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Biology 30 Human Reproduction & Development. Anatomy of the Male and Female Reproductive Systems Gamete Formation Hormonal Control of Reproduction Conception, Pregnancy, Development, Birth. Biology 30. Male Reproductive Anatomy. You solve the problem. - PowerPoint PPT Presentation
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Biology 30Human Reproduction
& Development Anatomy of the Male and Female
Reproductive Systems Gamete Formation
Hormonal Control of Reproduction Conception, Pregnancy, Development, Birth
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Biology 30
Male Reproductive Anatomy
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You solve the problem. “Recently I have experienced my right
testicle slipping upwards into my body and ‘disappearing’. It can be felt through the skin, and then can be slid back down. The only pain is a dull ache that ensues. It seems to require some pressure on the scrotum to occur, such as my wife being ‘frisky’. Is there a term and/or a treatment for this? Is it serious?”
December 7, 1999
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External genitalia– Penis and Scrotum
Internal Reproductive Organs– Pair of gonads
Produce gametes (sperm cells) Produce hormones
– Accessory glands Secret products essential to sperm
movement– Set of ducts
Carry sperm and glandular secretions.
Anatomy of the Male Reproductive System
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Penis– Composed of 3 cylinders of spongy
tissue.– During sexual arousal, tissue fills with
blood from the arteries The increasing pressure seals off the veins
that drain the penis– Result = penis engorges with blood = erection
– The tip (Glans) is covered by a fold of skin called the foreskin, which may be removed by circumcision A tradition with religious roots. No verifiable health or hygienic advantage.
Anatomy of the Male Reproductive System
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Scrotum– Sac which contains testes– Regulates temperature of testes by
contraction of cremaster muscle. Cold = contracts
– Brings testes close to body to warm up. Warm = relaxes Goal = keep testes 3o below normal body
temperature.
Anatomy of the Male Reproductive System
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Testes– Stored in scrotum
Before birth, testes develop in the abdomen and then migrate down a canal into scrotum around the time of birth.
– Sperm producing organ Made in tightly coiled tubes called seminiferous
tubules inside testes Sperm produced is not fully mature when it leaves
testis (not motile yet)– Source of male hormone testosterone
Made by interstitial cells scattered between the seminiferous tubules
– Deposits sperm into epididymis
Anatomy of the Male Reproductive System
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Epididymis– Coiled tubes– About 6 meters long!!– Posterior to the testis– Stores sperm– Site of further sperm maturation
Gains motility– Contracts during ejaculation, expelling
sperm into vas deferens– Sperm can be store here for months
If not ejaculated, will eventually be phagocytized
Anatomy of the Male Reproductive System
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Vas Deferens– Muscular tubes that carry sperm from
epididymis to ejaculatory duct (and eventually the urethra) peristalsis
– Urethra drains both the excretory system and the reproductive system Not the case in females
Anatomy of the Male Reproductive System
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Ejaculatory Duct– Connects seminal vesicle to urethra– Passes through prostate gland
Anatomy of the Male Reproductive System
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Seminal Vesicle– Lies below and behind bladder– Secretes thick, clear fluid into
ejaculatory duct 60% volume of semen (the fluid that is
ejaculated) Alkaline – to neutralize acidic pH of vagina Fructose – used for energy by sperm Prostaglandins – chemical messengers
which, once in female, stimulate uterine peristalsis to help move semen up the uterus
Proteins – cause semen to coagulate after it is deposited in the female, making it easier for the uterine contractions to move the semen
Anatomy of the Male Reproductive System
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Prostate Gland– Doughnut shaped gland which surrounds
urethra– Secretes thin milky fluid into urethra
20% of seminal volume Liquefy the semen – prevents sperm from
clumping together Alkaline – continues to neutralize acid from
residual urine in urethra and natural acidity of vagina
Prostate Source of most common medical problems of men over 40. Benign enlargement in over ½ of all men in the age group.
Anatomy of the Male Reproductive System
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Cowper’s Gland (Bulbourethral Gland)– Pair of small glands along urethra,
below the prostate– Secrete viscous fluid before emission of
sperm & semen Thought to lubricate penis and vagina
– Released before ejaculation Fluid does contain some sperm One factor in the high failure rate of the
“withdrawal method” of birth control.
Anatomy of the Male Reproductive System
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Vasectomy– Incision through scrotum– Cut and tie off vas deferens– Sperm is still produced but can’t get out– Phagocytized– Increased risk of prostate cancer
Anatomy of the Male Reproductive System
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Passageway from testes to outside1. Multiple seminiferous tubules
site of spermatogenesis2. Single tubed epididymis3. Vas deferens4. Seminal vesicle5. Ejaculatory duct6. Urethra
Anatomy of the Male Reproductive System
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For Your Information– Volume of ejaculation = 2.75 ml– pH = 7.2 – 7.6– 50 – 150 million sperm per ml.– Only a few sperm reach the egg– Average sperm count has decreased from
113 million/ml to 66 million/ml in past 40 years.
– Infertility = <20 million/ml Factors leading to infertility are
environmental toxins, estrogens in meat, radiation,pesticides, marijuana, alcohol
Anatomy of the Male Reproductive System
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Solution to the medical problem.
