Reproduction (1)

8/6/2019 Reproduction (1)

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The Human

Reproductive System


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Male Reproductive System

scrotum

testis/testes

epididymis

vas deferens

Cowpers gland

rectum

seminal vesiclesurinary bladder

prostate

gland

urethra

penis


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(frontal view)

See p. 62 in Review book


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1. Scrotum sac of skin that holds testes. Hangs

below body to keep testes cool. Sperm cannot

be produced if body is too warm. Testes move

into scrotum just before birth.

2. Testis/testes male gonads. Made up of

small, coiled tubes seminiferous tubules.

300-600 per testis. Immature sperm made

here.

Secrete testosterone


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3. Epididymis storage area in upper rear oftestis. Immature sperm move here to mature takes 18 hours.

4. Vas deferens tube that leads upwards fromeach testis into lower part of abdomen fromepididymis.

5. Cowpers gland produces fluids that nourish

sperm and protect them from the acidity offemale.

Combination of sperm and fluids - semen


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6. Rectum holds wastes

7. Seminal vesicles secretes liquid thatextends sperm life including fructose

8. Urinary bladder stores urine

9. Prostate gland controls flow of urine &secretes alkaline solution.

10. Urethra passageway for excretion ofurine and for sperm to leave body. Vasdeferens empties into urethra


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11. Penis male reproductive organ.

Facilitates internal fertilization

Ejaculation muscular contractions force

semen through urethra. Before, during

and after ejaculation reflex actions keep

outlet of bladder closed


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Hormones and Negative Feedback

inM

ales Negative Feedback change that leads to

a response that causes something to

counteract that change

Luteinizing Hormone (LH) stimulates

testes to produce testosterone

Testosterone stimulates development of

sperm. Once there is a large number of

sperm, puberty is complete.


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Hormone Negative Feedback System


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What is the effect of high levels of LH? Testosterone is produced

What is the effect of high levels of

testosterone?

Slows production of LH which in turn slowsproduction of testosterone

What is the overall outcome of this on-off

negative feedback system involving LH and

testosterone? Nearly constant level of both hormones -

homeostasis


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Male Reproductive System and

Hormones1. Explain how LH stimulates the testes to producetestosterone.

Circulates in the blood- reaches the testes targetcells stimulates them to produce testosterone

2. What happens when the levels of testosterone are toohigh in the body?

LH level drops

3. What is negative feedback and how does it maintain

homeostasis?Change in conditions triggers response in body tocounteract that condition. Keeps hormones inbalance


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Female Reproductive System

ovary

uterus

rectumcervixvagina

urethra

Urinary

bladder

oviduct


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(frontal view)

See p. 61 in Review book


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1. Ovary female gonads. Secrete

estrogen produces secondary

characteristics, menstrual cycle

Produces eggs 2 ovaries 4cms long, 2

cms wide


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Follicles each ovary contains 200,000 egg sacscalled follicles. In each follicle is an immatureegg.

All the eggs are present at birth. During thewomans lifetime 500 eggs mature

When an egg matures, follicle moves to surfaceof ovary.

Follicle breaks & releases the egg ovulationEgg can be fertilized for about 24 hours afterovulation


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2. Oviduct (fallopian tube) Each ovary isnear but not connected to oviduct. Tubewith funnel-like opening. Cilia line it to

create a current that draws the egg intothe tube. Egg is fertilized in the oviduct

3. Uterus thick, muscular, pear-shaped

organ. Once egg is fertilized it finishesits development in uterus attached touterine wall


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4. Urinary bladder storage of urine

5. Urethra passage of urine to outside of

body6. Vagina (birth canal) leads to outside of

body

7. Cervix narrow neck of uterus8. Rectum passage for wastes


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The Menstrual Cycle

What is the menstrual cycle?

Cycle during which an egg develops and isreleased from the ovary and the uterus is

prepared to receive a fertilized egg

Menarche: first menstrual period usuallyoccurs between 11 and 12

Menopause: time when a woman stopsmenstruating, usually between 45 & 55and is no longer able to conceive.


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The Menstrual Cycle


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The Menstrual Cycle

1. Menstruation: Loss of egg and uterine

tissue via vagina if fertilization does not

occur

2. Follicle Stage (follicular stage): lasts 10

days, FSH & LH levels increase, egg

matures, follicle secretes estrogen to

prepare uterus


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The Menstrual Cycle

3. Ovulation: High level of estrogen detected by

hypothalamus, increased LH, decreased FSH,

follicle bursts egg released

4. Corpus Luteum Stage (Luteal Phase): LH

converts follicle to corpus luteum secretes

estrogen & progesterone. Progesterone

prepares uterus. Increased progesterone keeps

LH & FSH low


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Hormones ofMenstrual Cycle

What happens if fertilization occurs?Corpus luteum keeps producing progesterone to maintainpregnancy. After 5 weeks the embryo producesprogesterone this inhibits LH & FSH so no menstrual

cycleWhat happens if fertilization does not occur?

There is no implantation the corpus luteum breaksdown. Progesterone level drops, uterine lining breaksdown menstruation.

FSH & LH are produced again new cycle

Average Menstrual Cycle is 28 days long


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Ovulation to Implantation

ovaryfollicle

egg from

ruptured

follicle

oviduct

uterus

cervix

vagina sperm


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1. Ovary produces estrogen &

progesterone meiosis occurs & egg

develops

2. Egg matures in follicle of ovary

3. Ovulation egg released from follicle

may live for 24 hours

- egg moves into fallopian tube by cilia


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4. Events in fallopian tube

a. Fertilization occurs here. Sperm lives 4-5

days (egg lives 1 day)

b. Zygote undergoes mitosis & travels down

fallopian tube within 6-10 days. Zygote is

ready to implant into uterus.


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End of Presentation

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