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Brief History of the Brain and the “Neuron Doctrine”

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Brief History of the Brain and the “Neuron Doctrine” Brief History of the Brain and the “Neuron doctrine” - The Greek era: Hippocrates and Aristotle (300-400 B.C) - The Roman era: Galen (100-200 A.D.) - The Renaissance era: Vesalius, DaVinci, Descarte (1500’s) - The Enlightment era: Bell and Magendie, Gall, Flourens (1800’s) - Turn of the XIXth century: Golgi, Cajal FUN FACTS ABOUT YOUR BRAIN - the human Central Nervous System (CNS) weighs approximately __3 pounds; largest existing brain is approximately 17__ lbs (sperm whale) - there are approximately ___________100 billion neurons in the CNS; that’s 100 000 000 000 !!!!!!! - each of these neurons makes between _________1000 to ____________10,000 connections with other neurons - number of connections in the cortex alone has been estimated to ____________60 trillion - the size of a neuron varies from _____________4 to 100’s of ________________________micrometers (um) - length of one of the longest axon known: 15______ feet (from giraffe’s toe to neck) - conduction speed of action potential varies, in different axons, from ______________1 to 250 mph Chap. 3- 1 NEURON (biological psych definition): _______________A very specialized____________________________ cell type whose function_____________________ is to receive, process,____________________________ and send information;_____________________ these cells are found____________________________ in the central nervous_____________________ system (brain, retina,____________________________ spinal cord) as well as_____________________ in the peripheral nervous____________________________ system (the rest of the_____________________ body). PARTS OF A NEURON: 1. SOMA____________________ or CELL BODY____________________ (<gk “body”) 2. DENDRITE____________________ (<gk “tree”)___________________ and SPINES 3. AXON______________________ (<gk “axis” referring________________________ to “central/ structure__________________________ about which something____________________ is arranged”) 4. MYELIN______________________ SHEATH –________________________ Glia/Glial cell (gk – glue) 5. NODES_________________________ OF RANVIER 6. PRESYNAPTIC_________________________________ TERMINALS 7. AXON______________________ HILLOCK 4 5 3 6 7 1 2 Chap. 3- 3 Golgi stain Golgi stain Nissl stain Chap. 3- 4 TYPES OF NEURONS (according to structure): 1. ____________________Multipolar neuron: more__________________________ than two processes ________________________extending from its cell body.______________________ dendrites AP = where Action impulse Potential is created axon AP 2. _________________________Bipolar neuron: two processes_____________________ extending from the ___________________________cell body. ___________________ AP dendrite impulse axon 3. ____________________Pseudounipolar neuron:__________________________ one process extending ________________________from cell body. ______________________ dendrites axon AP impulse Chap. 3- 5 TYPES OF NEURONS (according to function): 1. SENSORY NEURONS: Neurons_________________________ specialized to receive information____________________________ from the environment_____________________ about what’s out there -____________________________ light, sound, pain, temperature, _____________________pressure, taste, smell, etc ____________________________and to send this information to the_____________________ brain. ____________________________AFFERENT NEURONS (gk – to_____________________ carry toward) 2. MOTOR NEURONS: Neurons__________________________ specialized to cause movements____________________________ (contraction of muscles)._____________________ They receive infor- ____________________________mation (“instructions”) from the _____________________brain (controls voluntary ____________________________movements) and from the body (withdrawal_____________________ reflexes, for ____________________________example). EFFERENT NEURONS_____________________ (gk – to carry away) 3. INTERNEURONS or INTRINSIC NEURONS:_____ ____________________________Neurons that handle local information;_____________________ ____________________________Ex. Connect sensory to motor information_____________________ in the spinal ____________________________cord (withdrawal reflexes), _____________________ ____________________________Ex. Some cells are contained completely_____________________ within the ____________________________cerebral cortex for intracerebral_____________________ cortex communication. ____________________________Note: Can also be called projection_____________________ neurons. Chap. 3- 6 Chap. 3- 7 And More Neurons! Cortical pyramidal neuron seen with Golgi stain NEURAL COMMUNICATION THE SYNAPSE: “gap”________ between_________________________ the presynaptic terminal ___________________________and the neuron it’s trying to “talk”____________________ to. FUN FACTS ABOUT SYNAPSES (gk “to join together”) 1. A synapse occurs _______________________________when one neuron wants to talk to _________________________.another neuron 2. Types of synapses based on structure: dendrites (a.)Axo-dendritic ___________ soma (b.)Axo-somatic ___________ (c.) Axo-axonic___________ axon presynaptic terminals 3. Types of synapses based on neurotransmitter and post- synaptic receptor Examples: Excitatory synapses - __________Glutamate - __________Aspartate Inhibitory synapses - __________GABA - __________Glycine Modulatory synapses - __________Adrenergic Chap. 3- 8 4. Relational terms: pre-synaptic vs. post-synaptic 5. Gross anatomy of the synapse: (a.) ________axon (h.) ______________dendrite (b.) __________________mitochondrion (c.) ____________________synaptic vesicles (d.) _________________________pre-synaptic membrane (e.) __________________synaptic cleft (gap) (f.) __________________________post-synaptic membrane (g.) _________________________post-synaptic receptors Neuron A impulse Neuron B b a c d e f g h Chap. 3- 9 Synaptic photography! PARTS OF A NEURON : 1. BASIC CELLULAR COMPONENTS - a. CELL MEMBRANE - the “skin” of the neurons; b. CYTOPLASM - everything inside the “skin” Dendrite: Cell extension that collects information from other cells Dendritic spine: Small protrusions on dendrites phat increase surface area Nucleus: Central structure containing the chromosome and genes Nuclear membrane: Membrane surrounding the nucleus Endoplasmic reticulum: Folded layers of membrane where proteins are assembled Mitochondria: Structure that Golgi body or apparatus: gathers, stores, and releases energy membranous structure that packages protein Intracellular fluid: Fluid in which the molecules for transport cell’s internal structures are suspended Microtubules: Tiny tubes that transport molecules and help give the cell its shape Cell membrane: Membrane surrounding the cell Axon: Extension that Microfilaments: Lysosomes: Sacs transmits information from threadlike fibers containing enzymes cell body to other cells making up much of that break down wastes the cell’s “skeleton” Chap. 3-10 General Neuron. From Kiernan (1998). The Human Nervous System. Fig. 2-5. SUPPORTING CELLS OF THE NERVOUS SYSTEM = ______GLIA 1. Oligodendrocytes : _______________________________cells that form myelin sheat in the ____________________________central nervous system (CNS). ______________________ 2. Schwann cells : _________________cells that form myelin_________________ in the ____________________________peripheral nervous system. ______________________ 3. Astrocytes : ________________provide structural_____________________ support for neurons of the____________________________ central nervous system. _____________________ ____________________________- also provide nutrients to neurons______________________ and regulate chemical ____________________________composition of extracellular fluid.______________________ 4. Microglia : ________________smallest glial cell and______________________ act as phagocytes to ____________________________protect the brain from invading ______________________microorganisms. ____________________________- phagocytosis: process by which______________________ cells “engulf” and digest ____________________________other cells or debris caused by ______________________cellular degeneration. 5. Ependymal cells: ________________epithelial cells lining_________________ the ventricles and ____________________________other cavities around the brain, acting______________________ as a barrier; ____________________________- might secrete cerebrospinal fluid,______________________ but in very small ____________________________amounts. ______________________ Chap. 3-12 Oligodendrocytes and Schwann Cells Chap. 3-13 Examples of astrocytes in the brain: Brain photo Cartoon reconstruction Chap. 3-14 Spinal cord astrocyte 21.
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