HUMAN BIOLOGY

Development anD aging 335 lengthen and rings of microfilaments in cells tighten like purse strings. Section 17.1 mentioned that ...

336 Chapter 17 allantois Extraembryonic membrane that gives rise to blood vessels of the umbili- cal cord. amnion Extraembryonic ...

Development anD aging 337 placenta Temporary organ in which blood vessels of the mother and an embryo (later the fetus) are in c ...

338 Chapter 17 the second Four Weeks: Human Features appear becomes more intricate, and the umbilical cord forms. Growth of the ...

Development anD aging 339 fetus A term used to desig- nate a human embryo after it has completed 8 weeks of development. hoW doe ...

340 Chapter 17 Development of the Fetus In the second trimester, movements begin When the fetus is 3 months old, it is about 4.5 ...

Development anD aging 341 What are the basic developmental events of the second and third trimesters? The second and third trim ...

342 Chapter 17 Birth and Beyond The hormonal flood is triggered by an as-yet-unknown signal that says, in effect, it’s time to b ...

Development anD aging 343 Recent years have seen a significant increase in births by cesarean section, in which a full-term fetu ...

344 Chapter 17 Disorders: miscarriages, stillbirths, and Birth Defects carbohydrates, lipids, and proteins it needs. Vitamins an ...

Development anD aging 345 Like many other drugs, alcohol crosses the placenta and affects the fetus. Fetal alcohol syndrome (FAS ...

346 Chapter 17 amniocentesis Testing fetal cells in a sample of amniotic fluid for evidence of birth defects. chorionic villus s ...

Development anD aging 347 What are the stages of human development? Following birth, development proceeds through childhood and ...

348 Chapter 17 time’s toll: everybody ages Cumulative damage to Dna may also play a role in aging A “cumulative assaults” hypoth ...

Development anD aging 349 hoW does aging affect body systems? Virtually every body system undergoes age-related declines in str ...

350 Chapter 17 summary section 17.1 The fertilization of an oocyte by a sperm launches several key stages in early development. ...

Development anD aging 351 section 17.8 During the last 3 months of gestation (the third trimester), the fetus grows rapidly and ...

352 Chapter 17 your Future Dr. E. Walker/Science Source Figure 17.25 This embryo, the result of an ectopic pregnancy, could not ...

When you were born, your body consisted of about a trillion cells. The growth that transforms a zygote—the first cell of a new i ...

chromosome A DNA molecule together with the proteins attached to it. chromosome number The sum of the chromosomes in a species’ ...