Reproductive System Gonads general term referring to the reproductive organs Functions of the gonads: 1. produce gametes 2. secondary sexual characteristics genitals or genitalia = external reproductive structures The Male: gamete sperm size much smaller than egg 300 500 million are released each ejaculation 130 million are needed to insure fertilization their journey is equivalent to a person walking 7 miles Gonad testis (also called testicles) contained in the scrotum outside the body where temperature is lower for sperm production and survival viable (= living) sperm cannot be produced at normal body temperature of 98.6 F (temperature within the scrotum is about 2 degrees cooler) contain hundreds of compartments packed with tightly coiled tubules called seminiferous tubules the testes begin secreting testosterone at puberty (about 10 14 years old). They will continue to secrete testosterone throughout their life. in the seminiferous tubules spermatogonial cells undergo meiosis to become sperm. The sperms are released into an elongated storage sac epididymis on the testis epididymis the epididymis is a comma- shaped coiled tube that curves partly around each testis it is within the epididymis that the sperm mature and develop the ability to become motile (it takes about 18 hours to mature within the epididymis) sperm duct from epididymis to urethra ductus deferens (vas deferens) (severing of this duct is a vasectomy) Three glands add secretions to the sperm: 1. seminal vesicles 2. prostate gland 3. bulbourethral glands The seminal vesicles (2) are pouch like structures that lie in back of the urinary bladder. Seminal vesicles this alkaline fluid functions to neutralize acidic urine acids inactivate and kill sperm they secrete an alkaline fluid (= seminal fluid) that contains the sugar fructose into the ductus deferens. fructose functions to provide energy to sperm for their long journey up the female reproductive tract The prostate gland (1) is located just below the bladder and surrounds the upper portion of the urethra it secretes a milky alkaline fluid into the urethra Prostate gland most males over the age 45 experience enlargement of the prostate gland which may close off the urethra reducing or completely stopping urination prostatic fluid functions to activate sperm and neutralize acids produced by the female reproductive tract The bulbourethral glands (2) are small pea-sized glands located below the prostate gland Bulbourethral gland they function to produce an alkaline fluid that neutralizes acid in the male urethra the urethra functions as the passageway for both urine and semen (obviously not at the same time) Semen is a mixture of: sperm secretions from bulbourethral glands prostatic fluid (secretion from prostate gland) seminal fluid (secretion from seminal vesicles) The greatest proportion of semen (60%) is seminal fluid when the number of sperm fall below 20 million/ml, the male is considered to be sterile The penis functions to introduce sperm into the vagina of the female it contains the urethra and 3 columns of tissue that contain blood sinuses (spongy tissue) these sinuses become filled with blood during sexual stimulation, resulting in an erection Ejaculation is the propulsion of semen from the urethra to the exterior during ejaculation a sphincter at the base of the bladder closes This prevents: 1. urine from entering the urethra 2. prevents semen from entering the bladder Foreskin covering the glans (head) of the penis - prepuce removal of this is circumcision foreskin Sperm structure sperm are typically described as being tadpole shaped The can be divided into 3 regions: 1. head contains a haploid nucleus (23 chromosomes); and enzymes that help sperm penetrate the egg 2. midpiece which contains mitochondria that use fructose to provide energy for sperm midpiece 3. tail propels the sperm toward the egg although males produce sperm from puberty until they die, the quantity of sperm they produce decreases as they age The Female: gamete ovum (egg) 75,000 times larger than sperm gonad - ovaries about the same size and shape as an unshelled almond females are born with about 2 million immature egg cells in their ovaries. These are all the eggs that she will ever produce however, by the time she begins ovulating at puberty, that number has dropped to about 400,000 a woman will begin ovulating her eggs when she reaches puberty (average age 9 13) she will continue to ovulate one egg about every 28 days until she goes through menopause although her ovaries contain about 400,000 eggs, she will only ovulate about 400 mature eggs over her lifetime The fallopian tubes (= oviducts) connect the ovaries to the uterus ovary Fallopian tube They have 2 functions: 1. serve as the site of fertilization (sperm penetrates ovum) 2. to transport the ovum from the ovaries to the uterus the tip of the fallopian tube is slightly expanded and covered with finger-like projections that are covered with cilia at ovulation (= ovum is released from ovary), the finger-like projections and cilia become very active, creating currents that suck the ovum into the fallopian tube the egg travels down the fallopian tube toward the uterus an egg can be fertilized at any time up to 24 hours after ovulation fertilization usually occurs in the first portion of the fallopian tube The fertilized egg (= zygote) takes about days to complete its journey down the fallopian tube it will implant in the uterus around day 7 if the ovulated egg is not fertilized it will degenerate The uterus (= womb) has several functions: 1. the site of menstruation 2. the site of implantation of a fertilized egg 3. the site of development of