BSC 109 Exam 3 Study Guide This study guide is to aid you in studying the course material for the exam The study guide does not replace lecture material or reading the text The topics listed below is a non exhaustive list of the core concepts in each chapter All material presented in lecture and the text is fair game for the exam Nervous System Name and describe the two principal parts of the nervous system Central Nervous System CNS Brain and Spinal Cord Functions receives processes and transfers information Anatomy is for protection Bone skull and vertebrae Meninges protective membranes Cerebrospinal fluid bathes the brain spinal cord Blood brain barrier prevents entry of certain chemicals and pathogens major defense against viruses and bacteria Spinal Cord Superhighway for action potentials between the brain and the rest of the body White matter outer portion of spinal cord consists of myelinated ascending sensory and descending motor nerve tracts basically axons Gray Matter center portion of spinal cord contains cell bodies dendrites Peripheral Nervous System PNS Nerves outside the CNS Sensory Division input carries info toward the CNS Motor Division output carries info away from the CNS Somatic Division Controls Skeletal Muscles Voluntary conscious control of skeletal muscles Involuntary reflexes Spinal Reflexes Involuntary responses mediated primarily by spinal cord and spinal nerves with little brain involvement Flexor reflexes Crossed extensor reflex Stretch reflex important in maintaining upright posture Autonomic Division Controls Autonomic Body Functions Part of the motor output of the PNS Controls automatic body functions of many internal organs Consists of two divisions Sympathetic Parasympathetic Both sympathetic motor neurons and parasympathetic neurons enervate each Targets smooth muscles cardiac muscle internal organs involuntary Nerve contains axons of many neurons wrapped together in a protective sheath carries info to and from the CNS Cranial nerves connect directly to brain Spinal nerves connect to spinal cord Describe the anatomy of neurons and the specific functions of each major part of the nerve cell Nervous Tissue made up of 2 types of cells Neurons are nerve cells specialized for carrying electrical signals from one part of the body to organ another Neurons CNS organelles cell body Glial Cells support neurons and modify neuronal communication Neurons are specialized cells for communication Generate and conduct electrical impulses Types of Neurons Sensory Neurons neurons found in the PNS that receive stimuli and transmit info to the Interneurons transmit info between components of the CNS Motor Neurons neurons found in the PNS that transmit info away from the CNS Cell Body main part of the cell has the nucleus and most of the cytoplasm and Parts of the Neuron Dendrites small slender extensions of the cell body receive incoming information Axon long slender extension specialized to conduct electrical impulses away from the An axon ends in a cluster of branches each with a bulb like synaptic terminal that relays signals to another neuron or an effector across a synapse Postsynaptic Neurons Integrate and Process Info Response to postsynaptic cell depends on How many neurons are forming synapses with it and whether the neurons forming synapses with it are excitatory or inhibitory Convergence occurs when one neuron receives input from many others Divergence occurs when one neuron sends action potential to multiple other neurons Describe a resting membrane potential and indicate how it is maintained in a neuron that is not actively generating an action potential Which Ions are used to generate the gradient Action Potential Neurons generate and transmit action potentials An action potential is basically an electrical impulse Primary means of communication throughout the nervous system All or none Individual neuron threshold sets extent of stimulus needed If threshold is achieved it triggers Once triggered an action potential is always the same in speed and voltage Self propagating Continues to propagate itself in the next region of the axon Moves like a wave down the axon with constant speed and amplitude The number of action potentials unit time encodes the strength of the stimulus Stronger stimuli generate more action potential unit time Speed of action potential Always the same for a particular neuron Can be different in different neurons In larger diameter axons action potentials travel at greater speed Resting Membrane Potential permeability to each type of ion Determined by concentration gradients of ions across the membrane and by membrane Sodium Potassium Pump maintains resting potential the exclusion of NA from the cell creates a voltage difference at about 70mV NA and K are the ions that participate Identify the neuroglial cell types that myelinate neurons and indicate whether each cell type would be found in the CNS or the PNS Neuroglial Cells Neuroglial cells make up 80 of nerve cells Function support protect do NOT transmit action potentials Three Types of Neuroglial Cells Schwann Cells Wrap axons as insulation in PNS form myelin sheath in PNS role of myelin sheath save the neuron energy wraps around neuron like insulation and carries nerve impulses faster Saltatory conduction leaping pattern of action potential conduction Oligodendrocytes Wrap axons as insulation in CNS form myelin sheaths in CNS Astrocytes Provide nutrients for neurons in brain CNS Acts as a butler for brain neurons Performs maintenance functions for nearby neurons Interact with the blood so the neurons do not reuptake and recycles neurotransmitters and electrolytes regulates glucose and blood supply coordinates with immune cells They are a buffer between the blood and neurons as an added layer of security for the brain neurons List several neurotransmitters and indicate the site in an axon where they are released Information is transferred from a neuron to its target using neurotransmitters Targets another neuron muscle cell or gland Synapse special junction between axon terminus and target cell Synaptic transmission process of transmission of impulse from sending presynaptic neuron across synaptic cleft to receiving postsynaptic target involves release and diffusion of chemical neurotransmitter Process of Synaptic Transmission 1 Action potential arrives at axon terminus causing Ca2 to diffuse into axon bulb 2 Ca2 causes release of neurotransmitter from vesicles 3