Chapter 026

The Human Body in Health and Illness, 4th edition

Barbara Herlihy

Chapter 26:Reproductive Systems

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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.

Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights

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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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Chapter 026

Health & Medicine

Transcript of Chapter 026