The+ Nervous+ System


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Period 2 Chapter 48

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The+ Nervous+ System

  1. 1. By: Cong, Edmund, Amanda, and Seung
  2. 2. Review! <ul><li>An overview of what you “should” already know about the nervous system. </li></ul><ul><ul><li>Dendrites: They receive impulses from nearby cells. </li></ul></ul><ul><ul><li>Myelin sheath: It insulates the axon membrane, and helps speed up the rate of depolarization down the axon. </li></ul></ul><ul><ul><li>Axon: Carries impulses from the cell body to the synaptic sites of other neurons. </li></ul></ul><ul><ul><li>Nodes of Ranvier: Gaps between myelin sheath on the axon. Impulses jump from one node to another at fast as 120 meter/second. </li></ul></ul>
  3. 3. New Terms! <ul><li>Presynaptic Nerve Cell: Neuron that is passing information. </li></ul><ul><li>Postsynaptic Nerve Cell: Neuron that is receiving information. </li></ul><ul><li>Excitatory Postsynaptic Potential (EPSP): An electrical change in the membrane of a postsynaptic neuron cause by neurotransmitters from a presynaptic cell to a postsynaptic receptor with a likely chance that the postsynaptic neuron will generate an action potential. </li></ul>
  4. 4. New Terms  Continued! <ul><li>Inhibitory Postsynaptic Potential (IPSP): An eletrical change in the membrane of a postsynaptic neuron caused by the binding of an inhibitory neurotransmitter from a presynaptic cell to a postsynaptic receptor with a unlikely chance for a postsynaptic neuron to generate an action potential. </li></ul><ul><li>Depolarization: The initial phase of Action Potential. Na+ ions flow into a neuron cell, making the inside more positive. </li></ul>
  5. 5. Nerve Pathway <ul><li>Nerve cells receive impulses from the axon terminals of other cells. They receive the impulse from their dendrites. After receiving an impulse, a nerve cell then sends a new impulse down the axon and the axon terminal to the synaptic terminal in which it depolarizes nearby nerve cells. </li></ul>
  6. 6. Reflex <ul><li>A reflex pathway is commonly known as a reflex. It is a automatic response to an outside stimuli. This happens when sensors detect external stimuli and sensory neurons sends an impulse to the spinal cord. It does not travel to the brain, but instead, interneurons relay the information immediately back to the motor neurons which causes movement. No thought is involved. </li></ul>
  7. 7. A Reflex Arc
  8. 8. How messages are sent… <ul><li>In neurons they are sent by electrical signals. </li></ul><ul><li>Between neurons: Messages are carried between neurons via neurotransmitters. They sent a neurotransmitter across with Na+ and K+. </li></ul>
  9. 9. Structure of a Neuron
  10. 10. Resting Potential <ul><li>The membrane potential of a neuron is maintained at -70mV (millivolts) potential, which is resting potential. Neurons maintain this -70mV potential by making a cell have less Na+ and Cl- inside the cell membrane than the outside. It has more K+ inside than the outside however. </li></ul>
  11. 11. Action Potential <ul><li>Action potential is when a rapid change of charge in the neuron membrane takes place, usually by being triggered by other cells. It is a spike of electrical discharge that travels along the membrane of a neuron cell. Selective opening and closing of voltage-sensitive gates in sodium and potassium ion channels occur. </li></ul>
  12. 12. How Action Potential works <ul><li>Resting State: Resting potential is sustained </li></ul><ul><li>Depolarization: A stimulus opens activation gates on some Na+ gates. It depolarizes the membrane. If it hits the threshold, it triggers action potential. </li></ul><ul><li>Rising phase of the action potential: This depolarizes all Na+ channels which causes the rising phase of the action potential </li></ul><ul><li>Falling phase of the action potential: The K+ channels are open, permitting K+ efflux which makes the cell negative. </li></ul><ul><li>Undershoot: The channels are still open, which cause an undershoot. The K+ channels and some Na+ channels open, returning the mV to normal. </li></ul><ul><li>Resting Potential: The mV returns to -70. </li></ul>
  13. 13. The Axon <ul><li>Impulse Travel: When a membrane is depolarized, it also depolarizes neighboring membrane enough so that it will cause action potential. This is repeated over and over again down the axon. </li></ul><ul><li>Terminal End: When an impulse reaches a terminal end, it depolarizes the terminal membrane, opening voltage-gated calcium channels. Ca+ enters and the rise of Ca+ causes some synaptic vesicles to fuse with the terminal membrane, releasing the neurotransmitter by exocytosis. The neurotransmitters diffuses across the synaptic cleff. </li></ul><ul><li>Synapse: This is the gap between each nerve cell. Neurotransmitters diffuse across the synaptic ceft. The effect on the postsynaptic cell may be direct or indirect. </li></ul>
  14. 16. Synaptic Transmission <ul><li>Temporal summation: A phenomenon of neural integration in which the membrane potential of the postsynaptic cell in a chemical synapse is determined by the combined effect of EPSPs or IPSPs produced in rapid succession to reach action potential. </li></ul><ul><li>Spatial summation: A phenomenon of neural integration in which the membrane potential of the postsynaptic cell is determined by the combined effect of EPSPs or IPSPs produced nearly simultaneously by different synapses to reach action potential. </li></ul>
