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The Nervous System

The Nervous System. Master Watermark Image: http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif. Functions of the Nervous System. The nervous system receives information about what is happening inside and outside the body. . Messages from outside: Senses

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The Nervous System

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  1. The Nervous System Master Watermark Image: http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

  2. Functions of the Nervous System • The nervous system receives information about what is happening inside and outside the body. • Messages from outside: Senses • Messages from inside: Through the nerves – fatigue, blood glucose, etc.

  3. Functions of the Nervous System • The nervous system also responds to information. • Changes in the environment are called stimulus. • A response is what your body does in reaction to the stimulus. • Some reactions are voluntary (swatting a fly), while others are involuntary (increased heartbeat).

  4. Functions of the Nervous System • Maintains homeostasis. • Homeostasis is the body’s ability to regulate itself. • The nervous system directs the body to respond appropriately to information it receives from the body and react accordingly (you lack energy, the brain signals your need to eat).

  5. The Neuron • The cells that carry information through your nervous system are the neurons. • The message a neuron carries is a nerve impulse. Dendrites: Carry impulses towards the neuron’s cell body Axon: Carries impulses away from the neuron’s cell body

  6. Neurons The brain decides how to respond to the stimulus. Interneuron: Carries the nerve impulses from one nerve to another until it reaches the brain Motor neuron: Sends an impulse to a muscle or gland, and the muscle or gland reacts in response. Sensory neuron: Picks up the stimuli from the internal or external environment

  7. What happens when a nerve impulse reaches the axon tip? • The junction where one neuron can transfer an impulse to another is called a synapse. • Nerve impulses must cross the gap between the axons and the dendrites. • The axon tips release chemicals that carry the impulse across the gap. These chemicals are called neurotransmitters.

  8. Divisions of the Nervous System • Central nervous system: Consists of the brain and spinal cord. • Peripheral nervous system: Consists of all the nerves located outside of the central nervous system

  9. Central Nervous System • This is the control center of the body. • All information about what is happening in the world outside and inside the body is brought to the central nervous system. • Information travels through the spinal cord to get to the brain

  10. Touch Cerebrum Movement Cerebrum Taste Reading Speech Hearing Abstract thought Vision Smell There are three main regions of the brain that receive and process information: Cerebrum-The largest division of the brain. It interprets input from the senses, controls movement and carries out complex mental processes. http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

  11. Cerebellum: Coordinates muscle action and balance Brain Stem: Controls involuntary actions such as breathing and heart rate.

  12. Peripheral nervous system • Your brain is connected to the peripheral nervous system through the spinal cord. • The peripheral nervous system consists of the network of nerves that branch out from the central nervous system and connect it to the rest of the body. • It is involved in voluntary (somatic nervous system) and involuntary actions (autonomic nervous system).

  13. Reflexes • A reflex is an automatic response that occurs very rapidly and without conscious control. • Reflexes help protect the body. • In this case, the information travels to the spinal cord and directly to motor neurons; the information reaches the brain after the fact. • Example: Touching a sharp or burning object.

  14. Nervous System Injuries • The nervous system can suffer injuries that interfere with its functioning: • Concussions: A concussion is a bruising of the brain. They can happen when you bump your head in a fall, a car crash or during sports. Swelling or hematomas can develop into debilitating brain injuries. To decrease your chances of a concussion wear a helmet and a seat belt. • Spinal Cord Injuries: These injuries occur when the spinal cord is crushed or cut. These injuries result in paralysis. The most common causes are car crashes.

  15. Final thought • Although you cannot “grow more brain cells”, you can increase the number of synapses between neurons. Brain scan of a “reader” Brain scan of a “non-reader” Blue areas indicate inactive synapses

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