Nervous System Part 1 PDF

Nervous System Part 1 Anatomy & Physiology of Nervous Tissue Tutor Debbie Hemington Module Biomedical Sciences  GDC Learning Outcomes 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their applica;on to pa;ent management. 1.1.6 Des...

Nervous System Part 1 Anatomy & Physiology of Nervous Tissue Tutor Debbie Hemington Module Biomedical Sciences  GDC Learning Outcomes 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their applica;on to pa;ent management. 1.1.6 Describe relevant and appropriate physiology and explain its applica;on to pa;ent management Intended Learning Outcomes including Part 2 Students will be able to: List the characteris;cs of nervous ;ssue List and describe the cells of nervous ;ssue Explain the mechanism by which impulses are generated and their relevance in den;stry The Nervous System The nervous system detects and responds to changes inside and outside the body. Together with the endocrine system it controls important aspects of body func;on and maintains homeostasis. Nervous system s;mula;on provides an immediate response while endocrine ac;vity is, in the main, slower and more prolonged. There are 2 divisions of the nervous system ~ Brain + S card. 1. Central nervous system (CNS) –brain & spinal cord 2. Peripheral nervous system (PNS) –all other nerves all other) nerves  Peripheral Nervous System carries into to - Skin muche , organs unS - , Sensory division musche Motor division – voluntary- soma;c nervous system voluntary - respones of - involuntary-autonomic nervous system -involuntary the body. / \ outgoing from sympathe;c parasympathe;c ↓ / \ messaged Pght or Qight rest and digest radip + cNS to intense rate. delivers mosses grands = Controle functions e.. & rate g TO CNS Away CNS ~  3 cells of Nervous Tissue x Cells of the nervous system nervous System Neurones Schwann Cells Neuroglial/Glial Cells  clS Artwerve numbers - -Vast Neurones Bundles of them are called nervel. -Branching processes receptive in function (dendrites) / nerve fibre > into away from cell body between into passed necrons at Synapses. E Different forms (function depending Different shapes to wei X functions Neurons whereand Key Features of nerves. 1. Cell body 2. Axon 3. Schwann Cells 4. Nodes of Ranvier 5. Dendrites 6. Synap;c end bulb  found& phariphany Conagnity to see - + Centre Cell Body of brain spiralcrel. of - developed nuceau organelles -  - motorway for nerve impulses Axons Communica;on route between cell body & axon terminals Conducts electrical impulses away from the neurone's cell body Longer than dendrites – can be longer than 1m!! Large axons & those of the peripheral nervous system are I surrounded by a MYELIN sheath (series of Schwann cells) insulator  -form myelin swath Schwann Cells rapid transmission -gaps = nerve of impulses. Wrapped around axon so there are layers of Schwann cell Mainly provide myelin insula;on to axons in the peripheral nervous system MYELIN SHEATH: High phospholipid (fa\y) content o]ers electrical insula;on Nodes of Ranvier - gaps between Schwarm cells = rapid transmission Exposed areas between the Schwann Cells Assist rapid transmission of ac;on poten;als in myelinated neurones.  Extension of cell bod, Dendrites - large surface are Extensions of the cell body Provide a large surface area to receive informa;on to pass to the cell body Same structure as axons but shorter Plasma has dense chemical ion channels for impulse transmission Form synapses with other dendrites or terminate in specialised sensory receptors e.g. skin  to carry out fractions - ProperJes of Neurones (inside Lexcitability) Irritability – ability to ini;ate nerve impulses in ↑ CO2 in blood response to s;muli from either inside the body or ↑ outside. respiratory rate &. Curside) ConducJvity- ability to transmit an impulse. thought that (action potential closes involtag movenant. Neuroglial cells- support network prome to cancers. Three types of non-excitable glial (glue-like) cells support the neurones of the central nervous system. Unlike nerve cells, these con;nue to replicate throughout life. These are; Microglia blood brain barrier Astrocytes - Oligodendrocytes  MICROGLIA- are found mainly in the area of blood vessels. They enlarge and become phagocy;c in areas of inQamma;on and cell destruc;on. ASTROCYTES- form the main suppor;ng ;ssues of the central nervous system. Star shaped with Pne branching processes, they lie in a muccopolysaccharide ground substance. Found in large numbers adjacent to blood vessels. OLIGODENDROCYTES smaller then astrocytes and are found in clusters around the neurone cell wall, and adjacent to, and along the length of many myelinated nerve Pbres in the CNS. They form and maintain myelin and have the same func;on as Schwann cells in the peripheral nerves.  