Chapter 36 REPRODUCTION AND DEVELOPMENT
From the male reproduction system, what is the scrotum?
a fold of the body wall, maintains testis temperature about 2 degrees C below the core body temperatures.
From the male reproductive system what are the testes for?
produce sperm in highly coiled tubes called seminiferous tubules.
From the male reproduction system what are the Epididymis?
form the seminiferous tubules of a testis, the sperm pass into the coiled duct of an epididymis.
From male reproductive system what are the Vas deferens?
during ejaculation, the sperm are propelled from each epididymis through a muscular duct, the vas deferens.
from the male reproductive system, what is the Seminal vesicle for?
contribute about 60% of the volume of semen
From the male reproductive system what is the Prostate gland for?
secretes its products into the urethra through small ducts.
what is the Urethra for?
the outlet tube for both the excretory system and the reproductive system
from the female reproductive system what are the ovaries?
flank the uterus and are held in place in the abdominal cavity by ligaments
from the female reproductive systen what are the follicles?
outer layer of the ovary is packed with these.
from the females reproductive system what is the Oviduct (fallopian tube)?
extends from the uterus toward a funnel-like opening at each ovary.
from the female reproductive system what is the uterus?
also known as the womb is a thick, muscular organ that can expand during pregnancy to accommodate a 4-kg fetus
from the female reproductive system what is the cervix?
the neck of the uterus opens into the vagina
from the female reproductive system what is the vagina?
is a muscular but elastic chamber that is the site for insertion of the penis and deposition of sperm during copulation
what is oogenesis?
begins in the female embryo with the production of oogonia from primordial germ cells. production of an egg
what is oogonia?
The oogonia divide by mitosis to form cells that begin meiosis, but stop the process at prophase I before birth
what are the Primary oocyte?
developmentally arrested cells reside within a small follicle cavity lined with protective cells.
what are the Secondary oocycle ?
meiosis II is released at ovulation, when its follicle breaks open only if a sperm penetrates the oocyte
How many primary oocytes are present in the ovary at the birth of a female?
1-2 million primary oocytes about 500 fully mature.
At the birth of a female, what stage of meiosis is the primary oocyte in?
Prophase of meiosis I
When does the primary oocyte initiate the next step in meiosis?
When a female hits puberty every month one or more primary oocytes undergo meiosis I and create secondary oocytes.
When the secondary oocyte is released from the ovary (ovulation), what stage of meiosis is the secondary oocyte in?
What is the event that stimulates the secondary oocyte to complete meiosis?
OVULATION, SPERM ENTRY
Know the role of hypothalamus and the anterior pituitary gland in the reproductive cycle
Hypothalamus: secretes gonadotropin-releasing hormone (GnRH) which directs the anterior pituitary to secrete follicle-stimulating hormones (FSH) and luteinizing hormone (LH)
- Know the role of gonadotropin releasing hormone (GnRH) in the interaction between the hypothalamus and the anterior pituitary.
Understand that the anterior pituitary secretes two gonadotropins, namely follicle-stimulation hormone (FSH) and luteinizing hormone (LH), in both males and females
- Know the meaning of the term gametogenesis.
the process in which cells undergo meiosis to form gametes
Know which gonadotropin stimulates the sertoli cells. What is the purpose or function of sertoli cells?
Respond to FSH, they nourish developing sperm
Know which gonadotropin stimulates the Leydig cells. What is the purpose or function of the Leydig cells?
Respond to LH by producing testosterone and other androgens, which promote spermatogenesis
Know which sex hormone is present in males at 10 times the level present in females, and know which sex hormone is present in females at 10 times the level present in males.
The level of androgens in males is 10 times the level present in females. The level of oestrogens in females is 10 times the level present in males.
Understand the effect of androgens on the development of male secondary sex characteristics.
vocal cords/ deeper voice
Recognize that the male and female reproductive systems have some similar structures and hormones in common, namely the hypothalamus, anterior pituitary, FSH and LH, testosterone and estrogens, etc.
Recognize that estrogens have an affect on the development of female secondary sex characteristics.
development of breast etc.
Know the major stages of the ovarian cycle
what is the Follicular phase?
the part of the cycle during which follicles grow and oocytes mature
what the ovulation phase in the ovarian cycle?
