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The nervous system


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The nervous system

  2. 2. • Your body performs many functions that maintain life, such as heartbeat, temperature, digestion and blood pressure. • The regulation of conditions that maintain life is called homeostasis. • The nervous system is used by your body to maintain homeostasis
  3. 3. • Neurons are nerve cells • Neurons are made up of dendrites and axons • Dendrites receive impulses from other neurons • Axons carry impulses away from the neurons
  4. 4. • There are three types of neurons: - sensory neurons receive information and send impulses to the brain and spinal cord - interneurons in the brain and spinal cord relay impulses to the motor neurons - motor neurons conduct impulses to muscles or glands throughout the body
  5. 5. • To move from one neuron to another, an impulse crosses a small space called a synapse
  6. 6. • The Central Nervous System (CNS) contains the brain and the spinal cord
  7. 7. • The Peripheral Nervous System (PNS) is made up of all the nerves outside the CNS, including: - cranial nerves (in the head) - spinal nerves * The PNS connects the brain and spinal cord to other body parts
  8. 8. The BRAIN • The brain is an organ of soft nervous tissue which functions as the center of sensation and intellectual activity - (that’s your senses and ability to think) 
  9. 9. • The brain coordinates all of your body’s activities • The brain is protected by the skull, three membranes, and a layer of cranial fluid • The brain is divided into three major parts: the cerebrum, the cerebellum, and the brain stem
  10. 10. BRAIN STEM
  11. 11. • The cerebrum is the largest part of the brain. • It is where thinking takes place, the center of intellectual activity
  12. 12. • Also in the cerebrum: - impulses from the senses are interpreted - memory is stored - movements are controlled • The bumpy outer layer of the cerebrum is called the cortex
  13. 13. • The cerebellum is the part of the brain that controls voluntary muscle movements, maintains muscle tone and helps maintain balance
  14. 14. • The brain stem extends from the cerebrum and connects the brain to the spinal cord • The brain stem is made up of the midbrain, the pons, and the medulla
  15. 15. • The spinal cord is an extension of the brain stem • It is made up of bundles of neurons that carry impulses from body parts to the brain, and from the brain to the body parts
  16. 16. • The spinal cord is protected by bones called vertebrae • Injury to the spine can cause paralysis, the loss of muscle movement. • The higher up the spine the injury is, the more of the body that is affected
  17. 17. • In the Peripheral Nervous System (PNS), there are two divisions: • The somatic system controls voluntary actions – movements you choose • The autonomic system controls involuntary actions like heart rate and breathing
  18. 18. • A reflex is an involuntary response to a stimulus • A reflex involves a simple nerve pathway called a reflex arc • A reflex allows the body to react to a potentially dangerous stimulus quickly, without having to think about it (such as heat) • Reflexes are controlled in the spinal cord, not the brain; the brain acts after a reflex (putting on burn cream, for example)
  19. 19. • The sensory systems are parts of the nervous system responsible for processing sensory information • Sense organs are specialized organs that initiate the process of sensory perception • The body’s main sense organs are the eyes, ears, tongue, nose and skin
  20. 20. • A sensory system consists of sensory receptors, neural pathways, and parts of the brain involved in sensory perception