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Reproductive System

Birds and Bees

A & P/Reproductive System
Instructor: Jean Taylor

Homework: Complete the workbook exercises for chapter 26, pgs 209-213 (end coloring), 214-215 (end #15) (worth 113 points).
EXTRA CREDIT opportunity: complete the TERMS & OBJECTVES section at the beginning of each chapter 26. Write each objective out in complete sentences: listing, explaining and describing each objective. Worth 5 extra credit points.

Purpose of the reproductive system is to produce offspring.

Asexual – no partner is required for reproduction
Sexual – male and female are required for reproduction/ union of ova (23 chromosomes) and sperm (23 chromosomes)

Reproductive system produces, nurtures, and transports ova and sperm, and it secretes hormones.

Reproductive organs are called gonads. Gonads secrete hormones and they produce gametes.
• Female gonads are ovaries; gametes are ova (eggs)
• Male gonads are testes or testicles; gametes are sperm
• Secondary reproductive structures nourish and transport the ova and sperm and provide a safe and nourishing environment for fertilized eggs.

Male reproductive system
• Produces, nourishes, and transports sperm
• Deposits sperm within the female reproductive tract
• Secretes hormones

Testes
• Production of sperm
• Secretion of testosterone (male hormone)
• Testes develop within the abdominal cavity but descend into scrotum during last 2 months of fetal development. Two testes descend into the scrotum because of the temperature in the scrotum is lower than body temperature.
• Lobules – smaller unit of testis; contains seminiferous tubules and interstitial cells
o Seminiferous tubules form sperm
o Interstitial cells produce male hormones called androgens (testosterone)
• Sperm are formed by epithelium of seminiferous tubules. Millions of sperm/day are made
o Spermatogenic cells are sperm-producing cells
 Spermatogenesis is the formation of sperm
 Undifferentiated spermatogenic cells are called spermatogonia
 Each spermatogonium contains 46 chromosomes
 Spermatogonium influenced by testosterone enlarge and become primary spermatocytes
 Primary spermatocytes divide by meiosis, which reduces the number of chromosomes to 23
o Sertoli cells (sustentacular cells) support, nourish, and regulate spermatogenic cells
o
• Mature sperm have three parts
o Head
 Primarily a nucleus & contains genetic information
 Acrosome contains enzymes that help the sperm penetrate the egg at the time of fertilization
o Body
 Also called a midpiece, spiral-shaped structure that contains many mitochondria
 Supplies the sperm with energy needed for the “big swim”
o Tail
 Flagellum
 Whiplike movements enable the sperm to swim
• Sperm live up to 3 days; most only live a few hours after being deposited in female reproductive tract
Genital ducts – as the sperm form, they gather in the seminiferous tubules and then into genital ducts, where they mature and are transported from the testes to the outside of the body.
• Epididymis
o First part of the duct system
o About 20 feet in length
o Sits along top and posterior side of testis
o Sperm mature, become motile and fertile
o Walls of epididymis contract and push the sperm into the vas deferens
• Vas Deferens
o Ascends from epididymis as part of the spermatic cord through the inguinal canal
 Spermatic cord includes blood vessels, lymphatic vessels, nerves, muscles, and connective tissue
o Vas deferens continues through pelvic cavity, curves over the bladder and joins the duct of the seminal vesicle to form the ejaculatory duct
 There are 2 ejaculatory ducts
 Ejaculatory duct passes through the prostate gland and joins with urethra
• Urethra
o Extends from the base of the urinary bladder to the tip of the penis
o Male urethra serves reproductive and urinary systems
 Carries urine from the urinary bladder to the outside
 Carries semen from the ejaculatory ducts to the outside
 It only carries one at a time, never both urine and semen


ACCESSORY GLANDS
• Seminal Vesicles
o Yellowish secretion
o Contains fructose, vitamin C, and prostaglandins
o Nourish and activate sperm
• Prostate Gland
o Milky, alkaline substance
o Increases sperm motility
o Neutralizes acidic vaginal canal
o Smooth muscles of prostate contract and force secretions into urethra
• Bulbourethral Gland/Cowper’s Gland
o Secrete thick mucous into urethra
o Lubricant during sexual intercourse
SEMEN
• Mixture of sperm and secretions of accessory glands
• 60% of volume from seminal vesicles
• Alkaline pH
• Nourish sperm
• Aid in transport of sperm
• Lubricate reproductive tract
• Between 50-100 million sperm per ejaculation
EXTERNAL GENITALS
• Scrotum
• Penis
o Carries urine through the urethra to the outside of the body
o Organ of sexual intercourse/copulation
 Deposits sperm in the female reproductive tract
 Three columns of erectile tissue
 Enlarged tips called glans penis
 Loose skin covering called foreskin or prepuce
MALE SEXUAL RESPONSE
• Orgasm
o Occurs at height of sexual stimulation
o Accompanied by emission and ejaculation
Up – Erection – Parasympathetic Out- Emission - Sympathetic
• Emission
o Movement of sperm and glandular secretions from the testes and genital ducts into the proximal urethra
• Ejaculation
o Expulsion of semen from the urethra to the outside
Up – Erect – Parasympathetic Down – Flaccid – Sympathetic

MALE SEX HORMONES
• Testosterone
o Secreted by interstitial cells of the testes
o Small amount also secreted by adrenal cortex
o Between ages 10-13 secretions increase (puberty)
o Necessary for the production of sperm
o Responsible for primary sex characteristics
 Enlargement and development of the testes
 Increased growth of hair (face, axilla, pubic region)
 Deepening of the voice
 Thickening of the skin and increased activity of oil and sweat glands
 Increased musculoskeletal growth and development of male physique
• Hormonal control
o Controlled primarily by hormones in hypothalamus, anterior pituitary gland, and the testes
 Follicle-stimulating hormone (FSH)
• Promotes spermatogenesis by stimulating the spermatogenic cells to respond to testosterone
 Luteinizing hormone (LH) or Interstitial cell-stimulating hormone (ICSH)
• Promotes development of interstitial cells of the testes and the secretion of testosterone
• Negative feedback
o Regulates testosterone production (pg 461)

FEMALE REPRODUCTIVE SYSTEM
Produces eggs, secretes hormones, and nurtures and protects a developing baby during the 40 weeks of pregnancy.

