Pathophysiology Exam 1
Parkinson & Dementia
- 50% of persons have depression, an inherent part of the pathologic state & not a situational response - 30% treated on outpatient basis have dementia; 80% of persons requiring institutional care have dementia - disorientation, confusion, memory loss, distractibility & difficulty w/ concept formation, abstraction, calculations, thinking & judgement - symptoms fluctuate & progressively worsen - anxiety disorders; impulse-control disorders; & punding - excessive daytime sleepiness is experienced in more than 50% of persons
Severity of Brain Injury
- 75% to 90% of head injuries are not severe - focal brain injury & diffuse axonal injury (DAI) each account for 1/2 of all injuries - focal brain injury accounts for more than 2/3 of head injury deaths; DAI less than one 1/3 of deaths - DAI accounts for the greatest number of severely disabled survivors; most severe diffuse brain injury caused by rotational acceleration is most likely to be located in the diencephalon to brainstem - hallmark of severe brain injury: loss of consciousness for 6+ hours; decreased level of consciousness
*Structure of Plasma Membrane
- Contain Caveolae: are a special type of lipid rat, are small invaginations of the plasma membrane. These flask-shaped structures are rich in proteins & lipids such as cholesterol & have several functions in signal transduction. They are also believed to play a role in endocytosis & the uptake of pathogenic bacteria & certain viruses - Lipid Bilayer: Amphipathic lipids (hydrophilic & hydrophobic); phospholipids, glycolipids & cholesterol - Carbohydrates
Disorders of Posture (Stance)
- Dystonia: dystonic postures & movements; decorticate posture; decerebrate posture; basal ganglion posture; senile posture
Alterations in Movement
- Hyperkinesia: excessive movement; chorea, wandering, tremor @ rest, postural tremor etc - Paroxymal dyskinesias - Tardive dyskinesia: the involuntary movement of the face, trunk & extremities; antipsychotic drugs cause denervation hypersensitivity so that it mimics the effect of too much dopamine - Hypokinesia: decreased movement, akinesia, bradykinesia, loss of associated movement
Protective Structures
- Meninges: protective membranes surrounding the brain & spinal cord: dura mater, arachnoid, pia mater - unlike the dura mater & arachnoid & inner dura, the delicate pia mater closely adheres to the surface of the brain & spinal cord & even follows the sulci fissures - cerebrospinal fluid (CSF) & the ventricular system; a clear colorless fluid similar to blood plasma & interstitial fluid; 125 to 150 ml; produced by the choroid plexuses in the lateral, third, and fourth ventricles; reabsorbed through the arachnoid villi - vertebral column: 33 vertebrae (7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral & 4 fused coccygeal; intervertebral disks (nucleus pulposus)
*Hypertonic & Hypotonic Solutions
- NaCl 0.9% is isotonic. >0.9% is hypertonic and <0.9% is hypotonic - a hypertonic solution has a concentration of more than 285 to 294 mOsm/kg - an example of a hypertonic solution is 3% saline solution - water can be pulled out of the cells by a hypertonic solution, so the cells shrink - water can pulled into the cells by hypotonic solution, so the cells swell
Cranial Nerve VI
- Name: Abducens - Function: Both; motor fibers to lateral rectus muscle; propioceptor fibers from same muscle to brain, allowing eyes to move laterally - Origin & Course: fibers leave inferior pons & exit from skull & extend to eye - To Test: tested in common with cranial nerve III relative to ability to move each eye laterally
Cranial Nerve VII
- Name: Facial - Function: Mixed; supplies motor fibers to muscles of facial expression & to lacrimal & salivary glands; carries sensory fibers from taste buds of anterior part of tongue - Origin & Course: fibers leave pons & travel through temporal bone & extend to face - To test: anterior 2/3 tongue test for ability to taste sweet, salty, sour & bitter; symmetry of face; pt closes eyes, smiles,w whistles; test tearing w/ ammonia
Cranial Nerve IX
- Name: Glossopharyngeal - Function:Mixed: motor fibers serve pharynx & salivary glands; sensory fibers carry impulses from pharynx, posterior tongue (taste buds) & pressure receptors of carotid artery - Origin & Course: fibers emerge from midbrain & leave skull & extend to pharynx, salivary glands & tongue - To test: gag & swallow reflexes checked; pt asked to speak & cough; posterior 1/3rd of tongue may be tested
Cranial Nerve XII
- Name: Hypoglossal - Function: Both: carries motor fibers to muscles of tongue & sensory impulses from tongue to brain - Origin & Course: fibers arise from medulla & exit from skull & extend to tongue - To test: Pt asked to stick out tongue & any position abnormalities are noted
Cranial Nerve III
- Name: Oculomotor - Function: Both; motor fibers to eye muscles (inferior oblique & superior,inferior & medial rectus extraocular) that direct eyeball, levator muscles of eyelid, smooth muscles of iris & ciliary body & propioception (sensory) to brain from extraocular muscles - Origin & Course: fibers emerge from midbrain & exit from skull & extend to eye - To Test: pupils examined & reflexes tested w/ a penlight; ability to follow moving objects
Cranial Nerve I
- Name: Olfactory - Function: Purely Sensory - Origin & Course: Fibers arise from nasal olfactory epithelium & form synapses w olfactory bulbs that transmit impulses to temporal lobe - To Test: Pt sniff aromatic substances i.e. oil of cloves & vanilla & identifies them
