The Human Body in Health and Illness 4

The Human Body in Health and Illness, 4 th 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. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2

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. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3

Reproductive Systems Functions – Produce, nurture, and transport ova and sperm – Secrete hormones Primary Reproductive Organs Gonads Male: Testes Female: Ovaries Gametes Sperm Ova (eggs) Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4

Male Reproductive System: Roles • Produce, nourish, and transport sperm • Deposit sperm within the female reproductive tract • Secrete hormones Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5

Male Reproductive Structures • Testes • Genital ducts • Accessory glands • External genitals

Testes or Testicles • Scrotum – Lower temperature • Cremaster muscle • Lobules – Seminiferous tubules produce sperm. – Interstitial cells secrete testosterone. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7

Spermatogenesis and Meiosis • Spermatogonia mature into spermatocytes. • Meiosis divides spermatocytes. 46 chromosomes 23 chromosomes spermatogenesis Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8

Parts of the Sperm • • Head: Primarily a nucleus Acrosome: Contains enzymes for fertilization Body: Mitochondria (ATP) Tail: Flagellum Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9

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) Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10

Glands: Volume and Nutrients • Seminal vesicles 60% of semen’s volume; thick, yellowish, contains fructose, Vit. C, and prostaglandins • Prostate gland Around upper urethra; milky, alkaline • Bulbourethral glands – Thick mucus for lubrication • Glandular secretions mix with sperm to form semen. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11

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

External Genitals • Scrotum contains the testes • Penis, organ of copulation (intercourse) – Shaft contains erectile tissue which fill with blood to become erect – Glans penis – head of the penis – Prepuce, foreskin or covering for glans – Smegma – oily substance and dead skin cells; lubricant Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13

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 • Penis returns to its normal flaccid state after ejaculation Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14

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 Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15

Hormonal Control: Testes • FSH stimulates seminiferous tubules to produce sperm. • LH (ICSH) stimulates interstitial cells to secrete testosterone. • Testosterone – Negative feedback control Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16

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. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17

Female Reproductive System: Roles • Produce eggs • Secrete hormones • Nurture and protect a developing baby during 9 months of pregnancy Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18

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 • ovulation Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19

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 Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20

Ovarian Hormones: Progesterone • Works with estrogen to establish the menstrual cycle • Helps maintain pregnancy • Prepares the breasts for milk production after pregnancy Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21

Genital Tract • Fallopian tubes • Uterus • Vagina Copyright © 2011, 2007 by

Fallopian Tubes: Oviducts • Fimbriae – Sweep ova into tubes – Not attached to ovary • Site of fertilization • Carry ovum to uterus Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23

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 Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 24

Uterus: Parts, Layers, Connections • Parts: Fundus, body, cervix • Layers: Endometrium, myometrium, perimetrium • Connections: Vagina and fallopian tubes Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25

Vagina: Birth Canal • Fornices – Formed by cervix – Site of Pap smear

External Genitals: Vulva • Components: Labia majora, labia minora, mons pubis, clitoris, vestibule • Also visible: Urethra, opening of Bartholin’s glands, perineum, vagina Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 27

Female Reproductive Cycles • Purpose: To mature an egg monthly for fertilization • Two cycles work together – Ovarian – Uterine • Typical cycle: 28 days Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 28

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 Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 29

Ovarian Cycle: Luteal Phase • Corpus luteum secretes progesterone. • Progesterone enriches uterine lining. • Luteal phase progresses differently in the pregnant or nonpregnant state Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 30

Corpus Luteum: Dead or Alive? Dead Alive • Without fertilized ovum, corpus luteum corpus albicans (dead) • Plasma levels of ovarian hormones decline. • Without hormonal support, uterine lining sloughs off. • Fertilized ovum secretes human chorionic gonadotropin (h. CG). • h. CG sustains corpus luteum. • Hormones persist and maintain uterine lining. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 31

Uterine Cycle: Phases • Menstrual: Endometrial lining is shed. • Proliferative: Estrogen thickens uterine lining. • Secretory: Progesterone enriches endometrium. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 32

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). Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 33

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 Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 34

Methods of Birth Control • Barrier, hormonal, surgical, intrauterine device, and behavioral methods • Read pp. 489 -490 Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 35