the fetus during pregnancy 4. the site of labor The uterus is a muscular structure located just above the urinary bladder it is about the size and shape of an inverted pear the lowermost portion of the uterus is called the cervix the cervix is important because this is where cancer tends to develop in many females cervical cancer is easily detected by a test called a Pap smear when a physician performs a pap smear, he/she is scrapping a few cells from the vagina and cervix. these cells are examined to see if any of them appear cancerous females with a history of normal pap smears should have one every 2 to 3 years until age of 50 and annually thereafter females who have had suspicious pap smears in the past should have them annually cervical cancer has a high cure rate if it is caught early enough The innermost wall of the uterus is called the endometrium 2 layers: 1. outer endometrium thickens and is shed during menstruation 2. inner endometrium produces new outer endometrium every month The vagina is a muscular tube about 7 cm long that leads to the uterus it functions as the passageway for the menstrual flow and childbirth Trace the pathway that sperm would follow from the moment they were introduced into the body of the female vagina cervix uterus fallopian tube One thing worth mentioning is that although the urethra is part of the male reproductive system (passageway for both sperm and urine), it is not part of the female reproductive system males have only 2 opening to the outside of the body (urethra and anus), while females have 3 (urethra, vagina, and anus) Menstrual cycle the cycle of events that prepares the uterine lining for a possible pregnancy each month menstrual comes from the Latin word mensis = month the average menstrual cycle is about 28 days and can be divided into 4 phases: menstrual phase, proliferative phase, ovulation, and secretory phase menstruation occurs during the menstrual phase menstruation is the process by which the outer endometrium is shed Menstrual phase (days 1 6) the 1 st day of a womans period marks day 1 of her next menstrual cycle menstruation occurs because the egg that she ovulated earlier was not fertilized and did not implant itself in the uterine lining (endometrium) menstruation begins at puberty and will continue until she reaches menopause after menopause, a woman will no longer menstruate because she is not longer ovulating menopause normally begins between the ages of Proliferative phase (days 7 13) during this phase, the inner endometrium begins secreting a new outer endometrium Ovulation (day 14) during ovulation, the mature egg is released from the ovary and enters the oviduct Secretory phase (days 15 28) during the secretory phase, the outer endometrium doubles in thickness this prepares the uterus to receive a fertilized egg If the egg is fertilized, it implants within the uterus and the endometrium is not shed If the egg is not fertilized, the outer endometrium breaks down and menstruation begins again Contraception (= birth control) 1. abstinence the most reliable method of contraception 2. condom prevents pregnancy by blocking sperm entry into vagina this is the only method of birth control (besides abstinence) that prevents transmission of STDs 3. birth control pills various combinations of female sex hormones (estrogen and progesterone) which prevents ovulation must be taken daily to be effective 4. diaphragm device that fits over cervix, preventing sperm from entering the uterus 5. Depo-provera hormone injection given to females that prevents ovulation for 90 days 6. tubal ligation cutting or tying of the fallopian tubes of the female Tubal Ligation Normal Anatomy - Tubal Ligation The information provided herein should not be used for diagnosis or treatment of any medical condition. It is provided for your general information and is not a substitute for medical care or supervised medical treatment. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. adam.com is a founding member of Hi-Ethicsadam.com also subscribes to the HONcode principles of the Health On the Net Foundationand is a member of the American Accreditation HealthCare Commission (URAC) Health Web Site Advisory CommitteeCopyright 2002 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.http://www.hiethics.com prevents sperm from reaching ovulated egg 7. vasectomy cutting or tying ductus deferens of male male will form semen that does not contain sperm Methods 1 5 are easily reversible; however, tubal ligation and vasectomy are considered to be irreversible Sexually Transmitted Diseases 1. AIDS fatal STD caused by the HIV virus the virus destroys the helper T cells, which are a vital component of the immune system 2. genital herpes STD caused by the herpes simplex virus symptoms include periodic outbreaks of blisters in the genital area, flu-like aches and fever it is not curable babies born to women with genital herpes can become infected and suffer severe damage to their nervous system or death 3. syphilis STD caused by the bacterium Treponema pallidum symptoms include appearance of a small painless ulcer (chancre), fever, swollen lymph glands or rash if not treated it will cause death pregnant women can transmit to unborn child 4. Gonorrhea STD caused by the bacterium Neisseria gonorrhoeae symptoms include painful urination and pus discharge in males infected females usually do not exhibit any symptoms is treatable 5. Chlamydia STD caused by the bacterium Chlamydia trachomatis this is the most common STD in the U.S. symptoms include painful urination in males and vaginal discharge in females however, most individuals have no symptoms, so they do not know they have it