The Reproductive System PDF

The Reproductive System  The major function of the reproductive system is to ensure survival of the species. An individual may live a long, healthy, and happy life without producing offspring, but if the species is to continue, at least some individuals must produce offspring.  Within...

The Reproductive System  The major function of the reproductive system is to ensure survival of the species. An individual may live a long, healthy, and happy life without producing offspring, but if the species is to continue, at least some individuals must produce offspring.  Within the context of producing offspring, the reproductive system has four functions: To produce egg and sperm cells To transport and sustain these cells To nurture the developing offspring To produce hormones  Reproductive development  Gonad is a body organ that produces sex cells (the ovary in females and the testis in males)  Mesonephric ducts develops in males  Paramesonephric ducts develops in females Physiology of Onset  Puberty is initiated by hypothalamic- pituitary – gonad complex.  Puberty usually starts in Girls at 10-13 years old and Boys starts at 12-14 years old. Puberty is the stage of life at which secondary sex changes begin. Girls (estrogen) Boys (testosterone)  Growth Spurt  Increase in weight  Increase in the  Growth of testes transverse diameter of the pelvis  Growth of face, axillary & pubic hair  Breast development  Voice changes  Growth of pubic hair  Penile growth  Onset of menstruation  Increase in height  Growth of axillary  spermatogenesis hair  Vaginal secretions Female and Male Reproductive System Homologues  Female  Male Clitoral glans Penile glans Clitoral shaft Penile shaft Labia majora Scrotum Ovaries Testes Skene’s glands Prostate Bartholin’s Cowper’s glands glands Role of Androgens Androgenic hormones- responsible for muscular development, physical growth, and an increase in sebaceous gland secretions causing typical acne in both boys & girls. - produced by adrenal cortex & testes (males) Functions of the Male Reproductive System Production of gametes Male sex cells, i.e., sperm Synthesis of androgens Male sex hormones, e.g. testosterone Delivery of sperm into the female reproductive tract. MALE REPRODUCTIVE SYSTEM  The main reproductive organs of the male body are the testes, which produce sperm and also male hormones, in the form of testosterone. Male External Structures  Penis  Tubular structure located above the scrotum, composed of shaft and glans.  Half of it is an internal root and half is the external visible shaft.  Soft and flaccid (2.5 to 4 inches). Erection- blood vessels in the shaft become congested, penis become hard and erect (5.5 to 7 inches)   Glans  The distal end of the organ is bulging sensitive ridge of tissue which has the external urinary meatus at its tip.  Corona  The proximal margin of the glans.  Prepuce  Also called the foreskin.  Loose skin attached to the shaft, allowing for expansion during erection.  Retractable casing of skin that protects the nerve sensitive glans at birth.  Frenulum  Ventral fold of tissue attaches the skin to the glans. Contains the urethra as well as 3 erectile bodies: 2dorsal erectile tissues known as the corpora cavernosa 1 midventral tissue known as the corpus spongiosum Surrounds penile urethra Expands distally to form the glans penis   Sexual excitement → Nitric acid is released from the endothelium of blood vessels → Result in engorgement or an increase in the blood flow to the arteries of the penis →The Ischiocavernosus muscle at the penis base then contracts → Trapping both venous and arterial blood in the 3 sections of erectile tissue →Leading to distention and erection of the penis  SCROTUM  loose pouch-like sac of skin that hangs behind the penis  rugated, skin covered muscular pouch suspended from the perineum  contains testes, epididymis, and the lower portion of the spermatic cord Contains male gonads (testes)  help regulate the temperature of sperm through contraction and relaxation and moving closer to and further away from the perineum the looseness of the scrotum is intentional to provide expansion and contraction  lowers T by 3C Cool Temperature Scrotum contracts and draws the testes closer to the body for warmth. Warm Temperature Scrotum becomes very loose and allow the testes to hand further away from the near of the body. High temperature can cause delicate sperm cell to die.  