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Human Reproduction and Development Anatomy of the Male and Female Reproductive Systems Gamete Formation Hormonal Control of Reproduction Conception, Pregnancy, Development, Birth

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Male Anatomy 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.

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Male Anatomy 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.

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Male Anatomy 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 3 o below normal body temperature.

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Male Anatomy 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

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Male Anatomy 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

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Male Anatomy 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

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Male Anatomy Ejaculatory Duct Connects seminal vesicle to urethra Passes through prostate gland

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Male Anatomy 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

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Male Anatomy 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

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Male Anatomy Cowpers 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.

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Male Anatomy Vasectomy Incision through scrotum Cut and tie off vas deferens Sperm is still produced but cant get out Phagocytized

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Male Anatomy Review Passageway from testes to outside 1.Multiple seminiferous tubules site of spermatogenesis 2.Single tubed epididymis 3.Vas deferens 4.Seminal vesicle 5.Ejaculatory duct 6.Urethra

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Fun Facts 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 =

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Labelling Diagram 1.Pubic Bone 2.Seminal Vesicles 3.Rectum 4.Prostate Gland 5.Cowpers Gland 6.Anus 7.Vas Deferens (sperm duct) 8.Epididymis 9.Testes 10.Urethra 11.Penis 12.Scrotum 13.Head of Penis (Glans) 14.Foreskin 15.Bladder

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Hormonal Control Male Reproductive System Control Testosterone Primary Function Stimulate spermatogenesis Secondary Function Maturation of testes and penis Sex drive Facial hair Body hair Deeper voice Increased muscle strength Body oil secretion -- acne

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Hormonal Control Hypothalamus releases 1.Gonadotropin-Releasing Hormone (GnRH) Stimulates pituitary to release LH & FSH Pituitary releases 1.Follicle-Stimulating Hormone (FSH) Stimulates spermatogenesis by seminiferous tubules 2.Luteinizing hormone (LH) Stimulates testosterone production by interstitial cells Indirectly stimulates spermatogenesis because testosterone is required for sperm production.

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Hormonal Control LH, FSH, and GnRH concentrations in the blood are controlled by negative feedback systems

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Testosterone production Spermatogenesis

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Testosterone production Spermatogenesis

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Hormonal Control

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Female Anatomy 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

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Internal Organs

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Female Anatomy Ovaries Lie in abdomen, below most of the digestive system Enclosed in a tough protective capsule Produces eggs (follicles) Produces female sex hormones 1.Estrogen 2.Progesterone

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Female Anatomy

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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 womans reproductive years One (very rarely 2 or more) follicle matures and releases its egg during each menstrual cycle

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Female Anatomy 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.

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Female Anatomy Oviduct Fallopian tube Conducts eggs to the uterus Fertilization occurs here If embryo grows here = ectopic pregnancy The ovary and oviduct dont 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

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Female Anatomy

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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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Female Anatomy

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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

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Female Anatomy

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Gametogenesis 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) Sperm nourished by sertoli cells (in seminiferous tubules) Whole process takes 70 days Whole process takes 70 days

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Gametogenesis 1. Takes place in ovaries 2. 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.

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Hormonal Control Hypothalamus - produces releasing GnRH Anterior Pituitary secrete gonadotropic hormones. FSH - follicle stimulating hormone. LH - luteinizing hormone. Ovaries - secrete the female sex hormones. Estrogen thickening of uterine lining Progesterone matures/maintains uterine lining

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Hormonal Control FSH is released from AP Start the ripening of ovum within follicle Estrogen is produced by follicle Development of endometrium for possible pregnancy Feedback to hypothalamus to inhibit FSH and release LH

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Hormonal Control LH surge on day 14 Stimulates ovulation Conversion of follicle into corpus luteum Progesterone production Continued development of endometrium Feedback to inhibit release of LH

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Hormonal Control If no fertilization Degeneration of corpus luteum Drop in hormone level

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The 4 Phases of Menstruation

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Female Anatomy sdfsdfsdf

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Menstruation 1.Flow Phase (Menstrual Phase) Start of bleeding marks Day 1 of phase Shedding of the endometrium (uterine lining) Average = 4-5 days Sometimes up to 8 days Occurs due to low hormone levels

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Female Anatomy sdfsdfsdf 1

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Menstruation 2.Follicular Phase Occurs during day 6-13 Period of repair and thickening of endometrium.

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Female Anatomy sdfsdfsdf

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Menstruation 2.Follicular Phase Occurs during day 6-13 Period of repair and thickening of endometrium. FSH from the pituitary promotes follicle development in the ovary.

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Female Anatomy sdfsdfsdf

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Menstruation 2.Follicular Phase Occurs during day 6-13 Period of repair and thickening of endometrium. WHY?? FSH from the pituitary promotes follicle development in the ovary. As follicle develops it produces estrogen, thickening of the uterine lining LH production increase FSH production decrease

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Menstruation FSHDecrease

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3.Ovulation Phase LH causes ovulation to occur on day 14. Secondary oocyte is released from the follicle/ovary.

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Female Anatomy sdfsdfsdf

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Menstruation 4.Luteal Phase Final preparation of endometrium to receive the fertilized ovum LH stimulates development of the Corpus Luteum. causes progesterone levels to increase.

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Menstruation

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4.Luteal Phase Final preparation of endometrium to receive the fertilized ovum LH stimulates development of the Corpus Luteum. causes progesterone levels to increase. Estrogen and progesterone inhibit GnRH, thereby decreasing LH and FSH levels. This low level of hormones initiates the flow phase.

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Menstruation

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Menopause The end of a womans reproductive years Between ages of 45 55 Ovaries no longer respond to FSH & LH from AP Ovaries do not produce estrogen or progesterone Marked by circulatory irregularities (hot flashes), dizziness, insomnia, sleepiness, depression Hormone replacement therapy may help.

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