Exam II Study Guide Dr Figueroa PET3322 Exam II Study Guide Nervous system o Sensory input o Integration o Motor Output monitors changes stimuli inside and outside of body sense interpretation of sensory input decides what to do thought o Example response to stimuli change by activating effector organs movement motion contracting of muscle driving and see a red light ahead sensory input your nervous system integrates this information red light means stop and your foot goes for the brake motor output o Central brain and spinal cord ONLY If not central then peripheral o Peripheral all other nerves outside of brain spinal cord Sensory Motor Autonomic in detail on 3rd exam ANS independent of brain Ex myocardium Peripheral Nervous System o Sensory afferent outside source to brain Transmit sensations PNS CNS afferent carrying toward outside senses to brain Somatic Fibers impulses from skin muscles joints brain Visceral Fibers impulses from visceral brain If motor neuron is innervating my skeletal muscle somatic o Motor Division efferent brain to outside efferent carrying away brain to outside CNS PNS To skeletal muscle produces an EFFect Somatic Nervous System somatic nerve fibers conduct impulses from CNS to muscle voluntary sensory enters horns posterior leaves spinal cord anterior Autonomic Nervous System regulates impulses from CNS to smooth muscle cardiac muscle and glands involuntary ANS not in too much detail for exam II yes for exam III Sympathetic Parasympathetic o mobilizes body systems during activity helps deal w stress o more important bc it controls more organs and tissues and the PNS o conserves energy promotes house keeping functions during rest helps relax body o para works together parallel don t need to know spinal regions cervical lumbar etc Histology of Nerve Tissue o don t need to know about supporting cells o Neurons Nerve Cells cells of the NS o function transmit signals Exam II Study Guide Dr Figueroa PET3322 o composed of a body axon and dendrites Membrane potential is negative in all axons 60 more excitable than 100 cell Axon hillock where soma and axon connect Receptors located in the dendrites where signals are received NT binds receptors to stimulate the The Action Potential o cells stimulated activated by NT or hormones binding to receptors Resting Membrane Potential the electrical charge o Measured inside the cell o channels closed outside inside 1 Depolarization de lose polarization charge o Negative to positive o Na responsible entering cell o Na enters increases charge becomes less negative and more positive Starts bc Na channel opens ends bc Na channel closes when closes K channel opens Na outside into cell 2 Repolarization regain normal polarity o positive to negative o K opens due to positivity Na moves out of cell charge gets too positive so it goes back to its resting negative value K responsible inside outside of cell Starts w open on K channels open immediately after Na close K goes out of cell back to normal negativity 3 Hyperpolarization more negative than resting membrane potential 70 to 75 mV last part of repolarization To get here either add or remove 1 Resting state No ions move through channels closed 2 Depolarization is caused by Na flowing into the cell 3 Repolarization is caused by K moving out of the cell 4 Hyperpolarization is caused K continuing to leave the cell Exam II Study Guide Dr Figueroa PET3322 Ionic Events 1 Sodium channels open via NT 2 More sodium channels open due to charge 3 Sodium channels close 4 Potassium channels open 5 Potassium channels close Axons of the Central Nervous System o Tracts axons of different neurons that tend to travel in bundles in CNS o Nerves PNS no nerves in the CNS Myelin Sheath axons fast Structure whitish fatty protein lipoid formed by Schwann cells segmented sheath around most long Function protects insulates fibers axon increases speed of impulses AP fast Unmyelinated Axons conduct impulses slowly dendrites are always unmyelinated myelinated 1 The anterior ventral horn cell 2 The peripheral nerve ventral and dorsal nerve roots 3 The neuromuscular junction 4 The muscle Exam II Study Guide Dr Figueroa PET3322 Conduction Velocities of Axons o Rate of impulse determined by Axon diameter larger faster presence of sheath myelinated faster one neuron to another neuron junction that mediates information where the action is Synapses communicating o Presynaptic conducts impulses toward the synapse sender o Postsynaptic transmits impulses away from the synapse receiver o Synaptic Cleft separates the sending pre from the receiving post NT travel across here o Ca2 at axon terminal 1 AP arrives at axon terminal 2 depolarization opens ca2 channels ca2 floods into terminal 3 surge of ca2 terminal causes the NT full of synaptic vesicles to Fuse to the membrane and empty their contents into the synaptic cleft by exocytosis 4 NT diffuses across synaptic cleft and binds to receptors in the post Synaptic neuron o Neurotransmitter binding to postsynaptic neuron 1 produces a continuous postsynaptic effect 2 must be removed from its receptor o Removal of neurotransmitter 3 are degraded by enzymes enzyme cuts Ach 4 diffuse from synaptic cleft If not removed the AP would continue indefinitely Inhibitory Synapses Its effect Binding of NT at inhibitory synapses REDUCES postsynaptic neuron s ability to generate AP o produces hyperpolarization harder to reach AP by making membrane more permeable to K or Cl o makes it more negative by removing positive K or adding more neg Cl o Both cases make more negative making it harder to depolarize or stimulate K if K channels are opened K moves OUT of cell Cl If Cl channels are opened Cl moves INTO the cell o Central Nervous System Components Brain stem and Spinal Cord The Central Nervous System Cerebral Cortex o Motor Areas o Sensory Areas Voluntary movement activation of muscles inside outside FROM brain starts in motor cortex info from outside senses inside brings signal TO brain conscious awareness of sensation o Primary Motor Cortex allows conscious control of precise skilled voluntary movement Exam II Study Guide Dr Figueroa PET3322 Voluntary Movement controlled by motor cortex Motor Homunculus caricature of relative amounts of cortical tissue devoted to each motor function Cortex is darker bc dendrites and somas of motor neurons are there more mass Understand Proportion Concept more sensitive parts of body more area of sensory cortex needed to interpret messages larger
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