Biology 1: Basics of the Nervous System: Neuroanatomy (University of Nottingham) PDF

Biology 1 Basics of the Nervous System: Neuroanatomy Lodewijk Dekker  Aims ▪This lecture aims to provide some basic knowledge of nervous system anatomy needed to successfully complete the Pain module ▪The following topics are covered: o functional divisions of the nervous system o cellu...

Biology 1 Basics of the Nervous System: Neuroanatomy Lodewijk Dekker  Aims ▪This lecture aims to provide some basic knowledge of nervous system anatomy needed to successfully complete the Pain module ▪The following topics are covered: o functional divisions of the nervous system o cellular make-up of the nervous system o anatomical features of central and peripheral nervous system, including meninges o arterial and venal circulation of the brain and spinal cord o cerebrospinal fluid origin and circulation in CNS and PNS othe senses and the somatosenses, including pain 2  References ▪Fundamentals of Pharmacy year 1 ▪Lauralee Sherwood: Human Physiology – from cells to systems ▪DU Silverthorn: Human Physiology, An Integrated Approach ▪Neal Cook, Andrea Shepheard and Jennifer Boore: Essentials of Anatomy and physiology ▪Dale Purves et al: Neuroscience 3  Functions of the Nervous System ▪The main function of the nervous system is to maintain homeostasis (stability, constant internal environment, balance) by ▪Receiving information ▪Integrating and analysing information ▪Making decisions and sending instructions to: ▪Carry out voluntary movement ▪Influence endocrine function ▪Regulate unconscious activities 4  The nervous system consists of CNS and PNS ▪CNS: Central Nervous System. ▪Brain - responsible for responses, sensation, movement, emotions, communication, thought processing, and memory ▪Spinal cord – carries information from the brain to the peripheral body and vice versa ▪PNS: Peripheral Nervous System ▪Nerve fibres located in the parts of the body that are not the brain and spinal cord. ▪Carry information to and from the CNS 5  Nervous system divisions Central Nervous System Peripheral Nervous System Spinal Afferent Efferent Brain cord division Division Somatic Sensory: Somatic Nervous System: Autonomic Nervous System touch, pain, temperature but Motor innervation of skeletal Motor innervation of smooth also vision, hearing equilibrium muscles muscle, cardiac muscle, glands Visceral Sensory: Stretch, pain, temperature but Sympathetic division also taste and smell Parasympathetic division Enteric Nervous System Digestive organs only 6 Parasympathetic: rest and digest Sympathetic: fight or flight  Nervous system divisions Central Afferent Division carries Nervous Efferent Division carries information to the CNS System information from the CNS (afferent arrives) (efferent exits) Sensory neurons Efferent Stimulate (Afferents) neurons Autonomic Somatic motor Communicate neurons neurons Sympathetic ParaSympathetic Signa Sensory Control l receptors Stimulate Control Cardiac Muscle Smooth Muscle Skeletal Exocrine glands Muscle Control Some endocrine glands Some adipose tissue Enteric nervous system can act Signa Neurons of on its own or can be controlled enteric nervous by the CNS through the Tissue l responses system autonomic division of the PNS 7  Cells of the nervous system ▪Neurons ▪Many different structural types to serve many different functions ▪By structural type: Pseudo unipolar, bipolar, anaxionic, multipolar ▪By function: Sensory neurons, interneurons of the CNS, motor and autonomic afferent neurons ▪Do not work on their own but are organised in circuits to process specific information ▪Glial cells oCNS: oligodendrocytes, microglial, astrocytes, ependymal cells oPNS: Schwann cell and satellite cells 8  Structural classes of neurons ▪Neurons ▪Many different structural types to serve many different functions ▪Pseudo unipolar, bipolar, anaxonic, multipolar 9 Multipolar e.g. motor neurons controlling skeletal muscle Bipolar e.g. retina and olfactory system Pseudo e.g. pain sensory neuron Anaxonic e.g. in olfactory bulb or some interneurons. Also present in arthropods and nematodes  Three functional classes of neurons ▪Afferent neurons ▪From the Periphery to the CNS ▪Efferent neurons ▪From the CNS to the periphery ▪Interneurons ▪Within the CNS 10  Nerve cells and nerve communication Impulse transferred from cell to cell Electrical signalling along the axon using membrane potential Chemical signalling at synapses Arrows indicate places where drugs can act 11  Glial cells in CNS Oligodendrocyte Myelination of CNS neurons Astrocyte Star-like morphology Anchoring neurons and capillaries Maintenance of chemical environment Microglia Macrophage-like cells scavenging role, remove debris Ependymal cell In choroid plexus, CSF production 12  Glial cells in PNS Schwann cells Myelination of PNS neurons Satellite cells Surround neuronal cell bodies and provide support 13  Bundles of axons Axons are bundled into nerves (PNS) or tracts (CNS) In PNS, axons