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72 Cards in this Set
- Front
- Back
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What are the 3 basic functions of the Nervous System?
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1. Sensory input= monitoring of stimuli
2. Integration= interpretation of the sensory input 3. Motor output= responding to stimuli |
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What are the two main sections of the nervous system?
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- Central Nervous System (CNS)
- Peripheral Nervous System (PNS) |
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What is the CNS comprised of, and what is the purpose of the CNS?
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- Brain and Spinal cord make up the central command center
- Interprets sensory input |
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What makes up the PNS, and what is its main purpose?
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- Comprised of spinal nerves paired with cranial nerves
- Carries messages to and from the brain and spinal cord |
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What are the two functional divisions of the nervous system?
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- Sensory division
- Motor division |
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Describe the Sensory division of the nervous system.
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- *Afferent*
- Transmits impulses from skin, muscles, and joints to the brain (afferent) using sensory afferent fibers - Transmits impulses from visceral organs to the brain (afferent) using visceral afferent fibers |
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Describe the Motor division of the nervous system.
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- *Efferent*
- transmits impulses from the central nervous system to the effector organs |
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what is the difference of Afferent vs. Efferent?
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- Afferent - Approach= the flow of stimuli from the skin, muscles, joints and organs to the CNS
- Efferent - Exit = this is the flow of stimuli away from the CNS its respective motor neuron |
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The motor division of the nervous system has two sections, what are they and what do they do?
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1. somatic nervous system= having conscience control of skeletal muscles
2. Autonomic nervous system= regulation of smooth and cardiac muscle as well as sensory glands. (fight or flight) |
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What are the six types of Glial cells? (E-M-O-A-S-S)
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- Ependymal
- Microglia - Oligodendrocytes - Astrocytes - Schwann Cells - Satellite Cells |
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What does Neuroglia mean?
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- this refers to the cells which support nerves
- Nerve Glue = Glial Cells |
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What are the five functions of glial cells?
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- Support
- Segregate - Insulate - Guide young neurons to their proper connection sites - Promote health and growth of nerves |
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Name the glial cell type:
- Small ovoid cells with spiny processes - these cells are phagocytes that monitor the health of neurons |
- Microglia cells
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Name the glial cell type:
- Most abundant and versatile glial cells - Highly branched, which aid in clinging to neurons at their synaptic endings and covering capillaries - These cells are used for support, to anchor neurons to their nutrition supply, guiding young neurons, and controlling the chemical environment |
- Astrocytes
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Name the glial cell type:
- cells range from squamous to columnar - comprise the lining of the central cavities within the brain and spinal cord |
- Ependymal cells
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Name the glial cell type:
- the branched cells which wrap around the CNS nerve fibers |
- Oligodendrocytes
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Name the glial cell type:
- surround the PNS nerve fibers - promote an increase in communication rate of neurons |
- schwann cells
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Name the glial cell type:
- surround neuron cell bodies with ganglia |
- satellite cells
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Label the image.
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1. Schwann cells
2. Neuron cell body 3. Satellite cells 4. Nerve fiber |
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What are the two cell divisions within nerves?
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1. Neurons: excitable cells that transmit electrical signals
2. Support cells: cells wrap and surround neurons |
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_____________ are the structural units of the nervous system. They are comprised of a soma, ____________, and ______________.
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- Neurons
- Comprised of soma (cell body), axon, and dendrites |
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Neurons are _______________, which means they do not go through mitosis.
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amitotic
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What are nissl bodies?
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- granular bodies found within the soma of a neuron, and are comprised of rough endoplasmic reticulum
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What are the two functions of the neuron plasma membrane?
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1. electrical signaling
2. cellular signaling during neuron development |
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____________ is the site where the axon attaches to the soma.
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hillock
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What are dendrites?
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- short tapered processes found on motor neurons, which act as the receptionist for the cell
- the electrical signaling is a graded potential (signal gets weaker as it gets further from its place of origin) |
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What are axon collaterals and where can they be found?
