Repro system

Question 1

What things does sex repro require?

Answer 1

production of functional sex cells/gametes; union of the cells (fertilization to create zygote); development of zygote into adult (cycle complete at this point)

Question 2

gonads and functions of the males and females

Answer 2

testes–male, produce sperm in tightly coiled seminiferous tubes; ovaries–femaele, produce oocytes (eggs)

Question 3

what is gametogenesis

Answer 3

production of functional sex cells; in males, it is spermatogenesis and females, oogenesis

Question 4

what is internal fertilization and who practices it?

Answer 4

terrestrial vertebrates; offers a direct route from sperm to egg and increases the chance for fertilization success

Question 5

what are the factors that change the number of eggs produced by a female?

Answer 5

if early development occurs outside the mom, more eggs will be produce–increases change of offspring survival; amount of parental care–parents that care for their young produce fewer eggs

Question 6

• Male reproductive system
o Testes
♣ Located in the scrotum
• An internal pouch that maintains the testicular temperature 2-4 degrees lower than body temperature
• This is essential for sperm survival
♣ Sperm pass from the testes through the vas deferens to the ejaculatory duct and then to the urethra
♣ Urethra passes through the penis
• Terminates with an external opening at the glans of the penis
♣ Testes are the site of testosterone production
• Regulates secondary male characteristics
o Includes facial and pubic hair, voice changes, etc

Answer 6

ya

Question 7

♣ Once a male has reached sexual maturity, approx. 3 million primary spermatocytes undergo spermatogenesis per day

Answer 7

ya

Question 8

♣ Once a male has reached sexual maturity, approx. 3 million primary spermatocytes undergo spermatogenesis per day

Answer 8

ya

Question 9

what is a follicle?

Answer 9

a multilayered sac of cells that contains, nourishes, and protects an immature ovum

Question 10

what do follicle cells produce?

Answer 10

estrogen

Question 11

♣ Aprox once a month an immuature ovum is released from the ovary into the abdominal cavity and drawn by cilia into nearby oviduct
• Aka fallopian tube
• Each fallopian tube opens into the upper end of a muscular chamber called the uterus
o Lower, narrower end of the uterus is called the cervix
♣ Connects to the vaginal canal

Answer 11

ya

Question 12

♣ Primary oocytes

general info

Answer 12

diploid, form by mitosis in the ovary; • After menarche (first menstruation cycle of a woman), one primary oocyte per month completes meiosis I
o Yields two daughter cells of unequal size called secondary oocyte and a small cell called a polar body
o Secondary oocyte is expelled from the follicle during ovulation
Meiosis II does not occur until fertilization

Question 13

♣ Oocyte cell membrane surrouned by two layers of cells
• Inner zona pellucida layer and outer corona radiata layer
• Meiosis II is triggered when the layers are penetrated by sperm
• Yields two haploid cells
o A mature ovum and another polar body
• Mature ovum is a large cell
o Consists of cytoplasm, RNA, organelles, and nutrients needed by the developing embryo
Polar bodies lack resources and quickly degenerate

Answer 13

ya

Question 14

where are female sex hormones secreted, what is secreted, and what regulates secretion, and what regulates the regulators?

Answer 14

ovaries; estrogen and progesterone; FSH and LH; gonadotropin-releasing hormone

Question 15

estrogen general info

Answer 15

• Steroid hormones
• Necessary for normal female maturation
• Stimulate development of female repro tract,
• contribute to the development of secondary sex characteristics,
• and influence libido
• responsible for the thickening of the endometrium (inner lining of the uterine wall
• secreted by the ovarian follicles an the corpus luteum

Question 16

progesterone general info

Answer 16

• steroid hormone
• secreted by the corpus luteum during the luteal phase of the menstrual cycle
• stimulates development and maintenance of the endometrium in preparation for implantation

Question 17

what are the phases of the menstrual cycle?

