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Nervous System

Nervous System. By: Ms. Wetherington. Review. What is a neuron? Synaps ? Synaptic cleft, pre and post synaptic cells Myelin Cells CNS: Oligodendrocyte cells PNS: Schwann cells. Review. Resting membrane potential = -70mv Key Point?* Sodium potassium pump ( ATPase ) purpose

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Nervous System

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  1. Nervous System By: Ms. Wetherington

  2. Review • What is a neuron? • Synaps? • Synaptic cleft, pre and post synaptic cells • Myelin Cells • CNS: Oligodendrocyte cells • PNS: Schwann cells

  3. Review • Resting membrane potential = -70mv • Key Point?* • Sodium potassium pump (ATPase) purpose • Restores gradient after action potential

  4. Signaling review • Electrotonic potential causes cells to have a strong influx of sodium ions • Quickly diffuses to change membrane potential just slightly • Changes membrane potential just enough to cause action potential • Impulse propagation: movement of action potential • Refractory periods? • Salatory conduction?

  5. Types of neurons • Afferent neurons: carry information from PNS to brain or spinal cord (sensory information) • Efferent neurons: Carry information from brain/spine to PNS • Intraneurons: local circuits

  6. Nerves • Single axons only carry so much information • Nervous system bundles many axons together as nerves • Can be sensory, motor or mixed

  7. Ganglia and Nuclei • Somas also cluster • PNS known as ganglia • CNS known as nuclei

  8. Central Nervous System: Brain

  9. Brain • Consistancy similar to gelatin • Protected by??? • Integrates sensory, coordination, motor, movement, cognition • Mylenation: white matter • Unmyelinated (somas, dendrites, unmyelinated axons): Gray Matter

  10. Layout • Forebrain • Midbrain • Hindbrain

  11. Forebrain • Most recently acquired part of the CNS in terms of evolution • Broken down into: • Telencephalon (Cerebrum) • Frontal lobe • Parietal lobe • Occipital lobe • Temporal lobe • diencephalon

  12. Cerebral Cortex • Highly convoluted gray matter on brain surface (outermost cerebrum) • Deals with memory, attention, awareness, thought, language, consciousness • Each lobe is independent but communicate through corpus collosum (made of white matter)

  13. Frontal lobe • Future consequences from current actions • Good and bad • Long term memory (non-task based) - often emotions • Modifies for fitting into social norms

  14. Parietal lobe • Sensory information • Manipulation of objects • Reading • speech

  15. Occipital lobe • Visuals • dreams

  16. Temporal lobe • Long term memory • Verbal • language

  17. Diencephalon • Thalamus and hypothalamus • Thalamus: gateway to brain • Sensory information passed through thalamus before relayed to cortex

  18. Midbrain • Relay point between more peripheral structures and forebrain • Passes sensory information and visuals to forebrain from hindbrain • Returns motor instructions to hindbrain

  19. Hindbrain • Structures are seen in many organisms • Responsible for involuntary functions • Cerebellum • Medulla oblongata • pons

  20. Cerebellum • Quality control agent: error checking • Checks motor signal in agreement with sensory information coming into the body • Prevents things like falling by adjusting to new situations • Balance • Prevents you from looking like an idiot

  21. Medulla oblongata • Homeostasis • Breathing, heart-rate, blood vessel activity, swallowing, vomiting, digestion

  22. Pons • Helps out the medulla oblongata by regulating breathing

  23. Arousal and sleep • Network called reticular formation regulates sleep and arousal • Pons and medulla contain centers that cause sleep when stimulated • Milk has lots of tryptophan which can be used to make serotonin….maybe why you get sleepy when you drink it?

  24. Central Nervous System: Spinal Cord

  25. Spinal cord • Protected by vertebral column and broken into four parts • Cervical • Thoracic • Lumbar • Sacral

  26. Spinal cord • Contains both gray and white matter like the brain • Axons are for both motor and sensory function • Sensory neurons bring information from PNS and enter the dorsal (back) side of the spine • Motor neurons exit ventrally • Cell bodies (somas) found in dorsal root ganglia

  27. Peripheral Nervous System

  28. PNS • 12 pairs of cranial nerves and 31 pairs of spinal nerves • Made up of: • Somatic nervous system (SNS) • Autonomic nervous system (ANS)

  29. Somatic Nervous System • Voluntary movement • Release of acetylcholine from nerve terminal onto muscle leads to contraction • Binding of acetylcholine leads to muscle depolarizing • SNS also deals with reflexes (doesn’t go to brain) • Monosynaptic and polysynaptic

  30. Monosynaptic • Single synapse between sensory neuron and motor neuron (mono) • Knee jerk • Patellar tendon stretched and sends information up the sensory neuron to the spine where it meets motor neuron to contract quadriceps • Responding to dangerous situation

  31. Polysynaptic • At least one interneuron between sensory and motor neuron • Stepping on a tack • Foot jerks (monosynaptic) but you must balance on the other leg • To stimulate other leg to have downward motion internurons must provide connection from sensory information on the leg jerk to the opposite leg

  32. Autonomic Nervous System • Fight or flight response • Rest and digest response • Known as involuntary nervous system

  33. ANS • Uses cardiac and smooth muscle • Smooth: blood vessels, bronchi, bladder, gastrointestinal • ANS also controls blood pressure, ventilation, urination and digestion

  34. ANS • 2 neuron system (unlike SNS) which play telephone • 1st neuron = preganglionic • 2nd neuron = postganglionic • Preganglionic soma is in CNS and the axon travels to a ganglion in PNS • Synapses with post ganglionic neuron to affect target tissue

  35. Regulation of ANS • Can regulate individually or coordinate with both parts: • Sympathetic • Parasypathetic

  36. Sympathetic nervous system • Stress • Fight or flight BEAR ATTACK!!!!

  37. BEAR ATTACK!!! • Increase blood flow to heart and skeletal muscles • Decrease blood flow to GI tract and kidneys • Ensure proper oxygen to muscles • Pupils dilate so you can keep an eye on the bear as you run

  38. BEAR ATTACK!!! • Preganglionic neurons use acetylcholine or epinepherine • Postganglionic neurons use norepinephrine

  39. Parasympathetic nervous system • Rest and digest MMMMM PIZZA!!!

  40. Pizza time! • Increase blood flow to digestive and excretion organs • Decrease blood flow to skeletal muscles and heart • Heart rate and ventilation rate decrease • Vagus cranial nerve responsible for many parasympathetic effects in thoracic and abdominal cavity • Pre and postganglial neurons both use acetylcholine

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