What are the accessory organs of the reproductive system?
seminal vesicles, prostate, bulbourethral glands
What are the external genitalia of the reproductive system?
Facts about the Testes
Coverings of the testes. -Tunica albuginea-capsule that surrounds each testis. -Septa-extensions of the capsule that extend into the testis and divide it into lobules. Each lobule contains one to four seminiferous tubules -tightly coiled structures -function as sperm-forming factories -empty sperm into the rte testis (first part of the duct system) Interstitial cells in the seminiferous tubules
Sperm travles through the rete testis to the epididymis***
What makes up the "Duct System"
Epididymis, Ductus (vas) deferens, Urethra
What is the Epididymis?
Comma-shaped, tightly coiled tube. Found onthe "superior part of the testis and along the posterior lateral side". Functions to "mature and store sperm cells" (at least 20 days) "Expels sperm" with the contraction of muscles in the epididymis walls "to the vas deferens".
What are the Ductus Deferens (Vas Deferens)?
Carries sperm "from the epididymis to the ejaculatory duct". Passes throught the inguinal canal and over the bladder. Moves sperm by "peristalsis". Spermatic cord-ductus deferens, blood vessels, and nerves in a connective tissue sheath.
Facts about the Ductus Deferens (Vas Deferens)
Terminates in the ejaculatory duct which unites with the urethra Ejaculation—smooth muscle in the walls of the ductus deferens create peristaltic waves to squeeze sperm forward Vasectomy—cutting of the ductus deferens at the level of the testes to prevent transportation of sperm (form of birth control)
Facts about the Urethra
Extends from the base of the urinary bladder to the tip of the penis Carries "both urine and sperm" Sperm enters from the ejaculatory duct
What are the accessory organs?
Seminal vesicles Prostate Bulbourethral glands
Explain the Seminal Vesicles...
Located at the base of the bladder! Produces a thick, yellowish secretion (60 percent of semen) Fructose (sugar) Vitamin C Prostaglandins Other substances that nourish and activate sperm
Explain the Prostate...
Encircles the upper part of the urethra Secretes a "milky fluid" Helps to activate sperm Enters the urethra through several small ducts "Prostatitis"-inflammation of the prostate "Prostate cancer-third most common cancer in males"
What are the Bulbourethral Glands?
Pea-sized gland "inferior to the prostate" Produces a "thick, clear mucus" "Cleanses the urethra of acidic urine prior to ejaculation" Serves as a "lubricant during sexual intercourse" Secreted into the penile urethra
What is Semen?
"Mixture of sperm and accessory gland secretions" "Advantages" of accessory gland secretions Fructose provides energy for sperm cells Alkalinity of semen helps neutralize the acidic environment of vagina Semen inhibits bacterial multiplication Elements of semen enhance sperm motility
What are the external genitalia?
Explain the Scrotum..
Divided sac of skin outside the abdomen Maintains testes "at 3°C lower" than normal body temperature to protect sperm viability
Explain the Penis...
Delivers sperm into the female reproductive tract Regions of the penis Shaft Glans penis (enlarged tip) Prepuce (foreskin) Folded cuff of skin around proximal end Often removed by circumcision
What is Spermatogenesis?
"Production of sperm cells" Begins at puberty and continues throughout life Occurs in the seminiferous tubules
Explain further about Spermatogenesis.
"Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty" Follicle-stimulating hormone (FSH) modifies spermatogonia division One cell produced is a stem cell, called a type A daughter cell The other cell produced becomes a primary spermatocyte, called a type B daughter cell
More facts about Spematogenesis...
Primary spermatocytes undergo meiosis "One primary spermatocyte produces four haploid spermatids" "Spermatids—23 chromosomes" (half as much material as other body cells)
Explain the Human Life Cycle...
"Union of a sperm" (23 chromosomes) "with" an egg (23 chromosomes) creates a zygote (2n or "46 chromosomes")
What is Spermiogenesis?
Late "spermatids" are produced with distinct regions "Head " "Midpiece" "Tail" Sperm cells result after maturing of spermatids Spermatogenesis (entire process, including spermiogenesis) takes 64 to 72 days
Explain the Anatomy of a Mature Sperm Cell
Th only hman flagellated cell. Head ----contains DNA ----acrosome-helmet on the nucleus, similar to a large lysosome. ----breaks down and releases enzymes to help the sperm penetrate an egg. "Midpiece" ----wrapped by mitochondria for ATP generation
Explain Testosterone Production...
The "most important hormone" of the testes Produced in interstitial cells During puberty, "luteinizing hormone (LH) activate the interstitial cells" In turn, "testosterone is produced"
What are the functions of testosterone?
Stimulates "reproductive organ development" Underlies "sex drive" Causes "secondary sex characteristics" Deepening of voice Increased hair growth Enlargement of skeletal muscles Thickening of bones
Composed of ovarian follicles (sac-like structures) Each follicle consists of "Oocyte" (immature egg) "Follicular cells—surround" the oocyte
What is Ovulation?
when the egg is mature, the follicle ruptures; occurs about every 28 days
What do suspensory ligaments do?
secure ovary to lateral walls of the pelvis
What is the Duct System for females?
