How Does Brain Works

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How Does Brain Works

Unread postby UCERD.COM » Mon Oct 20, 2014 9:53 pm

The human brain is a complex organ that allows us to think, move, feel, see, hear, taste, and smell. It controls our body, receives information, analyzes information, and stores information (our memories).
The brain produces electrical signals, which, together with chemical reactions, let the parts of the body communicate. Nerves send these signals throughout the body.

Human brainThe average human brain weighs about 3 pounds (1300-1400 g).
At birth, the human brain weighs less than a pound (0.78-0.88 pounds or 350-400 g). As a child grows, the number of cell remains relatively stable, but the cells grow in size and the number of connections increases. The human brain reaches its full size at about 6 years of age.

Neuron The brain consists of gray matter (40%) and white matter (60%) contained within the skull. Brain cells include neurons and glial cells.
The brain has three main parts: the cerebrum, the cerebellum, and the brain stem (medulla).
Although the brain is only 2% of the body's weight, it uses 20% of the oxygen supply and gets 20% of the blood flow. Blood vessels (arteries, capillaries, and veins) supply the brain with oxygen and nourishment, and take away wastes. If brain cells do not get oxygen for 3 to 5 minutes, they begin to die.
Cerebrospinal fluid (CSF) surrounds the brain.

CNSThe brain and spinal cord make up the central nervous system (CNS). The brain is connected to the spinal cord, which runs from the neck to the hip area. The spinal cord carries nerve messages between the brain and the body.
The nerves that connect the CNS to the rest of the body are called the peripheral nervous system.
The autonomic nervous system controls our life support systems that we don't consciously control, like breathing, digesting food, blood circulation, etc.
The cells of the nervous system are quite fragile and need extensive protection from being crushed, being infected by disease organisms, and other harm. The brain and spinal cord are covered by a tough, translucent membrane, called the dura mater. Cerebrospinal fluid (CSF) is a clear, watery liquid that surrounds the brain and spinal cord, and is also found throughout the ventricle (brain cavities and tunnels). CSF cushions the brain and spinal cord from jolts.

Human skullThe cranium (the top of the skull) surrounds and protects the brain. The spinal cord is surrounded by vertebrae (hollow spinal bones). Also, some muscles serve to pad and support the spine.
More subtly, the blood-brain barrier protects the brain from chemical intrusion from the rest of the body. Blood flowing into the brain is filtered so that many harmful chemicals cannot enter the brain.
Strength of Human Brain and Quran : 
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Brain Structure and Its Operation : 
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Nova Science : 
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BBC Documentary  : 
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Brain Structure and Function : 
The brain has three main parts, the cerebrum, the cerebellum, and the brain stem. The brain is divided into regions that control specific functions.
Frontal Lobe
  • Behavior
  • Abstract thought processes
  • Problem solving
  • Attention
  • Creative thought
  • Some emotion
  • Intellect
  • Reflection
  • Judgment
  • Initiative
  • Inhibition
  • Coordination of movements
  • Generalized and mass movements
  • Some eye movements
  • Sense of smell
  • Muscle movements
  • Skilled movements
  • Some motor skills
  • Physical reaction
  • Libido (sexual urges)
Occipital Lobe
  • Vision
  • Reading
Parietal Lobe
  • Sense of touch (tactile senstation)
  • Appreciation of form through touch (stereognosis)
  • Response to internal stimuli (proprioception)
  • Sensory combination and comprehension
  • Some language and reading functions
  • Some visual functions
Temporal Lobe
  • Auditory memories
  • Some hearing
  • Visual memories
  • Some vision pathways
  • Other memory
  • Music
  • Fear
  • Some language
  • Some speech
  • Some behavior amd emotions
  • Sense of identity
Right Hemisphere (the representational hemisphere)
  • The right hemisphere controls the left side of the body
  • Temporal and spatial relationships
  • Analyzing nonverbal information
  • Communicating emotion
Left Hemisphere (the categorical hemisphere)
  • The left hemisphere controls the right side of the body
  • Produce and understand language
Corpus Callosum
  • Communication between the left and right side of the brain
  • Balance
  • Posture
  • Cardiac, respiratory, and vasomotor centers
  • Motor and sensory pathway to body and face
  • Vital centers: cardiac, respiratory, vasomotor
  • Moods and motivation
  • Sexual maturation
  • Temperature regulation
  • Hormonal body processes
Optic Chiasm
  • Vision and the optic nerve
Pituitary Gland
  • Hormonal body processes
  • Physical maturation
  • Growth (height and form)
  • Sexual maturation
  • Sexual functioning
Spinal Cord
  • Conduit and source of sensation and movement

