Conception & Fetal Development

Female External structures

labia majora, labia minora, clit

Female internal structures

vagina, cervix, uterus, fallopian tubes,, ovaries

Gametogenesis- Oogenesis

process of egg/ovum formation

Ovulation

• Fertilization= zygote formation

• No conception= ovum degenerates

Corpus luteum

stimulates progesterone, covering of the egg before it is released from the ovary

Hormone for menstruation

• Gonadotrophin releasing hormone

• follicle stimulating hormone

• luteinizing hormone

• progesterone

Gonadotrophin

stimulates ovaries

Follicle stimulating hormone

stimulates ova maturation

luteinizing hormone

ovulation hormone ova expelled from ovary

Progesterone

pregnancy hormone

Male external structures

foreskin, penis, scrotum

Male internal structures

testes, epididymis, vas deferens, seminal vesicles, prostate gland, urethra (process of ejaculation)

Testes

begins process of spermatogenesis

Fertilization

sperm and ovum unite at conception

• Sperm can live for 4-5 days

• Fertilization can occur within 12 hrs of ovulation

Zona Pallucida

protective covering around sperm

Fallopian tube to implantation in uterus

Zygote, Cleavage, Morula, Blastocyst, embryo, fetus

Zygote

coupling of male (23) and female (23) chromosomes

Blastocyst

baby (fetal)

Trophoblast

placenta (fetal cells)

Chorionic Villi

fingerlike projections, extends into endometrium

Function= obtains o2 + nutrients from maternal blood stream, dispose of carbon dioxide and waste products into maternal blood stream

Embryonic period

Most critical development of organ systems and main external features

• through 8 weeks post conception

Teratogen

agent that acts directly on the developing fetus, causing abnormal embryonic or fetal development (ex= viruses, bacteria, heavy metals, meds, etc.)

Critical Points of Vulnerability

• ONTD

• Heart

• Lips/Palate

Fetal Membranes

Chorion + Amnion

Chorion

• outside, towards uterus

  • develops from trophoblast, chorionic villi present on surface, covering of fetal side of placenta, contains major umbilical blood vessels

Amnion

inner cell membrane from interior cells of the blastocyst; covering of the umbilical cord, covers chorion of the fetal surface of the blood vessels

Amniotic Fluid

maintains temp, source of oral fluid, repository for waste, protects fetus from trauma, freedom of movement assisting musculoskeletal development

• diffusion from maternal blood first

• fetus urinates into fluid

Placenta

produces hormones (hCG, human placental lactogen, progesterone, estradiol)

• begins to form with implantation

hCG

human chorionic gonadotrophin

Human placenta lactogen

tells body to increase BG→send to placenta

progesterone

keeps smooth vessels loose

Estriol

increases vascularity, increases joint laxity

Placenta maternal side

dirty dunkin

Placenta fetal side

shiny shutz

Fetal Stage

lasts from 9 weeks gestation to birth

Umbilical cord

two arteries deliver deoxygenated blood to placenta (single vein returns oxygenated blood to fetus)

hematopoietic system

women risks isoimmunization if pregnancy lasts longer than 6 weeks

Resp system

develops in embryonic life and continues into childhood

• Pulmonary surfactants

• lecithin

• sphinogomyelin

Lecithin

most critical surfactant

• required for postnatal lung expansion present 21 weeks/ increases after 24 weeks

• determines lung maturity

Sphingomyelin

remains constant in amount

L/S ratio maturity

2:1

Pulmonary Surfactants

used to determine degree of fetal lung maturity- ability of lungs to function after birth

Renal systems

apart of amniotic fluid; babies void within 24 hrs

Common problem with newborns is

HYPOGLYCEMIA

Anterior fontanel

diamond like feeling

Posterior fontanel

flat like feeling

IgG

passively aquired immunity from mother (crosses the placenta)

IgM

fetus produces end of the 1st trimester (responds to blood group antigens, gram neg enteric organisms, some viruses)

IgA

not produced by the fetus, present in colostrum (breastfed infants)

Placenta

main route for bilirubin elimination