selective barrier-protects brain toxic Blood-brain barrier - from potential Substances Is a selec;ve barrier that protects the brain from poten;ally toxic substances and chemical varia;ons in the blood eg: acer a meal. Oxygen, carbon dioxide, glucose and other lipid soluble substances such as alcohol quickly cross the barrier into the brain. Some large molecules, many drugs, inorganic ions and amino acids pass more slowly or do not pass at all from the blood to the brain  conduction SynapJc End Bulbs nerve impulse Important for nerve impulse conduc;on from one neurone to another or neurone to an e]ector Contain enclosed sacs called saus synapJc vesicles& contains - / These store neurotransmiPers Synapse space between nevrons (gap) Pre-synap;c neurone Pre-synap;c knob Neurotransmi\ers – acetylcholine/noradrenaline Calcium Mitochondria Neurotransmi\er receptors Post-synap;c knob - Post-synap;c neurone kn messages passed. on Neuro-transmission Break Jme! The Nervous System Part 2 Nerve Impulses Tutor Debbie Hemington Module Biomedical Sciences GDC Learning Outcomes 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their application to patient Management 1.1.6 Describe relevant and appropriate physiology and explain its application to patient management Intended learning outcomes As for part one Assessment Formative Summative 6 An impulse is initiated by stimulation of sensory nerve endings or by the passage of an impulse from another nerve. Afferent A nerve impulse running TO the brain and CNS is known as Afferent (sensory). Tobrain + cros A nerve impulse running FROM the brain and CNS is known as Efferent (motor). From brain + CNS leferent 7 faction potentials ( - down aendrite Nerve impulses (action potential) direction only - travels in one - sends one message & are speed pulses can and number of frequency - vary gentle vs heavy - handel 8 9 longlived sodium (at) potassium + ) (k 10 11 Nerve impulses travel down the neurone nerve impose jumps to another wire chemical - not Synaptic transmission means electrical Nerves are not joined together or connected. The point at which the nerve impulse jumps from one nerve to another = SYNAPSE Approx 1000 trillion synapses in your brain 13 Synaptic knobs contain spherical, membrane bound synaptic vesicles which store a chemical, the neurotransmitter, that is released into the synaptic cleft. 14 Passing to another nerve neurotransmitte in a Synaptic X gated channels 15 The journey of a neurotransmitter Synthesized by nerve cell bodies 3 Actively transported along the axons Stored in the synaptic vesicles Released by exocytosis in response to the action potential Diffuse across the synaptic cleft Act on specific receptor sites on the post synaptic membrane. Action is short lived. After action, inactivated by enzymes or taken back into the synaptic knob. 16 17 in brain 50 + neurotransmitters card. and spira adrenalize e g.. Dopamine Histamine serotonin Noradrenaline Acetylcholine - 18 causes reversible blocks in nerve transmission to the pain centures in CNS. Local anaesthetics block the nerve transmission to pain centres in the central nervous system by binding to and inhibiting the function of an ion channel in the cell membrane of nerve cells known as the sodium channel. This action obstructs the movement of nerve impulses near the site of injection, but there are no changes in awareness and sense perception in other areas. Excessive nerve impulses can result in NEURALGIA most commonly trigeminal neuralgia. debilitating The HERPES SIMPLEX VIRUS lies dormant in the TRIGEMINAL GANGLION, when re- activated it travels down the TRIGEMINAL NERVE emerging on the lip and causing a cold sore. 19 https://www.youtube.com/watch?v=OvVl8 rOEncE https://www.youtube.com/watch?v=OZG8 M_ldA1M https://www.youtube.com/watch?v=VitFv NvRIIY Apps: Thank you for listening. Nervous System Part 3 Central Nervous System & Peripheral Nervous System Tutor Debbie Hemington Module BMS GDC Learning outcomes As for parts 1 & 2 Intended learning outcomes At the end of the session, you will be able to: Describe the 2 parts of the nervous system List the key features of the human brain and spinal cord Describe the main areas of the brain and their func=on List the func=ons of cerebrospinal >uid List the groups of spinal nerves Assessment Forma=ve Summa=ve Short answers End of module exams MCQ  cord The central nervous system = Brain + Spinal Brain Weighs around 1.4kg Lies in cranial cavity Comprises of: Cerebrum Thalamus Hypothalamus Mid brain Pons Medulla oblongata Cerebellum  mushroom shape Cerebrum outside layer - - folded / wrinkled Largest part of the brain 3 main func=onal areas associated with; Mental Ac=vi=es-memory, intelligence, problem solving, re>ec=on, judgement, thinking, reasoning, ini=a=ve, inhibi=on, moral