Uterine tubes (fallopian tubes) Uterus Vagina
Explain the Uterine (Fallopian) Tubes...
Receive the ovulated oocyte Provide a "site for fertilization" Attach to the uterus Little or no contact between ovaries and uterine tubes Supported and enclosed by the broad ligament
What are Fimbriae?
"Finger-like projections" at the distal end of the uterine tube Receive the "oocyte from the ovary"
What is Cilia?
Located inside the uterine tube Slowly move the oocyte towards the uterus (takes 3 to 4 days)
Fertilization occurs inside the uterine tube since oocyte lives about 24 hours**
What are the functions of the Uterus?
"Receives" a fertilized egg "Retains" the fertilized egg "Nourishes" the fertilized egg
What are the Regions of the Uterus?
"Body"—main portion "Fundus"—superior rounded region above where uterine tube enters "Cervix"—narrow outlet that protrudes into the vagina
What is the Endometrium in the walls of the uterus?
Inner layer Allows for implantation of a fertilized egg Sloughs off if no pregnancy occurs ("menses") Myometrium—middle layer of smooth muscle Perimetrium (visceral peritoneum)—outermost serous layer of the uterus
Explain the Vagina...
Extends from "cervix to exterior of body" Located between bladder and rectum Serves as the "birth canal" Receives the penis during sexual intercourse Hymen—partially closes the vagina until it is ruptured
Enclosed by labia majora Contains external openings of the urethra and vagina
Greater vestibular glands
Secretes lubricant during intercourse
Contains "erectile tissue" Corresponds to the male penis The clitoris is similar to the penis in that it is Hooded by a prepuce Composed of "sensitive erectile tissue" Becomes swollen with blood during sexual excitement
between the anterior ends of the labial folds, anus posteriorly, and ischial tuberosities laterally
female stem cells found in a developing fetus
Oogonia undergo mitosis "to produce primary oocytes"
Follicle stimulating hormone (FSH) causes some primary follicles to mature each month**
Follicle development to the stage of a vesicular follicle takes about 14 days Ovulation of a secondary oocyte occurs with the release of luteinizing hormone (LH) **
Oogenesis and the Ovarian Cycle
Meiosis is completed after ovulation "only if sperm penetrates" Ovum is produced Two additional polar bodies are produced Once ovum is formed, the "23 chromosomes can be combined with those of the sperm to form the fertilized egg (zygote)" If the secondary oocyte "is not penetrated by a sperm, it dies" and does not complete meiosis to form an ovum
Important Male and Female Differences
Sex cell size and structure: ----sperm are tiny, motile, and equipped with nutrients in seminal fluid. ----egg is large, non-motile, and has nutrient reserves to nourish the embryo until implantation.
Uterine (menstrual) cycle
Cyclic changes of the endometrium "Regulated by" cyclic production of "estrogens and progesterone" "FSH and LH regulate the production of estrogens and progesterone" Both menstrual and ovarian cycles are about "28 days in length" "Ovulation" typically occurs about midway through cycle on "day 14"
Uterine (Menstrual) Cycle
Stages of the menstrual cycle Menstrual phase Proliferative stage Secretory stage
Stages of the menstrual cycle Menstrual phase Proliferative stage Secretory stage
"Days 6 to 14" Regeneration of functional layer of the endometrium "Estrogen levels rise" "Ovulation" occurs in the ovary at the end of this stage
Days 15 to 28 Levels of progesterone rise and increase the blood supply to the endometrium Endometrium increases in size and readies for implantation
"If fertilization does occur" Embryo produces a hormone that causes the corpus luteum to continue producing its hormones "If fertilization does NOT occur" "Corpus luteum degenerates" as LH blood levels decline
Produced by follicle cells Cause "secondary sex characteristics" Enlargement of accessory organs of the female reproductive system Development of breasts Appearance of axillary and pubic hair Increase in fat beneath the skin, particularly in hips and breasts Widening and lightening of the pelvis Onset of menses (menstrual cycle)
Produced by the corpus luteum Production continues until LH diminishes in the blood "Does not contribute to the appearance of secondary sex characteristics" Other major effects Helps "maintain pregnancy" "Prepare the breasts for milk production"
Anatomy of Mammary Glands
Areola—central pigmented area Nipple—protruding central area of areola Lobes—internal structures that radiate around nipple Lobules—located within each lobe and contain clusters of alveolar glands Alveolar glands—produce milk when a woman is lactating (producing milk) Lactiferous ducts—connect alveolar glands to nipple
X-ray examination that detects breast cancers too small to feel Recommended "every 2 years" for women between "40 and 49" years old "and yearly thereafter"
period of time from fertilization until week 8
week 9 until birth
Sperm are viable for 24 to 48 hours after ejaculation"
For "fertilization" to occur, "sexual intercourse must occur no more than 2 days before ovulation and no later than 24 hours after"
When sperm reach the oocyte, "enzymes break down the follicle cells" of the corona radiata around the oocyte Once a path is cleared, sperm undergo an "acrosomal reaction" (acrosomal membranes break down and enzymes "digest holes" in the oocyte membrane) "Membrane receptors on an oocyte pull in the head of the first sperm cell to make contact"
