Mammalian Reproduction
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Transcript of Mammalian Reproduction
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Mammalian Reproduction
Group 2
III - Rubidium
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Keywords
glans penisHymenLeydig cellsmammary glandsmyotoniaoogenesisorgasmovariesoviduct/Fallopian tubesovulationpenisprepuce
prostate glandscrotumsemenseminal vesiclesseminiferous tubulesSpermatogenesistestisurethrauterusvaginavas deferensvasocongestion
acrosomebaculumBartholin’s glandsbulbourethral glandcervixclitoriscoituscorpus luteumejaculationendometriumepididymisfollicle
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Human reproduction involves intricate anatomy
and complex behavior
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Male reproductive system
External reproductive organs scrotumpenis
Internal reproductive organsgonads - produce gametes and hormonesaccessory glands - secrete products
essential to sperm movementducts - carry sperm and glandular
secretions
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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
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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.
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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.
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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.
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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)
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Ovaries lie in abdominal cavityattached to uterus through a mesenteryenclosed in tough protective capsule and
contains plenty of follicles
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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
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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
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Mammary Glandspresent in both sexes, but functional only in
womennot part of reproductive systemhas small sacs of epithelial tissue that
secrete milk that are drained through ducts that lead to the nipple
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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.
Hymena vascularized membrane that partly covers
the vaginal opening in humans
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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
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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
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Human Sexual Response
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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
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2. Myotonia increased muscle tension in both skeletal
and smooth muscleboth skeletal and smooth muscle may show
sustained or rhythmic contractions including those associated with orgasm
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Sexual Response Cycles
Phase 1 - ExcitementPrepares 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
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Phase 2 - Plateau continues responses from excitement
phasebreathing increasesheart rate increasesheart rate rises up to 150 bpm as an
involuntary response to stimulation of autonomic nervous system
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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
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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
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Phase 3 - Orgasm characterized by rhythmic, involuntary
contractions of the reproductive structures in both sexes
shortest phase of sexual response cycle
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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
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Phase 3 - Orgasm in both sexes, contractions occur at about
0.8-sec intervals and may involve the anal sphincter and several abdominal muscles
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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
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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
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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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