Male Reproductive System Overview

Male Reproductive System

• The male reproductive system includes organs like testes, located within the scrotum, and the penis.
• Ducts within the system include the epididymis, ductus deferens, ejaculatory duct, and urethra.
• Accessory glands include seminal glands (2), prostate (1), and bulbourethral glands (2).
• Sperm production (spermatogenesis) occurs in the testes.
• Meiosis is the specialized cell division process.
• 100 million sperm are produced daily.
• Immature sperm mature within the epididymis.
• The scrotum houses the testes, regulating temperature for sperm viability (lower than body temp).
• The position and size of the scrotum can change through muscle contractions.
• Sperm cells require less energy to produce compared to egg cells.
• The penis delivers sperm to the female reproductive tract, and also eliminates urine.
• Erectile tissue in the penis fills with blood, leading to erection.
• Semen is a mixture of sperm and fluids from accessory glands.
• Semen is propelled through ducts during ejaculation by smooth muscle contractions.

Female Reproductive System

• The female reproductive system includes organs like ovaries (2), located on either side of the uterus.
• The oviducts (fallopian tubes) carry the egg to the uterus, where fertilization usually occurs; implantation also occurs here.
• The uterus is a pear-shaped organ.
• The uterine wall has smooth muscle, contracting during childbirth (oxytocin).
• The endometrium is the blood-rich lining of the uterus.
• The cervix is the opening of the uterus, often closed and sealed with thick mucous.
• The vagina is a thin-walled tube connecting the uterus to the outside, allowing for delivery of infants and menstrual flow. It also serves as the site of sperm deposition.
• The clitoris and labia are external genital organs.
• Ovaries produce eggs.
• Progesterone levels rise after ovulation and maintain throughout pregnancy, dropping otherwise.
• Estrogens and progesterone regulate the menstrual cycle.

Functions of the Reproductive Systems

• Produce gametes (sperm and eggs).
• Bring gametes together for fertilization.
• Nurture the development of the zygote into an embryo, then fetus, and provide postpartum care.

Primary Sex Organs: Gonads

• Testes in males produce sperm and testosterone.
• Ovaries in females produce eggs and estrogen, progesterone.
• Gonad function is ultimately controlled by the hypothalamus.

Hypothalamus-pituitary-Gonadal (HPG) Axis

• The hypothalamus releases gonadotropin-releasing hormone (GnRH) to stimulate the anterior pituitary gland.
• The anterior pituitary releases LH and FSH triggering the gonads' activity and sex hormone production.
• Sex hormone production and release is auto regulated.

Spermatogenesis

• Immature sperm are formed in the testes using meiosis.
• Sperm travel from the seminiferous tubules via the epididymis to the ducts.

Reproductive Strategies

• Males produce millions of sperm for delivery to the female.
• Females produce nutrient-rich eggs (about 500 in a lifetime).

Male Accessory Glands

• Seminal glands produce the majority of semen's volume with nutrients for sperm.
• The prostate gland secretes a fluid that activates sperm neutralizing acidity in the female reproductive tract.
• Bulbourethral glands produce a fluid that cleanses the urethra before ejaculation.

Female Reproductive Tract

• Uterine tubes transport oocytes or fertilized embryos to the uterus.
• The uterus is the site of embryonic and fetal development.
• The vagina serves as a passageway for childbirth and menstrual flow, for sperm delivery and for receiving the penis during sexual activity.

Monthly Cycle

• Female cycles average 28 days.
• Ovulation typically occurs around day 14.
• Menstruation occurs when no pregnancy happens, releasing the uterine lining.

Estrogen

• A steroid hormone.
• Promotes female sexual development.
• Stimulates development of female reproductive structures.
• Regulates the menstrual cycle.
• Involved in maintaining blood cholesterol levels.

Progesterone

• Also a steroid hormone.
• Enhances development of the uterine lining.
• Crucial for maintaining pregnancy (and a pregnancy-like state)
• Regulates hormone release.
• Inhibits uterine muscle contractions.

Premenstrual Syndrome (PMS)

• Emotional and physical changes before menstruation
• Symptoms vary, including mood swings, tenderness, and headaches.

Premenstrual Dysphoric Disorder (PMDD)

• Severe form of PMS.
• Symptoms severely interfere with daily life.
• Likely increased sensitivity to progesterone in the limbic system.

Oral Contraceptives

• Supplement hormones or progestogen
• Inhibits ovulation by affecting the HPG axis.