* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download File
History of neuroimaging wikipedia , lookup
Axon guidance wikipedia , lookup
Optogenetics wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Neuroscience in space wikipedia , lookup
Neuropsychology wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Electrophysiology wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Neuroplasticity wikipedia , lookup
Proprioception wikipedia , lookup
Haemodynamic response wikipedia , lookup
Biological neuron model wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Central pattern generator wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Metastability in the brain wikipedia , lookup
Single-unit recording wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Node of Ranvier wikipedia , lookup
End-plate potential wikipedia , lookup
Neurotransmitter wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Synaptic gating wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Neural engineering wikipedia , lookup
Development of the nervous system wikipedia , lookup
Evoked potential wikipedia , lookup
Nervous system network models wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Circumventricular organs wikipedia , lookup
Synaptogenesis wikipedia , lookup
Microneurography wikipedia , lookup
Neuroregeneration wikipedia , lookup
Warm-Up 1. Name the 2 main organs of the nervous system. 2. Draw and label the parts of a neuron. Warm-Up • Label the parts of the neuron below. A D C B G E F Warm-Up 1. One neuron transmits a nerve impulse at 40 m/s. Another conducts at the rate of 1 m/s. Which neuron has a myelinated axon? 2. List the following in order: A. K+ channels open and K+ floods out of cell B. Membrane is polarized (resting potential) C. Neurotransmitters are released from vesicles into synaptic cleft D. Na+ channels open and Na+ floods into cell E. Stimulus triggers membrane depolarization 3. What restores the resting potential of a neuron? The Nervous System Chapter 9 Nervous System • Master controlling and communicating system ▫ ▫ ▫ ▫ ▫ ▫ Thinking Memory Movement Interpreting the world Coordination Homeostasis Basic Functions 1. Sensory input – gather information 1. Detect changes inside & outside of the body 1. Light, sound, temperature, [oxygen], internal environment 2. Integration – process and interpret sensory input 1. Receive impulses from sensory neurons and consciously or subconsciously act upon them 3. Motor output – response by muscles and glands 1. 1. Act on “decisions” made by sensory and integrative neurons and send message to effectors Muscle contraction or gland secretion Organization A. Central Nervous System (CNS) ▫ Brain & spinal cord ▫ Integrative and control centers B. Peripheral Nervous System (PNS) ▫ Nerves (spinal nerves, cranial nerves) ▫ Communication lines between CNS and rest of body ▫ Two Divisions: 1. Sensory (afferent) Division: Sensory receptors CNS 2. Motor (efferent) Division: CNS effectors (muscles & glands) Motor Division • Somatic nervous system (voluntary) – control skeletal muscles • Autonomic nervous system (ANS) (involuntary) – regulate smooth muscles, cardiac, glands ▫ Subdivisions: sympathetic & parasympathetic Divisions of the ANS • Sympathetic Nervous System ▫ Used when the body needs to expend energy ▫ “Fight or Flight” response • Parasympathetic Nervous System ▫ Maintain homeostasis under normal conditions Nervous Tissue 1. Neurons (mass of nerve cells) - transmit message 1. Three types: 1. Sensory, motor, and interneurons Anatomy: ▫ ▫ ▫ ▫ ▫ Cell body – contains nucleus; metabolic center Dendrite – fiber that conveys messages toward cell body Axon – conduct nerve impulses away from the cell body Axon terminals – end of axon; contain neurotransmitters & release them Synaptic cleft/synapse – gap between neurons Nervous Tissue 2. Neuroglia Cells (supporting cells) CNS: astrocytes, microglia, ependymal cells, oligodendrocytes barrier between capillaries and neurons protect neurons immune/defense line brain and spinal cord cavities wrap nerve fibers produces myelin sheaths (covering) PNS: Schwann cells, satellite cells surround large neurons protect & cushion • Myelin: whitish, fatty material that covers nerve fibers to speed up nerve impulses Schwann cells: surround axons and form myelin sheath Myelin sheath: tight coil of wrapped membranes Nodes of Ranvier: gaps between Schwann cells Synaptic Knob: round structure at end of axon that sends nerve impulse • • • • ▫ Dendrites lack Synaptic Knob, causing one-way nerve impulse • Ganglia: collections of cell bodies • Bundles of nerve fibers = tracts (CNS) or nerves (PNS) • White matter: dense collections of myelinated fibers ▫ CNS myelinated; smooth/quick impulses • Gray matter: unmyelinated fibers & cell bodies ▫ PNS unmyelinated; slow impulse (infant