Reproduction and Development Chapter 27

Multiple Births Becoming more common Increased use of fertility drugs High order multiple births are risky Increased risk of miscarriage Premature delivery Low birth weights

p.461b

Impacts, Issues Video Mind-boggling births

Methods of Reproduction Sexual reproduction Meiosis, gamete formation, and fertilization Offspring show genetic variation Asexual reproduction Single parent produces offspring Offspring are genetically identical

Asexual Reproduction

Cost of Sexual Reproduction Specialized cells and structures must be formed Special courtship and parental behaviors can be costly Nurturing developing offspring, either in egg or body, requires resources (usually from mother)

Early Development Where embryos develop

Male Reproductive System bladder seminal vesicle vas deferens prostate gland bulbourethral gland urethra epididymis scrotum testis penis

A Sperm’s Journey Testes Epididymis Vas deferens Ejaculatory ducts Produces immature sperm Epididymis Matures and stores sperm Vas deferens Ejaculatory ducts Urethra

Sperm Travel Route Route sperm travel

Male Components and Accessory Glands PROSTATE GLAND EJECULATORY DUCT SEMINAL VESICLE urinary bladder URETHRA urethra anus anterior posterior BULBOURETHRAL GLAND VAS DEFERENS PENIS erectile tissue EPIDIDYMIS TESTIS Fig. 27-7, p.467

Male Reproductive System

Glandular Secretions Secretions from epididymis aid sperm maturation Seminal vesicles secrete fructose and prostaglandins Prostate-gland secretions buffer pH in acidic vagina Bulbourethral gland secretes mucus

Sperm Production vas deferens seminal vesicle prostate gland bulbourethral gland urethra penis epididymis seminiferous tubule testis Fig. 27-9a, p.468

secondary spermatocyte immature sperm (haploid) Sperm Production MITOSIS MEIOSIS I MEIOSIS II lumen Sertoli cell spermato-gonium (diploid) secondary spermatocyte late spermatid immature sperm (haploid) early spermatids primary spermatocyte Fig. 27-9b, p.468

Spermatogensis Spermatogenesis

A Mature Sperm Spermatids mature to become sperm Head Midpiece Tail Glandular products + sperm = semen

Hormonal Control Testosterone Follicle-stimulating hormone (FSH) Produced by Leydig cells in testes Controlled by luteinizing hormone (LH) Follicle-stimulating hormone (FSH) Starts sperm production LH and FSH produced by pituitary, controlled by hypothalamus

Female Reproductive Organs ovary ovary oviduct uterus uterus oviduct vagina clitoris vagina

Female Reproductive Organs Female reproductive system

The Uterus Myometrium Endometrium Cervix Thick layer of smooth muscle in walls Endometrium Uterine lining Cervix Connects uterus and vagina

Menstrual Cycle The fertile period for a human female occurs on a cyclic basis Menstrual cycle lasts about 28 days on average

Menstrual Cycle Follicular phase Ovulation Luteal phase Menstruation Uterine lining regenerates Oocyte matures Ovulation Oocyte released from ovary Luteal phase Hormones thicken endometrium

The Ovarian Cycle Girl is born with primary oocytes already in ovaries Oocytes are suspended in meiosis 1 Meiosis resumes, one oocyte at a time, with the first menstrual cycle

Ovarian Cycle Ovarian function

Ovulation

Female Hormonal Control Hypothalamus GnRH Rising estrogen stimulates surge in LH Anterior pituitary Progesterone, estrogens LH FSH Ovary follicle growth, oocyte maturation Estrogen Corpus luteum forms

Cycle Overview hypothalamus GnRH anterior pituitary FSH LH FSH LH GnRH secretion affects LH and FSH secretion by pituitary LH and FSH affect follicle maturation Estrogens and progesterone from ovary affect uterus FSH LH LH ovulation estrogens estrogens progesterone estrogens menstruation FOLLICULAR PHASE LUTEAL PHASE

Menstrual cycle summary Cycle Overview Menstrual cycle summary

Female Hormones Follicular Phase

Ovulation and luteal phase Female Hormones Ovulation and luteal phase

Fertilization Sperm penetrates egg cytoplasm Secondary oocyte undergoes meiosis II, forms mature egg Egg nucleus and sperm nucleus fuse to form diploid zygote

Fertilization oviduct ovary Ovulation uterus follicle cell opening of cervix egg nucleus vagina zona pellucida Fig. 27-14, p.472

Fertilization Fertilization

Prevent fertilization Birth Control Options Prevent fertilization Prevent ovulation Block implantation

Contraception Effectiveness

Medical Manipulations In vitro fertilization (IVF) Hormone injections Removal and fertilization of eggs Reinsertion of dividing cells Abortion Spontaneous Induced

Sexually Transmitted Diseases Human papillomavirus infection (HPV) Trichomoniasis Chlamydia Genital herpes Gonorrhea Syphilis AIDS

Sexually Transmitted Diseases

Bacterial STDs Can be cured with antibiotics Syphilis Gonorrhea Chlamydia Pelvic Inflammatory Disease (PID) Scarring Tubal pregnancy Infertility

Viral STDs Cannot be cured HIV/AIDS Genital herpes Genital warts Human papillomaviruses (HPV) Can cause cancers

Table 27-1, p.475

Pregnancy Averages 38 weeks from fertilization Takes 2 weeks for blastocyst to form Weeks 3 to 8: embryonic period Weeks 9 to birth: fetal period

trophoblast (surface layer of cells of the blastoyst) fertilization uterine cavity endometrium implantation endometrium blastocoel inner cell mass inner cell mass DAYS 1-2 DAY 3 DAY 4 DAY 5 DAYS 6-7 Fig. 27-18a, p.476

First two weeks of development Implantation First two weeks of development

Human Chorionic Gonadotropin (HCG) Hormone secreted by blastocyst Prevents degeneration of corpus luteum maintains endometrium prevents menstruation Can be detected by week 3 with a home pregnancy test

The Placenta Interlocking fetal and maternal tissues Nutrients and wastes exchanged across membrane separating bloodstreams

4 weeks 8 weeks 12 weeks Fig. 27-19a, p.478

Embryonic Period Weeks 3 to 8 By week 8 Embryo appears human week 4 length 4mm week 8 length 2 cm

Fig. 27-21a,b, p.480

Fetal Period Weeks 9 to birth 22 weeks: fetus cannot survive birth 28 weeks: lungs still developing 36 weeks: survival is 95 percent 38 weeks: full term birth

Fetal Period Fetal development

Prenatal Care Nutrition Infection Drugs and alcohol must be provided from maternal diet through placenta Infection mother’s viruses can affect fetus Drugs and alcohol harm developing fetus Children of smokers at risk for heart defects and death

Fetal Alcohol Syndrome

Birth (Labor) Cervical canal dilates Amniotic sac ruptures Uterine contractions drive fetus from uterus Placenta is expelled as afterbirth

Birth Birth

Lactation During pregnancy, progesterone and estrogen stimulate gland development After birth, prolactin induces synthesis of enzymes for milk production Oxytocin triggers contractions that expel milk

Stages of Human Development: Prenatal Zygote: single cell Morula: solid ball of cells Blastocyst: ball with fluid-filled cavity Embryo: 2 weeks to 8 weeks Fetus: 9 weeks to birth

Stages of Human Development: Postnatal Newborn: birth to 2 weeks Infant: 2 weeks to 15 months Child: infancy to 10 or 12 years Pubescent: during puberty Adolescent: puberty to maturation Adult Old age