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353 Cards in this Set
- Front
- Back
Peripheral nervous system is made up of what types of nerves?
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Spinal nerves
Cranial nerves Autonomic nerves |
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Peripheral nervous system can be subdivided into what two major branches?
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Somatic and Autonomic
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The Somatic branch of the peripheral nervous system does what?
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Is both sensory and motor, and carries sensory nerve impulses to and motor impulses from the CNS from skin and skeletal muscle fibers
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The Autonomic Nervous system innervates:
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Smooth muscle, cardiac muscle, glands
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How many nerves are there in the CNS? Is most of their activity sensory or motor?
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Over 100 billion, most activity is sensory (input receiving)
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What do astrocytes do?
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1. provide for rapid transport for nutrients and metabolites
2. believed to form an essential component of the blood-brain barrier 3. appear to be the scar-forming cells of the CNS, which may be the foci for seizures 4. may play a role in segregating postsynaptic receptor surfaces from other regions |
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What do Oligodendroglia do?
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Deposit myelin within the CNS
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What do Schwann Cells do?
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Form the myelin sheath and neurilemma outside of the CNS (in the PNS)
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Microglia: what do they do?
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Phagocytic properties; they clear away cellular debris
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Ependymal cells: where are they and what do they do?
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Serve as a lining for the cerebral ventricles and chroid plexuses (which are responsible for CSF production)
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What are 6 other names for the sensory (afferent) system within the CNS?
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1. Dorsal
2. Spinothalamic 3. Anterolateral 4. Dorsolateral Spinal 5. Somatosensory 6. Post central gyrus |
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What are 3 other names for the motor (efferent) system within the CNS?
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1. Ventral
2. Alpha Motor 3. Corticospinal |
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What is a bipolar neuron, and where might you find it?
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spindle-shaped neuron with a dendrite at one end and an axon at the other, found in light-sensitive retina of the eye
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_______ neurons comprise 99% of all neurons, and are the major type found in the CNS
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Multipolar
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The _______ insulates nerve axons to prevent electrical loss and speed conduction.
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Myelin sheath
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The _______ are 2-3 micrometer sized gaps in the myelin sheath that allow the process of ______ conduction
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Nodes of Ranvier allow saltatory conduction
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Schwann cells wrap around the axons of nerves to form a fatty myelin insulator. This insulation is so tight that it prevents the movement of Na and K ions except at the ______. This allows the electrical signal to "jump" from Node to node down the axon, and is much _______
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Nodes of Ranvier, much faster (saltatory conduction)
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A Alpha Fibers: myelinated? diameter, speed, location/transmits:
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Myelinated, fastest conduction (60-120 m/s); largest diameter (10-18 micrometers)
Located/transmission: somatic motor fibers, muscle propricepors |
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A Beta fibers: myelinated? Diameter, speed, Transmits:
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Myelinated, diameter 5-10 micrometers, conductance: 38-70 m/s
Transmits: rapid sensory touch, pressure, kinesthesia |
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A Gamma fibers: myelinated? Diameter, speed, transmits?
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Myelinated, diameter 1-5 micrometers, conductance 15-45 m/s,
Transmits: motor to muscle spindle, rapid sensory (touch, pressure) |
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A Delta fibers: myelinated? Diameter, speed, transmits?
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Myelinated,2-5 micrometer diameter, conductance 5-30 m/s, Transmits: Pain, temperature, pressure
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B Fibers: myelinated, diameter, speed, transmits
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Thinly myelinated, diameter 3 micrometers, conductance 3-15 m/s, Transmits: Autonomic preganglionic transmission
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Autonomic preganglionic transmissions are carried by what type of fibers?
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B fibers
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sympathetic postganglionic transmissions are carried by ____ fibers.
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C
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C fibers: myelinated? diameter, speed, transmission
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No; 1-3 micrometers (smallest fibers), 5+ m/s conductance, Transmits: sympathetic postganglionic; slow pain
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Are sympathetic postganglionic nerve fibers myelinated?
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No
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What is an example of a mechanoreceptor?
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Carotid sinus baroreceptor
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What is are two examples of chemoreceptors?
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Carotid and aortic bodies (sense partial pressure of oxygen); supraoptic nuclei (sense serum osmolality)
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The Dorsal-column medial lemniscal tracts carry information regarding what 6 sensations?
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Touch-high localization
Touch-fine gradients Vibration Movement against skin Position sense (joints) Pressure |
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The anterolateral tracts carry information regarding what 5 sensations?
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Pain
Temperature Crude touch and pressure with crude localization Tickle and itch Sexual sensations |
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Dorsal Column medial lemniscal tract neurons decussate:
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In the medulla (second order neuron begins in medulla and crosses over to contralateral side from where impulse sensed)
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Anterolateral tract neurons decussate?:
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Immediately upon entering the dorsal horn
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Anterolateral tracts: where do the first, second, and third order neurons go?
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First order neuron enters through the dorsal horn, meets the second order neuron which immediately crosses over to the contralateral side and travels up the anterior or lateral portions of the spinal cord white matter through the medulla, meets the third order neuron in the ventrobasal and intralaminal nuclei of the thalamus, and ascends to the somatosensory area of the post central gyrus
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Describe the first, second, and third order neuron locations and destinations in dorsal column medial lemniscal tract?
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First order neuron enters through the dorsal root, travels into the dorsal horn, ascends through this DCML tract to the medulla where it meets the second order neuron. The second order neuron in the medulla immediately decussates to contralateral side, and ascends to ventrobasal region of the thalamus where it meets the third order neuron. The third neuron carries this information to the somatosensory area of the post central gyrus
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Enkephalins are _______; the increase the threshold needed to create an action potential
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Inhibitory on the presynaptic side
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Enkephalins cause less _____ and ______ to be released from the axon terminal
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less Glutamate and substance P are released
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Spinoreticular tract: what does it do?
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terminates in centers responsible for blood pressure, motor control, and descending inhibition of pain- causes less glutamate and substance P to be released at the level of the spinal cord and thereby decreases pain
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Spinomesencephalic tract: what does it do?
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terminates in centers for integrated motor, autonomic, and antinociceptive responses such as orienting, defense, and confrontation
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Spinolimbic tract: what does it do?
