Human development

due to problems in man, underproduction of sperm/poor quality or impotence/inability to maintain an erection

male infetility

low sperm count can be caused by….

smoking, hormone disruptors

lack of eggs, failure to ovulate, blocked oviducts

female infertility

administration of drugs to promote development of eggs by: drugs for ovulation; removal of eggs; collection of sperm; fertilization in a petri dish; injection of embryos into uterus

IVF (in vitro fertilization)

how do identical and fraternal twins differ

identical twins have 1 egg/sperm and same placenta but separate sacs; fraternal twins have 2 eggs/sperm and separate placentas/sacs

used to selectively terminate fetus w/ congenital abnormality or genetic d/o; terminate one or more fetuses of multiple gestation pregnancy while allowing some to live; ethical debate

multifetal pregnancy reduction (MFPR)

what is menopause in women

around age 50 cessation of ovulation/menstruation to increase fitness and invest more time/energy to children

what are the pro of embryonic stem cells debate

• can form all cell types in body

• potential cures for spinal injuries, MS, diabetes, etc

  • reduced risk of transplantation (copy of own heart for future)

what are the cons of embryonic stem cells debate

• destruction of blastocyst

• morally unacceptable

• when does life begin

• should past 2nd trimester aborted fetus be used for research

  • temptation to clone humans

what are alternative to embryonic stem cells debate

• use adult stem cells / bone marrow

  • use umbilical cord/placental blood

how does embryonic development begin

fertilization of sperm and egg → zygote (2n)

what’s the shape of sperm / why and how does it move

streamlined to swim through fluids / swim = spin

what does mom give that male does not

the mitochondria

what’s the anatomy of sperm

90% deformed; head has DNA; acrosome caps head; 2 centrioles; mitochondria; sperm tail last to devople

whats the path of sperm

epididymis → vas deferens→ ampulla→ seminal vesicle → ejaculatory ducts → urethra

what do the seminal vesicles secrete

fructose and prostaglandins

what does the prostate gland secretions do

buffer acidity

what does the bulbourethral glands secrete

mucus rich fluid / neutralizes any trace of acidity

what is capacitation

allows sperm to be lighter and be more active / penetrate and fertilize egg

what is the acrosine reaction

digest zona pellucida / membrane oocyt; bind head to Z3; allows spermatozoa membrane to fuse w/ egg

whats a slow block to polyspermy

physical barrier formed by vitelline membrane; egg releases cortical granules to extracellular space; strucutre prevents fertilizatioin

whats a fast block

changes electrical potential of egg plasma'; opens Na+ channels and flows into egg cell depolarizing the membrane; prevents additional sperm to fuse to the egg membrane

embryonic development begins with ____ and continues as an embryo moving down towards the uterus

cleavage → series of rapid cell division resulting in multicellular ball

____ forms 6-7 days after fertilization; consists of a fluid-filled hollow ball of 100 cells and small inner cells called ____ that forms the fetus

blastocyst; inner cell mass

after conception the embtyo undergoes ____

gastrulation → organized migration of cells

what are the 3 main tissue layers of the basic body plan in the gastrula stage?

1. ectoderm

2. mesoderm

3. endoderm

what is ectoderm

outer layer that forms nervous system, skin, retina

what is the mesoderm

middle layer that forms heart, kidneys, muscles

what is the endoderm

inner most layer: lungs, liver, innermost lining of digestive tract

• transient structure

• forms on day 15

• start of gastrulation

• bilateral symmetry

• initiaties germ layer formatioin

• rise to notochord & mesoderm

primitive streak

what are the 4 extraembryonic membranes

• originate from embryo but not part of it

• assist in development of embryo

• provide protection

• transport nutrients/waste

  • ultimately discared after birth

what extraembryonic membrane envelopes the fetus in amniotic fluid?

amnion

what extraembryonic membrane is the 1st site of RBC formation

yolk sac

what extraembryonic membrane has the blood vessels become the umbilical blood vessel

allantois

what extraembryonic membrane contributes to the placenta

chorion

development from fertilization to gestation goes through all adult stages of its evolutionary history

ontogeny recaptures phylogeny

programmed cell death

apoptosis

what happened in the Thalidomide tragedy 1962

german drug claimed to cure anxiety, insomnia, gastritis, tension and pregnant women used it to ease nausea which resulted in 5000-7000 infants to be born w/ Phocomelia/malformation of limbs; about 40-50% survived; deformed eyes, hearts, etc

• inhibitor of angiogenesis

• used to treat multiple myeloma

• shrinking cancerous tumors before surgery

• treating TB

• dont get pregnant under this treatment

thaliomide

• was prescribed to prevent miscarriages

• grand daughters - 40x chance developing lower genital tract clear cell adenocarcinoma

• banned in 1971

DES → diethystilbestrol = synthetic estrogen

what are characteristic of fetal alcohol syndrome

small head, hyperactivity, height/weight below average, mood swings, deformed limbs, learning disabilities, poor coordination

at the 8-9 week mark of development what are some characterisitcs

designated fetus, all major organs/body parts, genitals developing, presence/absence of SRY (male determining inhibitor for developing testis) DAX1 for females (develop ovaries/eggs), hormones (testosterone/estrogen) for secondary determination

blood vessels/maternal blood vessels in close contact, nutrients exchanged, fetal and maternal do NOT mix

mature placenta and fetus

what has happened at the 10 week development

placenta formed fully, hormone is produced by placenta, mom and fetal blood don’t mix; antibody Ig or rubella can cross placenta, microbes could cause infection

what happens at the 3-4 month development

eyelashes, eyebrows, hair, fingernails, nips, body length brain growth slows, ossification/osteogenesis (bone replaces cartilage at 8 week)

sex of fetus can be identified, amniotic fludi for amniocentesis, nonsurgical abortions till end of 1st trimester, legal to 24 weeks

1st trimester (1-12 weeks)

fetus looks human, 1lb, face of infant

2nd trimester (13-27 week)

what happens at the 5-7 month mark of development

kicking, lanugo, venix caseosa, eyes open, 3lb

at what age / weeks can a fetus survive outside the womb

28 weeks / 7 months (age of viability)

what happens inthe 3rd trimester

rapid growth, physical changes, 6-8lb, teratogen can disturb embryonic development (drugs, infectioins, chemicals)

describe childbirth

labor (contractions), oxytocin stimulant of wall muscles to induce, prostaglandins induce labor contraction of uterine smooth muscles/cervical ripening, closer contractions

what are the 3 stages of childbirth

1. dilation

2. expulsion

3. delivery

what is dilation in childbirth

longest stage of labor, opens the cervix (10cm), amniotic sac ruptures, mucus plug, more contractons

what happens during expulsion of childbirth

delivery of the infant

what is delivery in childbirth

the placenta w/in 15 mins after birth of baby

what contribute to the growth of mammary glands/ducts

estrogen & progesterone

prolactin is secrete, colostrum produced, high IgA, growth factors, antimicrobial factors

lactation

forces milk into ducts and contract, forces uterine contractions, can be a treatment of anxiety, schizophrenia, social bonding

oxytocin