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Anatomical Model

Anatomy & Physiology: Week Nine

Chapter 26: Reproductive System

Reproductive Systems

Functions

  • Produce, nurture, and transport ova and sperm

  • Secrete hormones

Primary reproductive organs

  • Gonads

          •Male: Testes

          •Female: Ovaries

  • Gametes

          •Male: Sperm

          •Female: Ova (eggs)

Male Reproductive System: Roles

  • Produce, nourish, and transport sperm

  • Deposit sperm within the female reproductive tract

  • Secrete hormones

Male Reproductive System: Structures

  • Testes

  • Genital ducts

  • Accessory glands

  • External genitals

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 Click to label the Male Repro System

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Testes or Testicles

Scrotum

  • Lower temperature

Lobules

  • Seminiferous tubules produce sperm

  • Interstitial cells secrete testosterone

Spermatogenesis and Meiosis

  • Spermatogonia mature into spermatocytes

  • Meiosis divides spermatocytes

            46 chromosomes → 23 chromosomes

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Parts of a Sperm

  • Head: Primarily a nucleus

  • Acrosome: Contains enzymes for fertilization

  • Body: Mitochondria

  • Tail: Flagellum

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Genital Ducts: Pathway

  • Sperm mature and gather nutrients and volume moving from testes to urethra

  • Epididymis (2)

  • Vas deferens (2)

  • Ejaculatory ducts (2)

  • Urethra (1)

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Accessory Glands: Volume and Nutrients

  • Seminal vesicles - 60% of semen’s volume

  • Prostate gland - Around upper urethra

  • Bulbourethral glands

  • Glandular secretions mix with sperm to form semen

External Genitals

  • Scrotum contains the testes

  • Penis, organ of copulation (intercourse)

          - Shaft contains erectile tissue

          - Glans penis

          - Urinary meatus, located in center of glans

          - Prepuce, foreskin or covering for glans

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     Click on the pdf
      for a printable                   male reproductive
     system diagram

Female Reproductive System: Roles

  • Produce eggs

  • Secrete hormones

  • Nurture and protect a developing baby during 9 months of pregnancy

Ovaries: Function

  • Meiosis: Reduces chromosomes from 46 to 23

  • FSH: Ovum becomes graafian follicle

  • LH: Ovulation - extruded ovum swept into fallopian tube, follicular cells become corpus luteum

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Ovarian Hormones: Estrogen

  • Promotes maturation of the eggs

  • Makes a female look female: Secondary sex characteristics

          - Maturation of reproductive organs, breasts

          - Characteristic fat distribution

          - Widening of the pelvis

          - Menstruation

          - Closure of epiphyseal discs in long bones

Ovarian Hormones: Progesterone

  • Works with estrogen to establish the menstrual cycle

  • Helps maintain pregnancy

  • Prepares the breasts for milk production after pregnancy

Genital Tract

  • Fallopian tubes

  • Uterus

  • Vagina

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Fallopian Tubes: Oviducts

  • Fimbrae: Sweep ova into tubes, not attached to ovary

  • Site of fertilization

  • Carry ovum to uterus

Tube Troubles

  • Ectopic pregnancy

          - Fertilized ovum implants in tube

  • Scarring and blockage of fallopian tubes

          - Often caused by repeated STDs

          - Major cause of infertility

  • Pelvic inflammatory disease (PID)

          - Genital tract opens directly into sterile pelvic cavity

Uterus: Parts, Layers, and Connections

  • Parts: Fundus, body, cervix

  • Layers: Endometrium, myometrium, perimetrium

  • Connections: Vagina and fallopian tubes

External Genitalia: Vulva

  • Components: Labia majora, labia minora, mons pubis, clitoris, vestibule

  • Also visible: Urethra, opening of Bartholin’s glands, perineum, vagina

fem3.jpg

 Click to label the Female Repro System

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fem4.png

     Click on the pdf
      for a printable                female reproductive
     system diagram

Hormonal Control of the Reproductive Cycles

  • A number of hormones control the female reproductive cycle

  • Unlike male hormones, female hormonal secretion occurs in a monthly cycle

          - A regular pattern of increases and decreases in hormone levels

Female Reproductive Cycles

  • Purpose: To mature an egg monthly for fertilization

  • Two cycles work together

          - Ovarian

          - Uterine

  • Typical cycle: 28 days

Ovarian Cycle: Follicular Phase

  • Gonadotropins: FSH, LH

  • FSH triggers maturation of follicle, ovum

  • Follicle secretes estrogen

  • Estrogen nourishes ovum, uterine lining

  • Midcycle surge of LH: Ovulation

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Ovarian Cycle: Luteal Phase

  • Corpus luteum secretes progesterone

  • Progesterone enriches uterine lining

  • Luteal phase progresses differently in the pregnant or nonpregnant state

Uterine Cycle: Phases

  • Menstrual: Endometrial lining is shed

  • Proliferative: Estrogen thickens uterine lining

  • Secretory: Progesterone enriches endometrium

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Corpus Luteum: Dead or Alive?

Dead

  • Without fertilized ovum, corpus luteum → corpus albicans (dead)

  • Plasma levels of ovarian hormones decline

  • Without hormonal support, uterine lining sloughs off

Alive

  • Fertilized ovum secretes human chorionic gonadotropin (hCG)

  • hCG sustains corpus luteum

  • Hormones persist and maintain uterine lining

Summary: Reproductive Cycles

Nonpregnant

  • Corpus luteum: Dead

  • Uterine lining loses hormonal support and sloughs off (the period)

  • Cycle starts again as declining ovarian hormones trigger FSH

Pregnant

  • Corpus luteum: Alive

  • Secretes progesterone and estrogen

  • Hormones sustain endometrium

  • Early embryo implants in endometrium (uterus)

Female Reproductive Terms

Menarche

  • First period of menstrual bleeding during puberty

Menses

  • Menstrual period

Menopause

  • Decrease in ovarian hormones

  • Menstrual periods decrease, eventually cease

  • Other systemic effects

Female Breast and Lactation

Mammary glands

  • 15-20 lobes

Alveolar glands

  • Located in lobes

  • Secrete colostrum and milk into lactiferous ducts

Nipple and areola

Suspensory ligaments

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