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- Branches that form off of the axon at the nodes of ranvier (gaps in the myelin sheath)
- these are rare |
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What is the function of an axon and what are the two ways in which action potential can travel on the axon?
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- the generation and transmission of electrical signals called the action potential
- action potential means that the signal produced doesn't fade away as it becomes further away from its place of origin - retrograde= signal moves away from axon terminal - Anterograde= signal moves towards axon terminal |
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What are processes called in the CNS? In the PNS?
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CNS = tracts
PNS= nerves |
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What is the myelin sheath?
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- a sheath produced by schwann cells that covers the axon and increases the speed of nerve impulses that travel along the axon.
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What is neurilemma? What is special about the axons seen in the CNS?
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-a schwann cell wraps around the nerve fiber, and has excess cytoplasm and nucleus which forms an outer layer around the myelin sheath.
- the myelin sheath of axons found in the CNS are formed by oligodendrocytes, there are no schwann cells present therefore neurilemma cannot exist in the CNS |
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What is white matter comprised of?
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- dense myelinated fibers
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What is gray matter comprised of?
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- cell bodies and unmyelinated fibers
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What are the three structural types of neurons?
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- Multipolar: three or more processes
- Bipolar: two processes - Unipolar: a single, short process |
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What are the three function classes of neurons?
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- Sensory (afferent)
- Motor (efferent) - Interneurons |
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What are interneurons?
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- shuttle signals through CNS pathways between sensory and motor neurons
- makes up the bulk of the spinal cord |
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What is the electrical current in the body?
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- reflects the flow of ions rather than electrons
- there is a Na+ gradient - the ion flow is regulated by the membrane |
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What are the four types of plasma membrane ion channels?
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-Passive= stay open
-Chemically gated= open upon binding of neurotransmitter -Voltage-gated= open and close in response to potential -Mechanically gated= open and close in response to the physical deformation of receptors |
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What are the three types of electrochemical gradients?
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-Chemical gradient= ions move from high concentration to low concentration
-Electrical gradient= ions move towards opposite charge -Electrochemical gradient= a combination of chemical and electrical gradients working together |
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What are the two reasons that cause ionic differences?
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-Differential permeability of the neurilemma to Na+ and K+
-Operation of the sodium-potassium pump |
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What are the three events which cause a change in membrane potential?
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-Depolarization= inside of membrane becomes less negative
-Repolarization= return to resting (-70mv) -Hyperpolarization= inside of membrane becomes more negative than the resting potential (relative refractory period) |
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Graded potentials vs. Action potentials?
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Graded= dendrites
-Short lived and only travel short distances -they decrease intensity as they become more distant -Stimulus s quickly dissipated due to leaky plasma membrane -Magnitude depends on the stimulus -Strong graded can initiate an action potential Action=nerve impulse on Axons -A brief reversal of membrane potential with a total amplitude of 100 mV -only generated by muscle cells and neurons -main type of neural communication |
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What is the action potentials' status at the resting state?
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- sodium and potassium channels are closed
-slight movement of ions due to leakage |
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How many voltage regulated gates does each Na+ channel have?
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two
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What is the action potentials' status during the depolarization phase?
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-the Na+ permeability increases and the potential reverses
-Na+ gates are opened and K+ gates are closed (Na+ moves freely and K+ doesn't) |
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What is the threshold?
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-55 to -50 mV
-Depolarization becomes self-generating |
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What is the action potentials' status during the repolarization phase?
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- Na+ gates close
-K+ gates open - the potassium ions are exiting the cell, restoring the cell potential back to resting |
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What is the action potentials' status during the hyperpolarization phase?
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-K+ gates stay open, pouring out an excessive amount of potassium
- This causes the cell potential to overshoot the resting potential and cause it to become more negative -The neuron is insensitive to stimulus at this time |
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Ionic redistribution (repolarization) is restored by _____________.
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Sodium-Potassium pump
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What is the "All-or-none" phenomenon?