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terminates in hypothalamus and amygdala- creates an emotional response to pain or other stimulus
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Threshold: definition
What factors influence this? |
The voltage that must be exceeded before depolarization will occur;
Influenced by: pH, temperature, and oxygen |
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Summation: What is it?
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A series of sub-threshold stimuli may additively create enough of stimulus to generate an action potential (think of lots of neurons sending low voltage stimuli regarding the same event to one axon; individually, each of these stimuli is not strong enough to generate an action potential, but together, they decrease the membrane potential to its threshold level and thus trigger impulse conduction
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accommodation:
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the ability of nerve tissue to adjust to a constant source and intensity of stimulation so that some change in either intensity or duration of the stimulus is necessary to elicit a response beyond the initial reaction. Accommodation is probably caused by reduced sodium ion permeability, which results in an increased threshold intensity and subsequent stabilization of the resting membrane potential; when a stimulus causes the membrane potential to change very slowly, the nerve is not as likely to create an action potential
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All or none law:
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If a stimulus is strong enough to initiate an impulse, it will do so to its fullest extent; if a stimulus is strong enough to generate an action potential, it will travel down the entire length of the axon or not at all
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Refractory period:
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For a short time after the development of an action potential, it is not responsive to further stimuli; The absolute refractory period places a limit on the rate at which a neuron can conduct impulses, and the relative refractory period permits variation in the rate at which a neuron conducts impulses. Such variation is important because it is one of the ways by which our nervous system recognizes differences in stimulus strength,
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The resting membrane potential of a nerve is:
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-90 mv
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When a stimulus changes the resting membrane potential of a nerve by a few mv, it causes the _____ channels to open
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Voltage gated Sodium channels (remember: Stimulus- Sodium); as the sodium enters the cell, it overshoots to + 35mv and this change in voltage shuts down the voltage gated sodium channels so no more sodium can enter the cell membrane
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The Sodium channels close very quickly after stimulation, and then the ______ open more slowly to restore the membrane potential
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Potassium channels open as the sodium channels close- remember "slow K channels"
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Threshold for an action potential is:
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-65 mv
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What serves to restore the concentrations of potassium inside the cell and sodium outside the cell?
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The sodium-potassium pump: pumps 3 Na molecules out for every 2 K that it pumps in; this requires ATP
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How do local anesthetics work?
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They act directly on the sodium channels, decreasing their excitability and impeding their ability to generate an action potential
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Myasthenia Gravis is caused by:
How is it treated? |
Autoimmune destruction of the postsynaptic Ach receptors (resulting in an inability to respond to Ach). It is treated with neostygmine which deactivates acetylcholinesterase and therefore causes Ach to accumulate within the NMJ
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Fatigue of synaptic transmission occurs with ______, ______ firing.
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Repeated, rapid firing (this may partly explain why seizures eventually stop even without intervention)
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Alkalosis ______ neuronal excitability
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Increases; it is easier to get neurons to conduct
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What three factors greatly decrease neuronal excitability?
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Acidosis, hypoxia, and anesthetic and other drugs (increase the threshold necessary or firing)
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Why does unconsciousness follow cardiac arrest?
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Brain cells stop firing within 3-7 seconds following cardiac arrest because they cannot transmit impulses in a hypoxic environment
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What are the two major types of synapses?
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Chemical and electrical
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Neurotransmitter release is _____ dependent
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Calcium
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Another name for facilitation:
Another name for inhibition |
EPSP (excitatory postsynaptic potential)
IPSP: Inhibatory Postsynaptic potential (hyperpolarizes the cell membrane) |
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What class of neurotransmitter is acetylcholine? What is its role?
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Ester;
Nicotinic: Fast synaptic transmission at NMJ and autonomic ganglia Muscarinic: Excitatory/inhibitory slow synaptic transmission r/t tissue |
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What class of neurotransmitter is NE? What is its role?
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Monoamine; Works on alpha and beta receptors; Slow synpatic transmission in CNS and smooth muscle
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Corticospinal tracts are _____. They come together in the _____ to form pyramids
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Descending; join in the medulla to form pyramidal tracts
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What percent of corticospinal tracts decussate in the medulla?
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75% decussate in medulla, remaining 25% do not
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Motor neurons NOT traveling in the pyramidal tracts descend in the ____
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anterior horn motor neuron
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Extrapyramidal motor neuron tracts are responsible for
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Coordination of routine muscle movements; Plays a crucial role in producing larger, more automatic movements; brings about contraction of muscles in sequence or simultaneously (swimming, walking), and all normal voluntary movements (the "riding a bike effect"- things you don't think about); also regulates ingrained emotional expressions (smiles, frowns, etc)
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The adrenal medulla is innervated by:
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preganglionic adrenergic neurons (nicotinic receptor- releases Ach and causes adrenal gland to release Epi and NE)
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Skeletal muscle is innervated by _____ arising from
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Skeletal muscle innervated by myelinated efferent motor nerve fibers (α motor neurons) arising from cell body in ventral horn of spinal gray matter
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Motor nerves divide and end on
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Individual muscle fibers
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Motor Unit
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Motor nerve + multiple innervated fibers
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Skeletal muscle neurotransmitter
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Ach (nicotinic)
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Motor end plate
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Post junctional membrane at neuromuscular junction
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post junctional receptors on the motor end plate
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alpha (2), beta, gamma, delta
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What is acetylcholine synthesized from?
What is it broken down into? By what? |
synthesized by enzyme choline acetyltransferase from the compounds choline and acetyl-CoA
Broken down by acetylcholinesterase into acetate and choline |
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How is acetylcholine released into NMJ?
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Action potential causes fast and slow calcium channels to open and release calcium. Calcium binds to nerve plasma membrane and causes it to expel Ach into NMJ.
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What are inhibitors of Ach release?
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Mg²
Aminoglycosides Calcium channel blockers |
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What causes the fast Ca channels to open? The slow channels?
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Fast calcium channels are voltage gated (activated by voltage change from action potential propagation), slow are opened using cAMP
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Where does acetylcholinesterase live?
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In the spongy connective tissue within the synaptic cleft
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The cerebrum is structured
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Outer gray holding cell bodies; inner white matter consisting of fiber tracts
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How thick is the cerebral cortex?
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2-3 mm
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What is the most basic way of describing the functions of the cerebrum?
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Storage of experience (memory)
Exchange of impulses with other cortical areas (association) |
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What does the frontal lobe do? What are the associated landmarks?
