Reproduction Notes from Old Notes Flashcards
Diploid cells
have 2 copies of each chromosome
Gametes
Haploid cells that fuse via process called syngamy to form a zygote (diploid cell)
Egg (ovum) - female gamete; big, non-motile
Sperm - male gamete; small, motile
Mitosis
Makes exact copy of itself
2n -> 2n
Phases of Mitosis
Prophase Metaphase Anaphase Telophase Cytokinesis
Interphase
Nuclear envelope intact
No chromosomes visible
Prophase
Nuclear membrane dissolves
Metaphase
Chromosomes align down center
Spindle forms
Anaphase
Spindle breaks centromere connection and sister chromatids move to opposite poles
Telophase
Chromosomes reached poles
Cytokinesis
Membrane forms around both cells
Meiosis
Reduction division; daughter cells are haploid, parental cell is diploid
Spermatogenesis
Creation of male gametes
The germ line cells that give rise to testes is called spermatogonia (2n)
Spermatogonia undergoes mitosis and gives rise to 2 diploid cells
One of these diploid cells is called a primary spermatocyte (2n), the spermatocyte will undergo meiosis I and form 2 haploid daughter cells called secondary spermatocytes (1n); they have 2 chromatid per chromosome
The other diploid cell is called a spermatogonia (2n). Spermatogonia will undergo mitosis again. The 2 secondary spermatocytes will undergo meiosis II and form a total of 4 haploid spermatid (1n)
Primary spermatocytes
When spermatogonia undergo mitosis and give rise to 2 diploid cells. One of the diploid cells is called a primary spermatocyte. The spermatocyte will undergo meiosis I and form 2 haploid daughter cells called secondary spermatocytes (1n). The 2 secondary spermatocytes will undergo meiosis II and form a total of 4 haploid spermatid.
Spermeogenesis
Maturation of the products of spermatogenesis, namely the spermatid into spermatozoa. Most of the cytoplasm has been reclaimed and recycled
Oogenesis
Creation of the female gametes
Oogonia (2n) are present in the women’s body before birth, originate in yolk sac and migrate down during development. They divide by mitosis to form 2 daughter cells. Both daughter cells are primary oocytes (2n). Both will undergo meiosis. The primary oocyte will undergo meiosis I and form secondary oocyte (1n w/ 2 chromatids) and a polar body. The polar body will atrophy and die. In meiosis I in females, there is unequal cytokinesis. The secondary oocyte undergoes meiosis II and form a haploid ovum (1n) and another polar body that is also discarded
What happens to the primary oocytes?
Both will undergo meiosis. The primary oocyte will undergo meiosis I and form secondary oocyte (1n w/ 2 chromatids) and a polar body. The polar body will atrophy and die. The secondary oocyte undergoes meiosis II and form a haploid ovum (1n) and another polar body that is also discarded
What happens to the secondary oocyte?
The secondary oocyte undergoes meiosis II and form a haploid ovum (1n) and another polar body that is also discarded
What happens to the polar body?
The polar body will atrophy and die
In females cytokinesis is equal or unequal?
Unequal
What is growth in embryo?
Growth is addition of material. There is no growth until implantation into uterine wall and placenta is formed
What is differentiation?
Differentiation is turning on certain genes and dividing
Name a difference between male and female gamete generation
Males keep producing spermatogonia and never run out their whole life, but females will run out of oogonia once they hit menopause. Also there is an unequal cytoplasm in females
Testes
male gonad, located in scrotal sac. Site of sperm production
Epididymis
tubular structure which the sperm is stored prior to ejaculation
Seminal vesicle
produces fructose for sperm
Prostate Gland
produces alkaline fluid to combat acidity of female vagina
Bulbourethral gland
lubricates the urethra prior to ejaculation
Spermatogenesis occurs in
the seminiferous tubules
Is the ovary connected to a duct?
