreting progesterone to maintain the endometrial lining and the corpus luteum fades away.
- hCG (human chorionic gonadotropin).
- corpus luteum
- placenta
composed of lobes that are subdivided into lobules which contain glandular alveoli that secrete milk
mammary glands
what converge into larger and larger ducts that eventually lead to the nipple from which milk is released.
alveoli
what happens at partuition to increase in milk production?
estrogen levels in the system fall which decreases the amount of prolactin inhibiting hormone (PIH) secreted by the hypothalamus.
both estrogen and progesterone levels fall with the removal of what, which decreases the inhibition of milk secretion?
the placenta
Increases in oxytocin from the posterior pituitary (labor) trigger what?
milk ejection or milk let-down.
the act of nursing or suckling triggers the release of more ________ which promotes more milk let-down.
oxytocin
True or false:
Visual (looking at your baby) and auditory (hearing your baby cry) stimuli can also trigger milk let-down.
true
Finger-like projections of tissue around the end of the uterine
Fimbrae