and their Schwann cell are surrounded by a basal lamina (endoneurium) Axon fibres are bundled into a fascicle surrounded by Perineurium Fascicles are bundled into a nerve surrounded by Epineurium 14  Ways to divide the nervous system/neurons ▪Afferent neurons or efferent neurons ▪Afferent neurons send information TO the brain ▪Efferent neurons send information FROM the brain ▪Afferent – arrive; efferent - exit ▪Motor neurons vs sensory neurons ▪Autonomic vs voluntary ▪Somatic vs visceral E.g. visceral sensory afferent ▪CNS vs PNS Motor efferent 15  Nervous system divisions important in Pain Central Nervous System Peripheral Nervous System Spinal Afferent Efferent Brain cord division Division Somatic Sensory: Somatic Nervous System: Autonomous Nervous System touch, pain, temperature but also Motor innervation of skeletal Motor innervation of smooth vision, hearing equilibrium muscles muscle, cardiac muscle, glands Visceral Sensory: Stretch, pain, temperature but Sympathetic division also taste and smell Parasympathetic division Enteric Nervous System Digestive organs only 16  CNS: Brain Develops from an embryonic tube Increasingly complex folding ultimately creates brain tissue and ventricles 17 Pons handles unconscious processes and jobs, such as your sleep-wake cycle and breathing. It also contains several junction points for nerves that control muscles and carry information from senses in your head and face Cerebellum:muscle control, balance, and much more Hypothalamus helps manage body temperature, hunger and thirst, mood, sex drive, blood pressure and sleep Thalamus: relay of sensory signals  CNS: Spinal cord ▪Transverse histological sections of the cord at four different levels, ▪gray matter and white matter in the cervical, thoracic, lumbar, and sacral regions. ▪The sections were processed to simulate myelin staining 18 PNS: Spinal nerves and cranial nerves midbrain Trigeminal (V) pons brainstem Vagus (X) medulla spinal cord 19  Spinal Cord and Spinal Nerves ▪Sensory information carried by the spinal nerves enters the cord via the dorsal roots ▪Motor commands leave the cord via the ventral roots. ▪Once the dorsal and ventral roots join, sensory and motor axons travel together in the spinal nerves. 20  Spinal Cord and Spinal Nerves, Sympathetic chain ▪Sensory information carried by the spinal nerves enters the cord via the dorsal roots ▪Motor commands leave the cord via the ventral roots. ▪Once the dorsal and ventral roots join, sensory and motor axons travel together in the spinal nerves. 21  Meninges ▪Membranes surrounding brain and spinal cord o Dura mater ▪In some places split into inner and outer dura o Arachnoid mater o Pia mater 22  Meninges ▪Membranes surrounding brain and spinal cord o Dura mater Cranium/Skull bone ▪In some places split into inner and outer Dura Mater Venus sinus dura Arachnoid Mater o Arachnoid mater o Pia mater Subarachnoid Space (theca) Pia Mater Brain tissue 23  CNS Fluid Compartments ▪Blood plasma ▪Cerebrospinal fluid (CSF) ▪Interstitial fluid (between cells) ▪Intracellular fluid (inside cells) ▪Have barriers but are also in contact with each other ▪Drug penetration 24  Brain Vasculature Arteries branch out into smaller arterioles that penetrate the brain cortex and merge into the brain microcirculation, consisting of the brain capillary beds. Brain capillaries that make up the capillary beds surround the brain tissue. Waste products are carried away from the capillary beds by the venules. The venules merge into the veins, which lead the blood and the waste products it contains back to the heart. 25  Blood brain barrier Tight junctions 'seal' endothelial cell Transport only through the plasma membrane or via specialised transporters Capillary surrounded by astrocytic end feet. Electron micrograph after G. W. Goldstein and A. L. Betz, 1986. Sci Am 255: 74–83. 26  Cerebrospinal fluid Flows in the ventricals, central spinal canal and subarachnoid spaces Secreted by filtration process in choroid plexus Physical protection of the brain and spinal cord tissues Provides a constant chemical bath for the CNS tissue Lumbar punction and intrathecal injection 27  Sensation and Sensory Processing ▪Ability to transduce, encode and perceive information from external and internal environment ▪Specialised nerve cells (receptors) convert energy from mechanical forces, light, sound or presence of chemicals into neuronal signals ▪Information conveyed to the spinal cord and brain via sensory afferents ▪Afferent signals activate central neurons that are capable of representing the nature, the strength and for some senses the location of the stimulus 27 Name, Department 28 September  Sensory systems ▪Somatosensory Systems: ▪Touch, Pressure, Vibration, Limb Position ▪Heat, Cold, Itch, Pain ▪Visual System (eye) ▪Auditory System (ear) ▪Vestibular System (labyrinth in ear) ▪Olfactory System - smell (nose) Chemical ▪Taste (tongue) Senses Adapted from DU Silverthorn, Human Physiology 29 Thank you