The Male and Female Reproductive Systems

Katie Mackin, Alex Brockdorf, & Kayla Lovett

IB Standards: 6.6.1

6.6.2 6.6.3 6.6.4

Nader Chapter (AP Standards): 41.1 (4.B.2)41.3 (2.C.1, 4.B.2) 41.4 (3.D.4)

Male Reproductive System

Note: In this diagram the “vas deferens” is referred to as the “ductus deferens

For IB need to label:BladderSperm ductSeminal vesicleProstate glandErectile tissuePenisUrethraForeskinScrotumTestis

Journey of the Sperm Testes: Produce sperm and sex hormone

› Male gonads suspended in scrotum› Begin in abdominal cavity, descend to scrotum during puberty

(if this does not happen and it left uncorrected the male suffers from sterility)

› Sterility: Cooler than body temp. is required for development of sperm

› **Testicular cancer is most common cancer in males 15-34

Epididymis: Sites of maturation and some storage of the sperm› Tightly coiled tubules lying just outside testes› Maturation is required for sperm to swim to egg

Vas deferens: Conduct and store sperm› Propelled here after maturation for storage› Sexual arousal sends sperm to ejaculatory ducts then to the

urethra

Journey of Sperm: Orgasm in Males Penis: Organ of copopulation

› Covered in foreskin until circumcision› During sexual arousal , nervous reflexes causes

increased arterial blood flow to penis› Erection: This increased flow fills the blood space

in erectile tissue and stiffens the normally flaccid penis to erect Erectile dysfunction

Semen: (from Seminal vesicle, Prostate gland, Bulbourethral glands)› Fluid that contains nutrients, prostaglandins/

motility activators, slightly basic pH, seminalplasmin/ lubricating fluid

› 2-5mL released on average: 60% seminal vesicle fluid, 30% prostatic fluids, <10% sperm

PENIS ANATOMY

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Journey of Sperm: Orgasm in Males

Ejaculation› 1st Phase: Emission

Sperm enters ejaculatory duct Glands release secretions, bulbourethral

enter urethra first to cleanse it of urine residue

› 2nd Phase: Expulsion Contractions at base of penis expels semen

from the opening of urethra Release of myotonia (muscle tenseness) Penis returns to flaccid state

Journey of Sperm

Sperm Spermatogenesis takes place in seminiferous

tubules Need to release 50-150 million sperm per mL of semen <100 sperm ever reachthe egg, 1 penetrates

Hormone Regulation in Males Hypothalmus control

testes by hormone GnRH that stimulates anterior pituitary to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

FSH promotes spermatogenesis

LH control production of androgen testosterone in interstitial cells

3 Roles of Testosterone 1. Causes male genitalia, such as penis,

to develop in the fetus2. Levels rise during puberty and causes

secondary sexual characteristicsEx) pubic hair, enlarged penis, skeletal/ muscular growth

3. During adulthood, maintains sex drive*** Also one of the hormones needed to stimulate sperm production in testes

Female Reproductive System

Female Reproductive Organs Ovaries: produce egg and sex hormone

› Normally alternate by producing one oocyte a month

› Oocyte = “egg” Oviducts: conduct egg, location of

fertilization› Extend from ovaries to uterus, › Not connected to ovary, instead have fimbriae

that sweeps over ovaries› When oocyte bursts during ovulation it is swept

into oviduct by fimbriae and cilia› If fertilized, the embryo is moved into uterus by

cilia and muscle contraction

Female Reproductive Organs Uterus: houses developing embryo and fetus

› Narrow end is called cervix› The embryo completes its development embedded

in the endometrium (uterine lining)› If the embryo is embedded elsewhere it is an

“ectopic pregnancy› A small opening in the cervix leads to the vaginal

canal Vagina: receives penis during copopulation and

serves as birth canal› A tube at a 45º angle to the small of the back› The mucosal lining is in fold and can distend

(important during childbirth and intercourse)› It is acidic due to bacteria to protect itself from

pathogenic bacteria (Recall: Semen is basic)

Female Reproductive Organs Vulva: collective name for the female

external genitalia Clitoris is similar to male penis in beingthe main organ offemale orgasm

Female Sex Hormones Pituitary gland produces FSH and LH

› FSH: stimulates the development of follicles (fluid filled sacs containing an egg cell)

› LH: stimulates follicles to mature, release their egg (ovulation), and then develop into the corpus luteum

