he reproductive system is a collection of internal and external organs — in both males and females — that work together for the purpose of procreating, according to the Cleveland Clinic. Due to its vital role in the survival of the species, many scientists argue that the reproductive system is among the most important systems in the entire body.
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Human Reproductive system: Anatomy and physiology
1. Prof. Amol B Deore
MVP’s Institute of Pharmaceutical Sciences, Nashik
India
2. Reproduction
It is the process by which our genetic material is passed on
from one generation to the next generation. This maintains
continuation of the species. It involves passing of genetic
material from parent cells to daughter cells.
This process requires the sperm from the male and the egg
from the female. The fertilization is the process of union of
a male sperm and female ovum to produce a fertilized egg,
or zygote.
When fertilization occurs, the zygote will possess 46
chromosomes (an ovum carrying 23 chromosomes and the
sperm carrying 23).
3. MALE REPRODUCTIVE SYSTEM
The male reproductive system consists of the testes, a
series of ducts and accessory glands. Sperms are produced
in the testes and are transported through the reproductive
ducts: epididymis, deferent duct, ejaculatory duct, and
urethra respectively.
The accessory glands produce secretions that become part
of semen, the fluid that is ejaculated from the urethra.
These glands are the seminal vesicles, prostate gland, and
bulbourethral glands (refer figure).
4. Organs of the Male Reproductive System
Scrotum
Penis
Testes
epididymis,
Deferent duct,
Ejaculatory duct,
Seminal vesicles, prostate gland,
and bulbourethral glands
Urethra
5.
6. SCROTUM
Scrotum is the loose pouch-like sac of skin that covered to
the testes between upper thighs. Scrotum hangs behind
and below the penis. The scrotum controls temperature for
of testes. The temperature within the scrotum is about
96˚̊F, slightly lower than body temperature, which is
necessary for the production of viable sperm.
7. PENIS
The penis delivers sperms into the vagina of female
reproductive tract. It is cylindrical in shape and consists of
head (or glans penis), body, and root. Glans penis is
covered with loose skin called the prepuce (or foreskin).
Internally, it is composed of three cylindrical masses of
spongy tissue containing blood sinuses.
When blood flow through these sinuses is minimal, the
penis is loose and soft. Sexual stimulation triggers the
dilation of the blood arteries in the penis. The blood
sinuses fill with blood, and the penis becomes erect,
enlarge, stuff and firm. The erect penis is capable of
penetrating the female vagina to deliver sperm and
semen during sexual intercourse.
8.
9. TESTES
Each testis is covered by a capsule of connective tissue
called the tunica albuginea, which extends inward to
form a series of compartments called lobules (refer
fig). Each lobule contains one to three convoluted
seminiferous tubules in which spermatogenesis
occurs. Spermatogenesis begins from spermatogonia.
It divided to form primary spermatocytes.
Primary spermatocytes divided to form secondary
spermatocytes that develop into spermatids.
Spermatids develop into mature sperm cells (or
spermatozoa).
In the lobules, sertoli cells supply nutrients to the
developing sperm cells. Leydig cells produce the male
sex hormone testosterone.
10.
11.
12. EPIDIDYMIS
The sperm that produced from the testes are immature
and unable for fertilization; therefore the epididymis
performs maturations of the sperm. During sexual
stimulation, epididymis transports the sperm into the
deferent duct.
DEFERENT DUCT
The deferent duct transports mature sperm to the
urethra, the tube that carries urine or sperm to outside
of the body, in preparation for ejaculation.
13. EJACULATORY DUCTS
These are formed by the union of the deferent duct
and the seminal vesicles. The ejaculatory ducts
transport the sperms to the urethra.
URETHRA
The urethra is the tube that carries urine from the
bladder to outside of the body. In males, it has the
additional function of ejaculate semen when the man
reaches orgasm.
