Shared Flashcard Set

Details

Chapter 11
The Nervous System and Nervous Tissue
102
Anatomy
Undergraduate 2
11/02/2011

Additional Anatomy Flashcards

 


 

Cards

Term
Nervous System Basics
Definition
Master controlling and communicating system of the body.
Term
Functions of the Nervous System
Definition
Sensory input - monitoring stimuli
Integration - interpretation of sensory input
Motor output - response to stimuli
Term
Organization of the Nervous System
Definition
CNS - Central Nervous System
PNS - Perepiheral nervous system
Term
Central Nervous System
Definition
Brain and spinal cord, integration and command center
Term
Peripheral nervous system
Definition
Paired spinal and cranial nerves. Carries messages to and from the spinal cord and brain
Term
PNS Functional Divisions
Definition
Sensory (afferent) and Motor (efferent)
Term
Sensory (afferent) division of the PNS
Definition
Sensory afferent fibers, carry impulses from skin, skeletal muscles, and joints to the brain. Visceral afferent fibers - transmit impulses from visceral organs to the brain
Term
Motor (efferent) division
Definition
Transmits impulses from the CNS to effector organs
Term
Motor Division: Two main parts
Definition
Somatic nervous system, Autonomic nervous system
Term
Somatic nervous system
Definition
Conscious control of skeletal muscles
Term
Autonomic nervous system (ANS)
Definition
Regulates smooth muscle, cardiac muscle, and glands.
Term
Divisions of the Autonomic Nervous System (ANS)
Definition
Sympathetic and parasympathetic
Term
Histology of nerve tissue
Definition
Two principal cell types: Neurons, supporting cells
Term
Neurons
Definition
Excitable cells that transmit electrical signals
Term
Supporting cells
Definition
Cells that surround and wrap neurons
Term
Supporting cells: Neuroglia
Definition
Provide a supportive scaffolding for neurons. Segregate and insulate neurons. Guide young neurons to the proper connections. Promote health and growth
Term
Astrocytes
Definition
Most abundant, versatile, and highly branched glial cells. Cling to neurons and their synaptic endings, and cover capillaries
Term
Astrocytes: Functions
Definition
Support and brace neurons. Anchor neurons to their nutrient supplies. Guide migration of young neurons. Participate in information processing in the brain. Control the chemical environment.
Term
Microglia
Definition
Small, ovoid cells with spiny processes. Migrate toward injured neurons. Phagocytize microorganisms and neuronal debris
Term
Ependymal cells
Definition
Range in shape from squamous to columnar. They line the central cavities of the brain and spinal column. Separate the CNS interstitial fluid from the cerebrospinal fluid in the cavities
Term
Oligodendroctyes
Definition
branched cells that wrap CNS nerve fibers
Term
Schwann cells (neurolemmocytes)
Definition
surround fibers of the PNS. Vital to regeneration of damaged peripheral nerve fibers
Term
Satellite cells
Definition
Surround neuron cell bodies with ganglia
Term
Neurons
Definition
Structural units of the nervous system
Term
Characteristics of neurons
Definition
Composed of a body, axon, and dendrites. Long-lived (up to 100 years), amitotic, and have a high metabolic rate dependent on continuous supply of oxygen and glucose
Term
Neuron plasma membrane functions in
Definition
Electrical signaling. Cell-to-cell signaling during development
Term
Nerve Cell Body (Perikaryon or Soma)
Definition
Contain the nucleus and a nucleolus. Major biosynthetic center. IS the focal point for the outgrowth of neuronal processes. Has well-developed Nissl bodies (rough ER). Contains an axon hillock - cone shaped area from which axons arise
Term
Axon hillock
Definition
Cone shaped area from which axons arise
Term
Processes of the Soma
Definition
Armlike extensions. Called tracts in the CNS nerves in the PNS.
Term
Two types of soma processes
Definition
Axons and dendrites
Term
Dendrites of Motor Neurons: Summary
Definition
Short, tapering and diffusely branched processes. THey are the receptive, or input, regions of the neuron. Electrical signals are conveyed as graded potentials (not action potentials)
Term
Axons: Structure
Definition
Slender processes of uniform diameter arising from the hillock. Long axons are called nerve fibers. Usually there is only one unbranched axon per neuron. Rare branches, if present, are called axon collaterals.
Term
Axonal terminal
Definition
Branched terminus of an axon
Term
Axonal terminal
Definition
Branched terminus of an axon
Term
Axon: function
Definition
Generate and transmit action potentials. Secrete neurotransmitters from the axonal terminals. Movements along axons occurs in two ways
Term
Way movement along axons occurs:
Definition
Anterograde: Toward axonal terminal
Retrograde: Away from axonal terminal
Term
Myelin Sheath:
Definition
Whitish, fatty (protein-lipoid), segmented sheath around most long axons
Term
Myelin Sheath: Function
Definition
Protect the axon, Electrically insulate fibers from on another. Increase the speed of nerve impulse transmission
Term
Myelin Sheath and Neurilemma: Formation
Definition
Formed by Schwann cells in the PNS.
