Post on 12-Jan-2016
Chapter 19Reproductive System
Anatomy
Male Reproductive System
Introduction• Primary Sex Organs
– Gonads• Testes – male
– Produce sperm – male gamete (sex cell) – exocrine function
– Produce testosterone – male hormone – endocrine function
• Ovaries – female– Produce Ova/egg – female gamete (sex
cell)– Produce estrogen – female hormone
• Accessory Sex Organs– Remaining sex organs
Sex Hormones
• Testosterone/Estrogen• For the development and functioning of the
reproductive organs• For growth and development of other organs
and tissues of the body
Male Reproductive Organs Figure 19.1
• Scrotum– Fleshy pouch divided into two chambers each
housing a testis (male gonads)– Extends outside of the body posterior to base of
penis– Superficial dartos smooth muscle which wrinkles
the scrotal surface– Deeper skeletal muscle – cremaster
• Contracts to pull testes closer to the body• Sperm need to be cooler than body
temperature
Testis Appearance
• Olive-size• Covered by capsule – tunica albuginea
– Capsule extends in dividing testis into lobules
• Lobules contain tightly coiled seminiferous tubules– Sperm producing factories– Empty sperm into rete testis which empty
into the epididymis
• Interstitial Cells– Surrounding the seminiferous tubules– Produce testosterone – male reproductive
hormone• Duct System
– Accessory male organs – Transports sperm from the testes through
the penis– Epididymis, ductus (vas) deferens,
ejaculatory duct, urethra
Male Reproductive Tract
• Epididymis• Appearance
– Tightly coiled threadlike tube; 20 feet long• Location
– On top of the testis, descends along the posterior surface
– Epididymis becomes the ductus/vas deferens as it turns up towards the body
Function
• Passageway for sperm to the ductus/vas deferens• 2 week journey
– Immature sperm and non-motile – Allows time for sperm to mature
• Contains cells to reabsorb cellular debris from abnormal or damaged sperm
• Contains cells to absorb nutrients from blood• Secretes a substance which prevents premature
capicitation– Becoming motile and fully functional– Requires secretion from seminal glands and
acidic conditions inside female tract
Ductus (Vas) Deferens• Appearance
– Long, winding tube• Location
– Continuation of the epididymis– Passes thru the inguinal canal into the abdominal
cavity – Arches over the urinary bladder– Enclosed with nerves and blood vessels in
connective tissue forming the spermatic cord– Peristaltic contractions empties sperm into the
ejaculatory duct which passes through the prostate gland
• Function– Store sperm for several months– Transport sperm from to ejaculatory duct
• Vasectomy– Small incision into the scrotum cutting
through the part of the vas deferens in the scrotum
– Sperm are still produced but can no long be expelled out of the body
Ejaculatory DuctFigure 19-5
• Junction of ductus deferens with duct from seminal vesicle
• Extends about 1 inch into the prostate gland• Empties sperm into the prostatic urethra
Urethra• Location
– Extends from the base of the urinary bladder to the tip of the penis
– Last part of the duct system• Regions
– Prostatic urethra• Passes through the prostrate gland• Contains the internal urethral sphincter
– Membranous urethra • Passes through the muscles of the pelvic floor• Contains external urethral sphincter
– Penile urethra • Passes through the length of the penis
Urethral Function
• Carries both urine and semen• Semen
– Sperm and fluids from the accessory glands
• Semen and urine never pass at the same time– During ejaculation, the internal urinary
sphincter contracts preventing passage of sperm to bladder and passage of urine to urethra
Accessory Glands • Produce seminal fluid
– Seminal vesicles– Prostate gland– Bulbourethral glands
• Functions– Contribute fluids of semen – seminal fluids – Nutrients for motility– Activate the sperm– Peristalsis of sperm and fluids– Produce buffers against acidity of urethra
and vagina
Seminal Vesicle
• Paired tubular glands which attach to the vas deferens at the base of the urinary bladder
• Secretes the major portion of the seminal fluid (60%)– Thick, yellowish secretion– Fructose - sugar - energy for the sperm motility– Prostaglandins for peristalsis in male and
female tract– Fibrinogen – forming a temporary clot of semen