14. ACCESSORY GLANDS
The accessory glands secrete the liquid portion of the
semen, the sperm-containing fluid called semen
which is produced during ejaculation. The accessory
glands are seminal vesicles, prostate gland and
bulbourethral gland
15. SEMINAL VESICLES
The seminal vesicles are sac-like pouches that attach to the
vas deferens. The seminal vesicles produce a fructose-rich
fluid that provides a source of energy for sperm motility.
The fluid of the seminal vesicles makes up most of the
volume of a man's ejaculatory fluid i.e. semen.
PROSTATE GLAND
The prostate gland is located below the urinary bladder.
The prostate gland secretes the semen to permit sperm
motility. Prostate fluids also help for nourishment of the
sperms.
16. BULBOURETHRAL GLANDS
They are also named as Cowper's glands, located on
the sides of the urethra just below the prostate gland.
These glands produce a clear, slippery fluid that
empties directly into the urethra. This fluid serves to
lubricate the urethra and to neutralize any acidity that
may be present due to residual drops of urine in the
urethra.
17. SEMEN
Semen is an alkaline milky sticky fluid containing
mixture of sperm cells and the secretions of the
seminal vesicles, the prostate, and the
bulbourethral glands.
The semen a transports, provide nutrients to the
sperms in the male urethra and female vagina. It
provides a transport medium for the swimming sperm.
Typical ejaculate is 2.5 to 5 ml in volume
Normal sperm count is 50 to 150 millions/mL
18. Composition of semen
The semen is comprise of fructose, antibiotic
seminalplasmin, hyaluronidase enzyme,
acid phosphatase enzyme, prostaglandins, lysozymes,
citric acid and certain clotting factors.
19. Sperms
Sperm production begins at puberty (10 to 14 years of
age), and millions of sperm are formed each day in the
testes. Sperms mature at the rate of about 300 million
per day and once released cannot survive more than 48
hours within female reproductive tract. A sperm cell is
composed of head, a mid-piece and tail.
The head contains the nuclear material (DNA) and a
lysosome like structure called acrosome which
contains enzymes hyaluronidase and proteinases
that help in penetration of sperms in the female egg.
20. Mid-piece containing mitochondrion provides ATP
energy for movement of sperms in female reproductive
tract. The tail helps to propel the sperms along its way.
Sperm Count: average range of sperms is about 50 to
100 million per mL of semen.
21. PUBERTY
Puberty is the development of secondary sexual
characteristics in male at age of 14-15 years due to
increased secretion of GnRH, FSH, LH and testosterone
hormones.
Physical and psychological maturity changes are as
follows:
Increase in rate of production and maturation of sperms
in the testes i.e. spermatogenesis.
Enlargement of testes and penis.
Increased in size of prostate gland, seminal vesicles and
bulbourethral gland.
Enlargement of the larynx and thickening of the vocal
cords results in a deep voice.
22. Growth of hairs on face (beard), chest, underarm,
abdomen and pubis.
Growth of the muscle & bone and marked increased in
height and weight.
Increased protein synthesis in skeletal muscles.
The skin thickens and become more oily.
It stimulates aggressive behavior.
It controls the development, growth, and maintenance
of the male sex organs.
It stimulates sex drive and desire.
23. DISORDERS
Male infertility
Infertility is an inability to fertilize a secondary oocyte
when the sperm count falls below 20 million per mL of
semen in the male. Then male is considered to be infertile.
Male fertility requires production of adequate quantities of
normal sperm count by testes, transportation of sperms
through the ducts and satisfactory deposition in the vagina.
The main causes of male infertility include: X-rays,
infections, malnutrition, significantly higher than normal
temperature of scrotum. These factors may cause
degenerative changes and produce male infertility.
24. Impotent
Impotency is an inability of penis erection
(enlargement and stiffness) long enough for sexual
intercourse. Such male is considered to be impotent. It
may be due constriction of blood sinuses in penis.
The main causes of impotency include diabetes
mellitus, physical abnormality of penis, syphilis,
neurological disturbances, testosterone deficiency and
certain medicines including alcohol, antidepressants,
antihypertensive, narcotics etc.