Ovary produces estrogen and progesterone› Development of secondary sexual

characteristics› Stimulate the development of the uterus lining

needed during pregnancy› Levels rise and fall according to menstrual

cycle

The Female Breast Contains 15-24 lobules, each with

its own mammary duct Duct begins at nipple and divides

into more ducts ending with alveoli Lactation: production of milk by

cells of alveoli caused by prolactin Milk contains water proteins, amino

acids, sugars, and lysozymes (750 cal/ L)› Not produced during pregnancy

because of feedback inhibition effect of estrogen and progesterone

› Milk production begins a few days after delivery

› Colostrum (rich in IgA) is produced in between

The Ovarian Cycle Take place in the ovaries Occurs as a follicle changes from primary to

secondary to a vesicular follicle under the influence of FSH and LH from the anterior pituitary

Phases of Ovarian Cycle Follicular phase (1st): FSH promotes the development of a follicle that

primarily secretes estrogen› As estrogen rises in the blood it exerts negative feedback over the secretion of

FSH, ending the follicular phase› When levels of estrogen become very high it exerts positive feedback on

hypothalamus and anterior pituitary› The hypothalmus will secrete a large amount of GhRH› This leads to a surge in LH and ovulation to be about the 14 th day of a 28 day

cycle Ovulation

› The vesicular follicle bursts, releasing the secondary oocyte (egg) surrounded by a clear membrane

› Once a vesicular follicle has lost the secondary oocyte it becomes a corpus luteum

Luteal phase (2nd): LH promotes the development of the corpus luteum that primarily secretes progesterone› As the blood level of progesterone rises, it exerts negative feedback over LH

production so the corpus luteum begins to degenerate› The remaining low levels of progesterone and estrogen begin the menstrual

cycle

The Uterine Cycle The 28 day cycle produced by estrogen and

progesterone affecting the endometrium of the uterus

Day 1-5 (Menstruation): Low levels of female sex hormones causes endometrium to disintegrate and blood vessels to rupture

Day 6-13 (Proliferative): Increased estrogen production causes endometrium to thicken

Day 14 (Ovulation) Day 15-28 (Secretory): Increase progesterone

production by corpus luteum causes endometrium to double in thickness, producing a thick mucus signaling the lining can now receive an embryo

If not pregnant, the cycle restarts

Menstruation Facts 7-10 days before menstruation some women suffer from

PMS During menstruation arteries that supply the

endometrium constrict and capillaries weaken Blood spillage detaches lining in random patches (not

all) so mucus, blood, and degenerating endometrium descend from uterus through the vagina› Fibrinolysin keeps blood from clotting› Lasts 3-5 days

Menarche, or first period, usually occurs between 11-13 › Amenorrhea: period does not occur by 16 or stops in women

of reproductive age (pregnancy, menopause, birth control) Menopause occurs when the ovaries cease functioning

and menstruation ceases (age 45-55)

Behavorial Contraceptives: Abstinence: not engaging in sexual intercourse

Rhythm method (Natural family planning): refraining from intercourse when conception is most likely › 10-20% pregnancy rate› Also method for achieving pregnancy› Option for religions that do not allow birth control

Coitus interruptus (Withdrawal): removal of the penis from the vagina before ejaculation› Unreliable method because of willpower and

possibility the bulbourethral fluids contain sperm secreted before ejaculation

Permanent Mechanical Contraception

Vasectomy: Surgical severing of the vas deferentia that prevents sperm from entering the ejaculatory duct, instead phagocytized by macrophages

Tubal litigation: in which a woman’s oviducts are burned or clipped preventing sperm from reaching the oocyte

Nearly 100% effective

Mechanical Contraceptive Male Condom (<10%): membrane

sheath that fits over penis and collects semen. Only contraceptive to protect from STDs

Female Condom or Diaphragm Both work best with spermicidal foam

or jelly Intrauterine Devices: Prevents

fertilization or implantation

Chemical Contraception The most commonly used birth control pills are a

combination of a synthetic estrogen and a synthetic progestin (progesterone-like hormone). This combination acts by negative feed back to stop the release of GnRH by the hypothalamus and thus of FSH and LH by the pituitary. The prevention of LH release prevents ovulation. As a backup mechanism, the inhibition of FSH secretion by the low dose of estrogen in the pills prevents follicles from developing.

Minipill or Depo- Provera injection prevents fertilization mainly by causing thickening of a woman’s cervical mucus so that it blocks sperm from entering the uterus.

After Intercourse Morning- after pill: Taken 72 hours after

intercourse and is 85% effective. Most effective when the women was already using birth control

RU-486 is a pill currently being developed that blocks progesterone receptors in the uterus and can terminate a pregnancy non-surgically for 7 weeks

Abortion: termination of a pregnancy in progress› Each year about 1.5 million women in the U,S,

choose abortions performed by physicians