Pineal Body
  • Unknown
Ventricles and Cerebral Aqueduct
  • Contains the cerebrospinal fluid that bathes the brain and spinal cord
Brain Cell : 
The brain and spinal cord are made up of many cells, including neurons and glial cells. Neurons are cells that send and receive electro-chemical signals to and from the brain and nervous system. There are about 100 billion neurons in the brain. There are many more glial cells; they provide support functions for the neurons, and are far more numerous than neurons.
There are many type of neurons. They vary in size from 4 microns (.004 mm) to 100 microns (.1 mm) in diameter. Their length varies from a fraction of an inch to several feet.
Neurons are nerve cells that transmit nerve signals to and from the brain at up to 200 mph. The neuron consists of a cell body (or soma) with branching dendrites (signal receivers) and a projection called an axon, which conduct the nerve signal. At the other end of the axon, the axon terminals transmit the electro-chemical signal across a synapse (the gap between the axon terminal and the receiving cell). The word "neuron" was coined by the German scientist Heinrich Wilhelm Gottfried von Waldeyer-Hartz in 1891 (he also coined the term "chromosome").
The axon, a long extension of a nerve cell, and take information away from the cell body. Bundles of axons are known as nerves or, within the CNS (central nervous system), as nerve tracts or pathways. Dendrites bring information to the cell body.Myelin coats and insulates the axon (except for periodic breaks called nodes of Ranvier), increasing transmission speed along the axon. Myelin is manufactured by Schwann's cells, and consists of 70-80% lipids (fat) and 20-30% protein.
  • The cell body (soma) contains the neuron's nucleus (with DNA and typical nuclear organelles). Dendrites branch from the cell body and receive messages.
  • A typical neuron has about 1,000 to 10,000 synapses (that is, it communicates with 1,000-10,000 other neurons, muscle cells, glands, etc.).
There are different types of neurons. They all carry electro-chemical nerve signals, but differ in structure (the number of processes, or axons, emanating from the cell body) and are found in different parts of the body.

  • Sensory neurons or Bipolar neurons carry messages from the body's sense receptors (eyes, ears, etc.) to the CNS. These neurons have two processes. Sensory neuron account for 0.9% of all neurons. (Examples are retinal cells, olfactory epithelium cells.)
  • Motoneurons or Multipolar neurons carry signals from the CNS to the muscles and glands. These neurons have many processes originating from the cell body. Motoneurons account for 9% of all neurons. (Examples are spinal motor neurons, pyramidal neurons, Purkinje cells.)
  • Interneurons or Pseudopolare (Spelling) cells form all the neural wiring within the CNS. These have two axons (instead of an axon and a dendrite). One axon communicates with the spinal cord; one with either the skin or muscle. These neurons have two processes. (Examples are dorsal root ganglia cells.)
Unlike most other cells, neurons cannot regrow after damage (except neurons from the hippocampus). Fortunately, there are about 100 billion neurons in the brain.
Glial cells make up 90 percent of the brain's cells. Glial cells are nerve cells that don't carry nerve impulses. The various glial (meaning "glue") cells perform many important functions, including: digestion of parts of dead neurons, manufacturing myelin for neurons, providing physical and nutritional support for neurons, and more. Types of glial cells include Schwann's Cells, Satellite Cells, Microglia, Oligodendroglia, and Astroglia.
Neuroglia (meaning "nerve glue") are the another type of brain cell. These cells guide neurons during fetal development.
Spinal cord : 
The spinal cord is a bundle of nerves that connects the brain to other parts of the body. It is protected by a series of doughnut-shaped bones called vertebrae, which surround the spinal cord.
The human spinal cord is about 43-45 cm long and approximately as wide as a human finger. There are 13,500,000 neurons that transmit electro-chemical signals in the spinal cord. The cord weighs aproximately 35 grams. The vertebral column (bones) that supports it is about 70 cm long and has 31 segments and 31 pairs of spinal nerves.
Spinal Cord Vertebrae
  1. 7 cervical (neck) segments
  2. 12 thoracic segments
  3. 5 lumbar segments
  4. 5 sacral segments
  5. 4 fused coccygeal segment
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