Reproductive System.docx

4/22/10 5:33 PM One of major functions of reproductive system is production of gametes Haploid?only have one copy of DNA Two different types of gametes Male?sperm Very small cell Can move around Female?oocyte (egg) Much larger than a sperm Great deal of cytoplasm associated with it Fertilized egg is called zygote Diploid cell?two copies of DNA Development Cell division Differentiation of cells Leads to new individual Production of Sperm Within testis there are spermatogonium Stem cells that produce sperm Go through a number of divisions in developmental process to get sperm cells At puberty sperm production starts, lasts lifetime as long as male is healthy Quality and quantity of sperm may decline with age Enzymes don?t operate at normal body temperature, must keep these cells cooler than normal body temperature Testis kept in scrotum away from abdominal cavity, better chance for keeping temperature lower Three structures help us maintain this temperature 1. Cremaster muscle Extension of abdominal oblique muscles Can raise and lower the testes relative to the body wall This is a skeletal muscle, can sometimes control it Mostly controlled by temperature 2. Dartos muscle Right in scrotal wall Controls folding of the scrotum itself If very cold, don?t need a lot of surface area, so scrotum pulled up into many tight folds If warm, muscle relaxes and get less folds 3. Pampiniform plexus Helps to maintain constant blood supply temperature via countercurrent exchange system Keeps relatively constant temperature lower than body temperature Serous membranes associated with testis that move independently with the scrotum so that they move easily Tunica vaginalis Fold of peritoneum that comes down from the abdominal cavity into the scrotum, 2-layered structure Visceral layer against the testis Parietal layer that lines the scrotum Scrotal septum down the middle that separates the testes Too much movement can spin testes within the scrotum, causes testicular torsion Swelling and possible loss of a testis Inguinal canal is a passageway from the body cavity to the scrotum Two rings?internal and external inguinal ring that are the openings at each end of the inguinal canal Spermatic cord is in the inguinal canal, has cremaster muscle on outside of it Underneath this is spermatic fascia Gubernaculum helps to pull testes down into scrotum during development If material goes down into the scrotum, called hernia Reproductive System 4/22/10 5:33 PM 4/22/10 5:33 PM