Mammalian Reproduction
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Mammalian Reproduction

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Rb2010 - group 2

Rb2010 - group 2

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Mammalian Reproduction Mammalian Reproduction Presentation Transcript

  • Mammalian Reproduction Group 2 III - Rubidium
  • Keywords glans penis Hymen Leydig cells mammary glands myotonia oogenesis orgasm ovaries oviduct/Fallopian tubes ovulation penis prepuce prostate gland scrotum semen seminal vesicles seminiferous tubules Spermatogenesis testis urethra uterus vagina vas deferens vasocongestion acrosome baculum Bartholin’s glands bulbourethral gland cervix clitoris coitus corpus luteum ejaculation endometrium epididymis follicle
    • Human reproduction involves intricate anatomy and complex behavior
  • Male reproductive system
    • External reproductive organs
      • scrotum
      • penis
    • Internal reproductive organs
      • gonads - produce gametes and hormones
      • accessory glands - secrete products essential to sperm movement
      • ducts - carry sperm and glandular secretions
    • Testes
      • male gonads
      • seminiferous tubules
        • highly coiled tubes where sperm form
      • Leydig cells
        • scattered between the seminiferous tubules
        • produce testosterone and other androgens, which are the male sex hormones.
    • Scrotum
      • a fold of the body wall
      • holds the testes of animals that are located outside of the abdominal cavity
    • Epididymis
      • bundle of coiled tubes
      • it takes about 20 days for sperm to pass through the 6-m-long tubules of each epididymis of a human male
      • Here, sperm become motile and gain the ability to fertilize
    • Vas Deferens
      • 2 muscular ducts.
      • run from the scrotum around and behind the urinary bladder, where each joins a duct from the seminal vesicle, forming a short ejaculatory duct.
    • Ejaculatory Duct
      • mixes the sperm stored in the ampulla with fluids secreted by the seminal vesicles
      • transports these substances to the prostate.
    • Accessory Glands
      • seminal vesicles
      • prostate
      • bulbourethral glands
    • Prostate Gland
      • The largest semen-secreting gland.
      • secretes its products directly into the urethra through several small ducts.
    • Erectile Tissue
      • The human penis is composed of three cylinders of spongy erectile tissue derived from modified veins and capillaries.
    • Bulbourethral Glands
      • A pair of small glands along the urethra below the prostate
      • Before ejaculation they secrete clear mucus that neutralizes any acidic urine remaining in the urethra.
    • Prepuce
      • Covers the human glans
      • Also caled foreskin
      • Removed during circumcision
    • Glans penis
      • The head of the penis
    • Baculum
      • A bone possessed by certain mammals, such as rodents, raccoons, and walruses
      • contained in, and helps stiffen, the penis
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  • Female reproductive system
    • External reproductive structures :
      • clitoris,
      • two sets of labia (surrounds clitoris and vaginal opening)
    • Internal reproductive structures:
      • Pair of gonads
      • system of ducts and chambers (carry gametes and house the embryo and fetus)
    • Ovaries
      • lie in abdominal cavity
      • attached to uterus through a mesentery
      • enclosed in tough protective capsule and contains plenty of follicles
        • Follicle
          • an egg cell nourished and protected by one or more layers of follicle cells surrounding it
          • usually one follicle matures and releases its egg cell during each menstrual cycle-produce estrogens (primary female sex hormones)
        • Ovulation
          • the process by which an egg cell is released from the follicle
        • corpus luteum ("yellow body")
          • solid mass formed by remaining follicular tissue that grew in the ovary
          • secretes additional estrogen and progesterone (hormone responsible for maintaining the uterine lining during pregnancy)
          • the corpeus luteum disintegrates when the egg cell is not fertilized
    • Oviduct (fallopian tube)
      • funnel like opening
      • cilia on the epithelium lining the duct help collect the egg cell
      • cilia also convey the egg down towards the uterus (womb)
    • Uterus
      • thick, muscular organ that expands during pregnancy
        • Endometrium
          • inner lining of the uterus, richly supplied with blood vessels
        • Cervix
          • neck of the uterus
    • Mammary Glands
      • present in both sexes, but functional only in women
