Page 211 - The Truth Landscape Format 2020 with next section introductions-compressed

During the second trimester, the fetus is still testing out movements, kicking and stretching. At some point between week 16 and week 20, the fetus should be
large enough that mom can feel the baby kick. These movements are directed by the cerebellum. At this point, the fetus develops the full range of specific
fetal movements. In the second trimester, the fetal brain begins to direct the compression of the chest muscles and movement of the diaphragm. These are
kind of like practice breaths and are controlled by the brain stem.

The fetal brain stem is almost entirely developed by the end of the second trimester. This part of the brain is located just above the spinal cord. The nervous
system has developed enough to detect loud noises from outside — mom may feel the baby startle when there’s a loud clap of thunder or a car honking. The
baby will start to identify the sound of mom’s voice and may turn its head up toward the sound. Finally, the brainwaves that occur during sleep, controlled by
the hypothalamus, begin occurring around week 28. Baby will begin experiencing sleep cycles, including REM sleep, the stage where dreaming occurs.

The third trimester
Brain development in the third trimester is marked by the rapid development of neurons in the brain and explosive growth. The baby’s brain will triple in size
during this time, growing from a little over 3 ounces to almost 11 ounces at birth. The cerebrum will begin to develop grooves and ridges and separate into
the left brain and right brain. The cerebellum is the fastest-growing part of the brain in the third trimester. This is the part responsible for motor control, so
baby will begin to move more, wiggling fingers and toes, stretching, and kicking.

Brain development in the third trimester is marked by the rapid development of neurons in the brain and explosive growth. Your baby’s brain will triple in
size during this time, growing from a little over 3 ounces to almost 11 ounces at birth. The baby is large enough that mother will notice quite a bit of
movement, some of which may be a little uncomfortable. In addition, the fetal sensory system shows integration and functionality during this period.

The baby’s brain will grow five main parts, each responsible for a different aspect of directing the body and (eventually) the mind and decision making:
1. The cerebrum is responsible for thinking, feeling, and memory. It’s the largest part of the brain and contains the cerebral cortex and the frontal and
temporal lobes of the brain.
2. The cerebellum is responsible for directing the body’s motor control, from moving arms and legs to the fine motor skills of pinching and grasping.
3. The brain stem controls the vital functions that keep the body alive. These are mainly involuntary systems like heartbeat, blood pressure, and
breathing. It also controls the digestive process, although hunger cues come from elsewhere.
4. The pituitary gland is in charge of releasing most of the hormones in the body that direct the metabolism, ovulation, growth, and more.
5. The hypothalamus regulates body temperature, hunger and thirst cues, sleep, and emotions.

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