The ovary is not physically connected to a duct
Secondary oocyte has to be swept into the fallopian tubes by the fimbriae
Ectopic pregnancy
If you have implantation anywhere but the uterus
e.g. fallopian tube implantation common, can also implant outside duct work were baby cant be born
Follicle tissue
specialized cells of ovary that produces oocyte
Stages of ovarian cycle
Follicular stage –14 days
Luteal stage – 14 days
What happens to the corpus luteum as it applies to the ovarian cycle
Will eventually degenerate into a corpus albicans, and restart cycle
Graafian
Oocyte reaches this stage after about 2 weeks of development
Ring of follicle tissue, leaves with the ovulated oocyte
Corona radiata
T/F: As follicle develops, uterine lining gets thicker and thicker
T
Follicular stimulating hormone (FSH)
A gonadotropin
Stimulates follicular growth
the number of receptors for LH increases on the follicle
Lutenizing hormone (LH)
Gonadotropin
Formation and Maintenance of corpus luteum
LH acts on follicle to trigger estrogen release and will cause a positive feedback loop in brain
Estrogen levels spike when at peak of follicle maturation
T/F: High levels of estrogen act on hypothalamus to cause GRH surge therefore there will be a spike in FSH and LH (positive feedback loop)
T
Low levels of estrogen don’t affect the brain
What effect does the spike in LH have on follicle?
LH spike increases Iron pumping into the antrum of the graafian follicle and water enters by osmosis and the follicle ruptures leading to ovulation. Once the follicle explodes the source of estrogen is disrupted because the follicle is what was producing the estrogen. Estrogen production will then decrease after ovulation and we lose the positive feedback loop. However there is still baseline levels of LH which will act on the exploded tissue to form the corpus luteum and begin the luteal stage
The corpus luteum secretes which two sex steroids
Estradiol (same as estrogen)
Progesterone
What do the combination of estradiol and progesterone have on the body?
This combination of estradiol and progesterone is responsible for the development of the uterine lining. Estrogen responsible for growing the uterine lining. The progesterone is responsible for making the pits in the lining. The combination of high levels of estrogen and progesterone together acts to inhibit LH secretion (whereas estrogen alone will stimulate LH). Since LH maintains corpus luteum, inhibiting LH will cause the corpus luteum to atrophy and shut down the luteal stage (negative feedback). Since the corpus luteum produces these hormones, as it atrophies estrogen and progesterone levels will then fall leading to the uterine lining will atrophy and be lost
How does pregnancy stop the uterine lining from falling?
To maintain uterus – we need high levels of estrogen and progesterone. To get high levels of these hormones, you need the corpus luteum but high progesterone plus estrogen shuts off Gonadatrophic releasing hormone release in females so she drops LH production which is needed for corpus luteum. The developing embryo produces its own version of LH and gives it to the mother. LH analog is called the chorionic gonadotrophin it goes into the female blood at the placental attachment and it maintains the mother’s corpus luteum. Therefore estrogen and progesterone continue to be secreted and therefore the uterine lining continues.
Chorionic Gonadotropin
Analog to LH produced by developing embryo
How does birth control work?
Estrogen + Progresterone inhibit LH and without a burst of LH you cannot have ovulation hence cannot fertilize
When there is no sexual stimulation in the penis what’s going on with inputs and blood flow?
When there is no sexual stimulation there is a tonic sympathetic input to the arterioles in the penis that causes vasoconstriction. Therefore modest blood flow to the erectile tissues, matched easily by flow out of in venules/veins. There is not storage of blood there, the flow in and out are similar
What happens to the penis during sexual stimulation?
Decrease in sympathetic input. Increase in parasympathetic input to penile arterioles. Therefore vasodilation occurs. Can also increase sympathetic input to heart so cardiac output rise. In combination with vasodilation of penile arterioles leaves to blood pooling in penile arterioles.
What gas is required for an erection?
Nitrous oxide required needed to maintain an erection
Nitrous oxide produced during sexual sitmulation and is constantly formed and broken down
How viagra works is that it inhibits nitrous oxide breakdown
Emission
movement of sperm through the system from the epididymis up to ejaculatory duct
Secretion of seminal fluids and prostate makes the semen
Ejaculation
Movement of semen through urethral and out of the body. Parasympathetic input to muscles at the base of the penis rhythmical contracts squeeze the urethra. In the urethra itself are smooth muscles and sympathetic input causes constriction of the smooth muscles of the urethra
Female Orgasm
Parasympathetic input causes dilation of arterioles to erectile tissues in the clitoris & secretion of vestibular glands. Sympathetic input to smotoh muscle of uterus causes Fallopian tubes of vagina. Stimulation of tissues in clitoris causes rhythmical contractions
