Download Female Reproductive System

Sexual Reproduction
Why Sexual Reproduction?
(from a biological standpoint)
• Asexual Reproduction
– gives the same result over and over.
– No mate is required.
– Allows for no variation.
• Sexual Reproduction
– Another individual is required, usually of the
opposite gender.
– Gives different results every time
– Provides for variation
– Leads to better chance of survival for the species.
Types of Sexual Reproduction
• 1. External Fertilization
– Egg is fertilized outside the females body
– Ex. Fish, frogs, fungus, plants, worms, some
insects.
• 2. Internal Fertilization
– Egg is fertilized inside the females body
– Ex. Mammals, reptiles, birds, sharks, many insects
Hermaphrodites
– Organisms with both male and female sex organs
External fertilization
• Must occur in moist
environment.
• Large number of
gametes released.
(majority wasted or
eaten)
• Little to no parental
care.
Internal Fertilization
• Less gametes needed.
• Increased chance of
fertilization.
• Better protection for
developing young.
• Allows animals to
survive outside water.
Hermaphrodites
• Can be internal or
external, usually
external.
• Mates generally
exchange gametes
• Increases chance of
finding viable
partner.
Males
vs.
• Testes
– Male gonads (sex
organs)
– Produce sperm
• Sperm
– Males gametes
(sex cells)
– Are continually
produced once
puberty is reached.
Females
• Ovaries
– Female gonads (sex
organs)
– Produce eggs.
• Egg
– Female gametes
(sex cells)
– Female born with
limited number of
eggs.
Male Reproductive System
External Structures
Penis
Delivers sperm to female reproductive tract.
Scrotum
Sac of skin contain a pair of testes
Testes
Olive size structures…which contain tightly coiled seminiferous
tubules.
Duct System
Epididymus
Store sperm for several months; where sperm mature
Vas Deferens
45cm long(18”)…propels sperm to ejaculatory duct.
Urethra
15cm (6”) Carries both urine & semen out of the male’s body.
Male Reproductive System (con)
Accessory Glands
Seminal Vesicles
Secrete fluids with nutrients which accounts for 60% of
semen
Prostate Gland
Size of a chestnut…it encircles the urethra. Secretes
fluid that contains nutrients & enzymes which activate
sperm.
Cowper’s Glands
Secretes a mucus which neutralizes traces of acidic
urine in the urethra.
Semen
Mixture of sperm & fluids that provide a transport
medium, nutrients, & chemicals to help activate the
sperm.
Male Reproductive System
Spermatogenesis
• Sperm formation
– Begins in puberty
– Sperm are continually produced in the
testes.
– Stored in the epididymus until ejaculation.
– Travels via vas deferens past 3 glands
– Exits the penis through the urethra
– Human sperm are not truly viable until
inside the body of a human female.
Anatomy of a sperm
• Head
– Contains the nuclear
material = DNA
– Covered by acrosome =
enzyme for breaking
down egg barrier
• Midpiece
– Full of mitochondria =
Energy
• Tail
– Flagella for movement.
Males Secondary Sex Characteristics
Body Hair; pubic region, armpits, chest, face, etc…
Muscle development
Deepening up the voice
Other interesting tidbits
• Temperature
– In humans and many animals, sperm require temp
lower than body temperature.
– This is why testes are found outside the body.
• Ejaculated semen can reach the speed of 200” per
second.
• Sperm can survive in a females body for up to 3
days.
• 25% of sperm are deformed from beginning.
Female Reproductive System
*Female is more complex than the male, because
besides producing gametes, her body must prepare to
nurture a developing embryo for about 9 months.
Organ
Structure and Function
Ovaries
Each ovary contains many follicles (one egg surrounded by
follicle cells).
Formed at birth.
Produces estrogen.
Puberty-one follicle matures & releases an egg during each
menstrual cycle.
Fallopian
Tubes or
Oviducts
Do not touch the ovaries.
Funnel like opening surrounded with cilia.
Distil end connects to the uterus.
Site of fertilization
Female Reproductive System (con)
Organ
Structure and Function
Uterus
Thick muscular organ shaped like a pear.