  15. 18. Human Nervous System <ul><li>Central Nervous System(CNS): In vertebrate animals, the brain and the spinal cord. </li></ul><ul><li>Peripheral Nervous System (PNS): The sensory and motor neurons that connect to the central nervous system. </li></ul><ul><li>Sensory Neuron: A nerve cell that receives information from the internal and external environments and transmits the signals to the central nervous system. </li></ul><ul><li>Sensory Receptor: A cellular system that collects information about the physical world outside the body and inside the organism. </li></ul>
  16. 19. <ul><li>Motor Neuron: A nerve cell that transmits signals from the brain or spinal cord to muscles or glands. </li></ul><ul><li>Autonomic Nervous System: A subdivision of the motor nervous system of vertebrates that regulates the internal environment; consists of the sympathetic, parasympathetic, and enteric divisions. </li></ul>
  17. 21. Sympathetic and Parasympathetic System <ul><li>Sympathetic System: The sympathetic division corresponds to arousal and energy generation. </li></ul><ul><li>Parasympathetic: The parasympathetic causes an opposite reaction than the sympathetic system. It promotes calmness. </li></ul>
  18. 23. Brain <ul><li>Cerebrum: The main processing center for information. It includes learning, motor neuron control, thought and smell. </li></ul><ul><li>Cerebellum: The area in which coordination and error checking takes place. Motor perceptional and cognitive functions are stored here. Learning and memory of motor skills are remember here. Hand-eye coordination , vision, and hearing all takes place in the cerebellum. </li></ul>
  19. 24. <ul><li>Brainstem: It includes the Medulla, Oblongata, Pons, and Midbrain. </li></ul><ul><ul><ul><li>Medulla: It controls several visceral functions, like breathing, heart rate and blood vessel activity, swallowing, vomiting, and digestion. </li></ul></ul></ul><ul><ul><ul><li>Pons: It regulates the breathing centers in the medulla. </li></ul></ul></ul><ul><ul><ul><li>Midbrain: It contains the center for the receipt and integration of several types of sensory information. It also sends coded sensory information along neurons to specific regions of the forebrain. </li></ul></ul></ul>
  20. 25. More Things to Remember! <ul><li>Reticular Formation: It controls sleep arousal. </li></ul><ul><li>Epithalamus: They are glands that make cerebrospinal fluid. </li></ul><ul><li>Thalamus: It is the sensory information input/output center. </li></ul><ul><li>Suprachiasmatic nuclei: It is the internal clock. </li></ul><ul><li>Corpus Callosum: It is the communication between the lobes. </li></ul><ul><li>Cerebral Cortex: It is the thinking and processing process. </li></ul>
  21. 26. Brain
  22. 27. Cerebral Cortex <ul><li>The Cerebral Cortex consists of four different sections, the frontal lobe, parietal lobe, temporal lobe, and occipital lobe. In each of the these “lobes”, they control different functions of the human body. </li></ul><ul><ul><li>Frontal Lobe controls: speech, your motor cortex, and is your frontal association area. </li></ul></ul><ul><ul><li>Parietal lobe controls: speech, taste, somatosensory cortex, reading, and somatosensory association area. </li></ul></ul><ul><ul><li>Occipital Lobe controls: Visual association area and vision. </li></ul></ul><ul><ul><li>Temporal Lobe controls: smell, hearing, and auditory association area. </li></ul></ul>
  23. 28. Cerebral Cortex
  24. 29. Memory <ul><li>The human has two kinds of memory, short-term memory and long-term memory. </li></ul><ul><li>Short-term memory is located in the frontal lobes and is constantly uploaded every moment of life. If needed, we think back to it, about what happened a few moments ago. </li></ul><ul><li>Long-term memory is a process that requires the hippocampus. Long-term memory is remembered through repetition and when needed to be accessed, the information is transferred to your short-term memory and then interpreted. </li></ul>
  25. 30. Nerve cell development and stem cells <ul><li>Nerve cell do grow and develop over a course of a human’s life. They have a growth cone in which is the edge of the axon that grows. The growth cone just follows netrin-1 receptors and when the axon hits a floor plate, it follows adhesion molecules to turn. Simply, nerve cells grow and decide their direction by other stimuli. </li></ul><ul><li>Stem Cells are unspecialized cells that continually divide. From recent discoveries, the human brain does divide neurons over a course of a life time. (It was believed that a person is bored with the amount of neurons they have) </li></ul>
  26. 31. Disease and Disorders of the Nervous System <ul><li>Schizophrenia: A severe mental disturbance characterized by psychotic episodes in which patients lose the ability to distinguish reality. </li></ul><ul><li>Depression: Two types, bipolar disorder which involves swings of mood from high to low and major depression that have a low mood most of the time. </li></ul><ul><li>Alzheimer’s Disease: is a mental deterioration, or dementia, characterized by confusion, memory loss, and a variety of other symptoms. </li></ul><ul><li>Parkinson’s Disease: a motor disorder characterized by difficulty in initiating movements, slowness of movement, and rigidity. </li></ul>
  27. 32. The End! <ul><li>Credits: </li></ul><ul><li>Blah blah blah blah blah blah </li></ul><ul><li>blah blah blah blah blah blah </li></ul><ul><li>blah blah blah blah blah blah </li></ul><ul><li>blah blah blah blah blah blah </li></ul><ul><li>blah blah blah blah blah blah </li></ul><ul><li>~Cong, Edmund, Seung, and Amanda </li></ul>