Biology: Life on Earth (Audesirk)

Presentación del tema: "Biology: Life on Earth (Audesirk)"— Transcripción de la presentación:

1 Biology: Life on Earth (Audesirk)
Chapter 35 Reproducción y sexualidad Reproducción Animal Chapter 35

2 Estrategias Reproductivas: Asexual
Chapter 35 Estrategias Reproductivas: Asexual Gemación Regeneración Fisión Esporulación Partenogénesis

3 Estrategias Reproductivas : Sexual
Chapter 35 Requiere de la meiosis y de la unión de gametos Requiere la entrega del espermatozoide a la hembra Fertilización Externa Fertilización Interna

4 Biology: Life on Earth (Audesirk)
Chapter 35 Gemación The offspring of some cnidarians, such as the Hydra shown here, grow as buds that appear as miniature adults sprouting from the body of the parent. When sufficiently developed, the buds break off and assume independent existence. Chapter 35

5 Fisión seguida de regeneración
Biology: Life on Earth (Audesirk) Chapter 35 Fisión seguida de regeneración Crece la nueva cola Mitad anterior sin cola Some flatworm species reproduce by dividing across the middle. Then each offspring regenerates the missing half of its body. El gusano Planaria se corta en dos partes Mitad posterior sin cabeza Crece la nueva cabeza Chapter 35

6 Anatomía reproductiva humana: Masculina
Chapter 35 Gónadas Testículos en el escroto Producen gametos masculinos (espermatozoides) Espermatogonios _ mitosis _ espermatogonios Espermatogonios _ meiosis _ espermatozoides Producen testosterona

7 Anatomía reproductiva humana: Masculina
Chapter 35 Epidídimo Conducto deferente—paso desde los testículos hasta la uretra Glándulas asociadas Vesículas seminales, próstata, glándulas bulbouretrales Las screciones activan el nado de los spermatozoides Uretra Pene — transfiere el semen a la hembra

8 El tracto reproductivo masculino humano
Biology: Life on Earth (Audesirk) Chapter 35 El tracto reproductivo masculino humano The male gonads, the testes, hang beneath the abdominal cavity in the scrotum. Sperm pass from the seminiferous tubules of a testis to the epididymis, and from there through the vas deferens and urethra to the tip of the penis. Along the way, fluids are added from three sets of glands: the seminal vesicles, the bulbourethral glands, and the prostate gland. Chapter 35

9 Estructuras que intervienen en la espermatogénesis
Biology: Life on Earth (Audesirk) Estructuras que intervienen en la espermatogénesis Chapter 35 Corte del testículo Túbulos seminíferos Epidídimo Conducto deferente (b) Corte transversal de un túbulo seminífero Células de Sertoli Espermatogonios (a) A section of the testis, showing the location of the seminiferous tubules, epididymis, and vas deferens. (b) Cross section of a seminiferous tubule. The walls of the seminiferous tubules are lined with Sertoli cells and spermatogonia. As spermatogonia undergo meiosis, the daughter cells move inward, embedded in infoldings of the Sertoli cells. There they differentiate into sperm (spermatazoa), drawing on the Sertoli cells for nourishment. Mature sperm are freed into the central cavity of the tubules for transport to the penis. Testosterone is produced by the interstitial cells in the spaces between tubules. Chapter 35

10 Control hormonal de la espermatogénesis
Biology: Life on Earth (Audesirk) Control hormonal de la espermatogénesis Chapter 35 Hipotálamo - - Hormona liberadora de gonadotropina GnRH + Gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the anterior pituitary to release LH and FSH. LH stimulates the interstitial cells to produce testosterone. Testosterone and FSH stimulate the Sertoli cells and the spermatogonia, causing spermatogenesis. Testosterone and chemicals produced during spermatogenesis inhibit further release of FSH and LH, forming a negative feedback loop that keeps the rate of spermatogenesis and the concentration of testosterone in the blood nearly constant. - - Pituitaria (hipófisis) anterior Hormona luteinizante Hormona estimulante del folículo LH FSH + + + Células intersticiales Testosterona células de Sertoli y espermatogonios Spermatogénesis Chapter 35