Answer 17

follicular phase; ovulation; luteal phase; menstruation; fertilization;

Question 18

what is the follicular phase?

Answer 18

o Begins with the cessation of the menstrual flow from the previous cycle
o During this phase, FSH from the anterior pit promotes the development of the follicle
Grows and begin secretion estrogen

Question 19

what is ovulation?

Answer 19

o Midway through the cycle, ovulation occurs
♣ A mature, ovarian follicle bursts and releases an ovum
♣ Ovulation is caused by a surge in LH that is preceded and partially caused by peaking estrogen levels
o Women ovulate every 4 weeks
♣ Except during pregnancy and lactation

Question 20

what is menopause?

Answer 20

♣ Ovaries become less sensitive to the hormone that stimulates follicle development (FSH and LH)
• Ovaries eventually atrophy
• Remaining follicles disappear
• Estrogen and progesterone levels greatly decline
• Ovulation stops
• Profound hormone level changes result in psychological and physiological changes that persist until a new balance is reached

Question 21

what is the luteal phase?

Answer 21

o After ovulation, LH maintains the remnant of the ruptured follicles
♣ Called the corpus luteum
♣ Secretes estrogen and progesterone
• Progesterone
o Causes the glands of the endometrium to mature and produce secretions that prepare for the implantation of an embryo
Both progesterone and estrogen are essential for the maintenance of the endometrium

Question 22

what is the luteal phase?

Answer 22

o If the ovum is not fertilized, the corpus luteum atrophies
o Resulting drop in prog. And estro. Levels causes the endometrium (with is superficial blood vessels) to slough off, giving rise to menstrual flow (menses)
o If the ovum IS fertilized, the developing placenta produced hCG (human chorionic gondatropin)
♣ Maintains CL as well as the supply of P and E
• Which maintains the uterus
• Eventually the placenta will take over production of these hormones

Question 23

what is fertilization?

Answer 23

o An egg can be fertilized during the 12-24 hours after ovulation
o Most often occurs in the lateral, widest portion of the fallopian tube
o Sperm remain viable and capable of fertilization 1-2 days after intercourse
o First barrier for sperm:
♣ Must penetrate the corono radiate
♣ Enzymes secreted by the sperm aid in the penetration
♣ Acrosome is responsible for penetrating the zona pellucida
• Releases enzymes that digest this layer
o Allows to sperm to come into direct contact with the ovum cell membrane
o Once in contact with the membrane, sperm forms a tube-like structures called the acrosomal process
♣ Extends to the cell membrane and penetrates it
♣ Fuses the sperm cell membrane with that of the ovum
♣ Sperm nucleus enters the ovum’s cytoplasm
♣ Ovum completes meiosis II at this stage
• Acrosomal reaction triggers a cortical reaction in the ovum
o Causes calcium ions to be released into the cytoplasm
o Initiates a series of reactions that result in the formation of the fertilization membrane
♣ Fertilization membrane is a hard layer that surrounds the ovum cell membrane and prevents multiple fertilization
♣ Followed by the fusion of the sperm nucleus with the ovum nucleus to form a diploid zygote
First mitotic division of the zygote soon follows

Question 24

what are monozygotic twins?

Answer 24

♣ identical twins
• A result of a single zygote splitting into two embryos
• If the splitting occurs at the two-cell-stage of development, the embryos will have separate chorions and separate placentas;
o If it occurs at the blastula stage, the embryos with have only one chorionic sac
♣ Will therefore share a placenta and possibly an emnion
o Occasionally development is incomplete
Results in conjoined twins

Question 25

what are dizygotic twins?

Answer 25

fraternal twins
• Result when two ova are released in one ovarian cycle and fertilized by two different sperm
o Two embryos implant in the uterine wall individually
♣ Each develops its own placenta, amnion, and chorion
• Although the placentas may fuse if the embryos implant very close to each other
• Fraternal twins share no more characteristics than any other siblings because they develop from two different zygotes