742 Prenatal Development

prenatal development week 4

• heart begins beating (22 days)

• neural tube fuses (21-28 days)

• arm and legs bud

• lung primordia appear

prenatal development week 6

• heart development almost complete

• circulation established

• diaphragm complete

• early development of brain and ventricular system

• face more distinct

• generation of new neural cells

prenatal development week 12-16

• length of embryo doubles in this month

• increased muscle and bone development

• neuronal migration begins

• cerbellar plate formed

• increased movement

• body sensitive to touch by week 15

prenatal development week 21-24

• basic structure of eye complete, but immature

• able to hear sounds

• 24-25 weeks lungs are able to support extrauterine life

• organization of CNS begins ~24 weeks

• accelerated cerebellar development 20-30 weeks

prenatal development week 30-40

• fat and muscle tissue laid down

• bones fully formed

• CNS organization significant

• myelination progresses and continues after birth

• after 26 weeks, have breathing movements

• development of reflexes

what is the response/reflex at 8.5 weeks

tactile stimuli (reflex arc laid down)

what is the response/reflex at 12 weeks

sucking

what is the response/reflex at 24 weeks

sound

what is the response/reflex at 26 weeks

rhythmic breathing movements/controls body temperature

what is the response/reflex at 30 weeks

pupillary light reflex

what is the response/reflex at 35 weeks

grasp/spontaneous orientation