Reproductive System

Sexual Reproduction

The creation of an offspring by fusion of a male gamete (sperm) and female gamete (egg) to form a zygote.

Asexual reproduction

Creation of offspring without the fusion of egg and sperm.

Budding

A simple form of asexual reproduction found only among invertebrates.

Fission

Asexual reproduction in many invertebrates. Separation of a parent into two or more individuals of about the same size.

Fragmentation

Breaking of the body in pieces, some are all of which develop into adults. Must be accompanied by regeneration, regrowth of lost body parts.

Parthenogenesis

The development of a new individual from an unfertilized egg. Mainly observed in invertebrates, but is observed rarely in some vertebrates.

Hermaphroditism

Each individual has male and female reproductive systems.

Sex reversals

Some species exhibit male to female reversal (for example, certain oysters), while others exhibit female to male reversal (for example, a coral reef fish).

External fertilization

Eggs shed by the female are fertilized by sperm in the external environment.

Spawning

in which individuals cluster in the same area to release their gametes into the water at the same time.

Internal fertilization

Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract.

Gonads

organs that produce gametes

Spermatheca

in which sperm is stored during ovulation

Cloaca

A common opening between the external environment and the digestive, excretory, and reproductive systems.

Ovulation

the release of mature eggs, occurs at the midpoint of each cycle.

Pheromones

chemicals released by one organism that can influence the physiology and behavior of other individuals of the same species. These are
small, volatile or water-soluble molecules that disperse into the environment and, like hormones, are active at very low concentrations

Monogamy

the habit of having only one mate at a time. It is relatively rare among animals.

Scrotum and penis

external reproductive organs

Gonads

produce sperm and hormones

Accessory glands

secrete products needed for sperm movement

Ducts

carry sperm and glandular secretions

seminiferous tubules

sperm form in ________________

Leydig cells

surrounding the tubules produce hormones

Scrotum

Held outside the abdominal cavity in the __________ where temperature is lower.

vas deferens

where sperm are propelled thru during ejaculation

Semen

composed of sperm plus secretions from three sets of accessory glands.

Seminal vesicles

contribute about 60% of the total volume of semen, it is a gland in males that secretes a fluid component of semen that lubricates and nourishes sperm.

Prostate gland

secretes its products directly into the urethra. A gland in human males that secretes an acid-neutralizing component of semen

Bulbourethral glands

secrete clear mucus that neutralizes acidic urine remaining in the urethra

Penis

composed of three cylinders of spongy erectile tissue

Glans

head of the penis, has a thinner skin covering than the shaft

Prepuce

The glans is surrounded by a fold of skin called the _____________. also called foreskin, which is removed if a male is circumcised.

Viagra

promote the vasodilating action of the local regulator nitric oxide.

Vagina

muscular but elastic chamber that is the repository for a sperm during copulation and serves as the birth canal.

Clitoris

It has a head called a glans covered by the prepuce, a small hood of skin

Ovaries

female gonads that lie in the abdominal cavity and contains many follicles, which consists of oocytes surrounded by support cells

Oviduct

also called as the fallopian tubes where the egg cell travels from the ovary to the uterus

Endometrium

also called as uterus lining that has many blood vessels

Cervix

the uterus narrows at the _________, then opens into the vagina

Gametogenesis

production of gametes

spermatogenesis

The formation of sperm; continuous and prolific.

Oogenesis

The development of a mature egg; a prolonged process

Gonadotropin-releasing hormone

secreted by the hypothalamus that directs the release of FSH (follicle0stimulating hormone) and LH (luteinizing hormone) from the anterior pituitary

FSH and LH

Regulate processes in the gonads and the production of sex hormones

Testosterone

main androgen

Estrogens

consist mainly of estradiol and progesterone

Sex hormones

serve many functions in addition to gamete production, including sexual behavior and the development of primary and secondary sex
characteristics.

uterine cycle

changes in the uterus, also called as menstrual cycle

ovarian cycle

changes in the ovaries

follicle growth

Sequential release of GnRH then FSH and LH stimulates ____________.

Follicular phase

Characterized by follicle growth and an increase in estradiol. Ends at ovulation, and the secondary oocyte is released.

Luteal phase

Follicular tissue left behind transforms into corpus luteum.

Corpus luteum

secretes progesterone and estradiol, which exert negative feedback on the hypothalamus and pituitary.

Proliferative phase

thickening of the endometrium coincides with the follicular phase.