sense of responsibility and learning Sensory percep=on-percep=on of pain, temperature and touch Ini=a=on and control of voluntary muscle contrac=on  The Cerebrum The cerebral cortex is highly wrinkled, which makes the brain more eScient, because it can increase the surface area of the brain and the amount of neurons within it. A deep furrow divides the cerebrum L into two halves, known as the leT and right hemispheres. The corpus callosum A R is a bundle of axons which connects of these two hemispheres. Bundle atons Thalamus Relay Sensory and Motor Signals back to cerebral cortex. Small structure Sensory receptors in skin & viscera send info about touch, pain & temperature Input from the special sense organs travels here too where there is percep=on but only in basic form Thought to be involved in arousal and the processing of some emo=ons and complex re>exes  Thalamo , Go a  -controls hormones Hypothalamus gland attached to pituitary - Situated within the cerebrum AVached to the pituitary gland Controls the output of hormones Controls eHectors of the autonomic nervous system: Emo=onal reac=ons Hunger and thirst Body temperature S Biological clocks Mid brain Consists of nuclei and nerve Xbres which connect the cerebrum with the lower parts of the brain and spinal cord. Nuclei act as relay sta=ons for the ascending and descending nerve Xbres and have important roles in auditory and visual re>exes. + Visual auditory refuses  forms nerve fibre Pons - crebum halves the two bridging Contains nerve Xbres, which form a bridge between the two hemispheres of the cerebrum Processes info from several of the cranial nerves  continuous = spinal cord. Medulla Oblongata Is con=nuous with the spinal cord Controls eHectors: cardiovascular centre respiratory centre re>ex centres: coughing, vomi=ng, sneezing, swallowing  Cerebellum - coordinates voluntary muscle movements posture & - - Balance important for those - Smooth movements - Receives proprioceptor impuses v sensory receptor that receives Stimuli Ein body esp position. + movement  Brain to a tissues Spinal Cord organs Nerves conveying impulses from the brain to various organs and 7ssues descend through it. mediaengate Starts in the medulla oblongata and descends through the spinal column. 9 through spinal Colem Spinal cord Elongated, almost cylindrical part of the CNS. Suspended in the vertebral canal Surrounded by meninges & cerebro-spinal ?uid Approx the thickness of a liCle Dnger Approx 45cms long  brain buffer e cushion of - Cerebrospinal 0uid - subarachnoid space proteins, glucose Lymphocytes - , Cerebrospinal 0uid (CSF) is a clear colourless ?uid that: occupies the subarachnoid space in the brain acts as a "cushion" or buKer for the cortex is renewed 4 7mes daily contains proteins, glucose and - lymphocytes Func3ons of Cerebrospinal Fluid (CSF) Protec7on - shock absorber in CSF > - reduces weight Buoyancy - floats Excre7on of waste products - harmful substances , drugs directed away from brain (one-way Endocrine medium for the brain.. I transports hormones to certain brain areas.  shock absorbe - Protec3on The CSF protects the brain by ‘buKering’ the brain. This lessens the impact when there is a blow to the head. Image sourced April 2021 Dreamstime.com  in CSF-thos reducing Buoyancy floats pressure Because the brain is immersed in ?uid, the net weight of the brain is reduced from about 1400g to about 50g, thus reducing the pressure at the base of the brain. Image sourced April 2021 Q Files Excre3on of waste products The one-way ?ow from the CSF to the blood takes poten7ally harmful metabolites, drugs and other substances away from the brain Image sourced April 2021 Depositphotos Endocrine medium for the brain The CSF serves to transport hormones to certain areas of the brain. Hormones released into the CSF can be carried to remote sites of the brain where they may act. Image sourced April 2021 SubPNG The Peripheral Nervous System Peripheral Nervous System rate - ↑ digestia > involuntary /actions + restores calms voluntary J - movements Rest + GImage sourced April 2021 Biology Libre Texts. Fight or flight digest Autonomic Nervous System The sympathe3c nervous system ac7vates the “Cght or 0ight” response during a threat or perceived danger Needed for short term survival The parasympathe3c nervous system restores the body to a state of calm, the “rest and digest” phase Needed for long term survival. Cranial Nerves 5 1 + in particular to dental air 12P - Spinal Nerves 3) pairs - 8 x cervical 12 x thoracic 5 x lumbar 5 x sacral 1 X cocynged  Between Spina Intervertebral Foramina - vertebrae Peripheral Nerves location/functions Useful links Autonomic Nervous System: Sympathe7c vs Parasympathe7c, Anima7on – YouTube 2-Minute Neuroscience: Divisions of the Nervous System – YouTube Thank you