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Nervous System Basic
Chapter 10 Hole's Human Anatomy and Physiology
| Question | Answer |
|---|---|
| What a Neuron's cell body contains. | granular cytoplasm mitochondria lysosomes a Golgi apparatus many microtubules |
| What extends into the axon and supports it? | a network of fine threads called neurofilaments |
| What is another term for Nissl bodies? | chromatophilic substance |
| What consists of rough endoplasmic reticulum and is scattered throughout the cytoplasm of a nerve cell? | Nissl bodies |
| What can be found in the cytoplasm of a nerve cell? | glycogens lipids pigments like melanin |
| Dendrites receive communication from where? | other neurons |
| In some neurons what other than dendrites receives communications? | the cell body |
| What can be found on some dendrites serving as a contact point for other neurons? | dendritic spines |
| Nerve cells receive input through the dendrites and send output impulses through the what? | axon |
| Neurons may have many dendrites but no more than one what? | axon |
| What is the name of the part of an axon which arises from the cell body? | axon hillock |
| What is found in the cytoplasm of an axon? | many mitochondria microtubules neurofibrils |
| What may branch off of an axon? | collaterals |
| At the end of an axon there may be many find extensions with a specialized ending. What is it called? | axon terminal |
| Close to the receptive surface of another cell the axon terminal ends in a what? | synaptic knob |
| The space between the synaptic knob and the surface of another cell body is called what? | synaptic cleft |
| In addition to conducting impulses, what does an axon convey and what is this process called? | biochemicals and organelles through axonal transport |
| What products are transported in the reverse direction up an axon back to the cell body? | old organelles and other cellular components |
| What is a bundle of axons in the PNS called? | nerves |
| What is a bundle of axons in the CNS called? | tracts |
| In the PNS what are the neuroglia called? | Schwann cells |
| Schwann cells encase the large axons of peripheral neurons in what? | lipid-rich sheaths |
| What are the lipid-rich layers of sheaths of Schwann cells composed of? | myelin |
| Myelin is composed of what? | many types of lipids and proteins |
| What parts of a Schwann cell remain outside the myelin sheath? | parts that contain most of the cytoplasm and the nuclei |
| What is the part of a Schwann cell outside the myelin sheath and surrounding it called? | neurilemma |
| What are the names of the narrow gaps in the myelin sheath between Schwann cells? | nodes of Ranvier |
| The smallest axons of PNS neurons are not coated in Schwann cells, instead they do what? | are partially or completely in a longitudinal groove of the Schwann cell |
| Which axons conduct impulses rapidly? | myelinated axons |
| Which axons conduct impulses more slowly? | unmyelinated axons |
| Where does the 'white matter' of the brain and spinal cord get its name? | myelinated axons |
| In the CNS which type of cell produces myelin? | oligodendrocytes |
| In the CNS what do the myelinated axons not have which Schwann cells do? | neurilemmae |
| Gray tissue of the nervous system indicates what? | unmyelinated tissue |
| Most neurons whose cell bodies lie within the brain or spinal cord are of what type? | multipolar neurons |
| Some multipolar neurons are in ganglia associated with what? | autonomic nervous system |
| What type of neuron is found in specialized parts of the eyes? | multipolar neurons and bipolar neurons |
| What is unique about a multipolar neuron? | has many processes arising from its cell body |
| What is unique about a bipolar neuron? | has 2 processes arising from either end - dendrite and axon |
| Where are bipolar neurons found? | specialized parts of the eyes, nose and ears |
| What is unique about a unipolar neuron? | has a single process extending from its cell body |
| Where are the cell bodies of most unipolar neurons found? | ganglia |
| In a unipolar neuron there are 2 branches which function as a single axon and do what? | peripheral process and central process |
| What do afferent sensory neurons do? | conduct impulses from peripheral body parts into the brain or spinal cord |
| Eyes, ears or touch receptors send signals to the brain or spinal cord through which nerve cells? | afferent neurons |
| Temperature or blood pressure receptors send information to the brain and spinal cord via which nerve cells? | afferent neurons |
