Download - Chapter 026
The Human Body in Health and Illness, 4th edition
Barbara Herlihy
Chapter 26:Reproductive Systems
1
Lesson 26-1 Objectives
• List the structures and functions of the male and female reproductive systems.
• Describe the structure and function of the testes.
• Describe the structure and function of the male genital ducts.
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Lesson 26-1 Objectives (cont’d.)
• Describe the accessory glands that add secretions to the semen.
• Describe the hormonal control of male reproduction, including the effects of testosterone.
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Reproductive Systems
Functions– Produce, nurture, and transport ova and sperm– Secrete hormones
Primary Reproductive Organs
Gonads Gametes Male: Testes Sperm Female: Ovaries Ova (eggs)
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Male Reproductive System: Roles
• Produce, nourish, and transport sperm
• Deposit sperm within the female reproductive tract
• Secrete hormones
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Male Reproductive Structures
• Testes
• Genital ducts
• Accessory glands
• External genitals
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Testes or Testicles
• Scrotum– Lower temperature
• Cremaster muscle• Lobules
– Seminiferous tubules produce sperm.
– Interstitial cells secrete testosterone.
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Spermatogenesis and Meiosis
• Spermatogonia mature into spermatocytes.• Meiosis divides spermatocytes. 46 chromosomes 23 chromosomes
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Parts of the Sperm
• Head: Primarily a nucleus• Acrosome: Contains enzymes for fertilization• Body: Mitochondria (ATP)• 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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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.
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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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Male Sexual Response
• Erection: Blood engorges erectile tissue• Emission: Movement of semen from genital
ducts into proximal urethra• Ejaculation: Expulsion of semen from urethra • Orgasm: Pleasurable sensations at height of
sexual stimulation• Sexual response is under autonomic control
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Effects of Testosterone
• Sperm development• Primary sex characteristics
– Maturation, enlargement of penis and testes
• Secondary sex characteristics– Hair growth increases, distribution changes– Voice deepens– Skin thickens, its glandular activity increases– Male physique develops
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Hormonal Control: Testes
• FSH stimulates seminiferous tubules to produce sperm.
• LH (ICSH) stimulates interstitial cells to secrete testosterone.
• Testosterone – Negative feedback
control
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Lesson 26-2 Objectives
• Describe the structure and function of the ovaries.
• Describe the structure and function of the female genital tract.
• Explain the hormonal control of the female reproductive cycle.
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Female Reproductive System: Roles
• Produce eggs
• Secrete hormones
• Nurture and protect a developing baby during 9 months of pregnancy
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Ovaries: Function• Meiosis: Reduces chromosomes from 46 to 23• FSH: Ovum becomes graafian follicle• LH: Ovulationextruded 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
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Ovarian Hormones: Progesterone
• Works with estrogen to establish the menstrual cycle
• Helps maintain pregnancy
• Prepares the breasts for milk production after pregnancy
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Genital Tract
• Fallopian tubes
• Uterus
• Vagina
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Fallopian Tubes: Oviducts
• Fimbriae – Sweep ova into tubes– Not attached to ovary
• Site of fertilization
• Carry ovum to uterus
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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
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Uterus: Parts, Layers, Connections
• Parts: Fundus, body, cervix
• Layers: Endometrium, myometrium, perimetrium
• Connections: Vagina and fallopian tubes
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Vagina: Birth Canal
• Fornices– Formed by cervix – Site of Pap smear
• Rugae– Accommodates baby
• Hymen
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External Genitals: Vulva
• Components: Labia majora, labia minora, mons pubis, clitoris, vestibule
• Also visible: Urethra, opening of Bartholin’s glands, perineum, vagina
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Female Reproductive Cycles
• Purpose: To mature an egg monthly for fertilization
• Two cycles work together– Ovarian– Uterine
• Typical cycle: 28 days
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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
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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.
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Uterine Cycle: Phases
• Menstrual: Endometrial lining is shed.
• Proliferative: Estrogen thickens uterine lining .
• Secretory:Progesterone enriches endometrium.
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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).
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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
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Methods of Birth Control
• Barrier, hormonal, surgical, intrauterine device, and behavioral methods
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