Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Spawn (biology) wikipedia , lookup
Parental investment wikipedia , lookup
Animal sexual behaviour wikipedia , lookup
Drosophila melanogaster wikipedia , lookup
Reproductive suppression wikipedia , lookup
Plant reproduction wikipedia , lookup
Fertilisation wikipedia , lookup
Fish reproduction wikipedia , lookup
Joshua Chandra Shannen Guarina - Sexual reproduction: the fusion of haploid gametes to form a diploid cell (zygote). - The egg - The sperm - Asexual reproduction: generation of new individuals without the fusion of egg and sperm - Fission - Budding - What advantage does sex provide? - Produces offspring of different genotypes/phenotypes that enhances reproductive success of parents - Most animals reproduce sexually or asexually; but some alternate between the two. - parthenogenesis: asexual reproduction in which an egg develops without it being fertilized - Hermaphroditism - Sex reversal - External fertilization - sperm fertilizes eggs shed into the external environment - Internal fertilization – egg and sperm unite within the female’s body - Fertilization requires coordinated timing which can be mediated by environmental cues, pheromones, or courtship behavior - Internal fertilization requires behavioral interactions between males and females as well as compatible copulatory organs - Internal fertilization usually results in a small amount of offspring - It is usually accompanied by the greater protection of embryos and parental care - Reproductive systems range from undifferentiated cells in the body cavity that creates gametes to complex assemblages of male and female gonads - Although it usually occurs in a partnership, competition emerges between individuals and between gametes - Female reproductive anatomy: - External: labia majora, labia minora, clitoris – these form the vulva - Internal: vagina is connected to the uterus, which connects to two oviducts - There are two ovaries which is stocked with follicles containing oocytes - Male reproductive anatomy: - External: scrotum and penis - Male gonads (testes) are held in the scrotum - These contain the hormone-producing cells and sperm-forming seminiferous tubules - Human sexual response: - Sexual response cycle: - Excitement - Plateau - Orgasm - Resolution - Orgasm: rhythmic, involuntary contractions of the reproductive structures - Gametogenesis is the production of gametes - It consists of oogenesis in females and spermatogenesis in males - Sperm develops continuously - Oocyte maturation is discontinuous and cyclic - Meiosis results in one large egg that is created in oogenesis - Meiosis also results in four sperm in spermatogenesis - Hormonal control of the male reproductive system - Androgens from the testes cause the development of primary and secondary sex characteristics in the male - Androgen secretion and sperm production are both controlled by hypothalmic and pituitary hormones - The reproductive cycles of females: - Cyclic secretion of the GnRH from the hypothalmus and of FSH and LH from the anterior pituitary orchestrate the female reproductive cycle - FSH and LH bring about changes in the ovary and uterus via estrogens and progesterone - Estradiol is produced by the developing follicle - The progesterone and estradiol is excreted by progesterone - Menstrual Cycles - Menstrual Flow Phase - Proliferative Phase - Secretory Phase http://www.youtube.com/watch?v=WGJsrGmWeKE - After fertilization and meiosis occurs in the oviduct , the zygote will eventually undergo cleavage and will from there develop into blastocyst - From there the blastocyst will be implanted in the endometrium - Human pregnancy is divided into three trimesters - All majors will have begun to develop by the eight week mark - Positive feedback by prostaglandins and the hormones estradiol and oxytocin will help regulate labor - By accepting the “foreign” offspring it shows that the mother partially suppresses the immune response - Contraceptive methods may be used to prevent fertilization - Modern reproductive technologies can be used in multiple fashions - Detect problems before birth - Assist infertile couples through hormonal methods or in vitro fertilization