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Concerned with intellectual function such as
Reasoning, abstract thinking Aggression Sexual behavior Olfaction (smell) Articulation of meaningful sound (speech) Voluntary movement; Landmarks: Central sulcus separates frontal lobe from parietal lobe |
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Parietal lobe functions:
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Body sensory awareness
Taste (postcentral gyrus) Use of symbols for communication (language) Abstract reasoning (math) Body imaging |
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What does the temporal lobe do? What does it do in conjunction with the limbic system?
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Non-limbic portion
Interpretation of language Awareness, discrimination of sound Major memory processing area In conjunction with the limbic system: Formation of emotions Love Anger Aggression Compulsion Sexual behavior |
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Occipital lobe functions:
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Receiving, interpreting, discriminating visual stimuli from optic tract
Associating visual impulses with other cortical areas |
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What does the limbic system do?
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Incorporates parts of frontal, temporal, parietal lobe
Oldest part of cortex in evolutionary terms Center for emotional behavior |
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What cerebral hemisphere is responsible for speech?
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Left only
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What does the left cerebral hemisphere primarily do?
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Left hemisphere deals with higher functions
Mathematical Analytical Verbal |
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What is the right hemisphere primarily responsible for?
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Visual and musical orientations
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The idea of cerebral dominance is
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controversial
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The basal ganglia are
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Collections of grey matter deep in substance of cerebral hemispheres
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Structures associated with basal ganglia functionality are
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Subthalamic nucleus
Substantia nigra |
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What does the basal ganglia do (what is its function)?
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Planning, programming voluntary muscle movement
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Parkinson's disease is a disorder of the _______ caused by
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Basal ganglia; Degenerative disease of CNS with loss of dopaminergic fibers present in basal ganglia; Depletion of dopamine, the neurotransmitter that inhibits rate of firing of neurons controlling extrapyramidal motor system
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Parkinson's disease is manifest by:
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Decreased spontaneous movements
Rigidity of extremities Facial immobility Shifting gait Rhythmic resting tremor |
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Parkinson's disease is treated by
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↑ dopamine in CNS or ↓ neuronal effect of Ach
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Patients with Parkinson's disease should _____ on the day of surgery. Why?
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continue L-dopa including day of surgery; half-life is short, interruption for 6-12 hrs can result in loss of benefits
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What side effects might you see from L-dopa? What happens if you stop it abruptly?
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orthostatic hypotension, cardiac dysrhythmia, hypertension may occur with use; abrupt d/c might cause severe muscle rigidity
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Patients with Parkinson's disease may exhibit a _____ response to Ketamine
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Exaggerated SNS response; avoid use
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Is succinylcholine safe in patients with Parkinson's disease?
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Should be, only one reported case of hyperkalemia (perhaps r/t patient being bedridden, severe Parkinsons)
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hunting tons chorea is a degenerative disease of the CNS affecting _____
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Basal ganglia
Caudate nucleus Putamen Globus pallidus |
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Huntington's chorea results in
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Deficiencies of Ach and GABA basal ganglia
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S/S of Huntington's Chorea
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Progressive dementia
Chorea first symptom |
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What response might a patient with Huntington's Chorea exhibit to succinylcholine?
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Decreased plasma cholinesterase prolongs response to succinylcholine
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Patients with Huntington's Chorea are prone to ______
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Prone to aspiration due to involvement pharyngeal muscles
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The diencephalon is made up of what 4 structures?
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Epithalamus
Thalamus Hypothalamus Subthalamus |
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Where is the epithalamus located and what does it do?
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Forms roof of 3rd ventricle, most superior portion of diencephalon
It connects with and is closely associated with functions of limbic system Hormones of pineal body influence reproductive activity Secretion of melatonin (circadian rhythm) |
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Where is the thalamus and what does it do?
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Largest part of diencephalon; surrounds third ventricle
Major integrating center for afferent impulses to cerebral cortex Relay station for information from basal ganglia, cerebellum that is sent on to appropriate portions of motor area Crude appreciation of touch, pain, temperature, may occur here |
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The _____ forms the base of the diencephalon; what are its two generic functions?
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Hypothalamus;
Maintains a constant internal environment Maintains behavioral patterns |
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The hypothalamus is ______ to the limbic system
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Focal structure of limbic system; limbic system + hypothalamus performs role in overall behavior and emotional expression
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What are the specific functions of the hypothalamus?
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Visceral, somatic responses
Afferent responses Hormone synthesis Autonomic nervous system activity Temperature regulation Feeding responses Physical expression of emotions Sexual behavior Pleasure-punishment centers Awareness |
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The cerebellum is the _____ largest part of the brain. Where is it located?
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Second largest; Located just below posterior portion of cerebrum and is partially covered by it
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How is the tissue of the cerebellum arranged?
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Gray matter makes up outer portion, white matter in interior
Two cerebellar hemispheres; central section called vermis (resembles a worm coiled on itself) |
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What does the cerebellum do?
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Coordinates signals from muscle, joint, visual, auditory and equilibrium receptors with instructions from cortex
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What three structures make up the brain stem?
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Medulla, Pons, and midbrain
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Medulla: location and function
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Forms lower portion of brainstem
Contains centers controlling heart rate, blood vessels, respiration, coughing, sneezing, swallowing, vomiting Contains nuclei of VIII, IX, X, XI, XII cranial nerves Contains pyramidal tracts |
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Where is the Pons located? What is its function?
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Below midbrain
Primary function is transmission of information from cerebellum to brainstem and between two cerebellar hemispheres Important center for control of respiration Groups of neurons form sensory nucleus of V and VI, VII CN |
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Midbrain: function
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Superior and inferior colliculi are centers for visual and auditory reflexes
Tegmentum contains red nucleus and substantia nigra which help to control skilled muscular movements Contains nuclei of III, IV CN |
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Reticular Formation (RAS): function
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Controls level of excitability of brain neurons and helps maintain consciousness and the waking state
Inhibition of the RAS leads to sleep or coma |
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Red Nucleus
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Primal control of movement- controls crawling in babies and arm swinging
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What connects medulla, pons, midbrain with each other and spinal cord, thalamus, cortex
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Reticular formation
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Preganglionic fibers: (type)
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B fibers
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Postganglionic fibers (type)
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C fibers
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NO is occasionally a neurotransmitter in the ___ system
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Parasympathetic
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Another name for the PNS
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Craniosacral
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Another name for the SNS
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Thoracolumbar
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What is are catecolamines made of? Where are they produced?
