* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Motor Neuron - papbiobellaire
Activity-dependent plasticity wikipedia , lookup
Neuroplasticity wikipedia , lookup
Endocannabinoid system wikipedia , lookup
Multielectrode array wikipedia , lookup
Metastability in the brain wikipedia , lookup
Embodied language processing wikipedia , lookup
Axon guidance wikipedia , lookup
Neural engineering wikipedia , lookup
Mirror neuron wikipedia , lookup
Optogenetics wikipedia , lookup
Node of Ranvier wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Electrophysiology wikipedia , lookup
Neural coding wikipedia , lookup
Central pattern generator wikipedia , lookup
Microneurography wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
End-plate potential wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Neuroregeneration wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Single-unit recording wikipedia , lookup
Development of the nervous system wikipedia , lookup
Chemical synapse wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Neurotransmitter wikipedia , lookup
Synaptogenesis wikipedia , lookup
Circumventricular organs wikipedia , lookup
Synaptic gating wikipedia , lookup
Biological neuron model wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Nervous system network models wikipedia , lookup
Ch. 35 The Nervous System Nervous System 1. Neuron - basic unit of structure and function 2. Basic unit of neuron a.) dendrite b) cell body (soma or cyton) c) axon 3. The 3 functional kinds of neurons a) sensory (afferent) - receptor neurons carry impulses to brain and spinal cord (CNS) b) motor (efferent) - effector neurons carry impulses from CNS to effector (muscle or gland) c) interneuron (associative) - connector neurons found within CNS; transmit impulses between sensory, motor, and other interneurons SENSORY NEURON (AFFERENT) MOTOR NEURONS (EFFERENT) INTERNEURONS (IN CNS!) 4. Nerve - an organ composed of: a) many hundreds, thousands of neurons b) other tissues - epithelium, connective, blood vessels 5. 3 functional types of nerves a) sensory nerve - consists of sensory neurons - auditory Receptor CNS(brain, spinal cord) - optic (ear, eye, skin) b) motor nerve - consists entirely of motor neurons [ex:CNS effector (muscle or gland)] c) mixed nerve - consists of both sensory and motor neuron bundles neurons separated by connective tissues (spinal cord - all 31 pairs of spinal nerves) NERVE Motor Neuron - Longitudinal View 1. Dendrites - transmit impulses toward cell body 2. Nucleus - essential to cell functions 3. Cell body - synthesizes the neurohumor or neurotransmitter (adrenaline, acetylcholine) 4. Neurofibrils - protein tubules which carry impulses throughout cell 5. Schwann cell - cell around axon - membrane (neurilemma) essential to regeneration of neuron 6. Myelin sheath - lipid layer around axon; an insulator and also increases rate of impulse conduction 7. Axis cylinder - composed of neurofibrils - carry impulses throughout neuron 8. Nodes of Ranvier - spaces between Schwann cells 9. Motor end plate - (axon terminals) site where neurotransmitters (neurohumor) are stored and released into synapse or effector 10. Axon - carry impulses away from cell body to synapse or to effector Stimulus- Impulse 1. Stimulus - environmental change which causes a response; usually a form of energy a) radiant (heat, light) d) sound b) electrical e) chemical c) pressure 2. Impulse - electrochemical change along a neuron 3. Threshold level stimulus- minimum strength stimulus needed to initiate nerve impulse (varies for different neurons and individuals) 4. Nerve Impulse - “All or None” (Property of neurons) - Once impulse is initiated by threshold stimulus the neuron responds 100% - Impulse travels through the cell at the same rate and same strength Figure 35-7 An Impulse Section 35-2 NERVE IMPULSE 6. Refractory period - lapse of time required for neuron membrane to restore original charge (at this time the cell area is insensitive to another stimulus) 7. Human refractory periods (wide range) a) slowest neurons - longest refractory periods 1/250 sec. --- can transmit 250 impulses per second b) most rapid neurons - 1/2500 sec. --- can transmit 2500 impulses per second (shortest refractory time) 8. Rate of impulse conduction (dependent on 2 factors) a) diameter of neuron - the larger the cell diameter, the faster the rate b) myelin - myelin sheath enhances rate – non-myelinated cells - slowest conduction rate (sensory neurons) – myelinated cells (motor) - faster rates 9. At axon terminal of neuron - axon