brain) Classification of Neurons 1. Functional Classification: direction nerve impulse is traveling • Afferent (sensory) ▫ To the CNS • Efferent (motor) ▫ Away from the CNS • Interneurons ▫ Connect impulses 2. Structural Classification: # processes extending from cell body Multipolar Bipolar Unipolar 1 axon, several dendrites 1 axon, 1 dendrite 1 process Most common (99%) Rare Short with 2 branches (sensory, CNS) Eg. Motor neurons, interneurons Eg. retina, nose, ear Eg. PNS ganglia Nerve Impulses Neuron Function 1. Irritability: ability to respond to stimulus & convert to nerve impulse 2. Conductivity: transmit impulse to other neurons, muscles, or glands Exciting a Neuron: • Cell membrane at rest = polarized ▫ Lots Na+ outside cell, lots K+ inside cell ▫ Inside is (-) compared to outside • Stimulus excited neuron (Na+ rushes in) becomes depolarized • Depolarization activates neuron to transmit an action potential (nerve impulse) ▫ All-or-none response ▫ Impulse conducts down entire axon • K+ diffuses out repolarization of membrane • Na+/K+ ion concentrations restored by sodium-potassium pump (uses ATP) Resting membrane potential (-70mV) Gated Ion Channels (Na+ and K+) Depolarization • Saltatory conduction: electrical signal jumps from node to node along myelinated axon (30x faster!) • IMPULSE TRAVELS IN ONE-WAY DIRECTION Multiple Sclerosis (MS) • Autoimmune disease • Myelin sheaths destroyed reduced to hardened lesions (scleroses) • Blindness, muscle weakness, speech disturbance, urinary incontinence • Treatment: interferons, glatiramer (hold off attacks) Nerve Conduction • Action potential reaches axon terminal vesicles release neurotransmitters (NT) into synaptic cleft • NT diffuse across synapse bind to receptors of next neuron • Transmission of a nerve impulse = electrochemical event Neurotransmitters • 50+ identified • Excitatory: cause depolarization ▫ Ex. Acetylcholine, norepinephrine • Inhibitory: reduce ability to cause action potential ▫ Ex. Dopamine and glycine Neurotransmitters Neurotransmitter Action Affected by: Acetylcholine muscle contraction botulism, curare (paralytic), nicotine Dopamine “feeling good” cocaine, amphetamines Serotonin sleep, appetite, nausea, mood, migraines Prozac, LSD, ecstasy Endorphins inhibit pain morphine, heroin, methadone GABA main inhibitory NT alcohol, Valium, barbiturates Epilepsy • Abnormal & excessive discharge of impulses to skeletal muscles • Neurotransmitters depleted • Dilantin ▫ stabilizes Na+ so impulses aren’t over used • Anesthetics ▫ block permeability of Na+ so pain can’t be sensed ▫ http://www.youtube.com/ watch?v=MNQlq004FkE Types of Nerves • Sensory Nerves ▫ conduct impulses to the brain • Motor Nerves ▫ carry impulses to the effectors • Mixed Nerves ▫ both sensory and motor functions ▫ most typical type found Spinal Cord • Slender column of nerve cells that pass downward from the brain into the vertebral canal • “Begins” at the Foramen magnum • Ends at the intervertebral disc between L1 and L2 vertebrae Structure of the Spinal Cord • 31 segments – each has a pair of spinal nerves ▫ Cervical Enlargement Thickening in the neck region; supplies nerves to the upper limbs ▫ Lumbar Enlargement Thickening in the lower back region; supplies nerves to the lower limbs ▫ Nerve Tracts Bundles of myelinated nerve fibers; make up major nerve pathways ▫ Central Canal contains cerebrospinal fluid Fluid in the ventricles of the brain, meninges and the central canal of the spinal cord Functions of the Spinal Cord • Two major functions: ▫ Conducting nerve impulses ▫ Center for spinal reflexes • Axons supply 2-way communication between brain and body ▫ Ascending tracts Relay message to the brain ▫ Descending tracts Relay motor impulses from the brain to muscles and glands • Center for spinal reflexes reflex arcs pass through spinal cord ▫ Knee jerk ▫ Withdrawal Reflexes • Rapid, predictable, involuntary responses to stimuli 1. Somatic Reflexes: stimulate skeletal muscles ▫ Eg. jerking away hand from hot object 2. Autonomic Reflexes: regulate smooth muscles, heart, glands ▫ Eg. salivation, digestion, blood pressure, sweating Reflex Arc (neural pathway) Five elements: 1. Receptor – reacts to stimulus 2. Sensory neuron 3. CNS integration center 4. Motor neuron 5. Effector organ – muscle or gland Reflex Lab • Patellar Tendon Reflex (knee jerk) ▫ Sit on lab bench and tap lightly on partners leg right below the patella • Achilles Tendon Reflex (ankle-jerk) ▫ Hold partners foot in a relaxed manner ▫ Using the palm of your hand, tap the Achilles tendon and record response Babinski sign (Plantar Reflex) • Rub a pencil eraser from heel to toe on the outer edge of the sole of partners foot ▫ Normal response – foot curls ▫ Abnormal response – toes extend Normal under 2 years of age b/c the nervous system is not completely developed Later in