OVARIES
• Female gonads
• 2 (one on left, one on right) almond shaped ovaries
• Located in pelvic cavity
• Anchored in place by ligaments
• Not directly attached to fallopian tubes
OVARIAN FOLLICLE
• Female born with 2 million follicles
• By puberty only 400,000 remain
• Only approximately 400 will fully mature
o Female usually produces one egg per month
o Puberty through menopause
• Each follicle consists of oocyte and follicular cells
OVULATION
• The process of a mature follicle bursting to release/eject the egg
• Egg (ovum) swept up by sweeping fimbriae of fallopian tubes
• After egg has been discharged, follicular cells that remain in the ovary develop into corpus luteum
o Corpus luteum secretes two hormones
 Large amounts of progesterone
 Smaller amounts of estrogen
o If fertilization does not occur, corpus luteum becomes corpus albicans
OVARIAN HORMONES
• Estrogen
o Follicular cells of maturing follicles secrete estrogen
o Promotes maturation of egg
o Helps develop secondary sex characteristics
 Enlargement and development of the organs of the female reproductive system
 Enlargement and development of breasts
 Deposition of fat beneath the skin, especially in thighs, buttocks, and breasts
 Widening of pelvis
 Onset of menstrual cycle
 Closure of epiphyseal discs in long bones
• Progesterone
o Corpus luteum secretes progesterone
o Establishes menstrual cycle
o Maintains pregnancy
o Prepares breasts for milk production after pregnancy
GENITAL TRACT
Fallopian Tubes
• Also called oviducts or uterine tubes
• Extends from uterus to ovaries
• Fingerlike projections called fimbriae
o Sweep the egg from the surface of the ovary into the fallopian tube
• Functions:
o Transports the egg from the ovary to the uterus
o Site of fertilization of the egg by the sperm
Uterus
• Also called the womb
• Held in place by the broad ligament
• Primary function is to provide a safe and nurturing environment for the growing baby
• Three parts:
o Fundus is upper dome-shaped region above the entrance of the fallopian tubes
o Body is the central region
o Cervix is the lower narrow region that opens into the vagina
• Three layers
o Epimetrium or perimetrium – outer serosal layer
o Myometrium – smooth muscular layer
o Endometrium – inner layer
 Endometrial lining has two layers
• Basilar layer – thin and vascular, next to myometrium
• Functional layer – the layer that sloughs in menstruation or thickens to prepare for the fertilized egg (implantation)
Vagina
• Also called the birth canal
• Muscular tube that extends from the cervix to the vaginal opening in the perineum
• Covered by thin membrane called hymen
• Contains rugae that are capable of expanding to accommodate the baby during birth
• The organ that receives the penis during intercourse and serves as an exit for menstrual blood
EXTERNAL GENITALS/Vulva
Labia
• Labia majora are two folds of hair-covered skin that lie external to the two smaller labia minora
• Labia means “lips”
• Prevent drying of the mucous membranes
• Labia majora form area over the symphysis called the mons pubis
Clitoris
• Structure that resembles the penis
• Contains erectile tissue
• Capped by thin membrane called the glans
• Contains sensory receptors
Vestibule
• Contains openings of the urethra and the vagina
• Bartholin’s glands (or vestibular glands)
o Are on either side of the vaginal opening
o Secrete mucus-containing substance that moistens and lubricate the vestibule
Perineum
• Refers to entire pelvic floor
• Often times referred to as area between vaginal opening and the anus

FEMALE SEXUAL RESPONSE
• Females respond to sexual stimulation with erection and orgasm.
o Erectile tissue in the clitoris and surrounding tissue swell with blood in response to parasympathetic
o Vaginal mucosa, breasts and nipples also swell

HORMONAL CONTROL OF REPRODUCTIVE CYCLES – pg 467, Table 26-1

REPRODUCTIVE CYCLES (pgs 466-468)
• Ovarian cycle
o Follicular phase
o Luteal phase
• Uterine cycle/menstrual cycle
o Menstrual phase
 Days 1-6
o Proliferative phase
 Days 7-13
o Secretory phase
 Days 14-28
Menarche – the first period of menstrual bleeding that occurs during puberty
Menses – regularly occurring menses after menarche and into age 40-50
Menopause – cessation of menses

Birth Control
• Barrier method
o Prevents sperm from entering the female
• Hormonal contraceptives/BCP
o Prevents ovulation using estrogen and/or progesterone
• Surgical methods
o Vasectomy (male)
o Tubal ligation (female)
• Intrauterine devices
o Stimulates uterus to prevent implantation of the fertilized egg
• Behavioral
o Abstinence – most effective method of birth control – avoid sexual intercourse
o Rhythm method &/or coitus intercourse
 Rhythm - Avoid intercourse during ovulation (mid cycle)
 Coitus – Withdrawal of the penis from the vagina before ejaculation
• Emergency Contraception
o Preven
 Contains progesterone and estrogen to prevent ovulation
 Inhibits implantation in the event that fertilization occurs
o RU-486/mifepristone
 Cause the loss of the implanted embryo by blocking progesterone receptiors in the endometrium
 Endometrium sloughs, along with embryo
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