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Tyrosine produced in liver then transported to catecholamine-secreting neurons where a series of reactions convert it to dopamine, to norepinephrine and finally to epinephrine
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For every SNS preganglionic fiber,
there are _____ postganglionic fibers |
20-30
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Alpha 1 fibers of SNS: function
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constrict blood vessels, inhibit insulin sec
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Alpha 2 Fibers of the SNS
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Receptors presynaptic. Some vasodilation (negative feedback)
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Beta 1 fibers:
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Inc. HR, contractility, conduction. Lipolysis
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What parts make up the basal ganglia
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Claustrum
Corpus stratum Lentiform nucleus Globus pallidus Putamen Caudate nucleus |
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Which has a wider distribution: the SNS or the PNS?
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SNS;
SNS- distributed throughout body Transmitters: Ach, NE PNS- limited distribution. Ganglia near organs Transmitters: Ach, Ach (& occas, NO) |
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Dopa 1 Receptors
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Dilate splanchnic blood vessels, increase GFR
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Dopa 2 receptors
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Inhibit Norepi release
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What effects can Neurotransmitters produce?
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Change in membrane permeability (ions)
Activating/inactivating enzyme 2nd messengers Amplification Control Specificity |
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Receptors of the SNS are sensitive to levels of _________
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circulating catecholamines; up regulate number of in times of sparse catecholamines, down regulate when lots of catecholamine floating around
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Alpha 1-adrenergic stimulation causes _______ which causes arteriole vasoconstriction in the skin and GI tract and venous vasoconstriction increasing preload
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an increase in intracellular Ca
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Stimulation of Alpha 2 causes what reaction at peripheral presynaptic sites?
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Decreases synthesis and release of NE by negative feedback
Vasodilation |
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Stimulation of Alpha 2 at central post synaptic sites does what?
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Postsynaptic alpha-2 receptors found in brainstem inhibits outflow of SNS
Vasodilation Sedation |
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Where are beta 1 adrenergic receptors found?
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Heart, kidneys, adipose
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What does beta 2 stimulation cause?
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Dilation of smooth muscle of lungs and vasculature, liver and glands
Promotes hyperglycemia & hypokalemia (stimulation of beta 2 activates the Na-K pump) |
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Beta 3 stimulation causes
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Negative inotropy
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What cells in the adrenal medulla release Epi and NE when stimulated by presynaptic sympathetic acetylcholine receptors?
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chromaffin cells
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What percentage of catecholamines released from the adrenal medulla is Epi? NE? What is each of their intrinsic rates?
|
80% Epi, 0.2 mcg/kg/min
20% NE; 0.05 mug/kg/min |
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NE stimulates:
|
Alpha and beta fibers A>B
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Epi stimulates
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Alpha and Beta, A=B and results in greater metabolic stimulation than NE
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D1 increases_____
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Increases cAMP via adenylate cyclase
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D2 functions by _____
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Increases phosphodiesterase activity to decrease cAMP
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What effect does stimulation of muscarinic receptors have?
|
Heart: Decrease HR, contractility, conduction
Lungs: Bronchoconstriction, secretions stimulate GI (SLUDGEM- Salivation, lacrimation, urinanation, defecation, GI motility, emesis, Meiosis) |
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Parasympathetic nervous system fibers exit
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Out through CN III, V, IX, X, and Sacral nerves S2-S4
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What happens when Nicotinic receptors are stimulated?
|
opens an ion pore allowing Na+ and Ca+ influx and K+ efflux from postsynaptic tissue
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Where are Nicotinic receptors found?
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Autonomic ganglia (preganglionic neurotransmitter of PNS and SNS)
MNJ Adrenal chromaffin cells |
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What happens when muscarinic receptors on cardiac tissue are stimulated? Why?
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These receptors lie on presynaptic sympathetic nerve terminals; Stimulation decreases NE release leading to ↓ HR and contractility
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What does NO do?
|
Nitric oxide activates 2nd messenger cGMP to promote bronchodilation and vasodilation
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Prevertebral ganglia- what are they?
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Sympathetic ganglia that lie between the sympathetic chain and the organ of supply
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What do the pre vertebral ganglia consist of?
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Prevertebral ganglia consist of pre- and postganglionic sympathetic fibers and parasympathetic fibers and the ganglia cell bodies
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What is the Vasoconstrictor area of the Vasomotor Center?
|
Anterolateral of upper medulla that stimulates preganglionic vasoconstricting neurons
Lateral portions ↑ heart rate & contractility |
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What is the Vasodilator area of the Vasomotor Center?
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Anterolateral lower half of medulla that inhibits vasoconstrictor area
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What does the dorsal motor nuclei of the vagus do?
|
Receive input from medial vasomotor center to ↓ heart rate and contractility
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What cranial nerves help regulate blood pressure through the vasomotor center of the medulla?
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IX (glossopharyngeal) and X (Vagus
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Where is the vasomotor center located? What does it do?
|
a collection of cell bodies in the medulla oblongata of the brain that regulates or modulates blood pressure and cardiac function
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Information from Baroreceptors, Chemoreceptors, GI receptors is all processed in ______
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Vasomotor center
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How does the baroreceptor reflex work?
|
Initiated by baroreceptors in the carotid sinus via Hering’s nerve to CN IX and the aortic arch via CN X to the tractus solarius of the medulla to inhibit the vasoconstricting area and excite the vagus PNS area
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What is the effect of stimulating the baroreceptor reflex? How long will this reaction last?
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Net effects: vasodilation and decreased heart rate & contractility
Not effective long term, can be reset in 1-2 days |
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How does the chemoreceptor reflex work?
|
Decreased O2 (and to lesser extent increased CO2 and H+) stimulate Carotid bodies in carotid bifurcation (CN IX)
Aortic bodies in aortic arch (CN X) Transmit to vasomotor center via Hering’s nerves and cause excitation, resulting in increased BP |
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How does the oculocardiac reflex work?