life, it is a sign of a CNS problem Babinski Reflex Static Equilibrium • Stand with arms at side, feet square, shoulders level ▫ Eyes open ▫ Eyes closed ▫ After twirling Spatial Orientation • Take index fingers and press tips together with arms straight out ▫ Eyes open ▫ Eyes closed ▫ After twirling Ciliospinal Reflex • Rub one side of your partners neck lightly with a cotton swab ▫ Look for a change in pupil size on that side Convergence Reflex • Sit off the side of your partner and have them focus on distant object for 20 seconds • Then quickly focus on an object 10-12 inches in front of face ▫ Look for a change in pupil size Voluntary Reactions • More neurons and synapses are involved longer response times Reflex = Involuntary Reaction Voluntary Reaction 1. List and describe the 5 elements of a reflex arc. 2. List an example of a reflex. 3. What is the difference between a reflex and a voluntary reaction? 1. 2. 3. 4. Cerebral Hemispheres Diencephalon Brain stem Cerebellum L & R hemispheres Corpus callosum: large fiber tract; connects 2 hemispheres Lobes: major regions (named for cranial bones) Parietal, frontal, occipital, temporal Gyri (gyrus) = elevated ridges of tissue Sulci (sulcus) = shallow grooves Fissures = deeper grooves, separate large regions of brain Motor & sensory function: opposite hemispheres Hemisphere Dominance Dominant Hemisphere ▪ speech, writing, reading ▪ verbal, analytical, computational skills Non-dominant hemisphere ▪ motor tasks, interpreting music, nonverbal visuals ▪ emotional and intuitive thinking Outermost layer; grey matter “Executive suite” conscious mind Ventricles Reservoirs of cerebrospinal fluid ▪ Helps protect and cushion the brain ▪ Responsible for transporting nutrients and removing waste from the brain and spinal cord 3 main structures: 1. Thalamus: relay station for incoming info 2. Hypothalamus: A. B. C. D. E. F. 3. Autonomic control center (heart rate, BP, digestion) Emotional response (limbic system) Body temperature regulation Regulate food intake Sleep-wake cycles Control endocrine system pituitary gland at base Epithalamus: pineal gland (sleep-wake cycle) Programmed, automatic behaviors for survival 3 regions: 1. Midbrain: vision, hearing, reflex 2. Pons: breathing 3. Medulla oblongata: heart rate, BP, breathing, swallowing, vomiting, coughing, sneezing Balance, equilibrium, timing of skeletal muscle activity Meninges: connective tissue covering CNS structures Dura mater (leathery outer), arachnoid mater (web-like middle), pia mater (surface of brain) Meningitis: inflammation of meninges; bacterial or viral infection Cerebrospinal fluid (CSF): watery cushion to protect NS from trauma Lumbar (spinal) tap – test for infection, tumors, multiple sclerosis Bacterial antibiotics Herpes meningitis anti-viral meds IV fluids Prevention: vaccines for bacterial infections (HiB) NO: Urea Toxins Proteins White blood cells Bacteria Most drugs YES: Water Glucose Amino acids Gases Fat-soluble substances Some drugs: anesthetics, alcohol, nicotine 12 pairs of cranial nerves that originate from brainstem (all except one pair) I Olfactory Smell II Optic Vision III Oculomotor Eyelid movement, lens focus, pupil dilation IV Trochlear Eyeball movement V Trigeminal (3) Eye, mouth, jaw muscle movement VI Abducens Eyeball movement VII Facial Facial expression; taste; tear secretion VIII Vestibulocohlear (2) Equilibrium; hearing IX Glossopharyngeal Swallowing and saliva secretion X Vagus Speech, swallowing, heart and smooth muscle impulse XI Accessory (2) Soft palate, pharynx, larynx; neck and back XII Hypoglossal Tongue movement 31 pairs originate from spinal cord Cervical Plexuses Deep in neck; supply muscles and skin of neck Brachial Plexuses Located deep within shoulders between neck and armpits Supply muscles and skin of arm, forearm, and hand Lumbosacral Plexuses Located from lumbar region of back into pelvic cavity Supply muscles and skin of lower ab wall, external genitalia, buttocks, legs, and feet ▪ Major nerve braches include: ▪ Obturator, femoral, and sciatic nerves Parkinson’s Less dopamine released Overactive inhibitory movement Dopamine can’t pass the blood brain barrier – use L-dopa Huntington’s Dominant gene; late acting Neurons deteriorate; unrestrained movement Whiplash Damage to cervical nerves CVA Stroke Hemorrhage/cessation of blood flow to the brain Cerebral palsy Damage to brain tissue at birth Permanent, non-progressive damage to motor control area Varicella zoster virus Must have had chicken pox to develop shingles Inflammation of nerves No treatment Alzheimer’s Lesions develop in cortex Short term memory loss Hydrocephalus CSF accumulates in the brain Drug tolerance physiological response to a particular dose of a drug becoming less intense over time CNS depressants Barbiturates Opiates Cannabinoids Hallucinogens