Biology 12 Unit 2: Reproduction and Development Male System
The Male Reproductive System The Testes are the primary male reproductive organs or gonads. They produce sex hormones and sperm. The Scrotum is the sac that contains the testes.
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The testes are held outside the body cavity so the testes are kept at a temperature below body temperature. Sperm cannot be produced at body temperature. ClipClip
The Vas deferens is the tube that carries mature sperm towards the urethra. The Urethra is the structure that carries urine and semen. The Ejaculatory duct and a sphincter work together to prevent urine and semen from being in the urethra at the same time.
Semen is the fluid that contains the sperm and other fluids that assist in sperm motility. The Parasympathetic nerve that leads to the penis causes the sinuses of the erectile tissue to swell with blood during sexual arousal. The arteries leading to the penis becoming dilated while the swollen tissue constricts the blood flow leaving the penis.
Impotency occurs when the male is unable to sustain an erection. There are many factors that can cause impotency. (Stress, hormonal, damage to the parasympathetic nerve, etc.)
Testes and Spermatogenesis The Sertoli cell provides nourishment for the developing sperm cells. The sperm has a much- reduced cytoplasm to increase its motility. ClipClip
The head of the sperm has an enzyme filled entry capsule called an Acrosome. Its function is to digest the outer layer of the egg so the sperm can enter during fertilization. acrosome tail midpiece head
Seminal Fluid The Seminal vesicles add fructose (for sperm nutrition) and prostaglandins to the semen (seminal fluid). The prostaglandins triggers a response in the female reproductive tract that aids in sperm motility. The Prostate gland secretes a buffer that protects the sperm in the acidic environment of the vagina.
Protection of the sperm from any acidic urine found in the urethra is provided by the mucus-rich fluid from the Cowper's (bulbourethral) gland. The secretions may also help in sperm motility. ClipClip
Hormonal Control Androsterone and Testosterone are produced in the Interstitial cells of the testes. These hormones stimulate spermatogenesis, initiate the male sex drive, direct the development of the primary sex characteristics, and influence the development of the Secondary sex characteristics during Puberty.
Anabolic Steroids are male sex hormones that have important medical uses, but are also abused by many athletes looking for shortcuts in their training. Male FSH stimulates the production of sperm. Male LH promotes production of testosterone.
A Negative-feedback mechanism controls the male reproductive system. Recall from the endocrine chapter that the pituitary produces and stores Gonadotropic hormones, which regulate the testes.
The pituitary is under control of the hypothalamus (a region of the brain - not an endocrine gland). At puberty the hypothalamus begins releasing Gonadotropin- releasing hormone (GnRH). GnRH stimulates the pituitary to release FSH and LH. ClipClip
Male Structures
Vasectomy A small incision is made in the scrotum The vas deferens is tied off in two places and a section of the vas is removed The scrotum is closed, and the procedure is repeated on the other side This procedure is done in a doctors office under local anaesthetic
Hormonal Control in MalesMales
Hormonal Control in MalesMales
Spermatogenesis