Mechanisms of Fertilization
Fertilization occurs when the genetic material of a sperm combines with that of an oocyte to form a zygote
First cell of a new individual The result of the "fusion of DNA" from sperm and egg The zygote begins rapid mitotic cell divisions The zygote stage is in the uterine tube, moving toward the uterus
"Rapid series of mitotic divisions" that begins with the zygote and ends with the blastocyst Zygote begins to "divide" 24 hours after fertilization "Three to 4 days after ovulation, the preembryo reaches the uterus and floats freely for 2 to 3 days" Late blastocyst stage—embryo implants in endometrium (day 7 after ovulation)
"The embryo enters the uterus" at the 16-cell state (called a morula) "about 3 days after ovulation"
"Uterine secretions are used for nourishment"
The Blastocyst (Chorionic Vesicle)
Secretes human chorionic gonadotropin (hCG) to induce the corpus luteum to continue producing hormones
The Blastocyst (Chorionic Vesicle)
Primary germ layers are eventually formed Ectoderm—outside layer Mesoderm—middle layer Endoderm—inside layer The late blastocyst implants in the wall of the uterus (by day 14)
fluid filled sac that surrounds the embryo
Blood vessel-containing stalk of tissue Attaches the embryo to the placenta
Functions of the Placenta
Forms a barrier between mother and embryo (blood is not exchanged) Delivers nutrients and oxygen Removes waste from embryonic blood Becomes an endocrine organ (produces hormones) and takes over for the corpus luteum (by end of second month) by producing Estrogen Progesterone Other hormones that maintain pregnancy
"All organ" systems are formed by the end of the "eighth week" Activities of the fetus are "growth and organ specialization"
Enlargement of the uterus Accentuated lumbar curvature (lordosis) Relaxation of the pelvic ligaments and pubic symphysis due to production of relaxin
Gastrointestinal system Morning sickness is common due to elevated progesterone and estrogens Heartburn is common because of organ crowding by the fetus Constipation is caused by declining motility of the digestive tract
Physiological changes (continue
Urinary system Kidneys have additional burden and produce more urine The uterus compresses the bladder, causing stress incontinence
Effects of Pregnancy on the Mother(physiological changes (continued)
Respiratory system Nasal mucosa becomes congested and swollen Vital capacity and respiratory rate increase Dyspnea (difficult breathing) occurs during later stages of pregnancy
Physiological changes (continued)
Cardiovascular system Blood volume increases by 25 to 40 percent Blood pressure and pulse increase Varicose veins are common
series of events that expel the infant from the uterus Rhythmic, expulsive contractions Operates by the positive feedback mechanism
Hicks contractions are weak, irregular uterine contractions
Initiation of labor :Estrogen" levels "rise" Uterine contractions begin The "placenta releases prostaglandins" "Oxytocin is released" by the pituitary Combination of these hormones oxytocin and prostaglandins produces "contractions"
Stages of Labo
"Dilation" Cervix becomes dilated Full dilation is "10 cm" Uterine "contractions" begin and increase "Cervix softens and effaces" (thins) The "amnion ruptures" ("breaking the water") Longest stage at 6 to 12 hours
Infant passes through the cervix and vagina Can last as long as 2 hours, but typically is 50 minutes in the first birth and 20 minutes in subsequent births "Normal" delivery is "head first (vertex position)" "Breech" presentation is "butt"ocks-first
"Delivery" of the "placenta" Usually accomplished "within 15 minutes" after birth of infant Afterbirth—placenta and attached fetal membranes "All placental fragments should be removed to avoid postpartum bleeding"
Gender is determined at fertilization
Males have "XY" sex chromosomes Females have "XX" sex chromosomes
"Testosterone" determines whether male or female structures will form
Developmental aspects of the reprodutive system
reproductive system organs do not function until puberty.
enlargement of testes and scrotum signals onset of puberty (often around age 13)
budding breasts signal puberty (often around age 11)
first menstrual period
a whole "year" has passed without menstruation. Ovaries stop functioning as endocrine organs Childbearing ability ends
Birth control pill
most used contraceptive.
Relatively constant supply of ovarian hormones from pill is similar to pregnancy Ovarian follicles do not mature, ovulation ceases, menstrual flow is reduced
Mornig-after pill (MAP)
Taken within 3 days of unprotected intercourse Disrupts normal hormonal signals to the point that fertilization is prevented
Other pills for contraception are:
Minepill (tablet) Norplant (rods placed under the skin)
Intrauterine device (IUD)
Plastic or metal device inserted into uterus "Prevents implantation of fertilized egg"
"Tubal ligation (females)"—cut or cauterize uterine tubes "Vasectomy (males)"—cut or cauterize the ductus deferens
withdrawa of penis prior to ejaculation
fertility awareness)—avoid intercourse during period of ovulation or fertility Record daily basal temperature (body temperature rises after ovulation) Record changes in pattern of salivary mucus