Download Reproductive System Notes

Reproductive System Notes
The Reproductive System
Common Structural and Functional Characteristics Between the Sexes
• Commonalities between the systems in both sexes
• Systems adapted for development of sperm or ova followed by successful
fertilization, development, and birth of offspring
• Sex hormones important in development of secondary sexual characteristics and
normal reproductive system activity
Male Reproductive System
• Essential organs of reproduction –
• gonads (testes) - produce sex cells (sperm)
• Accessory organs of reproduction
• Ducts—passageways that carry sperm from testes to exterior
• Sex glands—produce protective and nutrient solution for sperm
• External genitals
• Testes—male gonads
• in scrotum—lower temperature
• covered by tunica albuginea - divides testis into lobules containing
seminiferous tubules
• interstitial cells - produce testosterone
• Functions
• Spermatogenesis - sperm production
• Spermatogonia - sperm precursor cells
• Meiosis produces primary spermatocyte - forms four spermatids
with 23 chromosomes
o Spermatozoa—highly specialized cells
o Heads - genetic material
o Acrosomes - enzymes to assist in penetration of ovum
o Mitochondria - energy for movement
o Production of testosterone by interstitial cells
o Testosterone “masculinizes” and promotes development of
male accessory organs
o Stimulates protein anabolism and development of muscle
strength
• Reproductive ducts— sperm pass through, after exiting testes, until they exit from
the body
 Epididymis—single, coiled tube about 6 m in length
 lies along the top and behind the testis in the scrotum
 sperm mature and develop the capacity for mobility
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Ductus (vas) deferens—
 sperm from the epididymis
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transports sperm from scrotal sac through the abdominal cavity
Passes through inguinal canal
Joins duct of seminal vesicle to form the ejaculatory duct
• Accessory or supportive sex glands
 Semen - sperm and secretions of accessory sex glands
• averages 3 to 5 ml per ejaculation
• each milliliter contains about 100 million sperm
 Seminal vesicles
• Pouchlike glands – produce about 60% of seminal volume
• Secretion is yellowish, thick, and rich in fructose for sperm
mobility
• Prostate gland
• Shaped like a doughnut and located below bladder
• Urethra passes through the gland
• Secretion 30% of seminal fluid - thin and milk colored
• Activates sperm and is needed for ongoing sperm mobility
• Bulbourethral (Cowper’s) glands
 Resemble peas in size and shape
 Secrete mucous-like fluid (less than 5% of seminal fluid)
• External genitals
 Genitalia - penis and scrotum
 Penis has three columns of erectile tissue:
• Corpora cavernosa - 2 dorsal columns
• Corpus spongiosum - ventral column surrounding the urethra
• Glans penis - covered by foreskin
 Circumcision - surgical removal of foreskin
 Essential organs –
• female gonads – ovaries
• produce sex cells - ova
 Accessory organs:
• Ducts or modified ducts— oviducts, uterus, and vagina
• Sex glands—including those in the breasts
• External genitals
Female Reproductive System
• Ovaries
 Structure and location
• Paired glands weighing about 3 g each
• Resemble large almonds
• Attached to ligaments in pelvic cavity on each side of uterus
• Microscopic structure
 Ovarian follicles—contain oocyte (immature sex cell)
 Primary follicles—covered with granulosa cells
 Graafian follicles – mature, ovulating, follicles
 Secondary follicles - have a hollow chamber called the antrum
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Corpus luteum forms after ovulation
Functions
• Oogenesis— meiotic cell division produces daughter cells with
equal chromosome numbers (23) but unequal cytoplasm
• Ovum is large
• polar bodies are small,degenerate
• Produce estrogen and progesterone
• Granulosa cells of oocyte in mature and growing follicles
produce estrogen
• Estrogen - development and maintenance of
secondary sex characteristics
• Corpus luteum produces progesterone
• Progesterone - stimulates secretory activity of
uterine epithelium and assists estrogen in initiating
menses
• Reproductive ducts
 Uterine (fallopian) tubes
• Extend about 10 cm from uterus into abdominal cavity
• Expanded distal end surrounded by fimbriae (“fingers”)
• Mucosal lining continuous with lining of abdominal cavity
 Uterus—composed of body, fundus, and cervix
• In pelvic cavity, behind urinary bladder
• Myometrium - muscle layer
• Endometrium - lost in menstruation
• Menopause—end of repetitive menstrual cycles (about 45 to 50
years of age)
 Vagina
• Distensible tube about 10 cm long
• Between urinary bladder and rectum in pelvis
• Receives penis during sexual intercourse
• Birth canal for normal delivery of baby
• Accessory, or supportive, sex glands
 Bartholin’s (greater vestibular) glands
• Secrete mucous-like lubricating fluid
• Ducts open between labia minora
• External genitals
 Include mons pubis, clitoris, orifice of urethra, Bartholin’s glands, vagina,
labia minora and majora, and hymen
 Perineum—area between vaginal opening and anus
 Episiotomy - surgical cut during birth
 Breasts
 Over pectoral muscles
 Size determined by fat quantity
 Lactiferous ducts drain at nipple
• Menstrual cycle—involves many changes in the uterus, ovaries, vagina, and
breasts
• Length—about 28 days
 Phases
 Menses:
• first 4 or 5 days
• sloughing of bits of endometrium (uterine lining) with
bleeding
• Proliferative phase:
 days between the end of menses and secretory phase
 shorter cycle = shorter proliferative phase
 in 28-day cycle, proliferative phase ends on day 13
 repair of endometrium
• Secretory phase:
 between ovulation and next menses
 about 14 days before next menses
 thickening of endometrium
 secretion by glands in preparation for implantation of fertilized ovum
 FSH and LH cause ovulation
Role of Pituitary in Menstruation
 Anterior pituitary:
 secretes FSH
 Ovarian follicles start growing and secrete estrogen
 Secretes LH
 Follicle matures and ovulation occurs
 Leutinization of corpus luteum
 Decrease in estrogens and progesterones bring on menstruation
Summary of Male and Female Reproductive Systems
 The male organs produce, store, and introduce mature sperm into the female
reproductive tract
• The female system produces ova, receives the sperm, and permits fertilization
• This is followed by fetal development, birth, and lactation afterward
• Sex hormones are required for development of secondary sex characteristics and
for normal reproductive functions in both sexes