sci 3rd

• The Nervous System is a network of nerves that connect the spinal cord and the brain to the rest of the body, allowing stimulus-response reactions to occur among different organs.
• The two major sections of the nervous system are: the central nervous system and the peripheral nervous system.
• Neurons are the fundamental units of the nervous system.
• Neurons are cells that translate external stimuli into electrical signals that are transmitted to the brain.
• The parts of neurons are the cell body or soma, axon, and dendrite.
• The cell body or soma is the main part of the neuron where the nucleus is located.
• Soma translates DNA information that is transported to the dendrites and the axon.
• Axon is the thick branch that trails behind the soma.
• The Axon Terminal at the end of the axon allows communication among various neurons.
• The axon is surrounded by Myelin Sheath, a protective overing that insulates the axon nd lets electrical impulses travel more quickly along the unmyelinated axon.
• Electrical impulses are called action potential.
• Dendrites are the smaller branch-like extensions attached to the ends of the soma.
• Dendrites process the electric impulses before transmitting them.
• Information received may be either Excitatory, which fires up neurons, or Inhibitory, which has a tendency to fire up.
• Dendrites connect to each other and can change sizes as they receive additional information.
• The three main classifications that serve individual functions for each section of the nervous system are sensory neurons, interneurons, and motor neurons.
• Sensory neurons react to both external and internal stimuli.
• Sensory neurons pick up information outside the body and deliver it to the central nervous system.
• Sensory neurons allow people to perceive their surroundings through the 5 sensory organs.
• These sensory neurons are controlled by a reflex arc that enables involuntary functions, through the spinal cord.
• Interneurons translate information between sensory and motor neurons.
• Interneurons integrate the sensory & motor neurons through the spinal cord.
• Motor neurons pick up information from the central nervous system and then transmit it through the nerves.
• Motor neurons mobilize a person and enable physical changes in the body.
• As the signals pass through, the axon terminals transmit the signals to the motor neurons in tissues and organs, such as muscles allowing them to perform their functions.
• Motor neurons mobilize a person and enable physical changes in the body. As the signals pass through, the axon terminals transmit the signals to the motor neurons in tissues and organs, such as muscles allowing them to perform their functions 
• Afferent neurons communicate information to the central nervous system (CNS) through electrical signals called nerve impulses
• In the peripheral nervous system, motor neurons carry information forward through impulses toward an effector cell called efferent neurons
• A response will be produced to the stimulus, which can be voluntary or involuntary, in either an external or internal body part
• The network of nerves is divided into two main sections that function co-dependently: the central nervous system and the peripheral nervous system
• Central nervous system consists of two main parts: the brain and the spinal cord
• The function of the central nervous system is to receive, process, interpret, and send information through electrical signals or nerve impulses that neurons carry toward the peripheral nervous system
• The brain is the major organ of the nervous system
• About 100 billion neurons are found in the brain alone, each cell processes countless pieces of information every second
• The brain’s exterior structure is made up of a protective layer called meninges which wraps the folds and indentations called gyri and sulci
• The brain reads information and controls all the functions of the human body with the help of nerves and neurons
• The brain consists of two hemispheres subdivided into three main parts during embryonic development: the forebrain, midbrain, and hindbrain
• Forebrain:

  • Responsible for sensory perception, thinking, processing information, understanding, speaking languages, and motor functions
  • Contains the largest section, the cerebrum, which comprises about 85% of the brain
  • Most information processing occurs in the cerebral cortex, categorized into frontal, parietal, occipital, and temporal lobes.
  • makes up the brain's frontal area.
• Frontal lobe:

  • Located at the forefront of the cerebral structure
  • Divided into the motor cortex (controls motor functions) and prefrontal cortex (governs personality traits, cognitive functions, memory, decision-making, reasoning, and judgment)
• Parietal lobe:

  • Located behind the frontal lobe
  • Contains the somatosensory cortex (processes sensory information and controls the sense of touch)
  • Influences spatial orientations and body coordination