in vagina after ejaculation• Alkaline secretion to neutralize acids• Secretion causes sperm to become motile
Prostate Gland• Appearance
– Single gland; chestnut shape– Ejaculatory duct passes through
• Location– Surrounds the prostatic urethra
• Function– Secretes prostatic fluid – 30% of seminal fluid
• Thin, milky, alkaline fluid• Contains an antibiotic that may help prevent
urinary tract infections in males– Secretion is released into the urethra
Bulbourethral Glands• Location
– Inferior to the prostate gland • Appearance
– Very small pea-sized gland • Function
– Secretes a clear, thick, sticky, alkaline mucous fluid • Lubricates the penis for sexual
intercourse• Cleanse the urethra of traces of acidic
urine
Penis Figure 19-6
• Tubular organ, contains penile urethra• Three regions
– Root• Attaches penis to body wall
– Body/shaft • Contains erectile tissue to deliver the
sperm to the female vagina• Spongy tissue that fills with blood
causing the penis to enlarge and become rigid – Erection
• Glans – Expanded distal end surrounding opening
• External urethral meatus– Covered by loose skin
• Prepuce (foreskin)• Removed by circumcision
Chapter 19The Reproductive System
AnatomyFemale Reproductive
System
Female Reproductive System
• Functions– Produce the female gametes (ova)– Nurture and protect the developing fetus– Produce female sex hormones
• Primary reproductive organ – Gonad– Ovaries
• Exocrine function – produce eggs/ova• Endocrine function – produce hormones
– Estrogens, progesterone
Ovary Figure 19-8
• Appearance– Paired, almond shaped organs– Pale white or yellowish color– Nodular consistency resembling lumpy oatmeal
• Location– Suspended by ligaments in the pelvic cavity
• Broad ligament; Ovarian ligament• Nourishment/removal of waste
– Ovarian artery and vein• Function
– Development of egg cells to maturation• About 3 months
Uterine Tubes/Fallopian Tubes Figure 19-11
• Location
– Extend from the ovaries to the uterus
• Appearance
– Muscular tube lined with cilia
– Expands near ovaries to form funnel shaped structure – infundibulum containing finger-like projections called fimbriae
– Does not make physical contact with the ovaries
– Fimbriae contain cilia that beat toward the tube forming currents with move the ovum into the tube
• Function– Receive the ovulated egg
• Depends on movements of the cilia of fimbriae• Some eggs are lost in the peritoneal cavity
and might even be fertilized there• If fertilization is to occur, the secondary oocyte
must meet the sperm in 12 – 24 hours• Unfertilized oocytes will degenerate
– Carry egg (zygote if fertilization occurred) to the uterus
• Muscular walls for peristalsis • Rhythmic beating of cilia in uterine tubes
Uterus• Appearance
– Hollow, muscular organ– Shape of an inverted pear
• Fundus, body, cervix– Cervix - Lower 1/3 of the uterus projecting
into the vagina• Location
– Between urinary bladder and rectum– Superior to the vagina usually bent forward over
the urinary bladder– Held in place in the pelvic cavity by ligaments
• Broad ligament
• Function– Implantation
• Attachment of embryo• Site of embryo development
– Prepares each month for zygote• If no fertilization, menstruation occurs
Tissue Layers of Uterus• Endometrium
– Inner mucus lining• Two layers • Superficial functional layer
– Undergoes changes due to sex hormone levels
• Deeper basilar layer– Reponsible for reforming the functional
layer monthly– Embryo burrows into this lining – implantation– Sloughs off about every 28 days if fertilization
does not occur
• Myometrium– Thick muscular layer– Contracts during childbirth
• Perimetrium– Outer layer– Visceral peritoneum
Vagina• Appearance
– Elastic, muscular tube; 3-4 inches long– Opening is the vaginal orifice covered by the
hymen– Contains resident bacterial supported by
nutrients in mucus of vagina• pH is 3.5 – 4.5 restricts growth of pathogens
• Location– Extends from the uterus to the outside– Posterior to the bladder/Anterior to the rectum
• Functions– Transports uterine secretions– Transports the fetus during childbirth –
birth canal– Receives the penis during intercourse
External Genitalia Figure 19-12
• Female reproductive structures external to the vagina
• Also called the Vulva– Mon pubis, labia, clitoris, vestibular glands
• Mons pubis– Fatty rounded area over the pubic
symphysis– Covered with pubic hair after puberty