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-Action potentials either happen completely or not at all
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What is the absolute refractory period?
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-Prevents the neuron from generating an action potential
-Ensures that each action potential is separate -Enforces one-way transmission of nerve impulses |
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What is the rate of impulse propagation determined by?
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- axon diameter (the larger the diameter, the faster the impulse)
- Presence of a myelin sheath (myelination dramatically increases impulse speed) |
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How does conduction happen over a myelinated axon?
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- Current passes through a myelinated axon only at the nodes of ranvier
- Voltage-gated Na+ channels are concentrated at these nodes - Action potentials are triggered only at the nodes and jump from one node to the next |
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What are the three classifications of nerve fibers?
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- Diameter
- Degree of myelination - speed of conduction |
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What are Synapses?
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- the junctions that mediate information transfer from one neurons
– to another neuron or to an effector cell -Presynaptic - conducts impulses toward the synapse - Postsynaptic - transmits impulses away from the synapse |
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What happens when a Neurotransmitter is bound to a postsynaptic receptor?
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–Produces a continuous postsynaptic effect
–Blocks reception of additional “messages” –Must be removed from its receptor |
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Removal of neurotransmitters occurs when they? (3)
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–are degraded by enzymes
–are reabsorbed by astrocytes or the presynaptic terminals –they diffuse from the synaptic cleft |
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Neurotransmitter receptors mediate changes in membrane potential according to what 2 factors?
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–The amount of neurotransmitter released
–The amount of time the neurotransmitter is bound to receptors |
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What are the two types of postsynaptic potentials?
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–EPSP – excitatory postsynaptic potentials
–IPSP – Inhibitory postsynaptic potentials |
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______________ are graded potentials (dendrites) that can initiate an action potential in an axon. They use only chemically gated channels and Na+ / K+ flow in opposite directions at the same time.
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EPSPs
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______________ membranes do not generate action potentials.
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postsynaptic
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Neurotransmitter binding to a receptor at _____________ synapses:
–Causes the membrane to become more permeable to potassium and chloride ions – leaves the charge on the inner surface negative –Reduces the postsynaptic neuron’s ability to produce an action potential |
inhibitory
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What are the 4 Chemical Neurotransmitters and the 3 messengers?
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-Acetylcholine (Ach)
-Biogenic amines -Amino acids -Peptides messengers: -ATP and dissolved gases of (NO and CO) |
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Amino Acids Neurotransmitters are only found ___________?
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in the CNS
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___________ are the mediators of pain signals.
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peptides
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The ______________ novel messenger is involved in learning and memory.
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Nitric oxide
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_________________ is a main regulator of cGMP in the brain.
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Carbon monoxide (CO)
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What are the two functional classifications of neurotransmitters?
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–Excitatory: neurotransmitters cause depolarizations
–Inhibitory: neurotransmitters cause hyperpolarizations |
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What are the two Neurotransmitter Receptor Mechanisms?
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-Direct: neurotransmitters that open ion channels and Promote rapid responses
-Indirect: neurotransmitters that act through second messengers and promote long-lasting effects |
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What are the three parts of simple neuronal pool?
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–Input fiber
–Discharge zone –Facilitated zone |
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What are the four types of Circuits in Neuronal Pools?
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-Divergent: one incoming fiber stimulates ever increasing number of fibers, often amplifying circuits -Convergent: opposite of divergent circuits, resulting in either strong stimulation or inhibition
–Reverberating: chain of neurons containing collateral synapses with previous neurons in the chain -Parallel after-discharge: incoming neurons stimulate several neurons in parallel arrays |
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What are the two patterns of Neural Processing?
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1.Serial Processing
–Input travels along one pathway to a specific destination –Works in an all or none manner –Example: spinal reflexes 2.Parallel Processing –Input travels along several pathways –Pathways are integrated in different CNS systems –One stimulus promotes numerous responses Example: a smell may remind one of the odor and associated experiences |
