Structure of the Nervous System AN2020 PDF

Structure of the Nervous System AN2020 Dr. Sarah Nicolas The nervous system: Definition → organized group of cells specialized for the conduction of electrochemical stimuli from sensory receptors through a network to the site at which a response occurs. Group of cel...

Structure of the Nervous System AN2020 Dr. Sarah Nicolas The nervous system: Definition → organized group of cells specialized for the conduction of electrochemical stimuli from sensory receptors through a network to the site at which a response occurs. Group of cells: Neurons and glia Electrochemical stimuli : neurotransmitters and synapses Structural organisation of the nervous system  Functions of the Nervous System Collecting Information Sensory input: PNS transmits information to the CNS via afferent neurons. Processing Information CNS Responding to Information Motor output: Transmission of motor information from the CNS to muscles or glands via efferent neurons. Functional organisation of the nervous system Functional organisation of the nervous system The Central Nervous System Where are we ? What am I looking at ? The importance of Brain-Body orientation  The Meninges 3 layers Dura mater Periosteal layer – Attached to skull bones Meningeal layer – Attached to other meninges Falx cerebri – extension of the dura mater in the longitudinal fissure Arachnoid mater Woven aspect Subarachnoid space – contains cerebro-spinal fluid Pia mater – deepest layer, tightly attached to the surface of the brain  The Meninges Spinal Meninges Cranial Meninges Dura Mater Dura mater Arachnoid mater Subarachnoid space Pia mater The Ventricular System The brain contains cavities (ventricles) which contain cerebrospinal fluid (CSF) CSF circulates in the ventricular system and in the subarachnoid space CSF is produced by the choroid plexus in the ventricles CSF provides protection and removes waster products White and Gray Matter Gray – cell bodies White – myelinated axons The presence of myelin on axons and its absence on cell bodies creates a pattern of grey and white regions in the central nervous system  The Central Nervous System Five major parts: – Cerebrum – Cerebellum Diencephalon – Diencephalon Cerebrum – Brain Stem – Spinal Cord Cerebellum Brain Stem Spin Spinal al Cord Cork  Cerebrum Longitudinal fissure Gyri Sulci ANTERIOR POSTERIOR  Cerebral Lobes Parietal Frontal Occipital Temporal ANTERIOR POSTERIOR Parietal Lobes Control of muscle movement Sensory processing Temporal Lobes Language and communication Learning and memory Occipital Lobes Vision  Frontal Lobes Executive function Personality  Cerebellum Coordination of movement Posture Balance Motor learning  Brain Stem Relays sensory and motor information between the spinal cord and the brain Regulates breathing and blood pressure Regulates heart rate, swallowing, vomiting, coughing, sneezing Cranial Nerves (12 pairs) Brain Stem Spin al Cork To sum up… Brodmann’s cytoarchitectural map In 1909 Korbinian Brodmann constructed a map of the cerebral cortex based on the organisation of neurons. He designated each area a number and proposed that each performed a different function. Functional organisation of the cerebral cortex Cortical Homunculus Somatotopic map A cortical homunculus is a distorted representation of the human body, based on a neurological "map" of the areas and proportions of the human brain dedicated to processing motor functions, or sensory functions, for different parts of the body.  Limbic System Emotional centre of the brain Motivated and emotional behaviours: Anxiety Sexual behaviour Aggressive behaviour Food intake Thirst Memory  Diencephalon Diencephalon Thalamus Relays sensory and motor signals Hypothalamus Controls the endocrine system Controls body temperature, hunger, thirst, sleep-wake cycles Spin Regulates stress response al Cork  Spinal cord Extends from brainstem Protected by the vertebral column Composed by Gray and White matter 31 segments that each give rise to a pair of spinal nerves Conduit for sensory information to reach the brain and for motor commands to be sent to muscles and glands. Structural organisation of the nervous system  Attached directly to the brain Motor and sensory 12 pairs denoted by roman numerals ‘Oh Once One Takes The Anatomy Finals Very Good Vacations Are Heavenly’ Spinal nerves Spinal nerves and ganglia The ventral root: motor commands from the spinal cord to the muscles. The dorsal root: brings sensory information into the spinal cord Dorsal root ganglia: cell bodies of neurons of dorsal rout (component of the PNS) Somatic VS autonomic nervous system The somatic nervous system (SNS) Voluntary control of muscle movements Single neuron pathway from the CNS to the target muscle Research today: creating a “wiring map” of the entire brain The Human Connectome project is US government-funded collaborative project to map the entire neural network of a human brain. The connectome is the map of the 100 trillion plus neural connections within the brain. Eyewire: an online game to map the brain “Eyewire.org is a citizen science project. Our AI is not accurate enough to map the connectome by itself. We still need human intervention. So we have now created this website that allows anybody to do it.” Sebastian Seung, Princeton University