• Labia – Labia majora
• Hair covered skin folds– Labia minora
• Located between the labia majora• Hairless
• Clitoris– Small projection at anterior end of vulva– Corresponding to penis of the male
• Hooded by the prepuce• Contains erectile tissue which becomes
swollen with blood during sexual excitement
• Vestibular glands– Produce mucus– Lubricates distal end of vagina during
intercourse
Mammary Glands Figure 19-13
• Glands of the breast secreting milk in a process called lactation
• Breast is divided into lobes each containing ducts which converge to a single lactiferous duct
• Near the nipple, the lactiferous ducts expands into the lactiferous sinus– Open onto surface of the nipple
• Nipple surrounded by reddish-brown tissue called areola containing sebaceous glands
• Breast is connected to chest muscle wall by suspensory ligaments
Chapter 19Reproductive System
Physiology of the Reproductive System
Human Life Cycle Figure 16.4
• Somatic body cells contain 46 chromosomes – diploid number or 2n
• Sex cells – gametes – haploid number or n– Sperm cell – 23 chromosomes– Egg cell – 23 chromosomes
• Fertilization– Union of sperm and egg produces a zygote
with 46 chromosomes– Half the characteristics from male sex cell– Half the characteristics from female sex cell
Meiosis
• Special type of division which occurs in gonads – ovaries, testes
• Production of gametes with n number of chromosomes
• Reduces the diploid number of chromosomes to the haploid number
• Oogenesis – Production of the female sex cells – ova
• Spermatogenesis – Production of the male sex cells - spermatozoa
Meiosis
• Consists of two successive divisions of the nucleus– Meiosis I and Meiosis II– Each division is divided into stages
• Prophase, metaphase, anaphase, telophase• Results in 4 daughter cells (gametes) instead of 2• A way to reduce the number of chromosomes in
half
Spermatogenesis Figure 19-3
• Sperm production• 3 processes
– Mitosis• Stem cells – spermatogonia • Beings during puberty and continues throughout
life• Millions of sperm produced daily• Occurs in the seminiferous tubules• One daughter cell remains in seminiferous tubule;
the other is pushed into the lumen– Primary Spermatocyte
Meiosis I
• Meiosis I– Chromosomes replicate– Homologous pairs – maternal and paternal come
together in a process called synapsis• 4 chromosomes called a tetrad• Crossing over of genetic information may occur
– At the end of meiosis I daughter cells receive both copies of either the maternal chromosome or the paternal chromosome from each tetrad
– Forms the secondary spermatocytes
Meiosis II
• Each secondary spermatocyte contains 23 chromosomes but each consists of 2 chromatids
• Duplicate chromatids will separate in meiosis II
• Forms the spermatids– Each with 23 single chromosomes– n number of chromosomes
Spermiogenesis Figure 16.5b
• Process of the last stage of sperm development– Excess cytoplasm is sloughed off– Sperm is compacted into three regions –
head, midpiece and tail– Tail – flagella develops
Mature Sperm Figure 19-4
• Head
– Nucleus containing DNA – 23 chromosomes
– Covered with an acrosome
• Similar to a large lysosome
• In close contact with the oocyte the acrosomal membrane breaks down and releases enzymes that help the sperm penetrate through the follicle cells surrounding the oocyte
• Midpiece– Contains centrioles which contain filaments that
form the flagella– Filaments are covered by mitochondria providing
he energy for movements of the flagella• Tail
– Flagella• Only example of a flagellum in humans
– Enable sperm to move long distances in a short time
Hormones
• FSH stimulates the seminiferous tubules to produce sperm• LH luteinizing hormone/ISCH interstitial cell stimulating
hormone
– Testosterone Production– Function of the interstitial cells in seminiferous tubules
• Testosterone– Stimulates reproductive organs to develop – Functions in the sex drive– Causes the secondary male sex characteristics to appear
Male Secondary Sex Characteristics
• Deepening of voice due to enlargement of larynx
• Increased hair growth all over the body• Axillary regions
– Pubic regions– Face
• Enlargement of skeletal muscles• Thickening of bones
Oogenesis Figure 19-9
• Process of production of female gametes – ova
• Total number of eggs a female can release is determined by the time she is born
