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The Nervous & Immune System

The Nervous & Immune System. Bio and the Body 2014 Ms. Boehm . What is the Nervous System?. A network of nerve cells and fibers that transmit signals between parts of the body, and the brain- the control center. Functions of the Nervous System.

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The Nervous & Immune System

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  1. The Nervous & Immune System Bio and the Body 2014 Ms. Boehm

  2. What is the Nervous System? • A network of nerve cells and fibers that transmit signals between parts of the body, and the brain- the control center.

  3. Functions of the Nervous System • Control of all of the body’s activities -the brain being the control center • Responds & adapts to changes that occur both inside & outside the body (helps maintain homeostasis) - pain, temperature, fear, etc.

  4. 2 Main Parts:

  5. 2 Main Parts: • Central Nervous System (CNS) • The body’s main processing center, includes the brain and spinal cord. • Plans the body’s response to a stimulus (an environmental change) • Orders a response to the stimulus Ex. You put your hand on a very hot stove top (stimulus= heat) and you move your hand away quickly.

  6. Anatomy of the CNS • Brain = Control center of entire body • Brain Stem = Connects brain to spinal cord • Controls breathing, heart rate, digestion, etc. • Spinal Cord = Column of nerves from brain to tailbone • Protected by vertebrae of spine • Sends impulses from brain to rest of body, and relays messages from the body to the brain

  7. 2 Main Parts: 2) Peripheral Nervous System(PNS) a. Receives information from a stimulus. b. Delivers information to the CNS. Anatomy of the PNS • Nerves –bundles of neurons that extend from spinal chord to the rest of the body

  8. The Nervous System • The nervous system sends messages throughout entire body (to & from brain) • Neurons= Specialized nerve cells that make up the brain, spinal cord, & nerves • Send impulses (messages) throughout body

  9. Anatomy of Neuron

  10. Anatomy of Neuron • Each Neuron has: • Cell Body = holds the nucleus • Dendrites = fibers that receive signals from other neurons • Axon = conducts electrical impulses along neuron • Myelin Sheath = insulates axon to increase speed of signal • Schwann Cells = help to make myelin sheath • Node of Ranvier = gaps along axon that are not insulated. This is where electrical activity is generated. • Axon Terminal = transmit electrical signal across synapse & onto another neuron

  11. Communication within a Neuron • A signal is received at the dendrites. • An electrical signal is sent down the axon to the axon terminals • This is done by ion exchange (Na+ and K+ ions) • Na+ and K+ pumps, a form of active transport,help make a neuronhave a negative charge. • The myelin sheath’sjob is to insulatethe electrical signal-just like rubber on the outside of a cord.

  12. Communication between Neurons • Neurons do not touch – there is a gap between them called a synapse • An electrical signal can not cross a gap • Messages are sent across synapses through special chemicals called neurotransmitters, a chemical signal • Neurotransmitters leave the axon terminal by the process of exocytosis, a form of active transport.

  13. Summary of Neuron Function

  14. Types of Neurotransmitters • Some neurotransmitters excite receiving neurons, causing an electrical signal (Excitatory) • Others prevent, or block, the electrical signal from forming in receiving neurons (Inhibitory) • Examples: • Acetylcholine- causes muscle cells to contract (Botox fun fact) • Dopamine- reward motivated behavior, a feel good chemical(low levels related to depression)

  15. Effect of Drugs on the Nervous System • Drugs can affect the nervous system in different ways • Drugs can: • Increase the release of neurotransmitters • Decrease the release of neurotransmitters • Mimic a neurotransmitter

  16. Drug Addiction • Abuse of drugs can cause a tolerance of the drug • Meaning that more and more of the drug is needed to produce the same effects. • Addiction is an uncontrollable dependence on a drug. • Withdrawal is experienced when the drug is not taken • Symptoms are physical and psychological • Examples are shaking, sweating, nausea, depression

  17. Types of Drugs • Stimulants • Increase the activity of the CNS, highly addictive • Typically increase heart rate, blood pressure, and decrease appetite. • Examples: caffeine, nicotine, cocaine, methamphetamines • Depressants • Slow the activity of the CNS, overdoses prevent the CNS from functioning leading to death • Cause drowsiness, poor judgment, lack of coordination • Examples: alcohol, sedatives, sleeping pills • Marijuana • Acts as both a stimulant and a depressant • Side effects include problems with memory and learning, distorted perception, loss of coordination and anxiety.

  18. Types of Drugs, cont. • Narcotics • Mimic natural chemicals in the CNS and bind to receptors, HIGHLY addictive, and withdrawal is extremely painful. • Opiates are narcotics derived from the opium poppy, a plant. • Side effects include feelings of euphoria, block pain signals • Examples: morphine, codeine, heroin • Inhalants • Vapors from certain substances can cause mind altering effects. • Causes slurred speech, clumsiness, increased heart rate, damage to major organs • First time users can die suddenly from heart failure or suffocation. • Examples: volatile solvents, aerosols, certain gases

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