      • not part of reproductive system
      • has small sacs of epithelial tissue that secrete milk that are drained through ducts that lead to the nipple
    • Vagina
      • a thin-walled chamber that forms the birth canal through which the baby is born; it is also the repository for sperm during copulation
    • Vulva
      • the region of external genital organs.
    • Hymen
      • a vascularized membrane that partly covers the vaginal opening in humans
    • Vestibule
      • where the vaginal and separated urethral openings are located
    • Labia Minora
      • is composed of a air of slender skin folds which borders the vestibule
    • Labia Majora
      • is a pair of thick and fatty ridges, which encloses and protects the labia minora and the vestibule
    • Clitoris
      • found at the front end of the vestibule, it consists of a short shaft supporting a rounded glands, covered by a small hood of skin, the prepuce. It is one of the most sensitive points of sexual stimulation
    • Bartholin's Glands
      • located near the vaginal opening, which secrete mucus into the vestibule, keeping it lubricated and facilitating intercourse
  • Human Sexual Response
  • 2 Types of Physiological Reactions
    • 1. Vasocongestion
      • filling of a tissue with blood caused by increased blood flow in arteries in that tissue
      • causes the hardening of penis during erection
      • Causes the hardening of the clitoris and vaginal lubrication
      • other forms of vasocongestion:
        • blushing, swelling of nipples during sexual arousal
    • 2. Myotonia
      • increased muscle tension in both skeletal and smooth muscle
      • both skeletal and smooth muscle may show sustained or rhythmic contractions including those associated with orgasm
  • Sexual Response Cycles
    • Phase 1 - Excitement
      • Prepares vagina and penis for coitus, or sexual intercourse
      • vasocongestion is evident in:
        • erection of penis and clitoris
        • enlargement of the testes, labia, and breasts
        • vaginal lubrication
      • myotonia may occur resulting in
        • nipple erection
        • tension in the arms and legs
    • Phase 2 - Plateau
      • continues responses from excitement phase
      • breathing increases
      • heart rate increases
      • heart rate rises up to 150 bpm as an involuntary response to stimulation of autonomic nervous system
    • Phase 2 - Plateau
      • in males:
        • urinary bladder closes (to prevent urine from mixing with semen, and guard against retrograde ejaculation)
        • muscles at the base of the penis begin a steady rhythmic contraction.
        • males may start to secrete seminal fluid or pre-ejaculatory fluid 
        • Testicles rise closer to the body
    • Phase 2 - Plateau
      • in females:
        • outer third of vagina becomes vasocongested
        • inner two-thirds becomes slightly expanded
        • uterus is elevated
        • forms depression that receives sperm at the back of vagina
    • Phase 3 - Orgasm
      • characterized by rhythmic, involuntary contractions of the reproductive structures in both sexes
      • shortest phase of sexual response cycle
    • Phase 3 - Orgasm
      • in males - 2 stages:
        • Emission – contraction of the glands and ducts of the reproductive tract which forces semen into the urethra
        • Expulsion or ejaculation – occurs when urethra contracts and semen is expelled
      • In females
        • uterus and outer vagina contract, but the inner two-thirds of the vagina do not
    • Phase 3 - Orgasm
      • in both sexes, contractions occur at about 0.8-sec intervals and may involve the anal sphincter and several abdominal muscles
    • Phase 4 - Resolution
      • completes the cycle and reverses the responses of the earlier stages
      • vasocongested organs return to normal size and color, and muscles relax
      • most of the changes during resolution are completed in 5 minutes
      • loss of penile and clitoral erection may take longer
  • Structure of the sperm cell
    • Head
      • Acrosome
        • helps penetrate the egg cells with its enzymes
      • Nucleus
      • Centriole
    • Middle piece
        • contains large amounts of mitochondria that provide ATP for movement of the tail
    • Tail
  •  
  • Structure of the egg cell
    • Corona radiata
      • covering that supply vital
      • proteins to the cell
    • Zona pellucida
      • binds spermatozoa
      • required to initiate the acrosome reaction
      • used for protection.
      • very essential for the oocyte’s death and fertilization
    • Nucleolus
      • non-membrane bound structure made of protein and nucleic acid and transcribes RNA.
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