| Most sensory neurons are what type of polar? | unipolar |
| The neurons which lie within the brain or spinal cord are of what kind? | interneurons |
| Which type of polar are the neurons within the brain or spinal cord? | multipolar |
| Multipolar neurons forms links with what? | neurons |
| Which neurons relay information from one part of the brain or spinal cord to another? | interneurons |
| Similar to the ganglia of the PNS, the specialized masses of nervous tissue formed by interneurons are called what? | nuclei |
| What are the multipolar neurons which conduct impulses out of the brain or spinal cord to the effectors? | efferent neurons |
| What is another name for efferent neurons? | motor neurons |
| The motor neurons controlling skeletal muscle contraction are under voluntary control are part of what? | somatic nervous system |
| The motor neurons of the autonomic nervous system controlling cardiac and smooth muscle contraction, and the secretions of glands are under what type of control? | involuntary |
| What are the functions of the neuroglial cells? | structure control guidance growth cleansing maintenance |
| Which types of neuroglial cells signal neurons to form and maintain synapses? | astrocytes and Schwann cells |
| Which neuroglial cells are commonly found between neurons and blood vessels to provide support and hold structures together? | astrocytes |
| Astrocytes aid metabolism of glucose, among others, and help regulate concentrations of important ion, like Potassium, where? | interstitial space of nervous tissue |
| Which neuroglial cells respond to brain injury and form special scar tissue filling in gaps of the CNS? | astrocytes |
| Which neuroglial cell plays a role in the blood-brain barrier? | astrocytes |
| What is the name of the link between astrocytes? | gap junctions |
| Which ion travels between the gap junctions of astrocytes? | calcium ions |
| What neuroglial cell is smaller than an astrocyte and has fewer processes, forming rows along axons and myelinating them? | oligodendrocytes |
| A single oligodendrocyte may myelinate many what? | axons |
| What is the smallest neuroglial cell? | microglia |
| Which type of neuroglial cell is scattered throughout the CNS to support neurons and phagocityze bacterial cells and cellular debris? | microglia |
| When do microglia proliferate? | inflammation from injury or disease |
| What are the cuboidal or columnar cells forming the inner lining of the central canal extending down through the spinal cord? | ependyma |
| Ependyma may have what structural feature? | cilia |
| Which cells form a one-cell-thick epithelial-like membrane covering the ventricles of the brain? | ependyma |
| What quality of the ependymal layer allows substances to diffuse freely between the interstitial fluid of the brain tissues and the fluid in the ventricles? | porous |
| Which neuroglial cells cover the specialized capillaries called choroid plexuses? | ependyma |
| What cell comprises over half the volume of the brain, outnumbering neurons 10 to 1? | neuroglia |
| When neuroglia malfunction what can happen? | tumor neurodegeneration disease |
| Which types of neuroglia are found in the PNS? | Schwann cells and satellite cells |
| Which types of neuroglia are found in the CNS? | astrocytes oligodendrocytes microglia ependyma |
| Which neuroglial cells of the PNS provides nutritional support and helps regulate the concentrations of ions around neuron cell bodies within ganglia? | satellite cells |
| Which type of cells facilitate the regeneration of injured PNS axons? | neuroglia macrophages |
| How many millimeters per day does a regenerating axon grow? | 4 |
| Why is regeneration of CNS cells unlikely? | there is no tube of sheath cells to guide its regrowth |
| Where does new neural tissue arise from? | neural stem cells |
| What type of cell gives rise to neurons or neuroglia? | neural progenitor cells |
| What charge are most cells on the inside? | negative |
| What is the normal charge of extracellular space? | positive |
| What is it when an area has a difference in charges? | polarity |
| What does it mean for a nerve cell to be "excitable"? | they can respond to stimuli by rapidly and dramatically changing their internal charge to positive |
| What is the charge inside of cell? | membrane potential |
| What is created when charges flow from one area to another? | electrical current |
| What is it called when a neuron is at rest or inactive at a charge of -70 mV? | resting membrane potential |