27. The term vulva refers to the external genitalia of the
female (refer fig15.5). The following components comprise
the vulva:
Mons pubis: It is an elevation of adipose tissue covered by
skin and coarse pubic hair that cushions the pubic
symphysis.
Labia majora: From the mons pubis, two longitudinal
folds of skin are referred as labia majora. They are covered
by pubic hair and contain an adipose tissue, sebaceous (oil)
glands, and apocrine sweat glands.
Labia minora: Medial to the labia majora, two smaller
folds of skin called the labia minora. They are covered by
many sebaceous glands.
28. Clitoris: The clitoris is a small cylindrical mass
composed of two small erectile bodies. The clitoris is
located at the anterior junction of the labia minora.
The clitoris is like to the glans penis in males. The
clitoris is capable of enlargement upon in sexual
excitement in the female.
Vestibule: The region between the labia minora is the
vestibule. Within the vestibule are the hymen, the
vaginal orifice, the external urethral orifice, and the
openings of the ducts of Bartholin’s glands.
29. The main internal structures of the female
reproductive system include:
The vagina
The uterus
The ovaries
The Uterine or fallopian tubes
30.
31. VAGINA
The vagina is a muscular tube about 4 inches (10 cm) long that extends from the
cervix to the vaginal orifice. It also is known as the birth canal. The vaginal opening
is usually partially covered by a thin membrane called the hymen, which is
ruptured by the first sexual intercourse.
Vagina consists of three membranes:
a. Mucosa: inner layer made up of squamous epithelium which secretes an acidic
fluid in vagina. However the alkaline contents of semen neutralize the acidity
of vagina.
b. Muscularis: composed of smooth muscle layers that can stretch considerably
to receive the penis during sexual intercourse
c. Adventitia: superficial layer of vagina made up of areolar connective tissue.
32. Functions of vagina
The functions of the vagina are to receive sperm from
the penis during sexual intercourse.
It serves as a passageway for the menstrual flow.
It became the birth canal at the end of pregnancy.
The vaginal mucosa after puberty secretes organic
acids to create an acidic pH environment that helps to
inhibit the growth of pathogens.
33. UTERUS (WOMB)
The uterus is a hollow, pear-shaped organ that is the site of
menstruation, implantation and development of fetus
during pregnancy. The uterus is divided into two parts:
The fundus is the upper portion above the entry of the
fallopian tubes, and the body is the large central portion.
The narrow, lower end of the uterus is the cervix, which
opens into the vagina. The mucus layer of cervix produce a
secretion called cervical mucus. Generally female of
reproductive age secrete 20 to 60 mL of mucus per day.
34.
35. The wall of the uterus is made of three layers of tissue.
Perimetrium: It is the outermost layer of uterus made of serous
membrane.
Myometrium: The middle layer of the uterus i.e. myometrium
is the smooth muscle layer; during pregnancy these smooth
muscle cells increase in size to accommodate the growing fetus.
During childbirth, contraction of smooth to expel the fetus from
the uterus.
Endometrium: The innermost layer is the highly vascular
endometrium. The endometrium is divided into two layers. The
stratum functionalis and stratum basalis.
The stratum functionalis is shed approximately every 28
days in in noon-pregnant woman by the process called
menstruation cycle. The stratum basalis is permanent
and give rise to new stratum functionalis after each
menstruation.
36. OVARIES
The ovaries are small, oval-shaped glands that are located
in the upper pelvic cavity, on both sides of uterus. They
are 2.5 to 3.5 cm long and 2 cm wide. Each ovary is
attached to uterus by ovarian ligament.
The surface of an ovary is covered with germinal
epithelium. The capsule of an ovary consists of
connective tissue called the tunica albuginea.
Before puberty, ovary consists of primordial follicles. At
maturity, each primordial follicle develops into primary
follicle (with primary oocyte)
37. The primary follicle matures, and develops in to
secondary follicle. A mature secondary follicle with a
mature egg is called a graafian follicle (with
secondary oocyte), which is ready for ovulation.
