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Understand the changes in the male reproductive system during adolescence, including puberty, hormonal influence, physical changes, and the functions of testes, scrotum, seminal vesicles, prostate glands, and penis.
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Adolescence • Puberty • Burst of hormones activate maturation of the gonads: testes • Begins: 9 – 14 yrs of age • Abnormally early = precocious puberty • Delayed = eunuchoidism
General Physical Changes • Enlargement of the external and internal genitalia • Voice changes • Hair growth • Mental changes • Changes in body conformation and skin • Sebaceous gland secretions thicken/increase acne
Male Reproductive system • The scrotum • The testes • The spermatic cord • The seminal vesicles • The ejaculatory ducts • The prostate glands • The penis
The scrotum Functions: The scrotum forms a pouch in which the testes are suspended outside the body. It lies below the symphysis pubis and between the upper –parts of the thighs behind the penis.
Structure • It is formed of pigmented skin and has two compartments ,one for each testis.
The testes Function: • The testes are the male gonads and produce spermatozoa and the hormone testosterone. • Testosterone is responsible for the development of secondary sex characteristics. • Together with FSH,it also promotes production of sperm.
Position • The testes are situated in the scrotum. • In order to achieve their proper function they must be kept below body temperature, and that is why they are situated outside the body. Design Plan
Structures • Each testis is 4.5 cm long,2.5 cm wide and 3 cm thick.
The seminiferous tubules • These are where spermatogenesis or production of sperm takes place. • Between the tubules are interstitial cells that secrete testosterone. • The tubules join to form a system of channels that leads to the epididymis
Epididymis • This is a comma shaped coiled tube that lies on the superior surface and travels down the posterior aspect to the lower pole of the testis.
The seminal vesicles Function: • production of a viscous secretion to keep the sperm alive and motile.
Position • The seminal vesicles are two pouches situated posterior to the bladder. Structure • The seminal vesicles are 5 cm ,long and are pyramid shaped.
The ejaculatory ducts • These small muscular ducts carry the spermatozoa and the seminal fluid to the urethra.
The prostate glands Function: • The prostate gland produces a thin lubricating fluid that enters the urethra through ducts.
The penis Functions • It carries the urethra, which is a passage for both urine and semen. • During sexual excitement it stiffens ( an erection ) in order to able to penetrate the vagina and deposit the semen near to the women’s cervix.
consists of three columns of erectile tissue that are wrapped in connective tissue and covered with skin. The two dorsal columns are the corpora cavernosa. The single, midline ventral column surrounds the urethra and is called the corpus spongiosum.
penis • 3 parts: a root, body (shaft), and glans penis. • The root of the penis attaches it to the pubic arch • the body is the visible, pendant portion. • The corpus spongiosum expands at the distal end to form the glans penis. • The urethra, which extends throughout the length of the corpus spongiosum, opens through the external urethral orifice at the tip of the glans penis. A loose fold of skin, called the prepuce, or foreskin, covers the glans penis.
Hormones • Follicle-stimulating hormone (FSH) stimulates spermatogenesis • Interstitial Cell Stimulating Hormone (ICSH) stimulates the production of testosterone • testosterone stimulates the development of male secondary sex characteristics & spermatogenesis.
Production of sperm begins at puberty and continues throughout adult life. • Spermatogenesis takes place in the seminiferous tubules under the influence of FSH and testosterone. • The mature sperm is stored in the epididymis and the deferent duct until ejaculation
At each ejaculation , 2-4 ml of semen are deposited in the vagina. • The seminal fluids contain about 100 million sperms per ml. • The individual spermatozoan has a head, a body and a long motile tail that lashes to propel the sperm along .
The tip of the head is covered by an acrosome ; this contains enzyme to dissolve the covering of the ovum inorder to penetrate it.