Term
Myelin Sheath Formation: Schwann Cell
Definition
Envelopes an axon in a trough. Enclose the axon with its plasma membrane. Has concentric layers of membrane that make up myelin sheath.
Term
Neurilemma
Definition
remaining nucleus and cytoplasm of a Schwann cell
Term
Nodes of Ranvier (Neurofibral Nodes)
Definition
Gaps in the myelin sheath between adjacent Schwann cells. They are the sites where axon collaterals can emerge
Term
Unmyelinated Axons
Definition
Schwann cell surrounds nerve fibers but coiling does not take place. Schwann cells partially enclose 15 or more axons
Term
Axons of the CNS
Definition
Both myelinated and unmyelinated fibers are present. Myelin sheaths are formed by oligodendrocytes. Nodes of Ranvier are widely spaced. There is no neurilemma
Term
Brain and Spinal Cord
Definition
White Matter, Gray Matter
Term
White Matter
Definition
Dense collections of myelinated fibers
Term
Gray matter
Definition
mostly soma and unmyelinated fibers
Term
Neuron Classification: Structural
Definition
Multipolar - three or more processes
Bipolar - two processes (axon and dendrite)
Unipolar - single, short process
Term
Neuron Classification: Functional
Definition
Sensory (afferent) - transmits impulses toward the CNS
Motor (efferent) - carry impulses away from the CNS
Interneurons (association neurons) - shuttle signals through CNS pathways
Term
Changes in membrane potential: Depolarazition
Definition
A reduction in membrane potential (toward zero). Inside of the membrane becomes less negative than the resting potential. Increasing the probability of producing a nerve impulse
Term
Changes in Membrane Potential: Hyperpolarization
Definition
An increase in membrane potential (away from zero). Inside of the membrane becomes more negative than the resting potential. Reduces the probability of producing a nerve impulse
Term
Grade potentials
Definition
Found in dendrites. Decrease over distance. Magnitude varies with stimulus. Small area of membrane becomes depolarized: Positive ions in the area move toward negative ions and signal "spreads"; there is not consistent "passing" of ions in and out of cell
Term
Action Potential: Basics
Definition
Brief reversal of membrane potential with a total amplitude of about 100 mV. Occurs in muscle cells and axons of neurons. Does not decrease in magnitude over distance. Principal means of long-distance neural communication
Term
Action Potential Creation: States
Definition
Resting, Depolarization, Threshold, Repolarization, Hyperpolarization
Term
Action Potential Creation: Resting state
Definition
Sodium and potassium channels closed
Term
Action Potential Creation: Depolarization
Definition
Sodium channels open causing a cascade effect opening more sodium channels
Term
Action Potential Creation: Threshold
Definition
Critical level where sodium channel cascade drives membrane potential postive (+30mV). 1ms - AP created
Term
Action Potential Creation: Repolarization
Definition
Sodium gates close and potassium gates open - potassium leaves the cell
Term
Action Potential Creation: Hyperpolarization
Definition
"Undershoot' - So much potassium leaves the cells that it is more negative than at rest
Term
Conduction velocities of axons
Definition
Conduction velocities vary widely among neurons
Term
Rate of impulse propagation is determined by
Definition
Axon diameter, presence of a myelin sheath
Term
Conduction Velocities of Axons - Axon diameter function
Definition
The larger the diameter, the faster the impulse
Term
Conduction Velocities of Axons - Presence of a myelin sheath
Definition
Myelination dramatically increases impulse speed
Term
Saltatory Conduction
Definition
Current passes through a myelinated axon only at the nodes of Ranvier. Voltage-gated Na+ channels are concentrated at these nodes. Myelin sheaths insulate and prevent leakage of charge. Saltatory conduction in myelinated axons is about 30 times faster. Action potentials are triggered only at the nodes and jump from one node to the next. Much faster that conduction along unyelinated axons
Term
AP in a bare plasma membrane without voltage gated channels
Definition
As on a dendrite, voltage decays because current leaks across the membrane.
Term
AP movement through an unmyelinated axon
Definition
Voltage-gated Na+ and K+ channels regenerate the action potential at each point along the axon, so voltage does not decay. Conduction is slow because movements of ions and of the gates of the channel proteins take time and must occur before voltage regeneration occurs
Term
AP movement through a myelinated axon
Definition
Myelin keeps current in axons, voltage doesn't decay much, APs are generated only in the nodes of Ranvier and appear to jump rapidly from node to node
Term
Types of Synapses
Definition
Axodendritic, Axosomatic, Axoaxonic, Dendrodendritic, Dendrosomatic
Term
Types of Synapses - Axodendritic
Definition
synapses between the axon of one neuron and the dendrite of another
Term
Types of Synapses - Axosomatic
Definition
synapses between the axon of one neuron and the soma of another
Term
Electrical synapses
Definition
