chapter 33

blastocyst

ball of cells in the uterus that is a result of cleavage- consists of outer layer and inner group of cells

vagina

birth canal, receives sperm during intercourse, passageway for menstrual flow

follicle

cells that surround, protect, and nourish a developing egg

inner cell mass

cluster of cells within blastocyst

vas deferns

connecting ducts that transport sperm

cervix

connects uterus to vagina

uterus

contains and protects developing baby

acrosome

contains enzymes that help sperm penetrate egg, capsule located at front of sperm

midpiece (sperm)

contains mitochondria that supply energy for sperm to move forward

implantation

embedding of the blastocyst in the thickened endometrium; trophoplast grows and anchors blastocyst into place in the endometrium and endometrium completely surrounds the blastocyst- trophoplast then contributes to nourishing and protecting the growing embryo

zygote

fertilized egg cell

tail (sperm)

flagella that propels sperm in an "s" motion

placenta

formed by trophoblast cells and cells from the uterus; surrounds the embryo. Enables nutrients and waste products to be transferred between the mother and developing baby

First trimester

gastrulation, membranes form (amniom, yolk sac, chorion, allantois), placenta forms

fraternal twins

have about as much DNA in common as normal siblings, do not share internal womb structures such as placenta and amniotic sac, and they are produced when the mother ovulates more than one egg at a time and separate sperm cells fertilize each egg cell

identical twins

have identical DNA, share internal womb structures like the placenta and amniotic sac, and are produced when early in cleavage the mass of cells breaks into two and each smaller mass deevlops on its own

endometrium

lining of the uterus, contributes to placenta in pregnancy, tissue leaves body during menstruation

menstrual phase

makes up first part of menstrual cycle, lasts about 14 days with proliferation phase-when low estrogen levels cause endometrium to break down and be removed from the body during mensturation makes up Stage I along with with follicular phase and proliferation phase

ovum

mature egg cell with a haploid nucleus that is capable of fusin with the sperm nucleus

fertilization

occurs in the oviduct when egg and sperm cell fuse to form a zygote only one sperm can fertilize egg cell once inside egg, it signals for egg cell to form a barrier on its surface to prevent other sperm from entering the cell

trophoblast

outer layer of cells of the blastocyst

third trimester

rapid growth, respiratory/circulatory systems change to enable baby to start breathing air when born, labor

FSH-follicle stimulating hormone- males

secreted by pituitary, stimulates sperm production

Luteinizing hormone (LH)- males

secreted by pituitary, stimulates testes to produce testosterone

Releasing hormone

secreted by: hypothalamus Stimulates pituitary to release FSH and LH

testosterone

secreted by: testes stimulates sperm production along with FSH, increases in levels signal the hypothalamus to decrease secretion of releasing hormones and decreases in levels signal the hypothalamus to secrete more releasing hormone in charge of secondary sex characteristics

Lutenizing hormone (LH)- females

secreted by:pituitary Causes follicle to mature and break open and release the egg into the oviduct in the process of ovulation lower levels prevent additional follicles from developing in preparation for pregnancy

semen

sperm and fluids from several glands;several glands and vesicles add liquid to the sperm to make semen (Prostate, bulbourethral, seminal)

Ovarian cycle

takes place in the ovaries, three phases -Follicular Phase -ovulation phase -luteal phase

menstrual cycle

takes place in the uterus, four phases -menstrual phase -proliferation phase -ovulation -secretory phase

oviduct

tube that serves as passageway to uterus where egg and sperm meet- where fertilization happens

embryo

what developing organism is called up until 9 weeks

fetus

what organism is called after 9 weeks

ovaries

where egg cells are produced

Why so many sperm?

