Birth occurs in three stages.• Stage one of birth is the dilation of the cervix. – contractions push cervix open – if cervix dilates too little, C-section done

STAGE 1As regular, strong contractions occur,the cervix dilates and the baby turns.

• Stage two is the emergence of the baby.– baby usually born headfirst – oxytocin stimulates milk production

STAGE 2The baby is pushed through the cervixand out of the vaginal canal.

• Stage three is the expulsion of the placenta.– placenta detaches from uterine wall – contractions helps control bleeding

STAGE 3Contractions continue, expelling theplacenta and helping to control bleeding.

Human growth and aging also occur in stages.• Genetics, hormones, lifestyle, environment affect all stages.

– during infancy, growth is rapid– during childhood, motor and

language skills develop

• Genetics, hormones, lifestyle, environment affect all stages.– during puberty, sexually maturity begins

– during adolescence, growth is rapid and the brain rewired

– adulthood marks the peak of skills and independence

• Aging is also affected by genetics, hormones, lifestyle, environment.

Jerry Peel at age 1 1/2 Jerry Peel at age 17 Jerry Peel at age 71

• Effects of aging can be reduced with good diet, exercise, and continued learning.