chapter 47: growth and development

prenatal period

begins with conception and ends at birth

postnatal period

begins with birth and continues until death

human biology

study of changes occurring during the cycles of life from conception to death

making sex cells

spermatozoa are produced by spermatogenesis

ova are produced by oogenesis

meiosis II

reproduces each of the 2 cells formed by meiotic I

4 cells→ each with haploid # of chromosomes

1 egg; 3 polar

meiosis I

make secondary oocyte and 1st polar body

crossover occurs

chromatid segments become part of the adjacent chromosome

spermatogenesis

male sex cells →mature sperm

oogeneis

process by which primitive female sex cells transform into mature ova

ovulation

mature ovum→ mature ovarian follicle→ abdominopelvic cavity→ fallopian tube

insemination

male releasing semen into vagina

sperm travels thru cervix and uterus→ fallopian tubes

fertilization

known as conception

occurs in outer third of uterine tube

thermotaxis

sperm are attracted to warmth of uterine tubes

chemotaxis

ovum attracts and “traps” sperm with special molecules

acrosome reaction

permits the release of enzymes that burrow through the outer layers of the ovum

sperm enters ovum

ovum stops collecting sperm on surface

zygote

fertilized ovum; genetically complete

diploid→ 43 chromosomes

cumulus cells

release progesterone

follicular cels

release estrogen

morula

solid mass of cells formed from zygote

takes art 3 days; divides

blastocyst

hallow ball of cells→ implant into uterine lining

ovum

stores nutrients that support embryonic development until implantation occured

placenta previa

placenta is attached to cervix

→ difficult to give birth

placenta

excretory, respiratory, and endocrine organ

placenta endocrine

secretes large amounts of HcG

hcg

stimulates corpus lute to continue its secretes of estrogen and progesterone

gestation period

approximately 39 weels

embryonic phase

fertilization until end of week 8

fetal phase

weeks 8 to 39

lungs

developed last

stem cell

unspecialized cell that produces lines of specialized cells

range of types it can produce

totipotent stem cell

can produce any type of cell

found in zygote

pluripotent stem cell

embryonic stem cell that can produce a broad range of cell types

found in embryonic germ layers

multipotent stem cell

adult stem cell found in some tissues can produce a few cell types and thus maintain functional populations of specialized cells

endoderm

inside layer

• GI tract & respiratory & accessory organs

ectoderm

outside layer

• muscle, bone, kidney, heart

mesoderm

middle layer

• skin, eyes, brain

histogenesis

process by which primary germ layers develop into different kinds of tissues

organogenesis

how tissues orange themselves into organs

female

x chromosome

male

y chromosome

gonads develop

female reproductive tract

gonads become

male reproductive tract

cortisol

triggers labor by reducing hog and progesterone

removing the break on oxytocin→ stimulate uterine muscles→ contractions

labor stage 1

period from onset of uterine contractions until cervical dilation is complete→ 10cm

labor stage 2

period from which maximal cervical dilation until the baby exits through the vagina

labor stage 3

process of expulsion of the placenta through the vagina

identical twins

1 sperm and 1 egg

1 placenta

fraternal twins

2 sperms 2 eggs

2 placentas

apgar score

assesses general condition of a newborn infant