KULIAH 2 Sistem Reproduksi Overview

8/15/2019 KULIAH 2 Sistem Reproduksi Overview

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REPRODUCTION SYSTEM

Overview


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How does the human reproductive

system work?

• Mammals, including humans produce

gametes in paired organs called gonads

• In males: testes (singular = testis);

produce sperm

•In females: ovaries;produce eggs


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Human male reproductive tract


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Testes (in scrotum)

SpermTestosterone


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Accessorystructures

Seminal vesicles

Prostate glandBulbourethral gland

(together producesemen)


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Accessorystructures

Epididymis

(sperm storage)


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Accessorystructures

Vas deferens

(connects testes to

urethra)



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Testes produce sperm &testosterone

Sperm production occurs

in seminiferous

tubules


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in seminiferous

tubules

At puberty, testosterone

production begins

in interstitial cells


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in seminiferous

tubules

Sertoli cells regulate

sperm production &

nourish developing

sperm


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in seminiferous

tubules

Spermatozoa are

produced by

spermatogonia


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The Seminiferous Tubules


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The Seminiferous Tubules


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Spermatogenesis

Spermatogonia (2n) either undergo mitosis toproduce new spermatogonia, or undergo meiosis toproduce sperm (1n)


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Spermatogenesis


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Spermiogenesis and SpermatozoonStructure


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Human sperm – almost no cytoplasm;carries male DNA to egg DNA

HeadNucleus – DNAAcrosome –

Enzymes


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Enzymes

MidpieceMitochondria –

Energy


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Enzymes

MidpieceMitochondria –

Energy

TailFlagellum –

Propeller


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• Seminal vesicles Active secretory gland Contributes ~60% total volume of semen Secretions contain fructose,

prostaglandins, fibrinogen• Prostate gland

Secretes slightly acidic prostate fluid

• Bulbourethral glands Secrete alkaline mucus with lubricating

properties

Accessory glands


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• Typical ejaculate = 2-5 ml fluid Contains between 20 – 100 million

spermatozoaper ml

• Seminal fluid A distinct ionic and nutritive glandular

secretion

Contents of Semen


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Human female reproductive tract


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OvariesEggsEstrogen / progesterone

Accessory structuresreceive & move spermto egg & nourishdeveloping embryo

Vagina – receivessperm

Fallopian tubes–

site of fertilizationUterus – site of

development ofembryo

fimbriae

cervix

Fallopian tubes,

a.k.a . uterine tubes,

a.k.a . oviducts

ovaryuterus

vagina



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OvariesEggsEstrogen / progesterone

Accessory structuresreceive & move spermto egg & nourishdeveloping embryo

Vagina – receivessperm

Fallopian tubes–

sites of fertilizationUterus – site of

development ofembryo

fimbriae

cervix

Fallopian tubes,

a.k.a . uterine tubes,

a.k.a . oviducts

ovaryuterus

vagina



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•

During embryonic development, the female’slifetime supply of eggs are formed.

• Just before birth, the eggs develop to acertain size and then enter a resting stage

until puberty.• At birth, a female’s ovaries contain 1 million

eggs.

O i f ti f ll i


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Oogenesis – formation of egg cells viameiosisIt has long been thought that women have

all their primary oocytes (halted atProphase of Meiosis I) by

the time they are born


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Oogenesis


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• Ovulation occurs on approximately the 14th day

of the menstrual cycle.• Can be divided into four stages in terms of

ovarian activity.

Menstrual phaseProliferative (follicular) phase

(preovulatory)

OvulationSecretory (luteal) phase (postovulatory)


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• Increased levels of estradiol (or estrogen) inblood causes the pituitary gland to secreteLH.

• LH causes the follicle to rupture.

• The egg is released into the end of thefallopian tube and is moved along by ciliatedcells in the lining.

M thl t l l di t


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Monthly menstrual cycle coordinates:1) maturation of several eggs2) release of one egg3) preparation of the uterine lining forpossible pregnancy


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Hormonal control of the menstrual cycle:Hormones from the brain’s “master gland” (pituitary)initiate development of egg-bearing follicles in the

ovary

H l t l f th t l l


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Hormonal control of the menstrual cycle:Estrogen produced by egg-bearing follicles

stimulates the growth of the uterine lining


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Hormonal control of the menstrual cycle:Ovulation occurs on about day 14; remnants ofruptured follicle become the corpus luteum, which

produces both estrogens and progesterone

Hormonal control of the menstrual cycle:


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Hormonal control of the menstrual cycle:Combination of estrogens + progesterone:

1) Inhibits hormone release from pituitary,

preventing development of more follicles2) Stimulates further growth of uterine lining

Hormonal control of the menstrual cycle:


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Hormonal control of the menstrual cycle:If pregnancy does not begin:

1) The corpus luteum breaks down

2) Estrogens & progesterone levels fall3) Uterine lining is shed as menstrual flow


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• Myometrium –

outer muscular layer• Endometrium – a thin, inner, glandular

mucosa

• Perimetrium –

an incomplete serosacontinuous with the peritoneum

Uterine wall consists of three layers:

