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The Nervous System Chapters 9 & 10 Function? Is to RELAY messages from the INTERNAL and EXTERNAL environments Main Communication network of the body Homeostasis: Balance of the body Only great minds can read this This is weird, but interesting! fi yuo cna raed tihs, yuo hvae a sgtrane mnid too Cna yuo raed tihs? Olny 55 plepoe out of 100 can. i cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it dseno't mtaetr in waht oerdr the ltteres in a wrod are, the olny iproamtnt tihng is taht the frsit and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it whotuit a pboerlm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Azanmig huh? yaeh and I awlyas tghuhot slpeling was ipmorantt! The organization of the Nervous system Know for test! 2 main cell types 1.Glial ( neuralglial) -- Protect the neurons Some say maybe more Great research with stem cells 10 times more than neurons Total of 6 different types 4 in the CNS a) astrocytes: most abundant, provide barrier of blood to brain b)Microglial—act as immune cells of CNS c) Ependymal—ciliated—barrier between CSF and CNS—keeps csf flowing d) Oligodendrocytes—produce myelin sheaths 2 in PNS a) satellite—unsure of fuction b) Schwann---forms myelin of PNS—allows it to regenerate Find the Oligodendrocyte? Microglial? Astrocyte? A variety of glial cells are shown. Oligodendrocytes (arrowhead) have round medium sized nuclei and may have a few short processes (oligo means few). Microglia (arrow) are smaller and often have an angular nucleus and fibers originating at opposite poles of the cell soma. Can you identify the structure curving into the field from the upper left? It is a blood capillary with several astrocyte processes attached 2) Neuron : The functional unit of the nervous system Very specialized Special characteristics 1. Extreme longevity—over 100 years 2) Amitotic—no mitosis---no new cells 3) Very high metabolic rate--The rules of 3’s DEMANDS O2 and glucose 3 weeks without food 3 days without water 3 hours without shelter 3 minutes without air But not three seconds without hope. 3 different types of neurons determined by # of branches 2 processes- axon & dendrite—very rare— retina eye, olfactory 3 or more processes Most common 99% these Unipolar pseudounipolar Begins as 2 then form single Mainly in ganglia of PNS Structure of Neurons A) Cell body (Soma) 2 special organelles 1. Nissl bodies— (Chromatophilic: orderly arrangement of Rough ER) 2. -large granular body -contains rough ER—produces protein -axoplasmic transport—transport of materials from cell body to axons Neurofibrils---long thin fibrils that give support and structure to neurons in the cytoplasm B) Cell Processes ( branches) 1. Dendrite—usually multiple/cell body -carry impulses to the cell body 2. Axon—usually only 1/cell body -carry impulses away from cell body United Streaming: Biologix: Nerve Impulse Conduction End is the SYNAPTIC KNOB— the “gap” Node of Ranvier Some fibers are myelinated—“jumps”—Salatory Conduction ---- Much faster mostly found in the PNS Myelinated = white matter Unmyelinated = gray matter If not myelinated impulse must move continuously as waves--chemicals involved sodium & potassium PNS—Neurilemma-outer covering of Schwann cell -Schwann cells surrounds axon--this allows repair CNS—lacks a Schwann cell so NO regeneration--YET!!!!! Receptor Classes A) Exteroreceptor External stimuli B) Interoreceptor internal (gut) D) Photoreceptors Light E) Chemoreceptors chemical C) Proprioreceptors body part relation G) Thermoreceptors H) Mechanoreceptors Temperature tension and pressure F) Pain receptors Nerve: Structure (pg 229) Epineurium: covering over the nerve Fascicle:bundles of wrapped axons Perineurium: covering over fascicle Endoneurium: wrapping around individual axons in a nerve A connective tissue sheath called the epineurium surrounds each nerve. Each bundle of nerve fibers is called a fasciculus and is surrounded by a layer of connective tissue called the perineurium. Within the fasciculus, each individual nerve fiber, with its myelin and neurilemma, is surrounded by connective tissue called the endoneurium. A nerve may also have blood vessels enclosed in its connective tissue wrappings. Nerve Impulses ( aka) Action Potenial Reaction time .5 –150m/sec 300mph The 4 steps of a reaction Irritability--- WILL BE ON TEST Neurons respond Conductivity--- Enable neurons to encode stimulus into impulse Integration--- CNS sorts impulses& interprets them Reaction--- CNS sends its own message telling which mucle or gland to react Nerve Impulse Transmission -neurons at rest have high K+ and low Na+ on inside of neuron and Low K+ and high Na+ outside the neuron -causes a slight – charge inside the cell and + outside -when an impulse is conducted the permeability of the membrane changes For Na+ ions and they rush into the cell -this causes the polarity to change--+ charge inside the cell and - charge outside the cell=--called Depolarization -this section of membrane immediately recovers and Repolarizes -However, depolarization stimulates adjacent membrane and Depolarization continues down length of axon until it reaches the synaptic Knob -if a region of myelinated axon is reached the impulse is able to jump over the myelinated