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Traction on the extracocular muscles stimulates afferent CN V with reflexive efferent CN X resulting in
Bradycardia Decreased SVR/BP Arrhythmias |
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What is the celiac reflex?
|
Traction or pressure on structures within peritoneal/thoracic cavities
Bradycardia Hypotension Apnea |
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What are the Atrial & Pulmonary Artery Reflexes?
|
Stretched atria (volume overload) results in slight reflex vasodilation of peripheral arterioles, stimulates hypothalamus to decrease ADH (causing increased UOP), Increased HR- Bainbridge reflex —> offload fluid from heart, Reflex dilation of afferent arterioles of kidneys to ↑ GFR, release of atrial natriuretic peptide to promote Na+ and thus water excretion
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What is the CNS ischemic response?
|
Stimulated by ABP <60 mm Hg; most potent activator of vasoconstricting system
Cushing reaction: when high ICP ↓ cerebral perfusion (HTN & bradycardia) |
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What is the net result of the renin angiotensin Aldosterone system?
|
Kidneys secrete renin in response to decreased blood flow, which results in aldosterone and ADH release causing increased sodium and water retention, and NE release (ACE inhibitors work here)
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In pediatric patients, CO is dependent on
|
HR
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At birth, the ______ is less developed
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SNS
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Name 4 common changes to the ANS in the geriatric population?
|
Impaired quality of adrenergic receptors in the heart
More dependent on atrial kick Greater incidence of shivering HTN common |
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Autonomic neuropathy occurs in ____ of diabetics, and results in ______
|
40%; vagal denervation
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Autonomic dysreflexia occurs in 85% of spinal cord injuries above the level of _____
|
T5
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What is autonomic dysreflexia?
|
Vasoconstriction via ANS mass reflex below lesion in response to noxious stimuli (full bladder, defecation, skin incision)
|
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What are S/S of autonomic dysreflexia?
|
Paroxysmal hypertension
Bradycardia Cardiac dysrhythmias Vasodilation above lesion (flushing) |
|
How do you treat autonomic dysreflexia?
|
Remove noxious stimulant
Direct vasodilators |
|
Cranial Nerves
|
Oh, Oh, Oh, To Touch And Feel Virgin Girl's Vaginas- AH
olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, and hypoglossal |
|
CN 1: Name and function
|
Olfactory, Sensory, Smell
|
|
CN 2: Name and function
|
Optic: Sensory: Vision
|
|
CN 3: name and function
|
Oculomotor: Motor: eye movements, pupillary constriction, Parasympathetic input to the ciliary ganglion to constrict pupil,
Damage manifests as blown pupil |
|
CN 4: Name and Function
|
Trochlear: Motor: eye movement
|
|
CN 5: Name and Function
|
Trigeminal; Mixed, Somatosensory information from the face and head; muscles for chewing
|
|
CN 6: Name and Function
|
Abducens, Motor, eye movement
|
|
CN 7: Name and Function
|
Facial; Mixed: Taste (anterior 2/3 of tongue); somatosensory information from ear; controls muscles used in facial expression; Paralysis of the facial nerve causes a facial droop. it carries Parasymapathetic input to the salivary and lacrimal glands; damage to this nerve is manifest as facial droop
|
|
CN 8: Name and Function
|
Vestibulocochlear; Sensory, hearing, balance
|
|
CN 9: Name and Function
|
Glossopharyngeal; Mixed, Taste (posterior 1/3 of tongue); Somatosensory information from tongue, tonsil, pharynx; controls some muscles used in swallowing; parasympathetic innervation to parotid gland
|
|
CN 10: Name and Function
|
Vagus; Mixed: supplies general sensory and motor function to the larynx and pharynx; Parasympathetic input to the heart and lungs and gastro intestinal tract
|
|
CN 11: Name and Function
|
Spinal accessory;Motor: Controls muscles used in head movement.
|
|
CN 12: Name and Function
|
hypoglossal; Motor: Controls muscles of tongue
|
|
Mnemonic for CSF production and flow
|
*Lady *Monroe has *3 *Aquaducts that lead to *4 *Luscious and *Magical *Subarachnoid places (Lateral, Foramen of Monroe, 3rd Ventricle, Aqueduct of Sylvus, 4th Ventricle, Foramen of Luschka, Foramen of Magendie into cerebellar cisterns and into subarachnoid space
|
|
CSF is reabsorbed by _____ in the _____
|
Arachnoid villi in the subarachnoid space into the venous sinuses
|
|
What are the % constituents of the contents of the cranium
|
80% Brain & Water
12% Blood 8% CSF |
|
What is the cerebral blood flow rate to the brain?
|
45-50 ml/100 g brain/min
|
|
What are the two major arteries that supply the brain?
|
Internal Carotid and Basilar arteries
|
|
At any given time, the intracranial blood volume is _____
|
100-150 ml
|
|
The anterior cerebral artery supplies what structures within the brain?
|
Basal ganglia; corpus callosum; medial surface of cerebral hemispheres; superior surface of frontal and parietal lobes
|
|
What would a stroke (occlusion) in the anterior cerebral artery manifest as?
|
Hemiplegia on the contralateral side of the body, greater in the lower than in the upper extremities
|
|
What structures does the Middle cerebral artery supply?
|
Frontal lobe, parietal lobe; temporal lobe (primarily the cortical surfaces)
|
|
What would an occlusion of the middle cerebral artery manifest as?
|
Aphasia in dominant hemisphere
|
|
What structures does Posterior cerebral artery serve?
|
Part of the diencephalon and temporal lobe; occipital lobe
|
|
What would an occlusion of the posterior cerebral artery manifest as?
|
Contralateral hemiplegia greater in the face and upper extremities than in the lower extremities; sensory loss; visual loss
|
|
Dura Mater
|
Hard mother, tough, nonstretchable membrane with 2 layers; outer dura periosteum of skull
|
|
Arachnoid Mater
|
Thin, avascular membranewhich skips from crest to crest; subarachnoid below contains CSF, large blood vessels
|
|
Pia Mater
|
Tender mother, intimately attached to brain and cord; vascular layer through which vessels pass to nourish neural tissue
|
|
CSF is manufactured in the _______ of which ventricles?
|
Choroid plexuses of the lateral ventricle and the roofs of the 3rd, 4th
|
|
What is the choroid plexus>?
|
Networks of capillaries that project out from the pia mater into the ventricles
|
|
What is the composition of CSF?
|
Composition is same as extracellular fluid; free communication between brain, ECF spaces, ventricles, SAS
|
|
How much CSF is produced each day? How much is present at any given time?