The Uterine Wall


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The Uterine Wall


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• Repeating series of changes in theendometrium• Continues from menarche to

menopause

• Menses• Degeneration of the endometrium• Menstruation

• Proliferative phase• Restoration of the endometrium

• Secretory phase• Endometrial glands enlarge and

accelerate their rates of secretion

Uterine cycle

Th Ut i C l


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The Uterine Cycle


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Fertilization may lead to pregnancy…

Sperm deposited in the vagina during copulation

swim through the uterus into the Fallopian tubes,where they may encounter an egg

Oocyte (egg)

SpermSperm

Sperm

Sperm

Fertilization may lead to pregnancy


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Sperm release enzymes that break down the

barriers around the egg (corona radiata and

zona pelucida)

Corona radiata – layer ofaccessory cells around egg

Zona pellucida –

jelly-like layeraround e

oocyte

Fertilization may lead to pregnancy


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Fusion of the nuclei of an egg and one sperm

(fertilization) produces a zygote

Corona radiata – layer ofaccessory cells around egg

Zona pellucida –

jelly-like layeraround e

oocyte

If b i th b t


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If pregnancy begins, the embryo secretes ahormone that prevents the breakdown of the

corpus luteum


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M t t t d t t th f


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Most pregnancy tests detect the presence of ahormone produced by the embryo – and present

in the woman’s urine

Fetal development


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Fetal development…• The inner wall of the uterus together with embryonic tissues

become the placenta, which transfers oxygen, carbon dioxide,

nutrients and wastes between the mother and the developing fetus

Umbilical cord

Fetalcapillaries

Maternal blood

pools

Umbilical cord

Maternal portion

of placenta

Fetal portion of

placenta (chorion)

Maternal

arteries

Maternal

veins

Placenta

Uterus


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Journey of Ovum

Ovum

Zygote

Mature ovum in

follicle

Menstrual Disorders


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Menstrual Disorders

• Amenorrhea

• Absence of menstrual flow• Dysmenorrhea

• Pain during or shortly before menstruation

• PMS

• A complex, poorly understood condition thatincludes a number of cyclic symptoms

occuring in the luteal phase of the menstrualcycle

Endometriosis


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Endometriosis

• Characterized by the presence and growth of

endometrial tissue outside of the uterus.• Tissue may be implanted on the ovaries, cul-

de-sac, uterine ligaments, rectovaginal

septum, sigmoid colon, pelvic peritoneum,cervix, and inguinal area.

Dysfunctional Uterine Bleeding


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•

Oligomenorrhea / Hypomenorrhea• Cause: physical (hypothalamic, pituitary,

ovarian function, oral contraceptives) orpsychological

• Rx: aimed at reversing the underlyingcause (hormonal therapy is often thetreatment of choice). Counseling may beindicated.



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•

Metrorrhagia• Intermenstrual bleedings. Any episode of

bleeding, whether spotting, menses, orhemorrhage, that occurs at a time other

than the normal menses.• Cause: hormonal, oral contraceptives, IUD,

pregnancy.

•

Rx: depends on cause.



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• Menorrhagia

• Excessive menstrual bleeding, in eitherduration or amount.

• Causes: hormonal disturbances, systemic

disease, benign & malignant neoplasms,infection, and contraception (IUDs).

• Rx: education about contraceptionmethods; medical & surgical management offibroids.



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• Abnormal Uterine Bleeding:

• Any form of uterine bleeding that isirregular in amount, duration, or timing andnot related to regular menstrual bleeding.

•

Causes: anovulation; pregnancy-relatedconditions; lower reproductive tractinfections; neoplasms; trauma; systemicdiseases; iatrogenic causes. Refer to box

7-1 in text (p.167).• Rx: dependant on cause.

Menopause


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Menopause

• Perimenopause: the period that encompasses

the transition from normal ovulatory cycles tocessation of menses and is marked by irregularmenstrual cycles.

• Menopause: refers to the complete cessation

of menses and is a single physiologic event saidto occur when women have not had menstrualflow or spotting for 1 year & can be identifiedonly in retrospect.

• Postmenopause: the time after menopause.

Osteoporosis


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Osteoporosis

• A generalized, metabolic disease

characterized by decreased bone mass andincreased incidence of bone fractures.

• Affects >25 million women loder than 45 years old, in the US.

• Approximately 50% of American women havesome degree of osteoporosis. 1 out of 2 havechanges severe enough to predispose them to

fractures.

NOTE:


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NOTE:

• Alternative therapies are beneficial in

relieving discomforts associated withmenstrual disorders and menopause.

• Osteoporosis, a progressive loss of bone mass

that results from decreasing levels ofestrogen after menopause, can be preventedor minimized with lifestyle changes andmedication.

NOTE:


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NOTE:

• Estrogen increases calcitonin levels toprevent bone resorption and maintain bonedensity.

• Sexuality and the ability for sexual

expression continue after menopause.


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Surgical Means of Birth Control

• MaleVasectomy – surgically taking portion

of vas deferens out

• FemaleTubal sterilization – surgically taking

portion of fallopian tubes out

Hysterectomy – removing all or part ofuterus and ovaries


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KULIAH 2 Sistem Reproduksi Overview

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