CHAPTER 2B. Male Reproductive System.pdf

MALE REPRODUCTIVE SYSTEM Anatomy and Physiology, Process of Spermatogenesis  Learning Objectives 1. Define the terms listed. 2. Identify the anatomy and physiology of the male external reproductive organs 3. Identify the anatomy and physiology of the male internal reproduct...

MALE REPRODUCTIVE SYSTEM Anatomy and Physiology, Process of Spermatogenesis  Learning Objectives 1. Define the terms listed. 2. Identify the anatomy and physiology of the male external reproductive organs 3. Identify the anatomy and physiology of the male internal reproductive organs. Male Internal Parts 8. Urinary bladder Rectum 1. Seminal vesicle 2. Prostate gland 3. Cowper’s gland 4. Vas deferens 5. Epididymis 9. Glans penis 6. 6.Testes/Testicle 10. Urethral orifice 7. Scrotum PARTS OF THE MALE REPRODUCTIVE SYSTEM  PENIS  External organ that gives the male his physical pleasure (orgasm)  During sexual intercourse it cannot ejaculate and urinate at the same time  Reproduction has priority  Parts of the Penis:  Shaft  Glans penis  Prepuce  Glans Penis  Cone-shaped end also called the “head” At the distal end of the organ is a bulging, sensitive ridge of tissue Forms the cap of the penis Prepuce  Also known as the “foreskin”, a retractable casing of skin, fold of skin that covers the head of the penis  SCROTUM  Sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis  Contains paired testicles separated by a midline septum Function: To support the testes and to help regulate the temperature of sperm; the temperature of the testes should remain at 3C lower than core body temperature as even as possible to promote the production and viability of sperm.  Wall of the Scrotum  In the dermis, there is a thin layer of smooth muscle known as the dartos muscle. Contractions of this muscle causes wrinkling of the skin.  The cremaster muscle is a thicker layer of skeletal muscle that lowers and raises the testes based on temperature.  TESTES Found inside the scrotum, beneath the penis AKA – balls or nuts Function is to produce sperm cells in the seminiferous tubules Sperm – the male reproductive cell Inside the Scrotum: TESTES  Each testes is enclosed by the tunica vaginalis, a continuation of the peritoneum that lines the abdominopelvic cavity.  A fibrous capsule covers each testis called the tunica albuginea. Leydig’s cells  Found adjacent to the seminiferous tubules in the testicle; Responsible for the production of testosterone  Testicle  The tunica albuginea gives rise to septa (partitions) that divide the testis into lobules (about 250)  Each lobule contains 3 or 4 highly coiled seminiferous tubules  These converge to become rete testis which transport 13 sperm to the epididymis  Spermatic Cord  Contains the structures running from the testicles to the pelvic cavity. – Passes through the inguinal canal  Contents: – Vas Deferens – Nerves – Blood Vessels 14  COWPER’S GLAND (Bulbourethral Glands)  Pea-sized glands inferior to the prostate  Sends a clear fluid through the penis before ejaculation that neutralizes any urine (acidic)  Also serves as a lubricant  EPIDIDYMIS 2 for each testicle for a total of 4 coiled tubing that stores sperm for up to 6 weeks (20 feet long) PROSTATE GLAND  Located beneath the bladder & surrounds the urethra  FUNCTION: Provides a fluid that both nourishes and allows greater mobility to the sperm VAS DEFERENS  There are two, one from each testicle (long tube)  Carries sperm from the testicle to the urethra (18 inches long)  Portion cut when Vasectomy is performed SPERM PRODUCTION  X chromosome = female sperm cell (23 chromosomes)  Y chromosomes = male sperm cell (23 chromosomes)  The male begins to produce sperm at puberty & will continue until he dies  Ejaculation – the releasing of sperm (300-400 million about a teaspoon of fluid)  Accessory Glands: SEMINAL VESICLES  Lie on the posterior wall of the bladder and secrete 60% of the volume of semen – Seminal fluid:  Fructose: provides energy for the sperm.  Fibrinogen: helps turn semen into a bolus that can be readily propelled into the vagina.  Prostaglandins: decrease cervical mucus viscosity and stimulate reverse peristalsis of the uterus.  Join the ductus deferens to form the ejaculatory duct 20 Three glands (The seminal vesicles, the prostate, and the bulbourethral gland)  Secrete seminal fluids that carry sperm into the vagina during intercourse.  The seminal fluid has four functions: 1) nourishing the sperm, 2) protecting the sperm from the hostile pH (acidic) environment of the vagina, 3) enhancing the motility of the sperm, and 4) washing the sperm from the urethra so that the maximum number are deposited in the vagina. MALE URETHRA/ URETHRAL ORIFICE  A tube that extends through the length of the penis  The tube leads out of the body  Urine and sperm exit out of this tube The Reproductive System  Male and female reproductive systems develop from similar embryonic tissue.  First few weeks of development, male and female embryos are indistinguishable.  Adult reproductive systems share some functional similarities.  Descent of the Testes  Ovoid structures about 5 cm long and 3 cm wide.  Located within the scrotal sac (scrotum)  During fetal development they are near the kidneys and slowly move inferiorly in the abdominal cavity.  During the 7th month they descend through the inguinal canals  Spermatogenesis  Spermatogenic stem cells of the seminiferous tubules give rise to sperm in a series of events – Mitosis of spermatogonia, forming spermatocytes – Meiosis forms spermatids from spermatocytes – Spermiogenesis: spermatids form sperm 26  SPERMATOGENESIS Spermatogenesis 27  Spermiogenesis: Spermatids to Sperm 28  Sperm Sperm have three major regions: 1.Head: contains DNA and has a helmet-like acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg (Hylauronidase) 2.Midpiece: contains mitochondria spiraled around the tail filaments 3.Tail: a typical flagellum produced by a centriole 29  Summary  Produced by: Seminiferous tubules  Stored at: Epididymis  Transported through epididymis by rhythmic peristaltic contractions as they mature  Epididymis Vas Deferens  Ejaculatory duct (ampulla of vas deferens fuses with duct of seminal vesicle “ejaculatory duct”)  prostate prostatic urethra (then passes the bulbourethral gland) membranous urethra  penile urethra 30