Pierce College Putman/Biol 242 Lecture Unit 09 notes: Reproductive System MALE REPRODUCTIVE SYSTEM 1. FUNCTIONAL ANATOMY
a) Corpora spongiosum: Surrounds urethra b) Corpora cavernosa: Paired sinusoids c) Erection: Contraction of venous supply + vasodilation of arterial supply;
(1) Blood collects in corpora sinusoids (2) Viagra (sildenafil)
(a) Stimulates production of (b) Need good BP for viagra to work. BP medications lower BP, so
b. Glans penis. Most sensory neurons, part of
c. Prepuce (foreskin). Protects & maintains sensitivity of glans penis.
1) No medical reason for routine removal
1) Body temperature stops spermatogenesis but does not kill mature sperm.
1) Bulbourethral (Cowper’s) glands. Paired.
(1) Neutralizes urine acidity (2) Lubricates urethra & glans
a) Secretes fluids + nutrients = semen (2/3 to 3/4 of ejaculate)
(a) In male, prostaglandins induce peristalsis of vas deferens.
(2) Seminal vesicle secretions activate sperm
a) Secretes fluids + nutrients = semen; does not secrete prostaglandins. b) Two major ducts:
Putman/Pierce College Biol 242/Unit 09 notes/20121210
(1) Ejaculatory duct. Passes sperm from vas deferens into prostatic urethra (2) Prostatic urethra. Passes urine from urinary bladder.
(1) Must be corrected by (2) May cause sterilization (3) Does not interfere with production of testosterone
(1) Spermatogonia (next to basement membrane) (2n)
(a) Form primary spermatocytes via meiosis I (b) Primary spermatocytes form secondary spermatocytes (1n) via meiosis II (c) Secondary spermatocytes develop into early spermatids (d) Early spermatids develop into late spermatids (Note that constant mitosis/meiosis pushes developing sperm toward lumen of seminiferous tubules)
(1) Late spermatids pushed into rete testes by sperm developing behind them
(1) Sperm maturation and storage area; sperm not motile here!
(1) Elongated cells attached to basement membrane of seminiferous tubules,
g. Control of testosterone production & spermatogenesis
1) At puberty, hypothalamus releases GnRH. 2) GnRH stimulates release of LH & FSH by anterior pituitary (adenohypophysis)
a) LH stimulates Leydig cells (interstitial cells) to secrete testosterone.
Putman/Pierce College Biol 242/Unit 09 notes/20121210
(a) Inhibit hypothalmic secretion of GnRH (b) Inhibit adenohypophyseal secretion of LH (c) Promotes early spermatid development
b) FSH + testosterone stimulate the Sertoli cells to secrete
(1) ABP: Binds to testosterone, keeping testosterone levels high
c) High sperm levels stimulate the Sertoli cells to secrete inhibin
(1) Inhibin inhibits adenohypophyseal secretion of FSH, providing negative
a. Volume: 2-5 cc b. Contains fibrinogen. Function? c. Life of sperm in female: Few hours to 10 days
a) Low NaHCO3 content in ejaculate b) Female rejection/allergy to sperm
3) X last longer in acidic environment 4) Y sperm swim faster 5) Blockers, etc. ???
FEMALE REPRODUCTIVE SYSTEM 1. FUNCTIONAL ANATOMY
1) Egg released from ovary directly into the 2) Egg caught by fimbriae of Fallopian (uterine)
tube>infundibulum>ampulla>isthmus>uterus
b. Fertilization usually occurs in Fallopian tubes, implantation in uterus
a) Implantation anywhere except in uterus
(1) Fallopian tube implantation most common ectopic pregnancy. Dangerous! (2) Implantation can occur anywhere; placenta can only develop in/on uterus
c. Vulva. External female sexual anatomy
1) Labia majora & minora. Protect vaginal orifice 2) Clitoral prepuce. Protects & maintains sensitivity of clitoris. 3) Clitoris. Highest numbers of sensory neurons here. 4) Hymen. Partially to fully occludes vaginal orifice in young girls; must be (usually is)
5) Vaginal orifice. Receives penis during copulation.
Putman/Pierce College Biol 242/Unit 09 notes/20121210
6) External urethral orifice. Allows for micturition. Note: Separate from reproductive
(1) Not produced by little girls or post-menopausal women
b) Secretes lactate (lactic acid), maintaining pH at 3.5-4.5
(a) Little girls and post-menopausal women susceptible to this infection.
2) Douching may inhibit Lactobacillus and/or change vaginal pH
a) This reduces Lactobacillus, thus douching can cause infections by
1) Extension of uterus into vaginal canal 2) Has very few nerve endings, thus removal of cells during pap smears cause relatively
little discomfort (some women disagree with this…) a) Pap smears remove cells from the cervix to detect cancer.
1) Depression or pocket around the os of the cervix. 2) Semen is deposited here after coitus
a) Prostaglandins cause peristalsis of uterus, semen taken up through os
a) At parturition, 1 million primary follicles per ovary
(1) Each containing primary oocytes in prophase I of meiosis
b) Puberty to menopause, ~20 primary follicles develop per menstrual cycle.
(1) 1 to 2 secondary follicles form from these, primary oocytes still in prophase I
c) Follicles secrete fluid containing estrogens, swell in size d) Primary oocyte in secondary follicle turns into secondary oocyte + polar body
(1) Secondary oocyte now in metaphase II of meiosis (2) Graafian follicle now; swollen with estrogen-containing liquids
(a) Explosion of Graafian follicle releases secondary oocyte (egg, still in
meiosis II) briefly into abdominal cavity; fimbriae catch egg; egg completes meiosis ONLY if fertilized!
3) Corpus luteum. Forms from pocket of tissue when secondary oocyte leaves corpus
luteum. a) Produces progesterone under LH influence
1) Perimetrium. Outermost connective tissue layer 2) Myometrium. Muscle layer of uterus 3) Endometrium. Innermost layer; involved most in hormonal cycles
Putman/Pierce College Biol 242/Unit 09 notes/20121210
2. Hormonal Cycles: Ovarian & Uterine Cycles
a. At puberty, hypothalamus releases GnRH.
1) GnRH stimulates adenohypophyseal secretion of FSH & LH
b. FSH initiates follicular stage of ovarian cycle.
1) ~ 20 primordial follicles develop per cycle, produce one to two secondary follicles
1) Maturation of secondary follicle 2) Increased estrogen secretion into antrum of follicle 3) Ovulation (when LH levels spike)
d. As estrogen levels from developing follicles rise, they stimulate
1) Anterior pituitary to secrete more FSH & LH 2) Hypothalamus to secrete more GnRH 3) Proliferative phase of uterine cycle (endometrium development)
1) Corpus hemorrhagicum immediately forms, develops into corpus luteum
a) Stimulates initial uterine development
a) Stimulates final uterine development b) Inhibits GnRH + LH (progesterone-based birth control pills) c) Promotes development of mammaries
Inhibition of GnRH, FSH, LH: 1. Stops uterus development, readying for implantation, etc.
a. Menstruation occurs b. Corpus luteum shrivels up into corpus albicans
2. If fertilization & implantation occurs
a. HCGn produced by placenta (detected in urine)
1) Stimulates corpus luteum to continue to produce progesterone
a) Endometrium continues to develop to support baby. b) Progesterone shuts off GnRH, FSH & LH so oogenesis & follicle development
Putman/Pierce College Biol 242/Unit 09 notes/20121210
Source: http://www.pierce.ctc.edu/Military/bputman/242%2009b%20notes%20Reproductive%20System.pdf
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