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26 Cards in this Set
- Front
- Back
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Briefly describe the two divisions of the PNS |
1. Somatic NS: Neurons that give voluntary signals to skeletal muscle 2. Autonomic NS: Neurons that involuntarily regulate glands, cardiac & smooth muscle Has 2 divisions: -Parasympathetic -Sympathetic |
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Where are the cell bodies located in somatic & autonomic PNS? |
Somatic: Cell bodies of motor neurons found mainly in CNS Autonomic: Has two motor neurons. Preganglionic cell bodies are found in CNS, while postganglionic are found in ganglia outside CNS |
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Describe origin of autonomic NS fibers and their axon lengths |
1. Sympathetic: Origin -Lateral gray horns of spinal cord from vertebral levels T1-L2 Axon - PreG short, PostG long (except to adrenal glands which does not have a PostG neuron) 2. Parasympathetic: Origin - Cranial nerves 3, 7, 9, &10 and S2-4 Axon - PreG long, PostG short (located near or in target organ) |
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Describe the various sympathetic neuron pathways (5 pathways) |
1. Lateral horn>ventral root>white ramus>synapses in symp. trunk/paravert. ganglia>gray ramus>target organ 2. Lateral horn>ventral root>white ramus>synapses in symp. trunk>mvmt up or down trunk>gray ramus>target organ 3. Lateral horn>ventral root>white ramus>passes through sympathetic trunk w/out synapsing>Splanchic plexus>prevertebral symp. ganglia>abdominal target organ 4. Lateral horn>ventral root>white ramus>passes through symp. trunk>passes through suprarenal glands>adrenal medulla 5. Exception: Lateral horn>ventral root>white ramus>synapses in symp. trunk>splanchnic plexus>heart & lungs target organs |
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Describe the various parasympathetic neuron pathways (3 pathways) |
1. Gray matter of brain>exit brainstem via cranial nerves 3, 7, or 9>synapses in "standalone" ganglia>innervates head 2. Gray matter of brain> exit brainstem via cranial nerve 10>synapses in "standalone" ganglia>innervates thoracic & abdominal viscera (85% of parasympathetic outflow) 3. Exits spinal cord via gray matter in S2-S4 regions>splanchnic nerve plexus>synapses in "standalone" ganglia>innervates pelvis |
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What are the main NTs and where are they released from? |
1. Ach: ALL preganglionic fibers; Symp cholinergic postganglionic fibers (Sweat glands/hair follocles) 2. Epi/NE: The majority of postG symp fibers (acts on glands, smooth muscle, and cardiac muscle); ALL postG parasymp fibers |
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What are the receptors that bind Ach & NE/Epi? |
Ach (2 cholinergic receptors): -Muscarinic R: Binds Ach & muscarine; ALL parasymp target organs & some symp cholinergic - sweat glands, hair follicles -Nicotinic R: Binds Ach & nicotine; found on ALL postG neurons Epi/NE (adrenergic Rs): majority of symp targets |
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Functions of the cranial nerves (3, 7, 9, 10) |
-CN III: Ciliary muscle of eye -CN VII: Lacrimal gland, submandibular & sublingual glands -CN IX: Parotid gland -CN X (vagus): Direct target organ stimulation (85% of parasymp outflow) |
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What are three kinds of sympathetic ganglia? |
1. Paravertebral/sympathetic trunk (beside vertebral column in chain sequence) 2. Pre-vertebral (in front of vertebral column, not connected to a chain) 3. Suprarenal Medulla (Above kidneys, not connected to a chain) |
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What can block muscarinic and nicotinic receptors? |
Muscarinic R: blocked by atropine & scopolamine (these block the normal functions of MRs -ex of normal- dec. HR, contract smooth muscle) Nicotinic R: blocked by a plant toxin 'curare' and some snakes venoms (competitve binding of toxins leads to wkness of skel. muscles and eventually death due to paralysis of diaphragm) |
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Where can we find muscarine? |
It's a water-soluble toxin derived from a mushroom, Amanita muscaria. If muscarine binds to a muscarinic receptor, it can cause convulsions and even death |
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There are 5 subtypes of muscarinic receptors (M1-M5). Where are they located? |
In two areas: 1. Postsynaptic parasympathetic junction 2. Postsynaptic sympathetic stimulation of sweat glands and hair follicles |
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What are the eye muscles controlled by postG symp fibers from the superior cervical ganglion? |
1. Dilator pupillae muscle 2. Superior tarsal muscle |
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Miosis |
When interruption of the symp postG signal to the dilator pupillae muscle occurs -Miosis is the constrictive effect of the pupils (permanent pupil constriction) |
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Ptosis |
When interruption of the symp postG signal to the superior tarsal muscle occurs -Ptosis is the effect of the eyelid permanently drooping |
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Hydropcephalus (General) |
The build up of CSF in the cranium -Too much being produced -Not enough reabsorption -Blockage in CSF pathway -Congenital & Aquired causes |
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Why is the skull expansion hyrdocephalus only seen in babies? |
The sutures in babies aren't yet fused. In adults, intracranial pressure would increase (sxs: severe headache, nausea, dizziness, sun-setting eyes, blurred vision) |
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Describe the two types of hydrocephalus |
1. Communicating (non-obstructive): Caused by disruption of uptake into subarachnoid space, but can flow freely through ventricles Congenital: Hemorrhage from birth trauma, rubella, toxoplasmosis, cytomegalovirus Acquired: infection, meningitis, subarachnoid hemorrhage, aneurysm 2. Non-communicating (obstructive): Caused by block in ventricles Congenital: aqueductal stenosis, stenosis of aperture Acquired: tumor, cyst/abscess, trauma In both cases, CSF must be drained to relieve pressure |
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What are some solutions to hydrocephalus? |
1. Drain fluid to relieve pressure (hydrocephalus shunt) 2. Short term sol.->Venticulostomy catheter - external ventricular drain 3. Long-term solution->Ventriculoperitoneal shunt - fluid drained into abdomen & reabsorbed |
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CSF Otorrhea |
Cause: Results from fracture of middle cranial fossa (parietal/sphenoid bones) Sx: Leakage of CSF from the external acoustic meatus |
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CSF Rhinorrhea |
Cause: Fracture of the ethmoid bone Sx: Leakage of CSF from nose |
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Epidural hematoma |
Results from traum (skull fracture). Since it involves arterial blood, this rapidly occurs after injury. Forms a disc shape (limited by sutures and stiff dura) Sx: Loss of consciosness, then awake, then rapidly deteriorate, ends in coma & death if not handled quickly |
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Subdural Hematoma |
-Results from a slamming/whiplash mvmnt -Tears bridging veins -Since it's venous blood, there is a slow pooling of blood in the subdural space -Since blood spread isn't limited, it forms a crescent shape at top of head -Sx: slow decline over days, dizziness, confusion, nausea |
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Subarachnoid Hematoma |
-No outside trauma, associated with an aneurysm that bursts -Suddenly someone gets a "thunder clap" headache -Arterial, so rapid symptoms occur -Sx: headache, vomiting, orbital pain -Since blood fills subarachnoid space, it displaces CSF |
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Spinal Tap |
Reasons for test: 1. If you suspect a CNS infection, the CSF will be carrying the waste products. 2. Check CSF pressure 3. Check for blood in subarachnoid You take it from subarachnoid space of L1/L2 so that there's less chance of piercing the spinal cord |
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Epidural block |
-Anesthetic injected into epidural space (at any level b/c not going near spinal cord) to block all incoming sensory signals from that level down -Used for pain control |
