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reproduction Flashcards

1
Q

Reproductive strategies

A

Sexual reproduction

Asexual reproduction

Mixed

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2
Q

sexual reproduction

A

Fusion of a sperm and an egg(haploids) forms a zygote(diploid)\

Split sexes
Hermaphrodites
Sex reversal

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3
Q

Hermaphroditism

A

Individual animal produces both gametes

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4
Q

Separate sexes

A

Male produces sperm and female produces eggs

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5
Q

Asexual reproduction

A

Budding
Fragmentation
Parthenogenesis

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6
Q

Budding

A

New individuals arise from outgrowths of existing ones

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7
Q

Fission

A

Splitting and separation of a parent organism into two individuals of approximately equal size

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8
Q

Parthenogenesis

A

An egg develops without being fertilized

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9
Q

Mixed

A

Both sexual and asexual, often influenced by environmental conditions

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10
Q

Pituitary hormones are central to both female and male reproduction in all vertebrates
There are significant variations between animal reproduction

such as

A

seasonal vs continuous breeders
Cycles are controlled by Hormones whose secretion is regulated by environmental cues

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11
Q

Hypothalamus important for reproduction too

why

A

Neurosecretory cells in hypothalamus release hormones in circulatory system that enter portal vessels and into the anterior pituitary

hormones trigger resproduction

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12
Q

In reproduction, the important hormones are

A

GnRH, FSH, and LH

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13
Q

GnRH

A

made by neurosecretory cells of the hypothalamus and goes into the blood, stimulates the anterior pituitary cells to release FSH and LH and depending on if you’re male or female, this stimulates estradiol production, testosterone production and do other things

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14
Q

Ovulation

A

Release of mature eggs
Occurs at the midpoint of each cycle

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15
Q

Why effect does climate change have on reproduction

A

It can decrease reproductive success because seasonal temperature is an important cue for reproduction

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16
Q

Gonads

A

Organs that produce gametes

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17
Q

In males what is the goal of the individual reproductvei cycle

A

spermatogenesis

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18
Q

Follicle-stimulating hormone (FSH) is

A

a hormone that regulates sexual development and reproduction in both men and women

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19
Q

the target of FSH in males is

A

sertoli cells

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20
Q

sertoli cells

A

support and nourish developing sperm cells throughout the process of spermatogenesis, providing a suitable environment for maturation

21
Q

The targets of LH Luteinizing hormone are the

A

Leydig cells

22
Q

Leydig cells are primarily responsible for

A

producing testosterone, playing a crucial role in male sexual development, maintaining secondary sexual characteristics, and supporting sperm production

23
Q

There is an optimal level of testosterone
We keep it at a desired setpoint with

A

negative feedback

As testosterone is produced in the testes, it acts both locally to stimulate spermatogenesis but as a hormone it gets into the blood and travels everywhere
this reaches the hypothalamus through the blood and inhibits the hormones that are stimulating testosterone
- inhibits anterior pituitary and reduces LH and FSH and inhibit GnRH

24
Q

If you have low testosterone there is no testosterone feeding back to the hypothalamus so

A

there is no inhibition and thus you get an increase in GnRH production, increase in LH and FSH and get back to the optimum point