Remember that before birth, the testes develop in the abdomen, and then migrate down into the scrotum at birth. The pathway they follow through the layers of the abdominal wall on each side is called the inguinal canal. Usually, when the testes have completed their descent they remain permanently within the scrotum from that time on. The slightly lower temperature in the scrotum is more favorable to sperm production after puberty. Slender bundles of muscle fibers derived from the middle layer the abdominal muscle are
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Solution to the medical problem.
drawn into loops around the descending testis and form what is know as the cremaster muscle. During sexual arousal, the smooth muscle of the scrotum contracts too. As a result, the testes are transiently held in a more protected position during sexual intercourse. It is possible that your right testis has remained more mobile that usual, and is drawn back partially in the to inguinal cal by contraction of the cremaster muscle during sexual activity. This is referred to as
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Solution to the medical problem.
a “retractile testis”. If you at all concerned about this possibility, it will be worthwhile visiting your doctor to discuss the situation and whether or not any treatment is required.
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Labelling Diagram1. Pubic Bone2. Seminal Vesicles3. Rectum4. Prostate Gland5. Cowper’s Gland6. Anus7. Vas Deferens (sperm duct)
8. Epididymis9. Testes10.Urethra11.Penis12.Scrotum13.Head of Penis (Glans)14.Foreskin15.Bladder
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Biology 30
Female Reproductive Anatomy
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Consists of: External genitalia
– Two sets of labia that surround the clitoris and vaginal opening
Internal Reproductive Organs– A pair of gonads (ovaries)– A system of ducts and chambers to
Conduct the gametes House the embryo and fetus
Anatomy of the Female Reproductive System
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Ovaries– Lie in abdomen, below most of
the digestive system– Enclosed in a tough protective
capsule– Produces eggs (follicles)– Produces female sex hormones
1. Estrogen2. Progesterone
Anatomy of the Female Reproductive System
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Follicles– Consists of one egg cell surrounded by
layers of follicle cells. Nourish and protect the developing egg
cell– All of the 400,000 follicles a woman
will ever have are present at birth. Only a few hundred will be released during
a woman’s reproductive years One (very rarely 2 or more) follicle matures
and releases its egg during each menstrual cycle
Anatomy of the Female Reproductive System
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Follicles– Follicle cells release the primary
female sex hormone… estrogen. Secondary sex characteristics, wider hips, more
body fat, Necessary for breast development
– At ovulation, the egg “explodes” out of the follicle leaving behind the follicular tissue This grows into a solid mass called a Corpus Luteum
– Secretes progesterone (necessary for pregnancy)
If fertilization does not occur, the corpus luteum disintegrates and a new follicle matures the next month.
Anatomy of the Female Reproductive System
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Oviduct– Fallopian tube– Conducts eggs to the uterus– Fertilization occurs here
If embryo grows here = ectopic pregnancy– The ovary and oviduct don’t actually touch.– The egg is released into the abdominal cavity
and is “sucked” into the oviduct. Oviduct has fingers called “fimbrae” and
hairs called “cilia” that vibrate and sweep the egg into the tube by swishing body fluids towards itself
These cilia also help move the egg towards the uterus
Anatomy of the Female Reproductive System
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Uterus (womb)– Houses and nurtures the developing
fetus– Oviducts enter at the top– Cervix (opening) at the bottom– The lining is called the endometrium
Richly supplied with blood vessels Varies in thickness depending on the stage
of the menstrual cycle Controlled by hormones 2 Layers
– Basal layer = stable, does not change thickness– Functional layer = changes thickness with
menstruation
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Vagina– Birth canal– Average = 7.5 cm in length– pH = 4-5– Upper end closes at cervix– Receives penis during sexual
intercourse– Elastic to facilitate sexual intercourse
and birth
Anatomy of the Female Reproductive System
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Biology 30
Gamete Formation
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Need– The human body cell contains 46
chromosomes that are paired together 23 pairs Called diploid cells
– If 2 diploid (means 46 chromosomes) cells fuse the result would be … 92 chromosomes (46 pairs) Chromosome number would increase exponentially
– Sperm and egg must contain 23 chromosomes each in order to maintain appropriate chromosome count
– Haploid = ½ the normal chromosome count23 chromosome sperm +23 chromosome egg = 23
pairs
Gamete Formation
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Spermatogenesis– Each ejaculation = 400 million sperm– Males can ejaculate daily without loss
of fertility– Occurs in the testes
Gamete Formation
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Gamete Formation Spermatogenesis
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Gamete Formation Spermatogenesis
1. The walls of the seminiferous tubules consist of diploid spermatogonia, stem cells that are the precursors of sperm.
2. divide by mitosis to produce more spermatogonia
3. The Meiosis of each spermatocyte produces 4 haploid spermatids.
4. These then differentiate into sperm, losing most of their cytoplasm and gaining motility in the process.
In epididymis Sperm nourished by
sertoli cells (in seminiferous tubules)
Whole process takes 70 days
Gamete Formation -- Spermatogenesis
1. Takes place in ovaries2. Primary Oogonium
develop into oocytes before birth
3. Oocytes complete maturation one at a time & once a month during reproductive years
4. Primary oocyte grows larger and begins meiosis
5. Forms a secondary oocyte and first polar body
6. After fertilization, secondary oocyte completes meiosis and become 1 egg and second polar body.
Gamete Formation -- Oogenesis
Before Birth
Once a month
If Pregnant
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Follicles– Consists of one egg cell surrounded by layers
of follicle cells.– Nourish and protect the developing egg cell – Follicle cells release the primary
female sex hormone… estrogen.– At ovulation, the secondary oocyte
“pops” out of the follicle leaving behind the follicular tissue This grows into a solid mass called a Corpus Luteum
– Secretes progesterone (necessary for pregnancy)
If fertilization does not occur, the corpus luteum disintegrates and a new follicle matures the next month.
Recap of Follicles
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ReviewComplete Lessons 1 & 2
from your Unit Objectives Package