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Chapter 29 Human Development

Chapter 29 Human Development. TERMS: Embryology : the study of the fertilized egg’s development Events: When egg meets sperm this creates a zygote . In the first two months the zygote becomes an embryo , then is known as a fetus until birth

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Chapter 29 Human Development

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  1. Chapter 29Human Development • TERMS: • Embryology: the study of the fertilized egg’s development • Events: When egg meets sperm this creates a zygote. In the first two months the zygote becomes an embryo, then is known as a fetus until birth • The above events are called: prenatal development, after birth this is known as the neonatal period • Pregnancy- 38 weeks from egg to kid also called Gestation period

  2. Sperm Meets Egg • Majority of sperm do not make it to egg • destroyed by vaginal acid • Presence of cervical canal mucus plug • go up wrong uterine tube (Didn’t ask for…) • Move by lashing of flagella • Assisted by female physiology • uterine contractions

  3. Boy Meets Girl • Spermatozoa can reach uterine tube within 10 minutes of ejaculation • Sperm fertile for 48 hours after ejaculation • Conception of a child is optimal if sperm are deposited anytime from 48 hours before ovulation to 14 hours after

  4. Fertilization • Fertilization- sperm meets egg • Syngamy- (sin-marriage, come together in marriage) the term for a sperm meeting the egg • Polyspermy is blocked by syngamy, no more than one sperm should fertilize an egg NOTE: location of egg during fertilization

  5. Fraternal twins are called Dizygotic twins- two different eggs and different sperm Maybe different sex as different as any other siblings Identical (maternal) twins are called Monozygotic twins- same eggs and same sperm, the egg separates into two yokes Always same sex? YES NO Why? Same genetic information is shared Conjoined twins also called Siamese twins, the yokes didn’t separate totally They are joined together and usually share body structure Twins

  6. Mitosis • The World Series of BODY cells, mitosis is rapidly occurring in the blastocyst (young bag) • Implantation is when the blastocyst attaches to the endometrium of the uterus • Due date: Count backward for ___ weeks, start 2 weeks after the first day of the last menstruation

  7. Clinical • Ectopic pregnancy (ec- = out of, -topic = place), the ovaries hang close to the follopian tubes but do not connect directly to them. • Tubal variety- the egg get stuck in the fallopian tube and develops • Abdominal variety- the egg slips into the abdomen and develops outside the reproductive tract • 9% of abdominal pregnancies result in live birth by cesarean section

  8. Embryology • Three primary germ layers: endoderm, mesoderm, ectoderm • From these “three derms” all tissues and organs develop. • GENERALLY: • Endoderm produces most epithelium of the inner body (In) • Mesoderm produces connective tissue and muscle (mes-el) • Ectoderm produces nervous tissue (ex toes- cross toes)

  9. The umbilical cord is the blood vessels that connect mom to baby. Mother and baby’s blood doesn’t mix Through diffusion stuff gets in and out Oxygen, diffuses from mom to baby and carbon dioxide diffuses from baby to mom The Umbilical Cord

  10. The Origin of the Navel • When the baby is born, the placenta detaches from the uterus called the afterbirth • this was the other end of the umbilical cord attached to mom • The umbilical cord is cut and tied off and will fall off in about two weeks leaving a scar called the umbilicus (navel) • Q. Name two people in history without belly buttons. A. _______ and _______

  11. Kid “In Vivo”What’s “in vitro”?

  12. Mutagen • Mutagen- Any agent that alters DNA or chromosome structure • Radiation, drugs (thalidomide) • thalidomide (unformed arms or legs) • microorganisms that can cross the placenta include • syphilis, herpes simplex, HIV • Sometimes are beneficial • TERATOGEN- an agent that causes development defects in the embryo • Fetal alcohol syndrome, smoking • cardiac & CNS defects, anencephaly, cleft lip and palate • Cigarette smoking- can cause anencephaly, absence of a cerebrum

  13. Errors of Meiosis • Errors of meiosis • Nondisjunction- chromosomes don’t separate, one side gets too many chromosomes and the other none • Translocation- the location of the chromosome changes to another chromosome

  14. Down’s Syndrome • Down’s syndrome- Trisomy 21, nondisjunction of chromosome 21 during meiosis • Causes= old eggs (1 in 9 chance in 48 year old female) • Eggs age, sperm is freshly made, usually only ten weeks old • Signs- mental retardation, structural retardation (short, slanted eyes)

  15. Aging • Aging is all changes occurring with the passage of time -- growth, development & degeneration • leading causes of death from 18 to 34 is accidents, homicides, suicides and AIDS • leading causes of death after 55 is age related • cancer, stroke, diabetes, heart & lung disease

  16. Exercise and Aging • Good nutrition & exercise are best ways to slow aging • exercise improves quality of life (providing endurance, strength & joint mobility) • Even a 90 year old can increase muscle strength • Resistance exercise reduces bone fractures • Reduce body fat, and increase cardiac output & oxygen uptake

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