Ovulation: rupturing of Graafian follicle and release
of female egg (ovum) near the fallopian tube.
The empty graafian follicle converted into the
corpus luteum, which secretes estrogen and
progesterone. The corpus luteum eventually
degenerates into the corpus albicans.
38.
39. Functions of ovary
Oogenesis, or formation of the female sex cells, begins
in the developing female fetus where female stem cells
called oogonia divide by mitosis to produce primary
oocytes.
The ovaries produce and release ovum (eggs) in
ovulation.
Ovulation: rupturing of Graafian follicle and release of
female egg (ovum) near the fallopian tube.
They also secrete the female sex hormones estrogen
and progesterone.
40.
41. UTERINE TUBES (OR FALLOPIAN TUBES)
The female body contains two fallopian tubes which
transport the ovum from the ovaries to the uterus. Each
fallopian tube is about 10 cm long. It consists of a funnel-
shaped end called the infundibulum.
The infundibulum is surrounded by finger-like projections
called the fimbriae. Fimbriae are attached to the lateral
end of the ovary. The ampulla of the fallopian tube is the
longest portion, making up about two-third of its length.
The isthmus of fallopian tube is the short portion that
joins the uterus.
42.
43.
44. Functions of Fallopian Tubes
Approximately once a month an ovum ruptures from the
surface of an ovary near the infundibulum of the uterine
tube, a process called as ovulation.
The ovum is brush off by ciliary action of the
infundibulum and by the waving fimbriae, which create a
current that transports the ovum into the uterine tube.
The two uterine or fallopian tubes transport the ova from
the ovaries to the uterus.
Fertilization usually takes place in the fallopian tube. If not
fertilized, an ovum dies within 24 to 48 hours and
disintegrates, either in the tube or the uterus. If fertilized,
the ovum becomes a zygote and is swept into the uterus;
this takes about 4 to 5 days.
The ovum is moved by peristalsis and the ciliary action
toward the uterus. Fertilization of male sperm and female
ovum usually occurs in the ampulla of the uterine tube
within 24 hours after ovulation.
45. PUBERTY IN FEMALE
Puberty is the development of the secondary sexual
characteristics and maturity of internal genitalia usually
at the age of 10 to 14 years in female. It is the sign of the
childbearing period. Puberty maturity changes are due
to increased secretion of GnRH, FSH, LH, estrogen &
progesterone hormones.
46. Physical and psychological maturity changes are as
follows:
1) Menstruation cycle begins
2) Increased growth of ovarian follicles in ovary
3) Maturation of ovaries, uterus and fallopian tubes
4) Enlargement and development of breast and vagina
5) Increased growth in height and widening of pelvic girdle
(become broad)
6) Mental and emotional maturity
7) Increased deposition of fats on breast, abdomen, mons-
pubis and hips
8) Increased protein metabolism
9) Increased voice pitch
10) Growth of underarm (axillary) and mons pubic hairs
11) Stimulates sebaceous glands to secrete sebum thereby
giving anti-acne action
47. MENSTRUAL CYCLE
This is a series of changes in ovary and wall of uterus
in a non-pregnant female throughout the childbearing
period. It is essential part of making sexual
reproduction.
Menstrual cycle is stimulated by changes in levels of
hormones in the blood. The duration of menstrual
cycle is normally about 28-35 days and occurs in three
phases:
Menstrual (follicular) phase:
Ovulatory phase:
Secretory Phase:
48.
49.
50. 1) Menstrual (follicular) phase:
This phase last for 1st to 13th day of the cycle.
