MALE REPRODUCTION and the effects of each 1 Explain the parasympathetic and sympathetic innervations of the male reproductive system PET3323 FINAL a Parasympathetic Erection enlargement and stiffening of the penis i Upon sexual stimulation parasympathetic fibers from the sacral portion of the spinal cord initiate and maintain an erection ii The PNS fibers produce and release nitric oxide causing the smooth muscle in the walls of the arterioles to relax vasodilation and widening of the blood sinuses suppressing the veins that leave the penis 1 Vasodilation causes large amounts of blood to enter the erectile tissue of the penis iii Priapism persistent and painful erection that does not involve sexual desire or excitement abnormal blood vessels and nerves in response to erection meds iv Once the stimulus on the penis has stopped the arterioles constrict and the blood sinuses become smaller relieving the pressure on the veins and allowing the blood to drain penis returns to flaccid relaxed state b Sympathetic Ejaculation powerful release of semen from the urethra i Before ejaculation occurs peristaltic contractions in the epididymis vas deferens seminal vesicles ejaculatory ducts and prostate propel semen into the penile portion of the urethra emission discharge of a small amount before ejaculation can occur during sleep ii The sympathetic reflex is coordinated by the lumbar portion of the spinal cord closing the sphincter at the base of the urinary bladder to prevent urine from being propelled during ejaculation and semen from entering urinary tract iii The bulbospongiosus musculature of the penis contracts at ejaculation iv Premature ejaculation occurs too early caused by anxiety or other psychological cases too much sympathetic innervations 2 Describe the exocrine and endocrine function of the testes Example Sertoli and Leydig cells a Exocrine function spermatogenesis the production of mature sperm gametes or spermatozoa via the Sertoli cells within the seminiferous tubules of the testes i Sertoli cells provide nourishment protection via phagocytes motility via fluid and regulation of hormonal effects b Endocrine function steroidogenesis the production of androgens testosterone involving the interstitial compartment and the Leydig cells i Leydig cells located in the spaces between the adjacent seminiferous tubules secrete testosterone 1 Cholesterol pregnenolone progesterone 17 hydroxyprogesterone androstenedione testosterone 5 reductase dihydrotestosterone 3 Explain IN DETAIL the entire process of spermatogenesis and we described in class what happens in each phase and it s time frame through the seminiferous epithelium Process a Mitotic differentiation Begins with the spermatogonia stem cells which contain the diploid 2n number of chromosomes The spermatogonia squeeze through the tight junctions of the blood testis barrier undergoing developmental changes and differentiating into 1 spermatocytes diploid i Proliferative phase Types of spermatogonia 1 Type A dark Ad dense chromatin generate Type Ap and Ad 2 Type A pale Ap chromatin less dense generate Type B 3 Type B divide by mitosis into 1 spermatocytes a Each daughter cell has 2 copies and the number of chromosomes is cut in half 46 23 b Meiosis sexual reproduction yielding gametes i 1 st Meiotic division Each 1 spermatocyte replicates its DNA and meiosis begins The two cells formed by meiosis I are called the 2 spermatocytes haploid No replication occurs in the 2 spermatocytes ii 2 nd Meiotic division In meiosis II the two chromatids from each chromosome iii Differentiation separate The four haploid cells that result are called spermatids cell Spermiogenic phase Each spermatid becomes a single sperm 1 Spermatids transform into elongated slender sperm as a flagellum develops and mitochondria multiply 2 Differentiation of a spermatid into a sperm through 4 steps a Golgi phase tail filament appears b Cap phase head cap appears from acrosomal granule c Acrosome phase nucleus and head cap elongate and acrosomal granule differentiates to form acrosome d Maturation phase cell completes differentiation to become a mature sperm c Spermination sperm released from Sertoli cells and enter the lumen of the seminferous tubule Fluid secreted from the Sertoli cells help push the sperm along their way i Parts of sperm 1 Head with nucleus 23 chromosomes a Contains either X or Y chromosome b Covered by acrosome which contains enzymes functioning in fertilization 2 Neck connecting piece between head and middle piece 3 Middle piece contains mitochondria machine for motility 4 Principle piece flagellum of tail d Overview spermatogonia initiate a new cycle every 16 days and there are a total of 4 cycles 4 x 16 64 days Once the sperm is released into the lumen another 10 days is required for movement to the epididymis total of 74 days The sperm are then stored in the epididymis TOTAL TIME IT TAKES TO GET TO EPIDIDYMIS 74 quiz question there are 4 cycles during spermatogenesis and each cycle is 14 days long T F TRUE Cycle of the seminiferous epithelium i 1st cycle 16 days type A spermatogonia 46 chromosomes Type B spermatogonia 46 ii 2nd cycle 16 days type B spermatogonia 1 spermatocytes 46 1 Meanwhile type A spermatogonia still give rise to type B iii 3rd cycle 16 days 1 1 spermatocytes 46 chromosomes 1st meiotic division 2 spermatocytes 23 chromosomes 2 Spermatids 23 chromosomes start to appear via 2nd meiotic division iv 4th cycle 16 days spermiogenesis is completed spermination begins 1 Spermatids differentiate into sperm e Comparison between mitosis and meiosis Property Number of divisions Number of daughter cells Produces what type of cells Purpose Mitosis One prophase metaphase anaphase telophase Two each diploid 2n 46 and identical to mother cell 1 spermatocyte All somatic cells in body Ensures consistency of the genetic makeup Meiosis Two DNA replication does not occur instead the chromosomes synapse forming tetrads groups of 4 chromatids Four each containing half as many chromosomes haploid n 23 as the mother cell non identical to mother cell Meiosis 1 2 spermatocyte 2 haploid cells Meiosis 2 spermatids 4 haploid cells Introduces variability and reduces the chromosomal number by half so that when fertilization occurs the normal diploid chromosome number is restored 2n 46 quiz question after the 1 st meiotic diploid to 23 haploid division not second the chromosome number goes from 46 4 Explain the hormonal control of spermatogenesis as it
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