The lining is the endometrium, it is richly supplied with
blood vessels.
Cervix
Neck of the uterus opens to the vagina.
Vagina
Thin walled chamber serves as repository for semen.
Forms the birth canal.
Vestibule
Chamber-like area formed by 2 pairs of skin folds
covering the vaginal and urethral openings.
Clitoris
Bulb of erectile tissue at the front edge of the vestibule.
Bartholin's
Gland
Small gland located near opening of vagina.
Secretes a mucus
Female Reproductive System
MAMMARY GLANDS
*Found in both sexes…normally only function in females.
Biological role is to produce milk for a newborn baby. This
occurs after reproduction. (Modified sweat glands)
Menstrual Cycle *Hand-out
Average length 28-30 days (21-40 days)
Ovulation—when a follicle of the ovary ruptures & releases an
egg.
Many Hormones play a role in Menstrual Cycle:
LH—luteinizing hormone
FSH—follicle-stimulating hormone
GnRH—gonadotropin-releasing hormone
Estrogen—female sex hormone
Progesterone—works with estrogen
OOGENESIS
(EGG PRODUCTION)
• Eggs are produced in follicles in the ovaries.
– They are not yet fully formed. They complete this
during each menstrual cycle. One at a time.
– The rest are just waiting!! (Suspended in a
metaphase state)
• Egg numbers are limited in females and are not
continually produced.
– Birth = 1 million eggs. No more are produced.
– Puberty = number is less than 400,000
– Less than 500 eggs are released from puberty to
menopause.
From Ovary to Uterus
• Once a month, a single egg finishes
production and is released by the ovary into
the oviduct or fallopian tube.
• If fertilization occurs, it occurs in the oviduct.
• The fertilized egg (Zygote) implants into the
uterus where it is nourished during
pregnancy.
• Menstrual cycle stops during pregnancy. It
resumes after birth.
If pregnancy does not occur...
• If fertilization does not occur, the egg does
not implant in the uterus. It may pass out of
the females body, or be absorbed by the
females body.
• If implantation does not occur, the females
body begins the process of menstruation,
where the body builds a new uterine lining
and discards the old one.
• This is all controlled by hormones released
from the egg itself.
– (Many birth control pills work using these
hormones)
Pregnancy
• Pregnancy is different for all species of
animals.
• Gestation Period – time from pregnancy
until birth of offspring.
– Dogs 51-80 days (7-12 weeks)
– Monkeys 5 – 8 months
– Humans - 9 months
– Elephants - 2.5 years
Types of Pregnancy
• Oviparous
– Embryo develops in egg outside the body
• Fish, amphibians, many reptiles, birds
• Ovoviviparous
– Embryo develops in egg, but inside the body
• Some snakes, most sharks.
• Viviparous
– Embryo develops inside the body connected to
mother by a placenta (organ that nourishes the
body)
• Most mammals
Human Pregnancy
• Consists of 3
trimesters
1.Most critical period of
development. All
body systems
develop
2. Very rapid growth of
fetus.
3. Fetus triples its
weight during the 3rd
trimester.
3 trimesters
Name of baby during
Pregnancy
• Zygote – when egg has
become fertilized.
• Embryo - 0-8 weeks.
– (see picture)
• Fetus - 8 weeks-birth.
– The baby can now
be identified as
human.
• Baby – after birth.
(Joe, Suzy)
Stages of labor
• Labor – a series of Uterine
contractions that force the
baby out of the body through
the vagina
• 1. Dilation
– Cervix dilates
– Amnion breaks.
• 2. Expulsion
– Baby exits through
vagina
• 3. Afterbirth
– Placenta and umbilical
cord are forced out the
vagina.
Multiple births
• Fraternal twins
– Result of two eggs
fertilized by different
sperm.
• Identical twins
– Result of one egg
splitting during
development.
• Siamese twins
– Result of one egg not
completely splitting
during development
Determination of sex
• Girl
– XX (51%)
• Boy
– XY (49%)
• Turner’s Syndrome
– XO (1/5000)
• Klinefelters
Syndrome
– XXY (1/700)