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______( 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