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Lec62 (reproductive system male)
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Lec62 (reproductive system male)

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  • 1. Male Reproductive System
    spermatogenesis, which means simply the formation of sperm
    (2) regulation of male reproductive functions by the various hormones
    (3) performance of the male sexual act
  • 2. MALE REPRODUCTIVE SYSTEM
    THE ORGANS AND THEIR FUNCTIONS:-
    SCROTUM:- TEMPERATURE REGULATION AND PROTECTION OF THE TESTES
    TESTES:- SPERMS PRODUCTION & THE SECRETION OF MALE SEX HORMONES
    DUCTS:- STORE & TRANSPORT SPERMS
    ACCESSORY GLANDS:- SECRETION OF THE FLUID PART OF THE SEMEN
    PENIS:- MALE ORGAN OF COPULATION
  • 3. 3
    MALE REPRODUCTIVE SYSTEM
  • 4. The testis is composed of seminiferous tubules, in which the sperm are formed
    The sperm then empty into the epididymis
    The epididymis leads into the vas deferens
    Two seminal vesicles, one located on each side of the prostate, empty into the prostatic end of the ampulla, pass into an ejaculatory duct
    The urethra is the last connecting link from the testis to the exterior
    The urethra is supplied with mucus derived from urethral glandsand also from bilateralbulbourethral glands (Cowper's glands) located near the origin of the urethra
    Physiologic Anatomy of the Male Sexual Organs
  • 5. 5
    TESTES
    SEMINEFEROUS TUBULES
    INTERSTITIAL CELLS
  • 6. Spermatogenesis
    Sequence of events by which spermatogonia are transformed into
    mature sperm orspermatozoa
  • 7. Spermatogenesis
    Spermatogonia that cross the barrier into the Sertoli cell layer become progressively modified and enlarged to form large primary spermatocytes
    Each of these, in turn, undergoes meiotic division to form two secondary spermatocytes
    After another few days, these too divide to form spermatidsthat are eventually modified to become spermatozoa (sperm)
  • 8. Spermatogenesis
    SPERMATOGENESIS: Occurs in the seminiferous tubules during active sexual life
    1º SPERMATOCYTE
    2º SPERMATOCYTE
    SPERMATIDS
    SPERMATOGONIA
    SPERMATIDS
    2º SPERMATOCYTE
    1º SPERMATOCYTE
    - The first stage is the spermatogonia migrate among Sertoli cells toward the central lumen of the seminiferous tubule
    SERTOLI CELLS: are large cells that surround the developing spermatogonia
    SERTOLI CELLS
    SPERMATOGONIA
  • 9. The Seminiferous Tubules
  • 10. Spermiogenesis
    The process by which thespermatidsalter their shape and differentiateinto sperm cellsisspermiogenesis
  • 11. Spermatogenesis & Spermiogenesis
    Takes about 2 months(64-74 days)
    Everyday a healthy adult male produces about 400 million sperms
    Sperm are mostly stored in the vas deferens. They can remain stored, maintaining their fertility, for at least a month
  • 12. Functions of Sertoli cells:
    1)Tight junctions between Sertoli cells form blood-testes barrier which maintains critical composition of tubular fluid for sperm maturation
    2) Secrete fluid for carrying sperm into the epididymis
    3) Provide nutrients for maturing sperm
    4) Secrete ABP (androgen-binding protein) that functions to maintain high levels of androgens in the tubular fluid
    5) Contain aromatase which converts androgens to estrogens
    6) Secrete inhibin
  • 13. 13
    THE SPERM
  • 14. The anterior 2/3 of the head is covered by theacrosome
    Acrosome:cap at top of sperm head, contains hyaluronidase and proteolytic enzymes, important in penetration into ovum
    Mitochondria – arranged around body
    Tail, or flagellum, undergoes whip-like movements that propel the spermthrough the female reproductive tract
    Spermatozoa - head
  • 15. Physiology of the Mature Sperm
    The activity of sperm is greatly enhanced in a neutral and slightly alkaline medium
    The activity of sperm increases with increasing temperature
    Life expectancy of ejaculated sperm in the female genital tract is only 1 to 2 days
  • 16. Function of the Seminal Vesicles
    Secretes a mucoid material containing an abundance of fructose, citric acid, large quantities of prostaglandins and fibrinogen
    The fructose considerable nutrient value for the ejaculated sperm until one of the sperm fertilizes the ovum
    Prostaglandinsare important in fertilization
  • 17. Function of the Prostate Gland
    Secretes a milky fluid that contains calcium, citrate ion, phosphate ion, a clotting enzyme, and a profibrinolysin