Testes Two ovoid glands, 2 to 3 cm wide that lie in the scrotum (walnut size)  Surrounded by 2 tunics: Tunica vaginalis Derived from the parietal peritoneum. Tunica albuginea Feel smooth and are freely movable within the scrotum. In most males, one testis is slightly larger than the other and is suspended slightly lower in the scrotum than the other (usually the left one) for less possibility of trauma to them Spermatozoa do not survive at the body temperature It is suspended outside the body where the temperature is approximately 1 F lower than the body temperature and sperm survival is ensured  Each testis is encased by a protective white fibrous capsule and is composed of a number of lobules, each lobule containing interstitial cells (Leydig’s Cell) and seminiferous tubules. SeminiferousTubules -Produce spermatozoa Leydig’s Cell -Responsible for producing of the male hormone testosterone. Male Internal Structures  Epididymis seminiferoustubule of each testis leads to a tightly coiled tube, the epididymis Approximately 20 ft long Site of sperm maturation and storage Responsible for conducting sperm from the testis to the vas deferens Contains smooth muscle to propel sperm during ejaculation Sperm are immobile and encapable of fertilization as they passed or are stored at the epididymis level Ittakes 12-20 days to travel the length of the epididymis A total of 64 days to reach maturity Aspermia – absence of sperm Oligospermia – less than 20 million per mL These are problems that do not appear to respond immediately to therapy but rather only after 2 months  Vas Deferens (Ductus Venosus) It carries sperm from epididymis through the inguinal canal into the abdominal cavity where it ends at the seminal vesicles and ejaculatory ducts. It is about 40cm long The vas deferens serves a transport function and the area of the ampulla serves as astorage reservoir of sperm for release at ejaculation. Sperm mature as they passed through the vas deferens It is believed that the vas deferens acts as reservoir for sperm between ejaculation  Seminal Vesicles 2 convoluted pouches that lie along the lower portion of posterior surface of the bladder and empty into the urethra by way of ejaculatory ducts  Secrete seminal fluid  Sperm become increasingly motile because of viscous portion of the semen secreted by these glands which serves as nutrients and more favorable pH) Ejaculatory ducts These are formed by the fusion of the vas deferens and the seminal vesicles. The ejaculatory ducts empty into the urethra. The ejaculatory ducts are part of the human male anatomy, which cause the reflex action of ejaculation. Each male has two of them.  They begin at the vas deferens, pass through the prostate, and empty into the urethra at the Colliculus seminalis. During ejaculation, semen passes through the ducts and exits the body via the penis.  Prostate Gland  a chest-nut size gland that lies just below the bladder, the urethra passes through the center of it, like the whole donut  When added to the secretion from the seminal vesicles and the accompanying  sperm from the epididymis, this alkaline fluid further protects sperm from being immobilized by the naturally low pH level of the urethra Bulbourethral Glands - 2 bulbourethral or Cowper’s gland lie beside the prostate gland and by short ducts empty into the urethra  Secrete an alkaline fluid that helps counteract the acid secretions of the urethra and ensure the passage of spermatozoa Produce small droplets of fluid during sexual activity that neutralizes the acidity of the male urethra and aid in the transport of sperm 5% semen  Urethra a hollow tube leading from the base of the bladder, which after passing through the prostate gland continues to the outside through the shaft and glans of the penis 3 sections Prostatic Within the prostate Membranous Within the urogenital diaphragm Penile (spongy) Within the penis  The seminal vesicles, prostate gland and Cowper’s gland produce a liquid called a seminal plasma. Seminal Plasma Aids in the transport of sperm Provides energizing nutrients for the sperm Contains form of sugar – fructose, mucous, salts, water, base buffers and coagulators to aid the sperm in their journey. The sperm collectively make up the semen.  Semen / seminal fluid  Thick, creamy white fluid with the consistency of mucus or egg whites  Normal amount is 2 mL – 6 mL per ejeculation  Fertile man will dispel 20-160 million sperm per ejaculate.  Spermatozoon – is made up of a head and a tail - the head carries the male’s haploid number of chromosomes (23) - the part that enters the ovum at fertilization - the tail specialize in motility ▪sperm maybe stored in the male genital system for 42 days ▪sperm can live only 2-3 days in the female genital tract once ejaculated.