-two oviducts, so 50/50 chance of entering wrong oviduct where egg is not -the more sperm, the more likely the chance of fertilization -most sperm die on way to the egg -ensures that strongest and healthiest sperm beat the others and reach the egg cell

egg development

Born with all the primary oocytes needed for lifespan (immature egg cells- at the beginning of meiosis I (Prophase I)) At puberty- one egg matures (i.e. finishes meiosis-creates 4 haploid cells) every 28 days (makes one egg and three polar bodies, which help develop part of the follicle) Egg released during ovulation into oviduct Egg cell is largest human cell in the body- takes some of the cytoplasm from the polar bodies

Stage I of menstrual and ovarian cycles

Follicular Phase/ Menstrual and Proliferation Phases estrogen levels are low, trigger the hypothalamus to secrete releasing hormone, which causes the pituitary to secrete FSH and LH. Increased FSH causes one of the follicles and its oocyte to start to mature in the ovary and causes endometrium to break down in the uterus (menstruation). As the follicle matures, it secretes less FSH/LH and lower levels prevent addition follicles from developing in the ovaries. Lower levels also cause endometrium to thicken- all in preparation for pregnancy

Stage III of menstrual and ovarian cycles

Luteal/Secretory phases after follicle breaks open, remaining follicle cells form corpus luteum, which secretes estrogen and progesterone (cause endometrium to thicken in preparation for pregnancy) If pregnancy does not occur, corpus luteum breaks down and secretes less estrogen and progesterone, and these low levels sinal the hypothalamus to secrete releasing hormone, starting the cycle all over again

corpus luteum

"yellow body", secretes estrogen and progesterone, which stimulate the endometrium to thicken further in preparation for pregnancy, structure made up of remaining follicle cells from the ruptured follicle

gastrulation

3 weeks after fertilization- ectoderm (skin and CNS), endoderm (digestive tract and lungs) and mesoderm (most other organs) form

Stage II of menstrual and ovarian cycles

Ovulation phase follicle begins maturity; causes estrogen levels to rise, and signals the hypothalamus to secrete releasing hormone, which in turn causes the pituitary to secrete FSH and LH. High levels of LH in the ovaries cause the follicle to break open and release the egg into the oviduct in the process of ovulation.

scrotum

contain testes, outside of internal body for proper sperm development (cooler than inside the body)

head (sperm)

contains nucleus; bring fathers DNA into egg cell

penis

contains urethra, tube through which urine or semen can pass

sperm development

develops at puberty and into old age

proliferation phase

makes up third part of menstrual cycle, roughly 14 days with menstrual phase- rising estrogen levels cause endometrium to thicken makes up Stage I along with follicular phase and menstrual phase

ovulation phase

part of both Menstrual and Ovarian cyles, lasts 1 day

second trimester

placenta secretes progesterone- corpus luteum breaks down, increases 14 in and 2 lbs, quickening, baby develops all major sensory organs

follicular phase

roughly the first 14 days, part of ovarian cycle, makes up Stage I along with menstrual phase and proliferation phase low estrogen levels trigger hypothalamus to secrete releasing hormone, which triggers the release of FSH and LH from the pituitary, and FSH causes one of the follicles and its occyte to mature (as follicle matures, it secretes estrogen, which signals for hypothalamus to secrete less releasing hormone and thus less FSH and LH, and these lower levels prevent additional follicles from developing)

progesterone-females

secreted by: corpus luteum causes and maintains endometrium thickening if pregnancy does not occur, corpus luteum breaks down and lower levels of hormone signal hypothalamus to secrete releasing hormone, starting the cycle all over eagain

Estrogen- females

secreted by: follicle and corpus luteum causes endometrium thickening when levels are high and causes it to break down when levels are low, development of secondary sex characteristics low levels trigger the hypothalamus to secrete a releasing hormone at the beginning of the cycles, high levels trigger the slowing of production of releasing hormone

Follicle-stimulating hormone (FSH)-females

secreted by: pituitary stimulates follicle and oocyte development/maturity in ovary low levels prevent additional follicles from developing in preparation for pregnancy high levels signal a new follicle to mature if pregnancy does not occur, causing the cycle to start over again

ovulation

when the follicle breaks open - happens at puberty, happens every 28 days

testes

where sperm cells begin development

epididymis

where sperm complete their development, attached to each testis

cleavage

zygote undergoes division- happens around 36 hours after fertilization. Produces large number of daughter cells that serve as building blocks for the developing organism