Secretory phase

secretion of nutrients coincides with the luteal phase.

Menstrual flow phase

shedding of the endometrium coincides with the growth of new ovarian follicles.

Sertoli cells

FSH stimulates _______________, located within the seminiferous tubules, to nourish developing sperm

Leydig cells

LH causes ____________, scattered in connective tissue between the tubules, to produce testosterone and other androgens, which promote spermatogenesis in the tubules.

Testosterone

regulates blood levels of GnRH, FSH, and LH through inhibitory effects on the hypothalamus and anterior pituitary.

Inhibin

a hormone that in males is produced by Sertoli cells, acts on the anterior pituitary gland to reduce FSH secretion

Endometriosis

About 7% of women of reproductive age suffer from a disorder called _________________, in which some cells of the uterine lining migrate to an abdominal location that is abnormal, or ectopic (from the Greek ektopos, away from a place).

menopause

After about 500 cycles, a woman undergoes _____________, the
cessation of ovulation and menstruation.

46 and 54

Menopause usually occurs between the ages of ____________.

Estrous cycle

characteristic of most mammals where the endometrium is reabsorbed by the uterus. • Sexual receptivity is limited to a “heat” period

Vasocongestion

filling of a tissue with blood

myotonia

increased muscle tension

vasocengestion

particularly evident in erection of the penis and clitoris and in enlargement of the testicles, labia, and breasts

myotonia

The vagina becomes lubricated, and __________may occur, as evident in nipple erection or tension of the limbs.

orgasm

characterized by rhythmic, involuntary contractions of the reproductive structures in both sexes

emission

occurs when the glands and ducts of the reproductive tract contract, forcing semen into the urethra.

Expulsion

also called ejaculation, , occurs when the urethra contracts and the semen is expelled.

refractory period

Following orgasm, the male typically enters a _______________, lasting from a few minutes to hours, when erection and orgasm cannot be achieved.

cleavage

The zygote begins a series of cell divisions called

Blastocyst

a sphere of cells surrounding a central cavity.

gestation

The condition of carrying one or more embryos in the uterus is called pregnancy, or ________________

266

Human pregnancy averages _______ days (38 weeks)
from fertilization of the egg,

21

gestation averages ___ days in many rodents

280

gestation averages _____ days in cows

600

gestation averages more than _____ days in elephants

first trimester

During the ____________________, the implanted embryo secretes hormones that signal its presence and regulate the mother’s reproductive system.

human chorionic gonadotropin

One embryonic hormone, ________________________________, acts like pituitary LH in maintaining secretion of progesterone and estrogens by the corpus luteum through the first few months of pregnancy.

endometrium

During its first 2–4 weeks of development, the embryo obtains nutrients directly from the ________________.

Trophoblast

outer layer of the blastocyst

placenta

disk-shaped organs, containing both embryonic and maternal blood vessels, can weigh close to 1 kg at birth.

monozygotic

Occasionally, an embryo splits during the first month of development, resulting in identical, or ______________ (one-egg), twins.

dizygotic

also called as fraternal twins where Two follicles mature in a single cycle, followed by independent fertilization and implantation of two genetically distinct embryos.

morning sickness

About three-fourths of all pregnant women experience nausea, misleadingly called ___________________ during the first trimester.

second trimester

During the _____________, the fetus grows to about 30 cm in
length. Development continues, including formation of fingernails, external sex organs, and outer ears

third trimester

During the ______________, the fetus grows to about 3–4 kg in weight and 50 cm in length. Fetal activity may decrease as the fetus fills the available space.

labor

a series of strong, rhythmic uterine contractions that push the fetus and placenta out of the body

Lactation

production of mother's milk

Prolactin

produced by anterior pituitary that stimulates the mammary glands to produce milk.

Oxytocin

secreted by posterior pituitary which triggers release of milk from the mammary glands

contraception

the deliberate prevention of pregnancy, can be achieved in a number of ways

natural family planning

temporary abstinence

coitus interruptus

also called withdrawal, removal of the penis from the vagina before ejaculation

Condom

thin, latex rubber or natural membrane sheath that fits over the penis to collect the semen.

Diaphragm

a dome-shaped rubber cap inserted into the upper portion of the vagina before intercourse.

Vaginal pouch

female condom

Intrauterine device

has a pregnancy rate of 1% or less and is the most commonly used reversible method of birth control outside the United States.