stores and releases neurotransmitter (NT) into adjacent tissues: a) effector - muscle or gland b) synapse neurotransmitter either activates or inhibits adjacent neuron 10. Activation of cell - Occurs when NT makes adjacent neuron membrane more permeable to Na+ - Impulse initiated 11. Inhibition of cell - Occurs when NT makes adjacent neuron (postsynaptic) membrane less permeable to Na+ - More permeable to Cl- and K+ - Adjacent cell membrane hyperpolarized Figure 35-6 Resting Potential RESTING POTENTIAL (POLARIZED) Section 35-2 RECAP: NEURONAL CELL MEMBRANE TRANSPORT • ACTIVE TRANSPORT: SODIUM- POTASSIUM PUMP; NEEDS ATP; AGAINST CONC. GRADIENT (LOW HIGH) • PASSIVE TRANSPORT: SODIUM & POTASSIUM CHANNELS (GATES); FACILITATED DIFFUSION; NO ATP; WITH CONC. GRADIENT (HIGHLOW) - Bell-Magendie Rule= IMPULSE AT SYNAPSE TRAVELS IN ONE DIRECTION - From axon of presynaptic neuron to dendrites/ cell body of postsynaptic neuron - Only axon end of neuron stores neurotransmitter 12. 4 Major types of Neurotransmitters a) Acetylcholine (Ach) - motor neurons b) Adrenalin(epinephrine) - motor, sensory, and associative c) Noradrenalin (norepinephrine) - motor, sensory, associative d) Seratonin - associative neurons Section 35-2 SYNAPSE Direction of Impulse Dendrite of adjacent neuron Axon Vesicle Receptor Axon terminal Synaptic cleft Neurotransmitter • NEUROTRANSMITTER ACTIVATES OR INHIBITS ADJACENT NEURON • ANESTHESIA: 1. PREVENTS OPENING OF SODIUM GATES 2. BLOCK RECEPTORS ON POSTSYNAPTIC NEURON 1. SPINAL CORD- LARGE MIXED NERVE A. WHITE MATTER- OUTER PORTION OF MYELINATED FIBERS RUNNING UP AND DOWN (TO & FROM BRAIN!) B. GRAY MATTER- CELL BODIES OF ASSOCIATIVE & MOTOR NEURONS 1. 31 PAIRS OF SPINAL NERVES (MIXED) – SENSORY FIBERS ENTER DORSAL ROOT, MOTOR LEAVE VENTRAL ROOT • DESTRUCTION OF DORSAL ROOT – LOSS OF SENSATION IN PARTS THAT SUPPLYSENSORY NEURONS • DESCRUCTION OF VENTRAL ROOT – MUSCULAR PARALYSIS OF BODY PART SUPPLIED BY MOTOR NEURON • 2 MAIN FXN OF THE SPINAL CORD: 1. COORDINATING CENTER – REFLEXES (MOST, LIKE KNEE JERK) 2. CONNECTS PNS TO BRAIN Cross Section of the Spinal Cord Section 35-3 Gray matter Spinal nerve Central canal White matter Meninges Figure 35-9 The Brain 2. BRAIN (MENINGES, CSF) - 4 VENTRICLES (FLUID CIRCULATES W/IN CAVITIES) - 12 PRS. CRANIAL NERVES - 2 LARGE HEMISPHERES (LONGITUTINAL HALVES) - 3 REGIONS (FORE-, MID-, & HINDBRAIN) Cerebrum Thalamus Pineal gland Hypothalamus Cerebellum Pituitary gland Pons Medulla oblongata Spinal cord STRUCTURAL DIVISIONS OF HUMAN BRAIN 1. HINDBRAIN A. MEDULLA OBLONGATA (BRAINSTEM) • ESSENTIAL TO LIFE (VITAL CENTER) • BREATHING RATE (VAGUS & PHRENIC NERVES) • HEART RATE • BLOOD PRESSURE • SWALLOWING, VOMITING, COUGHING CENTER B. CEREBELLUM • “LITTLE BRAIN”- LARGEST SEGMENT OF HINDBRAIN • CENTER FOR BALANCE & COORDINATION • COORDINATES MUSCLE ACTIVITY • COORDINATES IMPULSES FROM EYES & SEMICIRCULAR CANALS TO MAINTAIN BALANCE (EQUILIBRIUM) C. PONS (“BRIDGE”) • CARRIES IMPULSES FROM ONE SIDE OF CEREBELLUM TO THE OTHER • COORDINATES LEFT SIDE OF BRAIN WITH RIGHT 2. MIDBRAIN • BETWEEN CEREBELLUM AND PONS – SLIGHTLY ABOVE • CONTROLS SENSORY PROCRESSES 3. FOREBRAIN a.HYPOTHALAMUS (HOMEOSTATIC CENTER) REGULATES: • BODY TEMP • WATER BALANCE • FOOD INTAKE • GASTRIC SECRETION • ANTERIOR PITUITARY GLAND WITH RELEASING HORMONES b. PITUITARY (HYPOPHESIS) • ENDOCRINE GLAND THAT SECRETES HORMONES THAT MAINTAIN HOMEOSTASIS • HAS ANTERIOR & POSTERIOR LOBES ) C. THALAMUS • RELAY CENTER B/W BRAINSTEM & CEREBRUM (B/T SENSE ORGANS & CEREBRUM • REGULATES STATES OF SLEEP AND WAKEFULNESS D. CEREBRUM • SETS MAN APART FROM OTHER VERTEBRATES! • LEARNING, REASONING, MEMORY, JUDGEMENT • SPEECH: 1. BROCA’S AREA – MOTOR 2. WERNICKE’S AREA – COMPREHENSION OF SPOKEN OR WRITTEN LANGUAGE • LEFT BRAIN: SPEECH, LOGIC, WRITING, MATH • RIGHT BRAIN: DISCRIMINATION OF SHAPE & FORM E. CORPUS CALLOSUM CONNECTS RIGHT & LEFT CEREBRAL HEMISPHERES Concept Map Section 35-3 The Nervous System is divided into Central nervous system Peripheral nervous system Motor nerves which consists of that make up Somatic nervous system Autonomic nervous system which is divided into Sympathetic nervous system Parasympathetic nervous system Sensory nerves AUTONOMIC NERVOUS SYSTEM • CHECK & BALANCE SYSTEM THAT MAINTAINS HOMEOSTASIS (ANTAGONISTIC TO ONE ANOTHER) • 2 DIVISIONS: 1. SYMPATHETIC 2. PARASYMPATHETIC • FIGHT-FLIGHT RXN: NERVOUS CONTROL EVOKES THESE RXN’S RAPIDLY IN TIMES OF DANGER/STRESS. HORMONES PROVIDE A BACKUP THAT CAN MAINTAIN A RESPONSE FOR A LONGER PERIOD. AUTONOMIC NERVOUS SYSTEM REFLEX ARC REFLEX ARC