| Where do charges in cells arise from? | ions and proteins |
| Which type of ion cannot cross the cell membrane? | impermeant anions |
| What are the impermeant anions in a nerve cell? | large phosphate and sulfate anions |
| The first part of an action potential is the change from negative to a positive charge. What is this called? | depolarization |
| The additive effect of graded stimuli is called a what? | threshold stimulus |
| When the threshold stimulus has caused enough Na+ into the cell to change the potential from -70 mV to -55 mV which is the what? | threshold potential |
| What happens when the cell charge reaches the threshold potential? | voltage-gated sodium channels open at the trigger zone |
| What happens when the voltage gated sodium channels open? | the charge rises to +30 mV beginning an action potential |
| What change has occured inside the cell to achieve an action potential? | it has become positively charged |
| What occurs when an action potential has been achieved? | the neuron fires sending a signal along the axon |
| What is the second part of the action potential? | repolarization |
| When the channels which allow potassium to rush out of the nerve cell are opened, what part of the action potential are we at? | the second |
| What happens during repolarization? | the negative charge of the cell is re-established |
| What is the last step of the action potential? | hyperpolarization and return to original concentrations |
| What is the brief period in which an axon becomes unresponsive to another threshold stimulus? | refractory period |
| During the absolute refractory period the axon's voltage gated sodium channels are temporarily not responsive, so the axon cannot be what? | stimulated |
| What is the common number of impulses per second? | 100 |
| Where are most voltage gated channels in a neuron located? | axon |
| How does the nerve cell propagate an action potential along an axon without decreasing its amplitude? | multiple action potentials are triggered along the course of the axon |
| Where does an unmyelinated axon conduct its impulse? | entire surface |
| Myelin is composed of a high proportion of lipids and is therefore water-phobic, preventing what from happening? | almost all flow of ions through the membrane |
| Where the myelin sheath is interrupted in its electrical insulating properties, what occurs? | the axon membrane has channels for sodium and potassium ions that open during a threshold depolarization |
| What are the interruptions in the myelin sheath on an axon called? | nodes of Ranvier |
| Where do action potentials occur in an axon? | nodes of Ranvier |
| What type of impulse conduction appears to jump from node to node? | saltatory conduction |
| What dimension of an axon affects the speed of impulse conduction? | diameter |
| The greater the diameter of an axon the _________ the rate of impulse conduction. | greater |
| The neuron which is the sender - conducting the impulse to the synapse is the what? | presynaptic neuron |
| The neuron receiving the input at the synapse is the what? | postsynaptic neuron |
| The mechanism by which the impulse in the presynaptic neuron signals the postsynaptic cell is called what? | synaptic transmission |
| Synaptic transmission is a one way process carried out by what? | neurotransmitters |
| Once neurotransmitters bind to receptors on a postsynaptic cell the action is either _______ or _______? | excitatory or inhibitory |
| What do released neurotransmitter molecules diffuse across? | synaptic cleft |
| When neurotransmitters bind the receptors what happens? | ion channels in postsynaptic cells open |
| Ion channels that respond to neurotransmitter molecules are what? | chemically gated |
| Changes in chemically gated ion channels create what? | local synaptic potentials |
| What is the function of local synaptic potentials? | enable one neuron to affect another |
| Inhibitory neurotransmitters make reaching threshold potential less what? | likely |
| What are the uncommon synapses? | electrical synapses |
| Where are electrical synapses located? | certain parts of the brain and eyes |
| Which type of synapse allows direct exchange of ions between neurons through gap junctions? | electrical synapses |
| If a neurotransmitter opens sodium ion channels, the ions diffuse inward and depolarize the membrane. What is this membrane change called? | excitatory postsynaptic potential |
| If a neurotransmitter increases membrane permeability to potassium ions then they diffuse outward hyperpolarizing the membrane. What is this membrane change called? | inhibitory postsynaptic potential |
