Alberta Biology 30: Reproduction & Development

What is the difference between primary and secondary sex characteristics?

primary = direct role in reproduction (gonads)

secondary = features that distinguish the two sexes; develop at puberty

What is the process of creating a zygote called? How many chromosomes does it have?

fertilization; 46 chromosomes

What kinds of sex chromosomes can a sperm contribute? An egg?

sperm = X or Y

egg = only X

What is the function of the scrotum?

highly elastic skin; holds testes outside of body for optimal sperm production

What is the function of the seminiferous tubules? Where are they found?

produce sperm in response to FSH; found in testes

What is the function of the interstitial cells? Where are they found?

produce testosterone in response to LH; found in testes (between sem. tubules)

What is the function of the epididymis?

site of sperm maturation and storage

What is the function of the vas deferens?

tubes; carry sperm from epididymis to urethra; cut and tied during a vasectomy

What is the function of the Seminal vesicles?

produce Sugar which nourishes sperm & increases motility; produces prostaglandins which stimulate uterine contractions (aids the movement of sperm cells)

What is the function of the ejactulatory duct?

regulates release of sperm into urethra

What is the function of the prostate gland?

produces basic mucus to protect sperm from acidity of vagina

What is the function of the Cowper's gland?

produces basic mucus that Cleans the urethra of acidic urine

What is the composition of semen?

sperm, sugar (fructose), basic mucus, prostaglandins

Name the glands that contribute to the composition of semen.

testes, seminal vesicles, prostate gland, Cowper's gland

Which gland contributes a cellular component of semen?

only the testes

What is spermatogenesis? What are the products?

production of sperm in response to FSH; meiosis that occurs in the sem. tubules; produces four equal sized daughter cells

What is the function of the Sertoli cells?

nourish/protect the sperm; have FSH receptors; make inhibin (prevents spermatogenesis during childhood) not curricular

Name the three parts of sperm and their functions.

head = contains acrosome with digestive enzymes to help penetrate the egg & 23 chromosomes

midpiece = contain mitochondria to power the flagellum

tail = aka flagellum; moves sperm

What is the function of the ovaries?

produces an egg within the follicles in response to FSH; site of ovulation in response to LH

What is the function of the fallopian tubes?

carry ovum towards uterus; normal site of fertilization; cut & tied during tubal ligation

What is the function of the uterus?

implantation of zygote in the endometrium

What is the function of the cervix?

muscular ring; hold developing fetus in uterus; dilates during birth

What is the function of the vagina?

muscular, elastic canal; used for intercourse, birth and menstruation

What is oogenesis? What are the products?

production of eggs in response to FSH; asymmetrical form of meiosis; starts within follicles; produces 4 unequal daughter cells (1 useable gamete and 3 polar bodies)

What is ovulation?

release of egg from follicles in response to LH on approx. day 14 of menstrual cycle

What are the 4 phases of the menstrual cycle?

Flow, follicular, ovulatory, luteal

Describe the flow phase of the menstrual cycle.

if pregnancy did not occur, corpus luteum degenerates; secretions of estrogen & progesterone decrease; causes uterine contractions and shedding of endometrium

Describe the follicular phase of the menstrual cycle.

follicles within ovary develop in response to FSH; secretes estrogen which initiates development of endometrium.

Describe the ovulatory phase of the menstrual cycle.

DAY 14: the egg ruptures from follicle into fallopian tube in response to LH; remaining follicular cells develop into corpus luteum

Describe the luteal phase of the menstrual cycle.

corpus luteum produces estrogen (thickens endometrium) and progesterone (prevents contractions)

What kind of feedback does estrogen have on FSH?

negative; inhibits production

What kind of feedback does estrogen have on LH?

positive; increases production

What kind of feedback does progesterone have on LH?

negative; inhibits production

What two hormones are typically found in a birth control pill?

estrogen and progesterone

What kinds of twins are produced from the release and fertilization of two separate eggs?

fraternal (dizygotic) twins

What kinds of twins are produced from the release and fertilization of one egg that splits into two cell masses?

identical (monozygotic) twins

What happens to the zygote shortly after fertilization?

cleavage; a series of cell divisions without growth

What is a blastocyst?

zygote forms a hollow ball; inner cells form embryo; outer cells form extra embryonic membranes

What is the term for the period from implantation to parturition?

gestation

What is gastrulation?

blastocyst develops into a three layered disc called a gastrula

Name the three layers of the gastrula.

outer layer = ectoderm = skin, nervous system

middle layer = mesoderm = skeleton, muscles, reproductive structures

inner layer = endoderm = linings of digestive and respiratory tracts, endocrine glands

What is the function of the chorion?

embryonic portion of the placenta; secretes hCG; maintains corpus luteum

What is the function of the amnion?

filled with amniotic fluid; prevents shock to embryo; regulates body temperature, prevents infection, allows movement

What is the function of the yolk sac?

no nutritive purpose in humans; site of early RBC formation

What is the function of the placenta?

site of gas, nutrient, mineral, hormone, antibody, waste exchange; produces hormones (estrogen, progesterone, hCG and relaxin); acts as barrier to most except teratogenic agents

Describe what happens to levels of hormones during parturition.

estrogen/progesterone levels decrease; levels of prostaglandins/relaxin/oxytocin increase

What produces relaxin? What is it's purpose?

produced by placenta; causes relaxation of pelvic ligaments & widening of birth canal

What is the function of prostaglandins and oxytocin during parturition?

cause uterine contractions

What are the two hormones that participate in lactation?

prolactin = produces milk

oxytocin = releases milk