    A slightly alkaline characteristic of the prostatic fluid important for successful fertilization of the ovum
  • 18. Semen
    Semen is composed of the fluid and sperm
    Sperm from the vas deferens resemble about 10 per cent of the total
    Fluid from the seminal vesicles (almost 60 per cent)
    Fluid from the prostate gland (about 30 per cent)
    Small amounts from the mucous glands, especially the bulbourethral glands
    The average pH= 7.5
    Each ejaculation contains approximately 3.5 ml, about 120 million sperm/ml
  • 19. Capacitation
    Freshly ejaculated sperm do not possess the capacity to fertilize ovum
    This capacity to fertilize is acquired in the female genital tract, and, appears to involve a reversal of inhibitory factors secreted by the epididymis
  • 20. Acrosome Reaction
    Upon contact with the ovum, the acrosomal cap binds with the cell membrane of the ovum
    This allows release of digestive enzymes, which digest the cell membrane of the ovum allowing the sperm contents to enter
  • 21. Hormonal Factors That Stimulate Spermatogenesis
    Testosterone: secreted by the Leydig cellsis essential for growth and division of the testicular germinal cells, which is the first stage in forming sperm
    Luteinizing hormone: secreted by the anterior pituitary gland, stimulates the Leydig cells to secrete testosterone
    Follicle-stimulating hormone: stimulates the Sertoli cells; which stimulate the conversion of the spermatids to sperm
    Estrogens: formed from testosterone by the Sertoli cells when they are stimulated by follicle-stimulating hormone
    Growth hormone: Growth hormone promotes early division of the spermatogonia themselves
  • 22. Hormonal Feedback and the Regulation of the Male Reproductive Function
  • 23.
  • 24. Testosterone Secretion and Other Male Sex Hormones
    The testes secrete several male sex hormones, which are collectively called androgens, including testosterone, dihydrotestosterone, and androstenedione.
    Testosterone is formed by the interstitial cells of Leydig
    Leydig cells are almost nonexistent in the testes during childhood
    Leydig cells numerous in the newborn male infant for the first few months of life and in the adult male any time after puberty
  • 25. Different stages of male sexual functions: plasma testosterone and sperm production
  • 26. Functions of Testosterone
    1. fetal development:present at 2nd month of embryonic life
    presence or absence of testosterone determines
    development of genital organs and characteristics
    2. causes descent of testes into scrotum during last 2-3 months of
    pregnancy
  • 27. Functions of Testosterone
    adult primary and secondary characteristics:
    1)body hair distribution
    (pubis, face, chest, back, etc)
    2) voice: hypertrophy of laryngeal mucosa and larynx
    3) skin: thickens skin and
    increases ruggedness of subcutaneous tissues,
    sebaceous glands and oil production
    4) muscle development
  • 28. Functions of Testosterone
    5) bone growth and calcium retention: thought to inhibit production of osteoclasts
    6) red blood cells – causes increases in erythropoeitin –stimulates RBC production
    7) stimulates sodium and water reabsorption in DT of kidney
  • 29. BODY OF PENIS IS MADE FROM THREE COLUMNS OF ERECTILE TISSUE:-
    TWO CORPORA CAVERNOSA
    ONE CORPUS SPONGIOSUM
    GLANS PENIS IS MADE BY EXPANSION OF THE CORPUS SPONGIOSUM.
    PREPUCE IS A SKIN SHEATH COVERING THE GLANS PENIS.
    PENIS
  • 30. Male Sexual Response
    Erection: controlled by parasympathetic nervous system
    activity to penile arterioles = vasodilation of the
    arterioles and erection
    Parasympathetic release NO in addition to Ach
    - NO relaxes the arteries of the penis
    - relaxes the trabecular meshwork of smooth muscle
    fibre in the erectile tissue
    Of the corpora cavernosa and corpus spongiosum
    –veins are compressed causing reduction in venous
    return
  • 31. Male Sexual Response
    Emission: movement of ejaculate into proximal part of urethra
    under sympathetic control – causes sequential peristaltic
    contraction of smooth muscle of vas deferens
    –closing of bladder sphincter
    Ejaculation: spinal reflex – triggered by entry of semen into
    urethra causes nerve impulses to activate perineal muscles
    – forcibly expel semen from urethra
    Orgasm: culmination of sexual excitation
    At its termination, the male sexual excitement disappears entirely
    Within 1 – 2 minutes
  • 32. The Penis