| When chloride ion channels are opened what occurs? | negative chloride ions enter the cell and oppose depolarization |
| How many synaptic knobs may each neuron in the brain and spinal cord receive on its dendrites and cell bodies? | 1000 or more |
| Since a neuron receives both excitatory and inhibitory signals simultaneously from various sources, the integrated sum of EPSPs and IPSPs determine what what occurs? | action potential |
| The nervous system produces at least how many different types of neurotransmitters in the brain alone? | 100 |
| Which neurotransmitter stimulates skeletal muscle contraction? | acetylcholine |
| What are the monoamines? | epinephrine norepinephrine dopamine serotonin |
| What is the structure of monoamines? | modified amino acids |
| Neurotransmitters include 2 types of amino acid molecules. What are they? | modified and unmodified |
| What are the short chains of amino acids which function as neurotransmitters? | peptides |
| Where are peptide neurotransmitters synthesized? | rough endoplasmic reticulum |
| What are peptide neurotransmitters transported in from the cell body down to the nerve cell terminal? | vesicles |
| Passage of an action potential along the membrane of a synaptic knob causes what to happen? | opens calcium ion channels |
| What happens as a result of more calcium ions in the synaptic knob? | some of the synaptic vesicles fuse with the presynaptic membrane and release their contents by exocytosis into the synaptic cleft |
| The more calcium ions in the synaptic knob, the more what? | vesicles release neurotransmitters |
| What mechanism eventually returns the membrane material to the cytoplasm? | endocytosis |
| What is the name of endocytosis of material to form new secretory vesicles? | vesicle trafficking |
| What rapidly decomposes neurotransmitters in the synaptic clefts and on postsynaptic membranes? | enzymes |
| What process is that which causes neurotransmitter to be transported back to the synaptic knob or presynaptic neuron OR into nearby neurons or neuroglia? | reuptake |
| Which enzyme inactivates the monoamine neurotransmitters epinephrine and norepinephrine AFTER reuptake? | monoamine oxidase |
| Which enzyme decomposes acetylcholine on the postsynaptic membranes? | aceylcholinesterase |
| Where is monoamine oxidase found? | mitochondria in synaptic knob |
| Which substance acts as a neuromodulator? | neuropeptides |
| What is the function of a neuromodulator? | alter a neuron's response to a neurotransmitter or block its release |
| Which neuropeptides are present throughout the brain and spinal cord? | enkephalins |
| What are enkephalins made up of? | chain of 5 amino acids |
| Which neuropeptides bind to the 'opiate receptors' in the brain during periods of painful stress? | enkephalins |
| Which peptide is found in the brain and cerebrospinal fluid and has a morphinelike quality? | beta endorphin |
| Which molecule consists of 11 amino acids, is widely distributed and functions as a neurotransmitter or modulator in neurons conducting impulses of pain to spinal cord and brain? | substance P |
| How do enkephalins and endorphins relieve pain? | inhibiting release of substance P from neurons |
| Which neurons are found to be completely within the CNS? | interneurons |
| How are interneurons organized? | neuronal pools |
| What is special about interneurons in a neuronal pool even though they may be in different parts of the CNS? | share common function |
| When a single impulse repeated causes more neurotransmitter to be released what is made more likely? | threshold potential |
| What is the name of the mechanism in which a neurotransmitter increases likelihood of reaching threshold potential? | facilitation |
| Any single neuron in a neuronal pool may receive input from two or more what? | neurons |
| What is exhibited when the axons originating from different neurons lead to the same postsynaptic neuron? | convergence |
| What does convergence allow the nervous system to accomplish in the face of incoming impulses from various receptors detecting changes? | collect, process and respond to information |
| A neuron has a single axon but axons may do what? | branch |
| The branching of an axon allows neurons in neuronal pools to form synapses with several other neurons. This is called what? | divergence |
| What is the effect of divergence? | impulses reach increasing numbers of neurons within the pool |
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