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Neurons

Neurons. I bet your neurons are all fired up now!. The Nervous System. NEURON = 1 cell. Nerve = a bundle of neurons. Types of Neurons. Efferent (Motor) Neurons - carry outgoing messages from the brain and spinal cord to the muscles and glands

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Neurons

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  1. Neurons I bet your neurons are all fired up now!

  2. The Nervous System NEURON = 1 cell • Nerve = a bundle of neurons

  3. Types of Neurons • Efferent (Motor) Neurons - carry outgoing messages from the brain and spinal cord to the muscles and glands • Interneurons - neurons within the brain and spinal cord that communicate internally and between sensory inputs and motor outputs • Afferent (Sensory) Neurons - carry messages from tissues and sensory organs to the brain and spinal cord for processing

  4. Neurons

  5. Neurons

  6. How neurons communicate Neurons use an electro-chemical processto send messages • Why electrical? • Pushing information through axon is based on process of positive and negative charges of electrical atoms (ions) • Potassium (K+), Sodium (Na+), Chloride (Cl-) • Why chemical? • Neurotransmitters cross synapse: different ones send different impulses and need to find receptors • It can either excite (fire) or inhibit (prevent firing) • Messages are sent at a speed of 2-200 mph • Neurons are altered with use (learning) – unused neurons die (“neural sculpting)

  7. How does a neuron fire The electrical impulse is called the action potential Step 1 - Resting potential • Polarized – positive outside, negative inside (Na+) (Cl- & K+) • Selectively permeable – gates do not allow sodium ions to pass through the cell membrane Step 2 - Action potential – brief electrical charge that travels don the neuron • Transmits neural messages to other neurons, muscles or glands • When stimulated – depolarizes • Sodium (Na+) rushes in Step 3 - Repolarization • Potassium (Ka+) flows out repolarizing the Axon. Step 4 - Return to Resting Potential • Sodium/Potassium pumps push Sodium (Na+) out and Potassium in (Ka+) bringing axon back to a resting state Step 5 - Refactory period • Brief period of time when neuron won’t fire no matter how much stimulation

  8. Action Potential

  9. Electrical Transmission – The Action Potential http://outreach.mcb.harvard.edu/animations/actionpotential.swf

  10. How to generate a neural impulse • Neuron is stimulated by light, heat, pressure or chemical messages (neurotransmitters) from other neurons. • Signals from other neurons are either • excitatory - • inhibitory - • (excitatory) – (inhibitory)reach minimum threshold - • All or None Law –

  11. How do neurons communicate with each other?The chemical process

  12. How Neurons Communicate

  13. Synaptic Transmission http://learn.genetics.utah.edu/content/addiction/reward/neurontalk.html

  14. Neurotransmitters Neurotransmitters – Excitatory neurotransmitters Inhibitory neurotransmitters

  15. Acetylcholine (ACH) • Deals with motor movement, memory and learning. • Too much and you will _________ • Too little and you will __________ • Lack of AcH has been linked to ______________________ • Black widow – • Botox – • Curare –

  16. Dopamine • Deals with motor movement and alertness/attention, emotion, rewards. • Lack of dopamine – linked to _______________ • Too much - linked to _______________ • Too little – _______________

  17. Serotonin • Involved in mood control, hunger, sleep and arousal. • Lack of serotonin has been linked to _________________ • Anorexia = _______ • Bulimia = ________

  18. Norepenephrine • Helps control • Undersupply can depress mood

  19. GABA • Major • Hunger and Sleep • Undersupply linked to ______________ • _______________causes an increase in Gaba

  20. Endorphins • Involved in pain control. • “endorphins make you happy” – runners high (emotions) • Drugs that mimic -

  21. Glutamate • Major __________ meaning _________ • Involved in memory and learning • Oversupply can over stimulate brain, producing migraines or seizures

  22. Drugs can be….. • Agonists- • Antagonists- • Reuptake Inhibitors-

  23. Agonists and Antagonists http://thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_par/i_03_m_par_cocaine.html#drogues

  24. Agonist and Antagonists Examples: Agonists – Opiate Drugs Heroine, Morphine (Endorphins) Black Widow Spider Venom (AcH) Prozac (serotonin) Antagonists – Botulin (AcH), Botox (AcH), Curare (AcH)

  25. The Nervous System

  26. Central Nervous System • The Brain and spinal cord • CNS

  27. Peripheral Nervous System • All nerves that are not encased in bone. • Everything but the brain and spinal cord. • Divided into two categories….somatic and autonomic.

  28. Somatic Nervous System • Controls • Uses

  29. Autonomic Nervous System • Controls • Divided into two categories

  30. Sympathetic Nervous System • Fight or Flight Response.

  31. Parasympathetic Nervous System • Automatically

  32. Reflexes • Reflex - a simple, automatic, inborn response to a sensory stimulus • ______________take info up through spine to the brain. • Some reactions occur when • Survival adaptation.

  33. A Simple Reflex

  34. A Simplified Neural Network Neurons that learn to work together as a team.

  35. The Endocrine System A system of Similar to ___________________________ Work Hormones Neurotransmitters

  36. The Major Endocrine Glands

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