Nervous system

Brain of the Newborn

• A newborn baby's brain doubles in size during the course of its first year (1^✔ ✔Trusted Source
  Imaging structural and functional brain development in early childhood
  
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Human Brain

• The left side of the human brain controls the right side of the body, and the right side of the brain controls the left side of the body (2^✔ ✔Trusted Source
  Physiology, Brain
  
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• The Human brain stops growing by 18 years of age (3^✔ ✔Trusted Source
  The Teen Brain: 7 Things to Know
  
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• Only 4% of the brain's cells work while the remaining cells are kept in reserve.

Nerve Cells

• A newborn baby loses about half of their nerve cells before they are born.
• The human brain contains more nerve cells than the stars in the Milky Way (4^✔ ✔Trusted Source
  Grand Challenge: How Does the Human Brain Work and Produce Mental Activity?
  
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• Sixty percent of the human body's nerves end in the forehead and the hands.

Weight of the Brain

• As we get older, male brain weight decreases by 2.7 grams per year, whereas female brain weight decreases by 2.2 grams per year (5^✔ ✔Trusted Source
  Ageing and the brain
  
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• An average adult male brain weighs about 1336 grams (6^✔ ✔Trusted Source
  Normal weight of the brain in adults in relation to age, sex, body height and weight
  
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• An average adult female brain weight is around 1200 grams.

Neurons

• There are about 69 million neurons in the human spinal cord (7^✔ ✔Trusted Source
  The Cellular Composition and Glia-Neuron Ratio in the Spinal Cord of a Human and a Non-Human Primate: Comparison with other Species and Brain Regions
  
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• The human brain comprises around 100 billion neurons (8^✔ ✔Trusted Source
  Understanding neurogenesis in the adult human brain
  
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Size of the Brain

• The total surface area of the human brain is about 1820 cm2 (9^✔ ✔Trusted Source
  Physical biology of human brain development
  
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• The human brain develops to 90% of its adult size by the age of 6 (10^✔ ✔Trusted Source
  The Basics of Brain Development
  
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Length of the Brain

• The average length of the human brain is about 167 mm and its average height is 93 mm.

Body Weight and Brain

• The brain makes up only 2% of our body weight, but it utilizes 20% of our body's energy, i.e., it uses 20% of one's blood and oxygen (2^✔ ✔Trusted Source
  Physiology, Brain
  
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Brain Signals

• The brain continues to send out electric wave signals until approximately 37 hours after death (11^✔ ✔Trusted Source
  Electroencephalographic activity after brain death
  
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Chemical Reactions

• On average, 100, 000 to 1000, 000 chemical reactions take place in our brain.

Speed of Brain Communication

• The nervous system transmits messages to the brain at a speed of 180 miles per hour.

Size of the Spinal Cord

• The length of the spinal cord is around 45 cm in men and 43 cm in women, and its diameter is the same as that of the index finger (12^✔ ✔Trusted Source
  Anatomy, Back, Spinal Cord
  
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Brain development

• Reading aloud to children helps stimulate brain development (13^✔ ✔Trusted Source
  Reading Aloud and Child Development: A Cluster-Randomized Trial in Brazil
  
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Self-recognition

• The right side of the human brain is responsible for self-recognition (14^✔ ✔Trusted Source
  Self-recognition, theory-of-mind, and self-awareness: what side are you on?
  
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Gender Differences in the Brain

• Men listen with the left side of the brain, while women use both sides of the brain.
• Women have more white matter and fewer grey matter areas than men (15^✔ ✔Trusted Source
  The neuroanatomy of general intelligence: sex matters
  
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Connections in the Brain

• It is estimated that there are over 1,000,000,000,000,000 connections in the human brain (16^✔ ✔Trusted Source
  The Cellular and Molecular Landscapes of the Developing Human Central Nervous System
  
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