region -called saltatory conduction -increases speed of nerve impulse HOW IMPULSE TRANSMITTED---impulses go from bodyspinal cordbody Reflex arc—2-neuron arc -consists of only 2 neurons—1 sensory neuron and one motor neuron—only 1 synapse -ex. Knee-jerk reflex -3-neuron arc -consists of all 3 types of neurons and 2 synapses -withdrawal reflex -sensory neuron interneuron Functions of Neurons A? Sensory-Afferent C? Integration— Associative or Interneuron B? Motor-Efferent The Synapse Neurotransmitters, such as Acetylcholine, are stored in vesicles in the presynaptic terminal. Acetylcholine is secreted across synaptic clefts, where it binds to the post synaptic membrane and causes a change in the permeability of the postsynaptic cell, which results in an excitatory post-synaptic potential. Neurotransmitter—between presynaptic neuron and postsynaptic neuron different ones 5 main ones Neurotransmitters A)Acetylcholine—innervates skeletal muscles, slows the heart, -used to dilate constrict pupils in cataract surgery, reverse affects of muscle relaxants, treat myasthenia gravis, and alzheimer’s -used in nerve agent sarin and in some pesticides B)Norepinephrine—functions include increasing the rate of contractions, acts a stress hormone by increasing heart rate, triggering release of glucose from storage, increase blood flow to skeletal muscle -too much associated with schizophrenia, and too little associated with ADHD and depression C)Dopamine: functions include roles in cognition and behavior, motivation, punishment and reward, sleep, mood, attention, working memory, and learning -too little associated with ADHD and Parkinson’s disease, too much associated with pshychosis and schizophrenia D)Serotonin-the “feel good" neurotransmitter -insulin released when carbs are eaten—breakfast??? -protein containing tryptophan in conjunction with carbs -insulin allows tryptophan to be taken into brain and used to make serotonin -involved in mood, sexual desire and function, appetite, sleep, memory, learning, temp. regulation, and some social behavior Shortage---depression, sleep disorders, eating disorders, digestive disorders Excess—diarrhea, vomiting, headache, rapid heart rate, serotonin syndrome 1) light 3 ways to get to release— 2) exercise 3) diet E) Endorphins---natural painkillers in labor--Released under stress -leads to feelings of euphoria, appetite modulation Release of sex hormones, improved immune response, and dec Feelings of pain Sleep 24 hour period---circadian rhythm REM—Rapid Eye Movement without sleep Sleep video 2:51 http://player.discoveryeducation.com/index.cfm?guidAssetId=69D1E39F No Video, TV, flashing lights 1 hr before Nervous is body’s main communication system of the body works with the endocrine system (hormones) Central nervous system--- brain and spinal cord Meninges— infected = meningitis Dura mater Outer-tough Dense CT Arachnoid Transparent Pia mater Innermost, attaches to SC and Braincontains b.v Spaces-- Subarachnoid---filled with cerebrospinal fluid (CSF) --acts as a shock absorber and helps protect against pathogens used in treatments---page 247--spinal tap— collect CSF and check for substances (pathogens, etc.) hydrocephalus—accumulation of CSF in brain—results when CSF can’t drain away Epidural—introduction of an Anesthetic into the CSF in the Lumbar region of the spinal column The illustration to the left represents a post-mortem axial section of a normal lumbar spinal canal. The vertebral body is shown at the top and the lamina of the vertebrae at the bottom. The epidural space surrounds the dural membrane. Only the posterior portion of the epidural space is outlined in green as this is the area of clinical interest. Spinal Cord---Runs out of the foramen magnum 42-45 cm long (if of average height) Gray H--- composed of gray matter—mainly cell bodies and dendrites -Front 2 –ventral horns carry messages to skeletal muscle -Rear 2 – dorsal horns Receive and process incoming information—carry info toward the brain Spinal Nerves--(pg 245) 8 Cervical 12 Thoracic 1 Coccygeal 5 Lumbar 5 Sacrospinal Map of spinal nerves---- Dermatome: skin surface area supplied by A single spinal nerve Parts of the brain Dissection photo Next slide Sheep brain *1. cerebrum 4. cerebral aquaduct *5. Mudulla oblongata(turn arrow) *6. pons *7. cerebellum **9. spinal cord *14. Thalamus *15 & 21. optic chiasma *16. Pituitary gland *18. mammillary body *19. pineal gland *20. olfactory bulbs Dissected brain Brain --- 3 LBs on average 80-120 billion neurons Protected by skull, BBB and CSF Proportioned to body mass Difference between male and female??? Now the truth--- Male 1600 g Female 1450g Why? Proportioned to size http://www.bbc.co.uk/science/humanbody/sex/add_user.shtml?users=1 Pet scans Positron emission tomography This brain picture shows the communication centers in the male brain (designated by the blue areas) and the communication centers in the female brain (designated by the red areas). One of the final frontiers is the human brain. Current research reports that we change our brain with every conversation, every action we partake in. Our brain keeps changing and developing well into our 80’s (current research states 80’s but it could be longer). Just because your biological hand may have dealt you a