NERVOUS SYSTEM
Monitor changes External / internal Integrate input Primary Functions Process, interpret, make decisions, store information Initiate a response E.g., movement, hormone release, stimulate/inhibit organ function, etc. 2
NERVOUS SYSTEM 3
Neuron Cells of the Nervous System Primary functional cell of the nervous system Receive & relay information Neuroglial cells Support neurons 4
General Neuron Structure 5
Myelin sheath General Neuron Structure Speeds rate of impulse transmission 6
Functional classes Types of Neurons Sensory neurons Bring information TOWARD the brain or spinal cord Interneurons Pass information BETWEEN two neurons Motor neurons Send information AWAY from brain or spinal cord 7
Nerves Bundles of axons 8
Quick Quiz: A neuron receives input from other neurons, other cells, or the environment mostly at its. A) Axon B) Axon ending (axon terminus) C) Cell body (soma) D) Dendrites 9
Quick Quiz: The purpose of a myelin sheath around an axon is to A) Speed up transmission of signals. B) Slow down transmission of signals. C) Send multiple copies of signals. D) Prevent transmission of signals. 10
Electricity basics Nerve Impulses Voltage (V, V= volts) driving force Current (I, A=amperes) flow of charged particles Resistance (R, W=ohms) Impedence to current flow 11
Nerve Impulses 12
Nerve Impulses Electrical potential (voltage) created by ion concentration gradients across the plasma membrane Sodium (Na + ) At rest, highest concentration OUTSIDE membrane Potassium (K + ) At rest, highest concentration INSIDE membrane Na-K ion pump 13
Nerve Impulses Ion flow (current) across the membrane dependent on ion channels and pumps Na + /K + ion pump (builds concentration gradients) Leak channels (Na + leaks IN, K + leaks OUT) Voltage-gated channels Open/close in response to changes in voltage across membrane 14
Nerve Impulses Like the ideal toilet Threshold stimulus All or nothing response Refractory ( reset ) period 15
Transmitting a Nerve Impulse Membrane at rest (resting potential) All voltage-gated channels CLOSED Membrane polarized 16
Transmitting a Nerve Impulse Stimulus initiates impulse (action potential) to reach threshold Voltage-gated Na + channels open Na + rushes IN Membrane potential reversed (depolarized) 17
Transmitting a Nerve Impulse Membrane potential reset (repolarization) Voltage-gated Na + channels INACTIVATED Voltage-gated K + channels OPEN K + rushes OUT 18
Transmitting a Nerve Impulse Return to resting state Ions redistributed to original original locations Na + /K + ion pump Na + & K + channels closed 19
Neuron / Action Potential Review Threshold stimulus pushing the handle 20
Neuron / Action Potential Review All or nothing (action potential) bowl is draining 21
Neuron / Action Potential Review Refractory period (reset) tank is refilling 22
Quick Quiz: A nerve impulse (action potential) requires all of the following EXCEPT: A) Sodium-potassium pump B) Potassium leak channels C) Voltage-gated sodium channels D) Calcium channels 23
Transfer of Stimulus axon of a motor neuron muscle fiber axon terminal 24
Synaptic cleft Transfer of Stimulus Electrical signal converted to chemical signal Neurotransmitter Activate ion channels on effector cell membrane Changes membrane potential of effector synapse_function 25
Quick Quiz: In order to cross a synapse, an electrical signal in the first neuron must A) be converted into light energy B) be converted into a chemical signal C) be amplified D) Be reduced 26
Organization of the Nervous System Nerve net Simplest nervous system E.g., cnidarians Loose mesh of nerve cells Associated with epithelial tissue Reflex pathways (stimulus response) 27
Organization of the Nervous System Bilateral nervous systems Ganglia Localized cluster of nerve cell bodies Coordinate & integrate sensory & motor signals Brain Larger or master integration center 28
Quick Quiz: True or false: Simple animals cannot respond to their environment because they do not have brains A) True B) False 29
Vertebrate Nervous System Organization Functional divisions Central nervous system Brain & spinal cord 30
Vertebrate Nervous System Organization Functional divisions Peripheral nervous system Efferent division Motor (output) Afferent division Sensory (input) 31
Vertebrate Nervous System Organization Functional divisions Peripheral nervous system - Efferent Somatic division Voluntary Motor activity Autonomic division Automatic Visceral function 32
Vertebrate Nervous System Organization Functional divisions Autonomic division Sympathetic nerves Fight or flight 4-E s Parasympathetic nerves Rest & digest 3-D s 33
Quick Quiz: The autonomic nervous system is part of the A) Central nervous system B) Somatic nervous system C) Afferent nervous system (sensory) D) Efferent nervous system (motor) 34
Central Nervous System (CNS) The vertebrate brain 3 primary divisions Hindbrain Reflex centers, sensory integration, coordinated movement, sleep/wake cycles Midbrain Coordination of reflex responses to external stimuli Forebrain Higher brain functions (memory, learning, critical thinking) 35
Hindbrain Pons Autonomic reflex centers Medulla oblongata Autonomic reflex centers Cerebellum Coordinated movement Human Brain 36
Midbrain Relay center Other vertebrates Birds, reptiles, fish Well developed optic lobes Part of brain stem Human Brain Midbrain, pons, medulla 37
Forebrain Diencephalon Thalamus Human Brain Directs sensory input to cerebrum switchboard Hypothalamus Visceral control center Cerebrum Association, learning, memory, speech, vision, hearing, personality, etc. 38
Quick Quiz: The hypothalamus is part of the A) Cerebrum B) Diencephalon C) Brainstem D) Cerebellum 39
Cerebral hemispheres 83% of total brain mass Ridges = gyri Grooves = sulci Connected by nerve tracts Corpus callosum Cerebrum 40
Cerebral Cortex Functional divisions Frontal lobes Reasoning, personality, learned repetitive functions, somatic output Parietal lobes Sensory Temporal lobes Hearing, speech Occipital lobes Vision Localization of motor, sensory & association areas of the brain 41
Motor & Sensory Cortex Primary somatosensory cortex Neurons controlling sensory input from somatic areas Primary motor cortex Neurons controlling motor output Contralateralization 42
Limbic System Emotional brain Associations with emotions & organs 43
Vertebral foramen Meninges Ganglia Spinal Cord 44
Spinal Cord Organization of gray & white matter dorsal ventral 45
Quick Quiz: True or False: The spinal cord is part of the central nervous system A) True B) False 46
Spinal Reflexes 47
Peripheral Nervous System 12 pr cranial nerves 31 pr spinal nerves All carry both autonomic and somatic signals 48
Fight or flight Nerves exit from thoracic & lumbar areas Sympathetic Division 49
Rest & digest Parasympathetic Division Nerves exit from cranial & sacral areas 50
A) True Quick Quiz: True or False: The sympathetic nerves exit the spinal cord in the thoracic and lumbar regions. B) False 51