• Release of eggs begins during puberty and ends in her 50’s or earlier
• Menopause – gradual decline and end to a woman’s ability to reproduce
• Oogonia – female stem cells– Somatic cells containing the 2n number of
chromosomes• These cells are located in the periphery of the
ovary• These cells go through mitosis in the female
FETUS• Daughter cells are called primary oocytes – in
prophase I of meiosis– Primary ooctye is pushed into the ovary connective
tissue and is surrounded by follicle cells
• At birth all the cells are primary oocytes – Oogonia no longer exist– This the females’ life supply of eggs
approximately 2 million– Waiting to undergo meiosis and produce
functional eggs• Remain at this point until puberty
Meiosis
• Production of 4 daughter cells but the cytoplasm is not evenly distributed– One functional ovum with cytoplasm– 3 nonfunctional polar bodies which
disintegrate• Ovary releases a secondary oocyte not a
mature ovum– Meiosis II does not occur producing a
mature ovum unless fertilization occurs
Puberty• Ovarian cycle
– Cyclic changes that monthly in the ovary– Results in one of these oocytes ovulating each
month• Female has approximately 40 years of reproductive
life: age 11 – 51• Typically one ovulation per month• Fewer than 500 ooctyes are actually released
Ovarian Cycle Figure 19-10
• Step 1 Formation of primary follicles– Formation of follicle cells around the
primary oocyte• Step 2 Formation of secondary follicles
– At puberty pituitary gland secretes FSH, follicle stimulating hormone
– FSH stimulates a small number of primary oocytes to grow and mature each month
• Step 3 Formation of mature Graafian follicle– Up until this time the primary oocyte has
been suspended in meiosis I prophase– At this time LH luteinizing hormone
causes the primary oocyte to complete meiosis I
– Produces one daughter cell (secondary oocyte) and one polar body
– Secondary oocyte begins Meiosis II
• Step 4 Ovulation– Egg is released– Meiosis II is completed only occurs if
fertilization occurs– Otherwise the secondary oocyte
deteriorates and is removed from the body in the menstrual flow
• If fertilization occurs– Secondary oocyte divides into a second
polar body and an ovum– Second polar body deteriorates and dies
quickly• The fertilized ovum moves into the uterus
and attempts to embed itself• The ovum has the n number of
chromosomes
• Step 5 Formation and degeneration of corpus luteum– After ovulation, the empty follicle collapses and
the follicular cells multiply to produce an endocrine gland called the corpus luteum which secretes estrogen
• This secretion will continue for about 10 days and then stop if fertilization does not occur
• If fertilization does occur it will continue to secrete estrogen until the placenta develops to take over the secretion
Uterine/Menstrual Cycle
• Cyclic changes that the endometrium of the uterus undergoes– Response to changing levels of ovarian
hormone in the blood• Female cycle is about 28 days
– Ovulation generally occurs midway about day 14
Menses
• Day 1 – 5– Functional layer of endometrium is
detaching from the uterine wall– Bleeding occurs from 3 – 5 days– Detached tissues and blood pass through
the vagina as menstrual flow - menstruation
– Day 5 ovarian follicles are beginning to produce estrogen
Proliferative Stage
• Day 6 – 14– Basal layer of uterus regenerates the
functional layer– Endometrial blood supply is increased– Glands are formed– Endometrium thickens and becomes well
vascularized– Ovulation occurs
Secretory Stage
• Day 15 – 28• Corpus luteum producing progesterone and
estrogen– Increased blood supply in endometrium– Glands secrete nutrients into the uterine
cavity• Will sustain a developing embryo until it
has implanted
• If fertilization does not occur the corpus luteum will stop secreting hormones– Blood vessels in functional layer will go
into spasms and kink– Endometrial cells deprived of oxygen and
nutrients will begin to die leading to the menstrual phase
Secondary Sex Characteristics
• Caused by estrogen secretion• Enlargement of accessory female reproductive
organs – uterine tubes, uterus, vagina, external genitals
• Development of breasts• Appearance of axillary and pubic hair• Increased fat deposits in skin especially in abdomen
and hips• Widening and lightening of pelvis• Onset of menses