|
600-800 ml/day, 125-150 present at one time
|
|
What pressure does the CSF exert within the brain and spinal cord
|
12 mm Hg
|
|
What is the purpose of CSF
|
Cushions and protects brain and spinal cord
|
|
What is the main "brain drain" vein?
|
Internal jugular- occludes with improper positioning and head has decreased venous return
|
|
What percent of the cardiac output goes to the brain?
|
15%
|
|
What percentage of the CBF goes to gray matter? To white matter?
|
80% gray, 20% white
|
|
CBF is auto regulated within a range of
|
MAP 50-150 (Miller says 65-150)
|
|
What 5 areas are outside of the blood brain barrier?
|
–Pineal gland
–Neurohypophysis –Area postrema –Supraoptic crest –Subfornical organ |
|
Premature babies have an ______ BBB
|
immature; kernicterus can be a problem because of this
|
|
What factors make the BBB more permeable?
|
tumors, trauma, hypoxia, severe changes in CO2
|
|
What is useful for stabilizing the BBB?
|
Cortisone
|
|
What is the cerebral metabolic rate for oxygen (CMRO2)?
|
3.0 ml/100 g/min
|
|
What is the cerebral metabolic rate for glucose (CMRg)?
|
4.5 ml/100 g/min
|
|
In a normal (uninjured) brain, what is the major determinant of Cerebral perfusion?
|
MAP
|
|
In response to increased MAP, the auto regulation mechanisms of the brain cause
|
Vasoconstriction; maintains constant CBF
|
|
Time to autoregulation
|
30-120 seconds
|
|
What is the effect of a MAP > 150?
|
Cerebral edema
|
|
Normal CPP
|
100
|
|
EEG will be flat at normothermia at what CPP
|
25-40
|
|
Irreversible tissue damage to the brain occurs at a CPP of _____ at normothermia
|
<20
|
|
Myogenic theory of cerebral auto regulation:
|
Smooth muscle contracts in response to stretch, so when blood vessels stretched by increased BP, they vasoconstrict
|
|
Metabolic Theory of cerebral autoregulation
|
Tissue produces acid metabolites in response to hypoxia, and the increased acid causes cerebral vasodilation
|
|
When cerebral auto regulation is lost, there is a _____ relationship between BP and CBF
|
linear
|
|
What 5 factors can lead to a loss of cerebral auto regulation?
|
•Hypoxemia
•Ischemia •Hypercapnia •Trauma •Some anesthetic agents |
|
What effect does beach chair position have on cerebral hemodynamics?
|
•MAP, CVP, PAOP, SV, CO, and PaO2 decrease
•CPP decreases by ~15% in non-anesthetized Anesthesia blunts normal compensatory responses |
|
To accurately measure the CBF to the head with an art-line, you can
|
Level the transducer at the tragus instead of the phlebostatic axis
|
|
Cerebral blood flow varies linearly with CO2 ______
|
20-80 (other source says 25-70)
|
|
_______ profoundly affects CBF
|
PaCO2 (and spinal cord blood flow)
|
|
Increases in CBF do not occur until PaO2 < _______
|
50 mm Hg
|
|
•Hyperoxia (80-100% inhaled O2) in normal person associated with _______
|
10-12% decrease in CBF
|
|
The autonomic nervous system (SNS, PNS) appears less important in maintaining CBF except at
|
The upper and lower limits of cerebral autoregulation
|
|
Decreased body temperature decreases CBF by how much?
|
5% per degree centigrade drop
|
|
increasing body temperature increases _______
|
CBF and metabolism
|
|
There are no ____ stores in the brain; consciousness is lost at _____
|
no O2 stores; consciousness lost at PaO2 30
|
|
Hct affects CBF by altering blood viscosity; changes are not seen with Hct between
|
30-50%
|
|
In the brain, more than 90% glucose is _______
|
aerobic- brain does not use glucose well in hypoxic states
|
|
What classes of drugs offer neuroprotection?
|
•Barbiturates- mainstay
–Propofol –Etomidate –Benzodiazepines –Volatiles |
|
ICP- definition
|
supratentorial CSF pressure or pressure in a lateral ventricle or SAS
|
|
Which two agents increase both the CMRO2 and the cerebral blood flow?
|
Ketamine and N20
|
|
TIVA is offers what advantages over volatiles in neurosurgery?
|
Improved CPP, Better preservation of cerebral autoregulation vs. volatile, less interference with SSEP, MEP, AEP; potential neuroprotective effects via antioxidant properties.
|
|
Uncoupling effect:
|
High dose volatile increases CBF but decreases CMRO2
|
|
N20 is a ______ and therefore ______ ICP
|
Vasodilator, increases CBF and therefore raises ICP
|
|
Increases in ICP with N2O can be attenuated by
|
pretreatment with Benzo or thiopental
|
|
What 5 factors need to be considered in choosing anesthetic agents for neurosurgery?
|
1. Cerebral elastance (slack brain)
2. Control of cerebral blood flow and metabolism 3. Brain protection 4. Early neurological assessment 5. Hemodynamically stable emergence |
|
Analgesic and premedicant doses of narcotics have little effect on CBF or ICP unless ______
|
unless PaCO2 increases secondary to respiratory depression
|
|
Ketamine is only contraindicated in neurosurgery in the case of _____
|
known high ICP
|
|
Name 4 situations where TIVA is specifically indicated:
|
–Tight brain
–Unplanned TIVA •Progression of response to poor brain conditions –Neurotrauma _Neurological monitoring necessitates minimal influence of anesthetics |
|
What is lost in brain before permanent damage is done? How can you measure this?
|
Nerve function lost before cellular integrity is lost; Electrical changes (EEG) shows ischemia by showing decreased electrical activity
|
|
What is the downside of EEG for neurologic monitoring?
|
Not very specific as to areas of damage or ischemia
|
|
What 4 characteristics would an ideal intraoperative neurological monitor have?
|
•Used continuously during period of risk
•Sensitive to at-risk damage •Specific to at-risk damage •There is an intervention available to respond to detected problems |
|
What are 3 types of sensory evoked potentials?
|
1. Somatosensory EP
2. Brain stem ep 3. Visual EP |
|
What are two types of motor EP?
|
1. Motor EP
2. EMG |
|
What are somatosensory evoked potentials used for?
