Dorothy Wright
BIO 186-002
Chapter 26: Reproductive System
Study Guide Q&A Objectives
1. Describe the structure and function of the testes, and explain the importance of their location in the scrotum.
Structure: The sperm producing testes, or male gonads, lie within the scrotum. A pair surrounded by two tunics 1. Tunica vaginalis – outer layer derived from peritoneum. 2. Tunica albuginea – inner layer.
Function: deliver sperm to the body exterior thru a system of ducts including in order (epididymis, vas deferens, ejaculatory duct, urethra)
Importance of location in the scrotum: The scrotum is a sac of skin and superficial fascia that hangs outside of abdominopelvic cavity. 3 degrees Celsius lower than core body temperature. The lower temperature is necessary for healthy sperm production.
2. Describe the location, structure, and function of the accessory reproductive organs of the male.
The male duct system in order proximal to distal: epididymis, ductus (vas) deferens, ejaculatory duct, urethra.
Location accessory organs: the epididymis body and tail are on the posterolateral area of the testis. Structure: highly coiled, three parts, head, body, and tail. Pseudo stratified epithelial cells, contain non motile microvilli (stereo “no movement” cilia “hair like”). Micro villi absorb excess testicular fluid and pass nutrients to stored sperm. Function: houses immature sperm until mature takes twenty days, during ejaculation epididymis contracts, expelling sperm into ductus (vas) deferens. Location ductus (vas) deferens & ejaculatory duct: vas deferens runs upward at part of the spermatic cord from the epididymis thru inguinal canal into the pelvic cavity. Loops medially over the ureter and descends along the posterior bladder wall. Terminus expands to form the ampulla of vas deferens then joins with the duct of seminal gland to form the ejaculatory duct. Structure: pseudo stratified epithelium. Thick muscular layer of duct feels like hard wire when palpitated. Function: during ejaculation smooth muscle in its walls creates peristaltic wave’s rapid squeeze of sperm forward along tract into urethra. Location urethra: terminal portion of the male duct system. Three regions; 1) prostatic urethra surrounded by the prostate 2) Intermediate passes thru the urogenital diaphragm 3) spongy runs thru the penis and opens to the outside of body. Function: transports both urine and semen (always at separate times, never at same time).
3. Discuss the sources and functions of semen.
Definition: Semen is a milky white, sticky mixture of sperm, testicular fluid, and accessory gland secretions. Produce bulk of semen.
Accessory glands in order of proximal to distal: paired seminal glands, prostate gland, paired bulbo-urethral glands.
Semen Functions:
The liquid provides a transport medium and nutrients and contains chemicals that protect and activate the sperm and facilitate their movement.
Prostaglandins decrease the viscosity of mucus guarding the cervix entry of uterus. Stimulate reverse peristalsis in uterus. Facilitate sperm movement thru female RT.
Relaxin hormone, certain enzymes in semen enhances sperm motility.
Contains ATP for energy
Certain ingredients suppress the immune response in female RT.
Antibiotic chemicals destroy some bacteria
Clotting factors coagulate semen just after ejaculation. Coagulation cause sperm to stick to walls of vagina and prevents the initially immobile sperm from draining out of vagina. Then liquefied by fibrinolysin sperm swim out began their journey.
Semen alkaline pH 7.2-8.0 help to neutralize the acid environment of male urethra and female vagina.
Amount of semen release during ejaculation 2-5 ml. only ten percent sperm. Each ml contains 20-150 million sperm.
Sources & Locations:
Seminal glands located on posterior bladder surface. Smooth muscle contracts during ejaculation. Produce viscous alkaline seminal fluid. Fructose, citric acid, coagulating enzyme vesiculase, and prostaglandins. Yellow
