Reproductive System Flashcards
creation of an offspring by fusion of a male gamete and female gamete to form a zygote
Sexual Reproduction
creation of an offspring without the fusion of sperm and an egg
Asexual reproduction
mechanisms of asexual reproduction
Budding
Fission
fragmentation
parthenogenesis
Simple form of asexual
reproduction
Found only in invertebrate animals
New individuals arise from
outgrowths of an existing individual
budding
Reproduction in most of the invertebrates
Separation of a parent into 2 or more individuals of about the same size
Fission
Development of a new individual from an unfertilized egg
Mainly observed in invertebrates
Observed rarely in some vertebrate animals
parthenogenesis
almost all eukaryotic species reproduce this way
sexual reproduction
Sexual females have half as many daughters as asexual females
“two fold cost” of sexual reproduction
By producing offspring of varied phenotypes, sexual reproduction may enhance what?
reproductive success of parents when environmental factors change relatively rapidly
expected to be most advantageous in stable, favorable environments
Asexual reproduction
Most animals exhibit this
related to changing seasons
controlled by hormones and environmental cues
Reproductive Cycles
Release of mature eggs at the midpoint of a female cycle
Ovulation
Variations in Patterns of Sexual
Hermaphroditism
Sex Reversals
One individual has both the male and female reproductive systems
2 hermaphrodites can mate
Some can self-fertilize
Hermaphroditism
Some species exhibit male to female reversal
Sex Reversals
animals that exhibit Sex Reversals
Oysters
Coral reef fishes
2 types of Fertilization
External fertilization
Internal fertilization
Eggs shed by the female are fertilized by sperm in the external environment
A moist habitat is always required to allow sperm to swim to the egg and to prevent the gametes from drying out
External fertilization
(External fertilization)
Individuals cluster in the same area to release their gametes into the water at the same time
In some cases chemical signals trigger spawning; in other environmental cues are responsible
Spawning
Sperm are deposited in or near the female reproductive tract
Fertilization occurs within the tract
Requires behavioral interactions and compatible copulatory organs
Internal fertilization
compartment that holds sperm for later use in female insects
spermatheca
External reproductive organs of males
Scrotum
Penis
Internal reproductive organs of males
Gonads
Accessory Glands of males
Ducts
Produce the sperm and hormones
Gonads
Secrete products needed for sperm movement
Accessory Glands of males
Carry sperm and glandular secretions
Ducts
Sperm form in these seminiferous tubules
Testes
Produce hormones
Scattered between the tubules
Leydig cells
Production of normal sperm cannot occur at the body temperatures of most mammals
The testes of many mammals are held outside the abdominal cavity in the
scrotum
The temperature in the scrtoum is ______ than in the abdominatal cavity
lower
From the seminiferous tubules of a testis, sperm pass into the _______ of the epididymis
Coiled Ducts
During ejaculation, sperm are propelled through the muscular vas deferens and the ____, and then exit the penis through the urethra
ejaculatory duct
Accessory Glands
Semen
Seminal Vesicles
Prostate Gland
Bulbourethral Gland
Composed of sperm plus secretions from three sets of accessory glands
Semen
Contribute about 60% of the total volume of semen
Seminal Vesicles
Secretes its products directly into the urethra through several small ducts
Prostate Gland
Secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra
Bulbourethral Gland
dog bone penis
ospenis
makes the penis erected during arousal
corpara cavernosa
Made up of 3 cylinders of spongy erectile tissues Glans
Penis
Has a thinner skin covering than the shaft and is more sensitive to stimulation
Head of penis
Foreskin
A fold of skin the surrounds the glans
Prepuce
Female External reproductive organs
Vagina
Clitoris
Female Internal reproductive organs
Ovaries
Oviduct
Uterus
Cervix
Muscular but elastic chamber that is the repository for sperm during copulation and serves as the birth canal
Opens to the outside at the vulva,
Vagina
consists of the labia majora, labia minora, hymen, and clitoris
vulva
Has a head called a glans covered by the prepuce
Clitoris
Female gonads that lie in the abdominal cavity
Each ovary contains many follicles, which consist of a partially developed egg (oocyte) surrounded by support cells
Ovaries
Fallopian tube
Passageway for the eggs from the ovary to the uterus
Oviduct
Womb
Uterus
Uterine lining made up of blood vessels
Endometrium
Opening from the uterus to the vagina
Cervix
Formation of sperm
Continuous and prolific
Hundreds of millions of sperm are produced per day
Each sperm takes about 7 weeks to develop
Spermatogenesis
Development of a mature egg
Prolonged process Immature eggs form in the female embryo but do not complete their development until
years or decades later
Oogenesis
Spermatogenesis differs from oogenesis in three ways
All four products of meiosis develop into sperm while only one of the four becomes an egg
Spermatogenesis occurs throughout adolescence and adulthood
Sperm are produced continuously without the prolonged interruptions in oogenesis
serve many functions in addition to gamete production
Includes sexual behavior and the development of primary and secondary sex characteristics
Sex Hormones
Secreted by the hypothalamus
Directs the release of FSH (follicle-stimulating hormone) and LH (luteinizing hormone) from the anterior pituitary gland
Gonadotropin-Releasing Hormone
FSH and LH in men
Testosterone
Main androgen
FSH and LH in women
Estrogen
Consist mainly of estradiol and progesterone
FSH Hormonal Control of Male Reproductive System
Promotes activity of Sertoli cells
Gives nourishment to the developing sperm
Sertoli cells
LH Hormonal Control of Male Reproductive System
Regulates Leydig cells
Secrete Promotes spermatogenesis
Leydig cells
testosterone Hormonal Control of Male Reproductive System
Promotes spermatogenesis
Regulates production of GnRH, FSH, and LH through negative feedback mechanisms
Promotes spermatogenesis
Hormonal Control of Female Reproductive System
Secretion of hormones and the reproductive events they regulate are cyclic
Prior to ovulation, the endometrium _______ with blood vessels in preparation for embryo implantation
Thickens
If an embryo does not implant in the endometrium, the endometrium is shed
Menstruation
two cycles of female
reproduction
Uterine cycle
Ovarian cycle
Changes in the uterus
Menstrual cycle
Uterine cycle
Changes in the ovaries
Ovarian cycle
The sequential release of GnRH then FSH and LH stimulates follicle growth
Ovarian Cycle
Characterized by follicle growth and an increase in estradiol
Ends at ovulation
Release of secondary oocyte
Follicular phase
Follicular tissue left behind transforms into corpus luteum
Luteal phase
Secretes progesterone and estradiol
Exert negative feedback on hypothalamus and pituitary gland
Corpus luteum
Menstrual cycle
Proliferative phase
Secretory phase
Menstrual flow phase
Uterine Cycle
Thickening of endometrium
Coincides with follicular phase
Proliferative phase
Shedding of endometrium
Coincides with growth of new ovarian follicles
Menstrual flow phase
Characteristic of most mammals
The endometrium is reabsorbed by the uterus
Estrous cycle
Sexual receptivity is limited to a “heat” period called ___
The length and frequency of estrous cycles vary from species to species
estrus