Hypothalamus produces GnRH
(Gonadotropin Releasing Hormone)
GnRH acts on Anterior Pituitary gland
Anterior Pituitary gland secretes hormones
FSH and
LH
FSH acts on ovaries
In ovaries, several primordial follicles begin
to develop into immature primary follicles in
the ovary. Primary follicles consist of
primary oocyte
About 20 primary follicles develop in to
secondary follicles. Secondary follicles
consist of secondary oocyte
The one dominant secondary follicle
undergo maturation to form Graafian
follicle with a mature egg i.e. ovum; while
others degenerated due to fall in FSH level
Graafian follicle secretes estrogen
hormone
Estrogen secretion
Estrogen secretion
51. 2) Ovulatory phase:
The ovulatory phase starts about 14 days after the follicular phase. During this phase,
the following events occur:
Graafian follicle secretes estrogen
hormone
High levels of estrogen hormone stimulates
GnRH from hypothalamus and LH from
pituitary gland by positive feedback
mechanism
High level of Luteinizing hormone triggers
the ovulation usually on 14th day of cycle
Ovulation: Rupturing of Graafian follicle and release
of female egg/ ovum near the fallopian tube. Cervical
mucus secretion and women experience pain in the
ovary at the time of ovulation
Ciliary action and movement of fimbriae
create current and waves which transport
ovum in to fallopian tube
If a woman were to have sexual intercourse
during this time, then female ovum and male
sperm undergo fertilization
52. 2)Secretory Phase:
The Secretory phase begins right after ovulation (at 15-28 days) and involves the
following stages:
Once Graafian follicle releases its ovum, the
empty Graafian follicle collapse and develops
into the corpus luteum (i.e. yellow body).
Under the influence of LH, the corpus luteum
start secreting estrogen and progesterone
Estrogen and progesterone stimulate the
proliferation and thickening of the endometrium
of uterus. It prepares the endometrium to receive
the fertilize ovum
If the female ovum not fertilized, then
levels of estrogen, progesterone and
LH decline. Due to which corpus
luteum degenerates and converted in
to the corpus albicans (or white
body).
The endometrium lining of the
uterus breaks down and the next
menstrual cycle begins.
If the sexual intercourse has taken
place and female ovum fertilized by
male sperm then implantation of
embryo takes place through fallopian
tube in to the uterus.
The embryo starts secreting
human chorionic gonadotropin
(hCG) that stimulates the secretory
activity of the corpus luteum for first 3-
4 months of the pregnancy. During that
placenta develops.
The presence of hCG in maternal
blood or urine is an indicator of
pregnancy and is the hormone
detected by home pregnancy tests.
53. MENOPAUSE
It is the period between the age group of 45-55 years,
marking the end of childbearing period of the female.
It is caused by changes in sex hormone levels due to
which ovulation & menstrual cycle become irregular.
The ovaries become non-responsive to FSH, LH,
estrogen and progesterone hormones.
54. Menopause is characterized by:
Discontinuation of menstruation cycle
Sex organ weaken
Primary follicles so not undergo normal development
Shrinking of the breasts
Loss of bones and bone density i.e. osteoporosis
Pelvic and underarm hairs become thin
Increased sweating and palpitation causing discomfort
Disturbances of normal sleep pattern (irregular sleep)
Episodes of uncharacteristic behavior:
i.e. irritability, mood changes, insomnia and depression
Gradual thinning of skin
Vaginal dryness
Muscular pain
Weight gain
55. Disorders
Gonorrhea
Gonorrhea is a sexually transmitted disease caused by the infection
of Neisseria gonorrhoeae to the female vagina and the male
urethra. Men experience burning sensations during urination, and
discharge of pus from the urethra.
In females, infection may occur in the urethra, vagina and cervix
and often discharge of pus. The vaginal fluid is the main source of
infection, and bacteria are transmitted by direct contact usually
sexual intercourse or during passage of a newborn through the
vagina (birth canal).
Female infertility
Infertility is the inability to get pregnant after a year of unprotected
sexual intercourse. Both men and women can be infertile.
The main causes of female infertility include: damaged fallopian
tube, hormonal imbalance, ovarian disease, and certain conditions
of uterus.