certain brain style doesn’t mean you can’t change, build, and reconstruct your brain. If you communicate indirectly you can practice communicating directly with a direct speaker. If you are a direct speaker you can work with an indirect speaker to build up your ability to speak indirectly. Dementia Each brain image shows the change in brain metabolism when subjects were asked to inhibit their response to food during food stimulation compared with when they were not told to inhibit their response. Two brain sections at different levels of the brain are shown for each group (women, men, and women vs. men). Top row, women: No color indicates that women had no significant differences in brain activity between the two conditions. Middle row, men: Blue colored areas were significantly less active when men were told to inhibit their response to food than they were without inhibition. Bottom row, women vs. men: Orange color indicates areas where men showed greater decrements with inhibition than women. These brain regions are involved in emotional regulation, conditioning, and the motivation to eat. Cranial nerves -- 12 pairs ( Page 252) Quiz Name & Function I.Olfactory: sense of smell II.Optic: vision III.Oculomotor: eye movements IV.Trochlear: eye movements V.Trigeminal:face, scale, teeth sensation, chewing movt VI.Abducens: eye movements VII.Facial: taste, facial muscle contractions VIII.Vestibulocochlear:hearing,balance IX.Glossopharyngeal: sensations of throat; swallowing, taste, saliva secretion X.Vagus: sensations of throat,larynx,thoracic & abdominal organs, swallowing, voice, slowing of heartbeat, speed up peristalsis XI.Accessory: shoulder movts, turn head XII.Hypoglossal: tongue movts Development- begins about 2 weeks after fertilization Neural plate—2 weeks 4 days—thickened plate of ectoderm in the embryo that develops into the neural tube 1) Hindbrain—upper part of spinal cord, brain stem, and cerebellum 2) Midbrain—uppermost part of the brain stem 3) Forebrain--cerebrum Fully developed -- 4 divisions Hindbrain– A) Brain stem— midbrain, pons, medulla oblongata Midbrain-B)uppermost part of brain stem Forebrain- C) Cerebrum, D) Diencephalon- hypothalamus, thalamus, epithalmus Ventricles—contain CSF Gyri—ridge on the cerebral cortex Brainstem --- 2-way—connects motor and sensory systems from the main part of the brain to the body 3 main parts ---medulla oblongata, pons, midbrain Medulla oblongata-3 main control centers-1.Respiration 2.Cardiac Center 3.Reflex centers of vomiting, coughing, sneezing, and swallowing Origin to 4 cranial nerves--- IX, X, XI, XII Pons—integral part of the brain’s pathway (connects various parts of the brain), as a Respiration control center (inhalation initiator), maybe REM sleep and arousal Origin to 4 cranial nerves --V, VI, VII, VIII Midbrain-associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and Temperature regulation 2 cranial nerves --III, IV DIENCEPHALON--(interbrain) thalamus—relays sensory and motor signals to the cerebral cortex, regulates consciousness, sleep, and alertness -switchboard that sends incoming info where it needs to go in the brain hypothalamus—links the nervous and endocrine systems via the pituitary gland -makes and secretes neurohormones that stimulate or inhibit the secretion of pituitary hormones -controls body temperature, hunger, thirst, fatigue, sleep, and circadian cycles Epithalumus—secretion of melatonin by pineal gland and regulation of motor pathways and emotions Cerebellum– 2nd largest part of the brain % of brain mass controls muscle movement and coordination works to maintain posture acts as our balance center -- gray matter—outer layer --- white matter—bulk of interior Cerebrum lobes Cerebrum– largest part of the brain 66% of brain mass --origin to 2 cranial nerves --I and II Quiz Responsible for perception, thought, decision making, primary sensory Areas (visual, auditory, etc), and primary motor area Quiz is a combo—P. 250 3 parts--1) Cortex---outermost layer Makes us aware of our environment 3 areas----motor, association, and sensory All neurons are—unmyelinated Each side (hemisphere) Olfactory area—involved in sense of smell referred to as “executive suite” 2)Basal Ganglia-- InnerAssociated with voluntary motor control, procedural learning relating to routine behaviours or habits, eye movts, and cognitive and emotional functions 3)Limbic System—functions include emotion, behavior, long term memory, and olfaction Islands of Calleja—aids in reinforcing effects of reward-like activities The limbic system wraps around the brain stem and is beneath the cerebral cortex. It is a major center for emotion formation and processing, for learning, and for memory. The limbic system contains many parts, including the cingulate gyrus, a band of cortex that runs from the front of the brain to the back, the parahippocampal gyrus, the dentate gyrus, and most notably, the hippocampus and amygdala. The hippocampus is involved in memory storage and formation. It is also involved in complex cognitive processing. The amygdala is associated with forming complex emotional responses, particularly involving aggression. The limbic structures are also connected with other major structures such as the cortex, hypothalamus, thalamus, and basal ganglia.