11 Los espermatozoides se reproducen por Meiosis
Biology: Life on Earth (Audesirk) Chapter 35 Los espermatozoides se reproducen por Meiosis espermatogonio Spermatogenesis is accomplished by meiotic divisions followed by differentiation, producing haploid sperm. Although 4 chromosomes are shown for clarity, in humans the diploid number is 46 and the haploid number is 23. espermatocito primario espermatocitos secundarios espermatozoides Meiosis I Meiosis II Diferenciación Chapter 35

12 Biology: Life on Earth (Audesirk)
Chapter 35 Esprmatozoide humano (a) A mature sperm is a stripped-down cell equipped with only the essentials: a haploid nucleus containing the male genetic contribution to the future zygote, a lysosome (called the acrosome) containing enzymes that will digest the barriers surrounding the egg, mitochondria for energy production, and a tail (a long flagellum) for locomotion. (b) False-color electron micrograph of a human sperm. Chapter 35

13 Anatomía reproductiva humana: Femenina
Chapter 35 Anatomía reproductiva humana: Femenina Gónadas—ovarios Producen gametos femeninos (óvulos) Ovogonios _ ovocitos primarios Folículos Oviductos (trompas de Falopio) Paso desde el ovario al útero Sitio de fecundación

14 Anatomía reproductiva humana: Femenina
Chapter 35 Útero Sitio de desarrollo del embrión Endometrio y miometrio Cervix — apertura muscular hacia el útero Vagina — receptáculo para el pene

15 El tracto reproductor femenino humano
Biology: Life on Earth (Audesirk) Chapter 35 El tracto reproductor femenino humano Eggs are produced in the ovaries and swept by cilia into the uterine tube. A male deposits sperm in the vagina, from which they move up through the cervix and uterus into the uterine tube. Sperm and egg normally meet in the uterine tube, where fertilization occurs. The fertilized egg attaches to the lining of the uterus, where the embryo develops. Chapter 35

16 The Structures Involved in Oogenesis
Biology: Life on Earth (Audesirk) The Structures Involved in Oogenesis Chapter 35 (b) (a) (a) External view of the ovary and uterine tube. (b) The development of follicles in an ovary, portrayed in a time sequence (clockwise from the lower right). 1) A primary oocyte begins development within a follicle. 2) , 3) The follicle grows, providing both hormones and nourishment for the enlarging oocyte. 4) At ovulation, the secondary oocyte, or egg, bursts through the ovary wall, surrounded by some follicle cells. The remaining follicle cells develop into the corpus luteum, which secretes hormones. If fertilization does not occur, the corpus luteum breaks down after a few days. Chapter 35

17 Hormonas y prducción de óvulos
Chapter 35 Hormonas y prducción de óvulos El ciclo menstrual GnRH LH FSH Estrógeno Progesterona Hormonas del embarazo Gonadotrofina coriónica humana (HCG) Estrógeno / progesterona Prolactina Oxitocina

18 Control hormonal del ciclo Menstrual
Biology: Life on Earth (Audesirk) Control hormonal del ciclo Menstrual Chapter 35 The menstrual cycle is generated by interactions among the hormones of the hypothalamus, the anterior pituitary, and the ovaries. The circled numbers refer to the interactions discussed in the text on page 728. Chapter 35

19 Los óvulos se forman por meiosis
Biology: Life on Earth (Audesirk) Chapter 35 Los óvulos se forman por meiosis óvulo The cellular stages of oogenesis. The oogonium enlarges to form the primary oocyte. At meiosis I, almost all the cytoplasm is included in one daughter cell, the secondary oocyte. The other daughter cell is a small polar body that contains chromosomes but little cytoplasm. At meiosis II, almost all the cytoplasm of the secondary oocyte is included in the egg, and a second small polar body discards the remaining “extra” chromosomes. The first polar body may also undergo the second meiotic division. In humans, meiosis II does not occur until a sperm penetrates into the egg. ovocito secundario (óvulo) cuerpo polar ovogonio ovocito primario cuerpo polar cuerpo polar cuerpo polar Meiosis I Meiosis II Chapter 35

20 Chapter 35 FIN