Less common than chemical synapses. Correspond to gap junctions found in other cell types - connexins - electrically coupled. Important in the CNS. Synchrony
Term
Electrical Synapses: Importance in the CNS
Definition
Arousal from sleep, mental attention,k emotions and memory
Term
Electrical Synapses: Synchrony
Definition
all neurons in the area are interconnected and working together
Term
Chemical Synapses
Definition
Specialized for the release and reception of neurotransmitters. Typically composed of two parts:
Axonal terminal of the presynaptic neuron, which contains synaptic vesicles
Receptor region on the dendrite(s) or soma of the postsynaptic neuron
Term
Synaptic Cleft: What is it?
Definition
Fluid filled spaced separating the presynaptic and post synaptic neurons.
Term
Synaptic Cleft function
Definition
Prevents nerve impulses from directly passing from one neuron to the next
Term
Synaptic Cleft: Transmission
Definition
Chemical event, not electrical. Ensure unidirectional commnunication between neurons
Term
Synaptic Cleft: Information Transfer Step 1
Definition
Nerve impulses reach the axonal terminal of the presynaptic neuron and open Ca2+ channels
Term
Synaptic Cleft: Information Transfer Step 2
Definition
Neurotransmitter is released into the synaptic cleft via exocytosis in response to synaptotagmin
Term
Synaptic Cleft: Information Transfer Step 3
Definition
Neurotransmitter crosses the synaptic cleft and binds to receptors on the postsynaptic neuron
Term
Synaptic Cleft: Information Transfer Step 4
Definition
Postsynaptic membrane permeability changes, causing an excitatory or inhibitory effect
Term
G Protein-Linked Receptors: Mechanism
Definition
Responses are indirect, slow, complex, and often prolonged and wide spread. Second messengers open or close ion channels, active kinase enzymes, phoporylate channel proteins, activate genes and induce protein synthesis
Term
Termination of Neurotransmitter effects:
Definition
Neurotransmitter bound to a postsynaptic neuron:
Produces a continuous postsynaptic effect
Blocks reception of additoinal "messages"
Must be removed from its receptor
Term
Termination of Neurotransmitter effects: Removal of neurotransmitters
Definition
Occurs when they are degraded by enzymes, are reabsorbed by astrocytes or the presynaptic terminals, diffuse from the synaptic cleft
Term
Synaptic Delay
Definition
Neurotransmitter must be released, diffuse across the synapse, and bind to receptors. Time to do this (.3-5 ms). Rate-limiting step of neural transmission
Term
Neurotransmitters: What are they?
Definition
Chemical used for neuronal communication with the body and the brain. 50 different have been identified. Classified chemically and functionally.
Term
Acetylcholine
Definition
First neurotransmitter identified and best understood. Released at neuromuscular junction. Synthesized and enclosed in synaptic vesicles. Degraded by the enzyme acetylcholinesterace. Released by All neurons that stimulate skeletal muscle. Some neurons in the autonomic nervous system
Term
Neurotransmitters: Biogenic Amines
Definition
Catecholamines, Indolamines. Broadly distributed in the brain. Play roles in emotional behaviors and our biological clock
Term
Neurotransmitters: Catecholamines
Definition
dopamine, norepinephrine, epinephrine
Term
Neurotransmitters: Indolamines
Definition
serotonin and histamine
Term
Neurotransmitters: Amino acids
Definition
GABA (gamma-aminobutyric acid)
Glycine
Aspartate
Glutamate
Found only in the CNS
Term
Neurotransmitters: Peptides
Definition
Substance P - mediator of pain signals
Beta endorphin, dynorphin, and enkephalins
Act as natural opiates, reduce pain perception
Bind to the same receptors as opiates and morphine
Term
Neurotransmitters: Novel Messengers
Definition
ATP, Nitric Oxide
Term
Neurotransmitters: Novel Messengers - ATP
Definition
Found in the CNS and PNS
Produces excitatory or inhibitory responses depending on receptor type
Induces Ca2+ wave propagation in astrocytes
Provokes pain sensation
Term
Neurotransmitters: Nitric Oxide (NO)
Definition
Involved in learning and memory. Carbon monoxide is a main regulator of cGMP in the brain
Term
Functional Classification of Neurotransmitters
Definition
Excitatory and Inhibitory
Term
Functional Classification of Neurotransmitters: Excitatory
Definition
Causes depolarizations
Term
Functional Classification of Neurotransmitters: Inhibitory
Definition
Cause hyperpolarizations
Term
Functional Classification of Neurotransmitters: Acting as both
Definition
Effects determined by the receptor rype of the postsynaptic neuron. ex: acetylcholine
Excitatory at neuromuscular junctions with skeletal muscle
Inhibitory in cardiac muscle
Term
Neurotransmitter Receptor Mechanisms
Definition
Direct, Indirect
Term
Neurotransmitter Receptor Mechanisms: Direct
Definition
Neurotransmitters that open ion channels. Promote rapid responses. eg, ACh and amino acids
Term
Neurotransmitter Receptor Mechanisms: Indirect
Definition
Neurotransmitters that act through second messengers. Promote long lasting effects. eg, biogenic amines, peptides, and dissolved gases
Supporting users have an ad free experience!