: follicular phase ends at ovulation about a day after the LH increase in response to this the follicle and adjacent wall of the ovary rupture releasing the secondary oocyte. (pain)
what is the Luteal phase?
follows ovulation LH stimulates the follicular tissue left behind in the ovary to transform into a corpus luteum, a glandular structure.unde continued stimulation by LH the corpus luteum secretes progesterone and estradiol(negative feedback) this feedback reduces the LH and FSH to very low levels preventing onother egg from maturing when there might be a pregnancy.
Follow the concentration of estradiol and progesterone at the each stage of the ovarian cycle.
During the follicular phase there is a slow rise in estradiol secreted
What is the source of increasing levels of estradiol in the follicular phase of the ovarian cycle?
The hypothalamus releases GnRH and that stimulates the anterior pituitary to secrete small amounts of FSH and LH which stimulate follicle growth and the follicles start to make estradiol.
Follow the concentration of FSH and LH at the different stages of the ovarian cycle. A peak in LH concentration(positive feedback) in the blood occurs just prior to what event in the ovarian cycle?
Final maturation of the follicle
Know the effect on the secretion of FSH and LH from the anterior pituitary gland of both high levels of estradiol and low levels of estradiol.
What is the origin of the corpus luteum? What are the two hormones secreted by the corpus luteum?
- Growing follicleà maturing follicle-à ovultation follicle ruptures
Progesterone and estradiol
When estradiol and progesterone are present at the same time, what effect does this have on FSH and LH secretion from the anterior pituitary gland?
- The levels of FSH and LH would decrease.
How does the presence of the corpus luteum affect the activity of follicles within the ovary?
Prevent another egg from maturing
Understand why it is important that the secretion of FSH and LH is greatly decreased during the luteal phase of the ovarian cycle.
Know the major stages of the uterine cycle
what happens during the Proliferation phase?
Proliferation phase: the estradiol and progesterone secreted by the corpus luteum stimulates maintenance of the uterine lining, as well as further development, including enlargement of arteries and growth of endometrial glands these glands secrete a nutrient fluid that can sustain an early embryo even before it implants in the uterine lining.
what happens in the Secretory phase?
Secretory phase: coordidated with the luteal phase once the corpus luteum has disintegrated the rapid drop in ovarian hormone levels causes arteries in the endometrium to constrict.
what is the menstrual flow phase?
Menstrual flow phase: small endometrial blood vessels constrict, releasing blood that is shed along with endometrial tissue and fluid. A new group of ovarian follicles begin to grow.
Know what the endometrium is, and the importance of the secretory phase of the uterine cycle in terms of the development of the embryo.
What is the chemical signal coming from the ovarian cycle that triggers the menstrual flow phase of the uterine cycle?
- Follow the path of the secondary oocyte after it is released from the ovary.
- In what part of the female reproductive system does fertilization of the secondary oocyte usually take place?
- After fertilization of the egg how long does it take before the blastocyst (a very early stage of embryonic development) imbeds in the endometrium?
--11–12 days after fertilization.
Understand why the implanted embryo secretes human chorionic gonadotropic (hCG
It acts like LH in maintaining secretion of progesterone and estrogens by the corpus luteum through the first few months of pregnancy.to signal its presence
Understand why is it necessary to prevent the disintegration of the corpus luteum.
What happens if fertilization of the egg does not take place and there is no embryo to embed in the wall of the uterus, i.e. what happens if no hCG is produced.
- From where does the developing embryo acquire its nutrition after it has become embedded in the wall of the uterus?
First the endometrium then the trophoblast grows outward and mingles with the endotherium forming the Placenta
- What is the source of the cells that make-up the placental structure?
Embryonic and maternal blood vessels
- Know the meaning of the term organogenesis. In the embryo, all the major organ systems are present, at least in rudimentary form, after how many weeks of development?
Organogenesis is the development of organs/ at 8 weeks
- Approximately how long is the embryo after 5 weeks of development, and after 14 weeks of development (see Fig. 36.21)?
After 5 weeks the embryo is 1 centimeter long after 14 weeks 6 centimeters long