Chapter 19 Reproductive System

1
Chapter 19Reproductive System

• Anatomy
• Male Reproductive System

2
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

3
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

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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

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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

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• 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

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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

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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

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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

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• 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

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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

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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

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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

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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

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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

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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

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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

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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

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• Glans
• Expanded distal end surrounding opening
• External urethral meatus
• Covered by loose skin
• Prepuce (foreskin)
• Removed by circumcision

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Chapter 19The Reproductive System

• Anatomy
• Female Reproductive System

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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

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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

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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

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• 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

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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

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• Function
• Implantation
• Attachment of embryo
• Site of embryo development
• Prepares each month for zygote
• If no fertilization, menstruation occurs

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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

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• Myometrium
• Thick muscular layer
• Contracts during childbirth
• Perimetrium
• Outer layer
• Visceral peritoneum

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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

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• Functions
• Transports uterine secretions
• Transports the fetus during childbirth birth
  canal
• Receives the penis during intercourse

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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

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• 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

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• Vestibular glands
• Produce mucus
• Lubricates distal end of vagina during
  intercourse

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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

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Chapter 19Reproductive System

• Physiology of the Reproductive System

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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

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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

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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

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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

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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

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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

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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

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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

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• 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

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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

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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

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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 50s or earlier
• Menopause gradual decline and end to a womans
  ability to reproduce

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• 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

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• 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

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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

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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

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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

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• 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

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• 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

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• 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

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• 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

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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

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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

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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

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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

61

• 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

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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