|
Used to evaluate the integrity of the spinal cord or nerves during procedures when blood supply to cord or actual tissue of cord in potential danger of being damaged
|
|
Somatosensory waveforms are examined for ____ and _____. what do these measures tell you?
|
Latency and amplitude: increased latency and decreased amplitude signify a problem (damage to the neuronal pathway being monitored)
|
|
Neuro anesthesia relies heavily on _____ for the bulk of pharm management
|
opioid
|
|
General intravenous anesthetics and volatile agents do what to SSEP?
|
decrease the amplitude and increase latency in proportion to the dose
|
|
What is the 0.4, 0.4, 0.4 approach?
|
.4 MAC Iso, 0.4 mcg/kg Sufentanil infusion, (??? maybe 40% Nitrous?)
|
|
The order than things are knocked out under anesthesia (4 A's)
|
Amnesia
Analgesia Akinesia Autonomics |
|
The anesthetic goal of amnesia is achieved by affecting what part of the body? How much volatile is required to do this?
|
Cortex, 0.4 MAC, in neurosurgery, this is usually the only purpose of your volatile
|
|
The anesthetic goal of analgesia is achieved by affecting what part of the body? How much volatile is required to do this?
|
Thalamus; 0.8 MAC; in neurosurgery, this is the role of opiod (not volatile)
|
|
The anesthetic goal of akinesia is achieved by affecting what part of the body? How much volatile is required to do this?
|
Spinal Cord Reflex; 1 MAC;
|
|
How much volatile is typically required to knock out the autonomic reflexes? What system influences this?
|
1.5 MAC; Endocrine system
|
|
What is the 60/60 club in neuro anesthesia
|
Dose opioid until HR 60, MAP 60
|
|
According to the Monroe Kelly Doctrine, what 4 steps does the brain take to decrease ICP?
|
1. CSF translocation
2. Decrease CSF production 3. Decrease CBF (blood translocation) 4. Brain herniation |
|
Supratentorial refers to:
Infratentorial? |
Anything above the cerebellum
Infratentorial is the cerebellum |
|
The tentorium separates:
|
The cerebrum from the cerebellum (also supports occipital lobes)
|
|
Which is more common: supratentorial or infratentorial lesions?
|
Supratentorial
|
|
What are symptoms of supratentorial lesions?
|
•Seizures
•Hemiplegia •Aphasia •Ataxia •Syncope •Decorticate rigidity |
|
Supratentorial lesions are more common in _____ and infratentorial lesions are more common in ______
|
adults- supratentorial
Children- infratentorial (think infant-tentorial) |
|
What are two characteristics of skull masses?
|
–May be highly vascular
–Rarely elevates ICP |
|
What is the most common type of brain mass? How does it usually present?
|
Glioma (aka astrocytoma)- often presents as seizures, very poor prognosis
|
|
Tumors of the meninges are called _____. Name two important features.
|
Meningioma;
–Seizures Common –May be highly vascular |
|
Where do Vestibular Schwannomas arise? What cranial nerves might they involve?
|
Arise at CN VIII (vestibulocochlear), –Also affects 5, 7,8,9,10,11
–9 & 10 involvement may depress airway reflexes. |
|
Infratentorial lesions may result in what 2 broad categories of symptoms? Name the symptoms
|
Cerebellar dysfunction
•Ataxia •Nystagmus •Dysarthria Brainstem Compression •Cranial nerve palsies •Altered LOC •Altered respiratory patterns •Decerebrate rigidity |
|
Signs of infratentorial compression may also be caused by
|
herniation of a supratentorial lesion into the infratentorial space
|
|
Loss of ability to think rapidly and clearly; impaired judgment and decision-making
|
Confusion
|
|
Beginning loss of consciousness; disorientation to time followed by disorientation to place and impaired memory; lost last is recognition of self
|
Disorientation
|
|
Limited spontaneous movement of speech; easy arousal with normal speech or touch; may or may not be oriented to time, place, or person
|
Lethargy
|
|
Mild to moderate reduction in arousal (awakeness) with limited response to the environment; falls asleep unless stimulated verbally or tactiley; questions answered with minimum response
|
Obtundation
|
|
What is a potential drawback to use of meperidine
|
Normeperidine accumulation and cardiac depression
|
|
When choosing fluids for a neurosurgical patient, what should you avoid?
|
–Glucose containing solutions
–Hypoosmolar solutions (LR) –Albumin |
|
Ventilatory considerations for neurosurgery patients
|
•Mild to moderate hypocapnia (EtCO2 25-30)
•Low intrathoracic pressures •PEEP? |
|
What are the benefits and drawbacks to early emergence in neurosurgical patients?
|
–Immediate assessment and intervention
–Less HTN or catecholamine surge –Anesthesia provider is present –Hypoxia or hypercapnia –Monitoring critical during transport and recovery |
|
What are the benefits and drawbacks to letting a neuro patient wait to wake up after surgery (late emergence/extubation)
|
–Less risk for hypercapnia or hypoxia
–Confident respiratory and hemodynamic control –Controlled transfer to ICU –Continued benefits of anesthetics –Unable to monitor neuro status –Greater hemodynamic and catecholamine response |
|
How does venous air embolism occur?
|
•Subatmospheric pressure in an opened vein
–Air entrained into venous circulation Most common in sitting position, can happen with any surgery where surgical site is more than 5 cm above level of r. atrium |
|
What is the gold standard for Venous air embolism detection?
|
TEE
|
|
What methods can be used to detect Venous air embolism?
|
Precordial doppler (most specific non-invasive method), PA catheter (rising PA pressures, but not specific for air), ET Nitrogen (detects earlier than ETCO2, specific for air), ETCO2 (abrupt decrease d/t increased dead space), TEE
|
|
What are symptoms of Venous Air Embolism?
|
•Decreased ETCO2
•ET Nitrogen •Increasing PA pressures •Dysrhythmias •Hypoxemia •Murmurs •RV failure |
|
What are the treatment modalities, priorities when a VAE has been detected?
|
•Notify Surgeon
–Flood field –Apply bone wax •D/C N2O •Increase O2 delivery •Aspirate RA catheter •Change position •Jugular vein compression •ACLS Place on left side, head up position |
|
What are the general, overall goals of treatment when a VAE has occurred?
|
–Stop further entry
–Remove air already present (can be done with CVL/PA catheter) –Correct hypocapnia, hypotension, hypoxemia |
|
Epidural hematomas arise from what vessels?
