Adaptations for Sexual Reproduction Human Reproduction Adaptations for Sexual Reproduction

Section Outline The Reproductive System Sexual Development Role of Hormones 1. Pituitary Hormones: FSH + LH 2. Testes: Testosterone 3. Ovaries: Estrogen + Progesterone C. The Male Reproductive System 1. Sperm Development 2. Sperm Release D. The Female Reproductive System 1. Egg Development 2. Egg Release E. The Menstrual Cycle 1. Follicular Phase 2. Ovulation 3. Luteal Phase Menstruation

Hormones and Human Reproduction Hormones are powerful “chemical messengers” produced by Endocrine Glands. Hormones regulate most life activities (directly or indirectly); including the onset of sexual maturity (Puberty) The development of gametes and secondary sex characteristics are controlled by the INTERACTION of hormones produced by the Hypothalamus and Pituitary glands (brain) and hormones produced by the male and female gonads.

The Brain-Gonad “Connection” Hypothalamus The hypothalamus makes hormones that control the pituitary gland. In addition, it makes hormones that are stored in the pituitary gland. Pituitary gland The pituitary gland produces hormones that regulate many of the other endocrine glands. Ovary The ovaries produce estrogen and progesterone. Estrogen is required for the development of secondary sex characteristics and for the development of eggs. Progesterone prepares the uterus for a fertilized egg. ovary Testis The testes produce testosterone, which is responsible for sperm production and the development of male secondary sex characteristics testes

Hormones controlling Male Repro Two hormones produced by the Pituitary Gland (located in brain) are: FSH (follicle stimulating hormone) – “targets” testes to develop mature sperm LH (luteinizing hormone) – acts on the testes to produce testosterone Testosterone, is produced in the testes and is the primary sex hormone in males.

Action of Testosterone A sudden increase in Testosterone Initiates male puberty Acts to develop secondary male sex characteristics Development of Male Sex Organs Greater Bone and Skeletal Muscle Mass/density Growth of Beard and Body Hair Lowering of Voice

Male Reproductive Structures Urinary Bladder Pubic Bone Vas deferens Large intestine Urethra Penis Cowper’s Gland Seminal Vesicle Rectum Epididymis Scrotum Prostate Testes Coiled Seminiferous Tubules

Main Functions of Male Repro System Sperm production in paired testes Requires lower temperature Scrotum adaptation for max. sperm production Flagellum Mitochondria 2. Delivery of Sperm into Female’s Reproductive Tract Head Nucleus

Cross-section of Testes Site of Sperm and Testosterone Production

Female Repro Structures Fallopian tube Fallopian Tube Ovary Urinary Bladder ovary Uterus Pubic bone Urethra Cervix Vagina Vagina Rectum

Cross-section of Ovary Follicles at various stages of Development (photo) Follicles produce eggs, Estrogen and Progesterone ONLY one Follicle/ month will Produce the egg That’s ovulated follicle Egg

Egg maturation in ovary releases progesterone maintains uterus lining produces estrogen

Human Menstrual Cycle

Menstrual cycle Controlled by interaction of 4 hormones FSH & LH estrogen progesterone FSH ovulation = egg release egg development corpus luteum estrogen progesterone lining of uterus days 7 14 21 28

Four Hormones Regulate the Menstrual Cycle Pituitary Gland produces FSH (follicle stimulating hormone) + LH (lutenizing hormone) Pituitary Gland ↑ Pituitary Releases FSH; Stimulates the Maturation of Follicles and Estrogen production ↑Estrogen causes Release of LH ↑ LH causes Ovulation Corpus luteum Secretes progesterone Follicles in the Ovaries produce estrogen and progesterone

Menstrual Cycle Summary Chart Follicle Stage ↑FSH Follicle develops Follicle produces Estrogen Egg Matures Estrogen Thickens Uterus lining Lasts 10-14 days Low Estrogen + progesterone allows FSH to be released again from pituitary Day 14 4. Menstruation Sudden decrease in estrogen and progesterone Shedding of Uterine Lining 2. Ovulation ↑ LH released Mature egg released Ovulation Lasts 10-12 days 3. Corpus Luteum Stage Ruptured follicle becomes the Corpus Luteum (yellow Body) Corpus luteum produces Progesterone Uterus lining becomes thicker, prepares For possible fertilization Corpus luteum Degenerates Causing Progesterone + estrogen to Drop

Fertilization Occurs In the Fallopian Tubes Day 4 4 cells 2 cells Zygote Morula Day 7 Fertilization Blastocyst Day 0 Implantation of blastocyst Uterine wall Egg released “ovulation” ovary

Early Embryonic Development All divisions of A zygote after Fertilization are Mitotic cell divisions Called Cleavage

The Three Germ Layers Differentiation of Cells Endoderm: Lining of Digestive And Respiratory tracts, Liver and Pancreas Mesoderm: Muscles and Skeleton, Circulatory and Reproductive systems Ectoderm: Nervous System Epidermis of skin

Multiple Births Fertilization is the fusion of a sperm and an egg to form a zygote, the single cell from which all cells of the human body are derived. When an egg is fertilized, the remarkable process of human development begins. 1. If two eggs are released during ovulation, each can be fertilized by a sperm. What do you think would be the result? Explain your answer. 2. If one zygote splits into two, each can continue development on its own. What do you think would be the result? Explain your answer. 3. Triplets are three babies born at the same time. Describe three ways that triplets could develop.

Fetus to Baby In spite of the placental “barrier” Small molecules and Viruses can still cross And affect the baby Alcohol (FAS) Carbon Monoxide (Smoking) Narcotics (Heroine, Crack) HIV Measles Chicken Pox Antibodies Rh incompatibility

Placenta Food & gases diffuse across blood vessels

Human Embryo: 3-8 weeks Gestation Note, the period from week 12 to week 38 is considered Fetal Development

Human fetal development 10 weeks

Human fetal development 12 weeks 20 weeks

Human fetal development The fetus just spends much of the 2nd & 3rd trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid Week 20

Human fetal development 24 weeks (6 months; 2nd trimester) fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix

Human fetal development 30 weeks (7.5 months) umbilical cord

positive feedback Birth

Birth (36 weeks) Intestine Placenta Umbilical cord Wall of uterus Bladder Cervix Vagina

And you think 9 months of Biology is hard! The end of the journey! And you think 9 months of Biology is hard!