Class notes
Bio 151 Reproductive System Notes
- Course
- Bio 151
- Institution
- Delaware County Community College
This is a comprehensive and detailed note on the reproductive System for Bio 151. *Essential and Valuable Study Material!!
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Ch 27 and 28: Reproductive Systems1. Welcome to the Reproductive System | Khan Academy
a. Male: testes (millions of sperm per day) and penis
i. Testes: produces testosterone
b. Female: Ovary (1 egg per month), uterus, breasts (lactation)
i. Ovary: produces estrogen and progesterone
c. Hypothalamus: releases GnRH: Gonadotropin-releasing hormone (GnRH) is a
releasing hormone responsible for the release of follicle-stimulating hormone
(FSH) and luteinizing hormone (LH) from the anterior pituitary.
d. Pregnancy: sperm + egg → zygote, implants in the uterus to grow,
gestation: Fetal development period from the time of conception until birth. For
humans, the full gestation period is normally 9 months, Labor: giving birth
2. Anatomy of the Male Reproductive System | Khan Academy
a. Testes: spermatogenesis → the creation of sperm
i. Also creates testosterone
b. Scrotum: contains the testes and regulates the temperature of the testes
i. Cremaster muscle: The cremaster muscle lowers and raises the testis in
order to control its temperature.
ii. Dartos muscle: The dartos muscle is the scrotal part of the dartos fascia,
composed of smooth cells. In the scrotum, the tunica dartos acts to
regulate the temperature of the testicles, which promotes
spermatogenesis. It does this by expanding or contracting to wrinkle the
scrotal skin.
c. Epididymis: provides a space for the sperm to hang and develop, on top of the
testes. Sperm develops flagella tails and gains energy for their long journey.
d. Vas deferens: The vas deferens is a long, muscular tube that travels from the
epididymis into the pelvic cavity, to just behind the bladder. The vas deferens
transports mature sperm to the urethra, the tube that carries urine or sperm
outside of the body, in preparation for ejaculation.
e. Spermatic cord: The spermatic cord is the cord-like structure in males formed
by the vas deferens (ductus deferens) and surrounding tissue that runs from the
deep inguinal ring down to each testicle. It’s serosal covering, the tunica vaginalis
is an extension of the peritoneum that passes through the transversalis fascia.
f. Seminal Vesicle: provide fluid for sperm that makes up semen.
i. Semen: semen refers to the seminal fluid that contains millions of
sperms. The fluid is alkaline (pH above 7), and it is rich in fructose which
is used for ATP.
g. Prostate gland: The prostate gland is a male reproductive organ whose main
function is to secrete prostate fluid, one of the components of semen. The
muscles of the prostate gland also help propel this seminal fluid into the urethra
during ejaculation
h. Bulbourethral glands (2): Bulbourethral glands, also called Cowper's Gland,
, either of two pea-shaped glands in the male, located beneath the prostate gland
at the beginning of the internal portion of the penis; they add fluids to semen
during the process of ejaculation.
i. Urethra: the duct by which urine is conveyed out of the body from the bladder,
and which in male vertebrates also conveys semen.
j. Penis: penetrates the vagina so that sperm can be conveyed inside the female
body.
3. Transport of Sperm via Erection and Ejaculation | Khan Academy:
a. Transport of sperm
i. Erection: when the penis is filled with blood
1. Starts in the brain from sexual excitement
ii. Ejaculation: the expulsion of sperm out of the reproductive tract
b. Structures of the Penis:
i. Corpora Cavernosa: either of two masses of erectile tissue forming the
bulk of the penis and the clitoris.
ii. Corpus Sponginosum: a mass of erectile tissue alongside the corpora
cavernosa of the penis and terminating in the glans.
c. Norepinephrine: comes from the sympathetic nervous system, stimulates the
penis to open up and allow blood into penis
d. Nitric Oxide: Vasodilation, Nitric oxide dilates blood vessels, raising blood supply
and lowering blood pressure.
e. An erection starts in your brain. Something you saw, felt, smelled, heard, or
thought makes your nerves send chemical messages to the blood vessels in your
penis. The arteries relax and open up to let more blood flow in; at the same time,
the veins close up. Once blood is in the penis, pressure traps it within the corpora
cavernosa. Your penis expands and holds the erection. When the inflow of blood
stops and the veins open, your penis becomes soft.
f. When ejaculation occurs, sperm is forcefully expelled from the tail of the
epididymis into the deferent duct. Sperm then travels through the deferent duct
through up the spermatic cord into the pelvic cavity, over the ureter to the
prostate behind the bladder.
4. Spermatogenesis | Khan Academy:
a. Testes: makes sperm and testosterone
b. Seminiferous Tubules: makes sperm travels to → the epididymis
c. Sertoli Cells: A Sertoli cell (a kind of sustentacular cell) is a "nurse" cell of the
testicles that is part of a seminiferous tubule and helps in the process of
spermatogenesis, the production of sperm. It is activated by follicle-stimulating
hormone (FSH) secreted by the adenohypophysis and has FSH receptor on its
membranes.
d. Spermatagonium: a precursor to the mature form of sperm
e. Spermatagonium divides and differentiates by mitosis and becomes a primary
spermatocyte.
f. The spermatocyte moves through the tight junction and the spermatocyte
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