|
–Middle Meningeal Artery (90%)
–Dural Venous Sinus(10%) |
|
Superior spinocerebellar tract
|
Sends information from cerebellum to midbrain by way of red nucleus
|
|
Middle spinocerebellar tract
|
Relays information from Pons to cerebellum
|
|
Lower spinocerebral tract
|
Relays info from Medulla to cerebellum
|
|
salutatory conduction increases the velocity by _____ and decreases the number of ions used
|
5-50 times; by 100 times
|
|
Size of the synaptic cleft
|
200-300 angstroms
|
|
GABA and glycine work by:
|
Binding to and making Cl ions go into the cell and hyper polarize the cell so that it cannot respond as easily
|
|
GABA- A
GABA-B Class of neurotransmitter? |
Fast inhibitory in the CNS
Slow inhibatory in the CNS Amino acid |
|
Glycine
|
Inhibitory in the Spinal cord
|
|
Excitatory neurotransmitters
|
Serotonin, acetylcholine, glutamate, ATP, Substance P
|
|
Monamines are broken down by
|
MAO in the cleft, COM-t in the liver
|
|
Ach is broken down in the blood by
|
plasmacholinesterase
|
|
Temporal:
|
TALP: taste, abstract thinking (math), language, proprioception
|
|
Frontal:
|
I MISS: Intellectual, movement, inhibition, speech, smell
|
|
Wernickes area
|
Area in posterior temporal lobe responsible for understanding spoken language; input zone; say what? Hear but don't understand
|
|
Broca's area
|
Speech formation (expressive): frontal lobe
|
|
Temporal functions
|
MEAL: memory, emotion, awareness of sound and language
|
|
Ventromedial nucleus
|
Satiety center- damage leads to inability to ever feel full
|
|
paraventricular nucleus
|
Cause oxytocin secretion
|
|
Lateral hypothalamic nucleus
|
Thirst center (some hunger, too)
|
|
Supraoptic nuclei
|
Stimulates Posterior pituitary to secrete ADH, and thereby increases body water
|
|
Amino acid neurotransmitters:
|
GABA, Glutamate, Glycine
|
|
Glutamate: Class of neurotransmitter
Type of receptor? and action |
Amino Acid
AMPA- fast excitatory in CNS NMDA- slow excitatory in CNS Metabotropic: neuromodulation |
|
Purines: what neurotransmitters does this include?
|
adenosine, ATP
|
|
Adenosine- receptor and type of action
|
A1- neuromodulation
|
|
ATP- receptor types and type of action
|
PAX- Fast excitatory in CNS
PAV- neuromodulation |
|
Acetylcholine is an _____ neurotransmitter; what are its effects?
|
Ester
Nicotinic- fast excitatory at at NMJ and autonomic ganglia Muscarinic- slow excitatory or inhibitory depending on the innervated tissue |
|
What are the monoamine neurotransmitters?
|
NE, Serotonin, Dopamine
|
|
Serotonin- class, receptors, and method of transmission
|
Monoamine, 5HT3 receptors, in CNS, smooth muscle, and gut (fast or slow)
|
|
Dopamine: class, receptors, and method of transmission
|
Monoamine, D1 and D2, slow synaptic transmission in CNS, blood vessels, and gut
|
|
Peptides: what neurotransmitters fall into this category?
|
Substance P, Enkephalins, Endorphins
|
|
Substance P- receptor, location, and method of transmission
|
Receptors unknown, Slow excitation of smooth muscle and neurons in CNS
|
|
Enkaphalins: Receptors, location, and method of transmission
|
mu and (?) opioid receptors, Slow synaptic signaling (reduction in excitability). Decrease in gut motility. Promotes analgesia
|
|
B-Endorphin: receptors, location, and method of transmission
|
Κ-opioid receptors, Slow synaptic signaling analgesia
|
|
Inorganic gas: example, receptor, and method
|
Nitric oxide, Guanylyl cyclase receptor, results in synaptic modulation
|
|
What are 4 names for white matter within the brain and spinal cord
|
Fasciculus
Peduncle Column Lemniscus |
|
What are 5 other names for white matter outside of the brain and spinal cord
|
Nerve
Nerve fiber Root Nerve trunk Ramus |
|
Glutamate (and other excitatory neurotransmitters) cause ______ to be released from the cell and ______ the membrane potential
|
Calcium- causes the membrane to become hypopolarized (less negative) and therefore easier to create an action potential
|
|
Glyicine (and other inhibatory neurotransmitters) may cause ion pores for _______ to be opened, and cause _________
|
Chloride, hyperpolarization
|
|
Barbiturates work by ______
|
opening chloride channels, making nerves less excitable
|
|
Calcium is a very common and active ______ system
|
Second messenger system
|
|
Anesthetics are_____ mimetic
|
GABA
|
|
Cell bodies for sensory neurons reside:
|
In the dorsal route ganglia
|
|
Where are you trying to affect with local anesthetics?
|
The dorsal roots of the nerves (cell bodies located in dorsal route ganglia)
|
|
Central sulcus separates:
|
motor cortex from somatosensory area (pre central gyrus (motor) from post central gyrus (sensory))
|
|
Another name for the midbrain
|
Mesencephalon
|
|
What percent of the anterolateral tracts do not decussate immediately? What is the clinical significance of this?
|
Approx. 10% do not decussate immediately, so if you have a partial spinal cord transection, you may still feel some pain
|
|
Spinal nerve = (other names)
|
Second motor neuron = lower motor neuron = alpha motor neuron
|
|
Spinal nerves are ______ type
|
A alpha
|
|
Gamma motor neurons
|
smaller than alpha, keep general muscle tone
|
|
Sympathetic nervous system is more diffuse because
|
All of the cell bodies are linked through the paravertebral ganglia (sympathetic chain); stimulating one nerve can send impulses up/down the chain to the whole body very quickly
|
|
choline acetyltransferase
|
Manufactures acetylcholine
|
|
The vasoconstrictor zone of the vasomotor center is responsible for ______
|
Vasomotor tone; spinal cord transection causes loss of this tone and therefore lower blood pressure
|
|
Nitrous oxide causes ______ in response to______
|
Vasodilation in response to tension on vessel walls; cgmp is second messenger in this reaction
|
|
Cannot give _____ to Parkinson's patients
|
Reglan- dopamine antagonist
|