BMS2011-L01 2023-24.pptx

BMS2011 Lecture 1 Cellular Neuroanatomy A basic understanding of the overall organisation and cell types Part 1 - Nervous System Part 2 - The cells  Part 1 - Nervous System Structure & Function of the Nervous System...

BMS2011 Lecture 1 Cellular Neuroanatomy A basic understanding of the overall organisation and cell types Part 1 - Nervous System Part 2 - The cells  Part 1 - Nervous System Structure & Function of the Nervous System http://www.sruweb.com/~walsh/cns_pns.jpg  Structure & Function of the Nervous System Functions: Monitors internal and external environments Integrates sensory information Coordinates voluntary and involuntary responses of other organ systems Two subdivisions: 1 CNS (Intelligence, memory, emotion etc) – Brain  Cerebrum  Cerebellum  Brain stem (midbrain, pons, and medulla) – Spinal Cord 2 PNS (all other neural tissue sensory, motor)  The Central Nervous System CNS - Brain: Cerebrum Cerebellum Brain stem (midbrain, pons, and medulla) - Spinal Cord  The Brain The cerebrum is the largest part of the brain. It is formed of right and left hemispheres. It carries out higher functions (e.g., vision, hearing, speech, reasoning, emotions, learning, memory, control of movement etc.) The cerebellum is positioned under the cerebrum. It coordinates muscle movements, maintains posture and balance. The brainstem (midbrain, pons, and medulla) is a relay center that connects the cerebrum and cerebellum to the spinal cord. It carries out many automatic functions (e.g., breathing, heart rate, body temperature, circadian cycles, sneezing, vomiting etc.). Ten of the twelve cranial nerves originate in the brainstem. Mammalian brains: variety and commonality g: Weight in grams M: number of neurons in millions Fixed Brain Fixed Brain Cerebrum Cerebellum Brainstem Unfixed Brain Directions and Planes of Section Views Sulci and gyri  Ventricles Ventricles Gray matter Unfixed Brain White matter Sulci and gyri GREY MATTER WHITE MATTER Part 2 - The cells Cells in the CNS  Types of cells in CNS and PNS Neurons Glial cells – or neuroglial cells – Ependymal cells Line ventricles Guide cell migration during development – Microglia Phagocytic – Astrocytes – largest & most abundant – Oligodendrocytes & Schwann Cells (myelin) Neurons  What are Neurons? Excitable cells specialised for reception of stimuli and conduction of impulses The majority of neurons are post mitotic Structure of Neurons Cell body (soma) and organelles (nucleus, Golgi, SER, RER etc.) Plasma membrane Nerve cell processes (neurites: dendrites & axon) Basic neuron  Neurons vs. Other Cells Similarities with other cells: Differences that make neurons unique: Neurons and other cells both Unlike other body cells, the majority of contain a nucleus that holds neurons stop reproducing shortly after genetic information. birth (post-mitotic). Neurons and other cells are Neurons have a membrane that is surrounded by a plasma designed to sends information to other membrane that protects the cells (excitable). cell. The axon and dendrites are specialized The cell bodies of both cell structures designed to transmit and types contain organelles receive infor mation. that support the life of the The connections between cells are cell, e.g. mitochondria, known as a synapses. Golgi bodies and cytoplasm Neurons release chemicals known as etc.. neurotransmitters into these synapses to The inner life of a cell communicate with other neurons. The Inner Life of the Cell: https://xvivo.com/examples/the-inner-life-of-the-cell/ https://www.youtube.com/watch?v=wJyUtbn0O5Y Structure of a Neuron Cell body or  n: nucleus s: soma d: dendrite a: axon d s n a  Cytoskeleton Microfilaments (5 nm) – Formed in cell body, from actin. Substances attach to them, then slide along microtubules. Anchored to membrane. Neurofilaments (10nm) – Very strong – structural. Microtubules (20 nm) – Run the length of axon; aid transport down axon.  Red: Actin http://www.microscopyu.com/articles/fluorescence/filtercubes/red/cy5muntjacactinaf633.html Green: Neurofilament  Red: Actin Green: Microtubules Etoc et al. Nature Nanotech (2013) 8:193 Axonal transport: – Slow: 1-10 mm/day (cytosolic and cytoskeletal proteins–anterograde) – Fast: >400 mm/day (Membranous organelles – retro- and anterograde)  Variety of neuron morphologies Examples (A—F) of the rich variety of nerve cell morphologies found in the human nervous system. Tracings are from actual nerve cells stained by impregnation with silver salts (the so- called Golgi technique, the method used in the classical studies of Golgi and Cajal). Asterisks indicate that the axon runs on much farther than shown. (Note that some cells, like the retinal bipolar cell, have a very short axon, and that others, like the amacrine cell, have no axon at all.) The drawings are not all at the same scale. Variety of neuron morphologies Cerebellum drawing - Ramon y Cajal  Classifying neurons By neurite number – Unipolar – Bipolar – Multipolar By dendritic tree – Pyramid-shaped; star- shaped – Spiny; aspinous By axon length By neurotransmitter type  Neuron communication synapse  Signal Transmission axon terminal synapse dendrite and soma  Basic Synapse Presynaptic Axon Mitochondrion Synaptic Vesicle Synaptic Cleft Neurotransmitter Neurotransmitter Receptor Postsynaptic Cell Glia  Microglia GLIA http://biocare.net/products/antibodies/m/290/ Oligodendrocyte - Node of Ranvier Astrocyte Oligodendrocyte http://neuro.bcm.edu/rasbandlab/?m=static&id=5 Oligodendrocyte - Myelin http://www.npr.org/templates/story/story.php? storyId=126229305 http://www.bris.ac.uk/anatomy/research/staff/molnar.html http://www.ucalgary.ca/styslab/Projects Oligodendrocytes  Myelin Wrap around axon Saltatory Conduction – faster transmission CNS: oligodendroglia or oligodendrocytes PNS: Schwann cells ~ 1: Neuron Nucleus * Core of cell body * Contains almost all genetic information 2: Nearby cells called oligodendrocytes wrap most axons with a fatty substance called myelin  Astrocytes Fill almost all of the space between neurons Induce, stabilise, and modulate neuronal connections Regulate content of extracellular space – Recycle neurotransmitters – Possess neurotransmitter receptors themselves Regulate blood flow to areas of neuronal activity Control CNS regeneration  Blood-Brain Barrier Typical astrocytes Capillary Brain Capillary Blood-Brain Barrier  BBB: Function Maintains stable brain environment – large fluctuations in periphery Barrier – to poisons – neurotransmitters & other chemicals Regulates nutrient supplies – glucose levels – active transport ~  Other non-neuronal cells Microglia – phagocytosis – immune-like function Ependymal cells – line walls of ventricles – develop from radial glia ~ Introduction to Brain Organisation and Function General reference (see also Module Study Guide – Reading List) Neuroscience: Exploring the Brain 4th Ed, Principles of Neuroscience 5th Ed.. And new Editions YouTube links: Unfixed Brain: https://www.youtube.com/watch?v=jHxyP-nUhUY Ventricles: https://www.youtube.com/watch?v=zqQ6iKw5DjY&feature=youtu.be The Inner Life of the Cell: https://xvivo.com/examples/the-inner-life-of-the-cell/ https://www.youtube.com/watch?v=wJyUtbn0O5Y A Day in the Life of a Motor Protein: https://youtu.be/tMKlPDBRJ1E Spine motility: https://youtu.be/Cjjdky96ubc Refer to material on Canvas