25
Sertoli cells have another inhibitor
They make another hormone called inhibin which negatively regulates FSH production
26
Spermatogenesis
Sperm production is continuous We need stem cells that divide and commit to making sperm We have a stem cell that commits to spermatogenesis and it will form primary spermicide and go through meiosis→ all four products go on to become sperm
27
Oogenesis
Egg production starts during embryonic development but is arrested at prophase of meiosis I This is called a primary oocyte Every 28 days, starting from puberty, one primary oocyte will restart meiosis and then arrest at metaphase meiosis II This is called a secondary oocyte Fertilization stimulates the second meiosis Results in one mature egg
28
Reproductive cycle
28 day cycle Have to do both Preparing and maturing egg and Preparing and maturing uterus
29
Days 0-14
Hypothalamus releases GnRH which causes anterior pituitary to release FSH and LH The target of these is the follicle cells Follicle grows under the action of FSH/LH and estradiol starts to increase Rising estradiol level stimulates endometrium proliferation in the uterus in preparation for implantation Rising estradiol levels also stimulate GnRH release by the hypothalamus leading to spike in LH around day 14 that results in ovulation
30
Day 15-28
LH stimulates the remaining follicle to form corpus luteum The corpus luteum becomes a temporary steroid hormone producing gland, making the hormone progesterone The combination of estradiol and progesterone inhibit GnRH release by the hypothalamus and LH and FSH levels will fall different things occur based on if fertilization occurs or not
31
If the fertilization does occur,
progesterone production by the corpus luteum persists and is essential for establishing and maintaining pregnancy by maintaining the thick lining of the endometrium The continued inhibition of GnRH prevents oocyte maturation during pregnancy
32
If fertilization does not occur,
the corpus luteum stops secreting progesterone and decays after approximately 10 days and the cycle starts again
33
Oral contraceptives
Contain a combination of a synthetic estrogen and a synthetic progestin They inhibit GnRH release by the hypothalamus and inhibit follicle maturation and ovulation Progestin only pills are common
34
What if fertilization does occur?
The fertilized egg must finish meiosis II before the two pronuclei fuse First cleavage occurs about 24 to 30 hours after fertilization The fertilized egg is carried down the oviduct to the uterus Implantation in humans occurs about 7 days after fertilization
35
Why do we maintain corpus luteum if fertilization occurs
6-10 days following fertilization, the embryonic cells called trophoblast start to produce the hormone human chorionic gonadotropin(hCG) \ hCG has the same activity as LH and maintains the secretion of progesterone and smaller amounts of estradiol by the corpus luteum
36
Mifepristone
In abortion pill It is an antiprogesterone that will bind to and occupy progesterone receptors without activating them This blocks endogenous progesterone from working
37
As pregnancy progresses, the placenta starts to develop at about week 4 how are the mother and fetus connected
Maternal and fetal circulation are entirely different but there is a equivalent of exchange of capillaries The placenta facilitates nutrient, gas, and waste exchange between the physically separate maternal and fetal circulations Placenta connects to the fetus via the umbilical cord Placenta is composed from both maternal and fetal tissues
38
Start of labor
Uterine contractions Something triggers it to begin Placental degradation may be the cause Estradiol will stimulate the presence of oxytocin receptors Oxytocin will stimulate uterine contraction Nerves in the uterine will stimulate more oxytocin Prostaglandins hormones are being produced by the placenta which also stimulate uterine contraction
39
Differences between spermatogenesis and oogenesis
Spermatogenesis is continuous in adult males Oogenesis is a prolonged process in human females In spermatogenesis the four products of meiosis develop into mature gametes\ In oogenesis meiosis produces unequal products with one daughter cell getting almost all the cytoplasm Spermatogenesis occurs throughout adolescence and adulthood whereas oogenesis mitotic divisions occurs before birth and the production of mature gametes ceases at about 50 Spermatogenesis produces sperm in a continuous sequence whereas oogenesis has long interruptions
40
Mammalian reproduction is governed by the coordinated actions of hormones from the
hypothalamus, anterior pituitary, and gonads
41
Endocrine control of reproduction begins with the
Hypothalamus which secretes gonadotropin-releasing hormone (GnRH)
42
GnRH directs the anterior pituitary to
Secrete the gonadotropins follicle-stimulating hormone(FSH) and luteinizing hormone(LH) FSH and LH support gametogenesis by stimulating sex hormone production by the gonads
43
What does the stimulation of FSH on sertoli cells do
It stimulates the cell located within the seminiferous tubules to nourish developing sperm
44
What does the stimulation of LH on leydig cells do
LH causes leydig cells to produce testosterone and other androgens which promote spematogenesis in the tubules
45
What two negative feedback mechanisms control sex hormone production in males
Testosterone regulates the blood concentration of GnRH, FSH, and LH through inhibitory effects on the hypothalamus and anterior pituitary Inhibin , a hormone that is produced by sertoli cells in males, acts on the anterior pituitary gland to reduce FSH secretion
46
There are two closely linked reproductive cycles in human females Both are controlled by cyclic patterns of endocrine signaling
Ovarian cycle uterine/menstrual cycle
47
Ovarian cycle
Cyclic events in the ovaries Once per cycle a follicle matures and an oocyte is released changes in uterus
48
In each menstrual cycle what occurs
The endometrium lining of the uterus thickens and develops a rich blood supply before being shed through the cervix and vagina if pregnancy doesn;t occur

mcdb1b (10 decks)

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