Cranial Nerve II
- Name: Optic - Function: Sensory - Origin & Course: fibers arise from retina of eye to form optic nerve, which passes through sphenoid bone; two optic nerves then form optic chiasm & eventually end in occipital cortex - To Test: vision & visual field tested w/ an eye chart; inside of eye viewed to observe blood vessels of eye interior
Cranial Nerve XI
- Name: Spinal Accessory - Function: Both; provides sensory & motor fibers for sternocleidomastoid & trapezius muscles & muscles of soft palate, pharynx, and larynx - Origin & Course: fibers arise from medulla & superior spinal cord & extend to muscles of neck & back - To Test: sternocleidomastoid & trapezius muscles checked for strength by asking Pt to rotate head & shrug shoulders against resistance
Cranial Nerve V
- Name: Trigeminal - Function: Both motor and sensory for face; sensory impulses from mouth, nose, surface of eye & dura mater; motor fibers that stimulate chewing muscles - Origin & Course: fibers emerge from pons & form 3 divisions that exit from skull & run to face & cranial dura mater - To Test: sensations of pain, touch & temp; corneal reflex tested with wisp of cotton; motor branch tested by asked subject to clench teeth, open mouth against resistance, & move jaw from side to side
Cranial Nerve IV
- Name: Trochlear - Function: Both; proprioceptor & motor fibers for superior oblique muscle of eye (extraocular muscle-downward & inward movement) - Origin & Course: fibers emerge from posterior midbrain & exit from skull to run to eye - To Test: tested in common with cranial nerve III:pupils examined & reflexes tested w/ a penlight; ability to follow moving objects
Cranial Nerve X
- Name: Vagus -Function: Both; fibers carry sensory & motor impulses for pharynx; a large part of this nerve is parasympathetic motor fibers, which supply smooth muscles of abdominal organs; receives sensory impulses from the viscera - Origin & Course: fibers emerge from the medulla, pass through the skull & descend through neck region into thorax & abdominal region - To Test: same as IX; gag & swallow reflexes checked; pt asked to speak & cough; posterior 1/3rd of tongue may be tested
Cranial Nerve VIII
- Name: Vestibulocochlear (acoustic) - Function: Purely Sensory; vestibular branch transmits impulses for sense of equilibrium; cochlear branch transmits or sense of hearing - Origin & Course: fibers run from inner ear (hearing & equilibrium receptors to temporal bone) to enter brainstem just below pons - To test: hearing checked by bone condution by use of a tuning fork; vestibular tests: Barany & caloric tests
The Cranial Nerves
- OOOTTAFVGVSH -SSMMBMBS...
Synaptic Transmission
- PM of presynaptic & postsynaptic neurons are close, but do not touch. The synaptic cleft is filled w/ interstitial fluid - for a nerve impulse to cross the SC, a # of structures are required: voltage-gated Ca2+ channels, synaptic vesicle containing a NT, postsynaptic neuron receptor & postsynaptic ligand-gated channels - for the stimulus to eventually discontinue, an enzyme must be present to break down the excitatory or inhibitory NT - disease can effect one or more of these structures, thus causing a prolonged excitatory or inhibitory response
*Somatic Nervous System
- PNS - motor & sensory pathways regulating voluntary motor control of skeletal muscle - NT: acetylcholine - spinal cord or brain ---> skeletal muscle
*Autonomic Nervous System
- PNS - motor and sensory pathways regulating the body's internal environment through involuntary control of organ systems (maintains steady state) - include the sympathetic and parasympathetic nervous systems - contains both preganglionic neurons (myelinated) & postganglionic (unmyelinated) - epinephrine will vasoconstrict, increasing BP, dilates bronchioles, elevates blood glucose level
Chemicals & Neurotransmitters of Pain
- Pain excitatory: Glutamate, sapartate - pain inhibitory: serotonin, GABA, endorphins - modulators of pain
*Nerve Injury & Regeneration
- Wallerian degneration - occurs distal to the cut :swelling appears, neurofilaments hypertrophy, myeline sheath shrinks & disintegrates, axon portion degenerates & disappears - proximal to the cut: swelling & dispersal of the Nissl substance; cell increases in metabolic activity, protein synthesis & mitochondrial activity; new terminal sprouts project from proximal segment; process limited to myelinated axons (usually only in PNS); depends on locate, type of injury, inflammatory response, & scar tissue formation
Temporal lobe
- Wernicke area (speech) responsible for - composed of the superior, middle & inferior temporal gyro - primary auditory cortex (Brodmann area 41) & its related association area (Brodmann area 42) lie deep w/ the lateral sulcus on the superior temporal gyrus
Subdural Hematoma
- a collection of blood between the inner surface of the dura mater & the surface of the brain, resulting from the shearing of small vins that bridge the subdural space - can result from blows, falls, or sudden acceleration/deceleration of the head i.e. shaken baby syndrome
Threshold
- a critical value that must be reached in order to generate an action potential - once reached, the cell will continue to depolarize w/ no further stimulation - the Na+ gates open & Na+ rushes into the cell, causing the membrane potential to reduce to zero & then become positive
*Relative Refractory Period
- a period after firing when a neuron is returning to its normal polarized state and will fire again only if the incoming message is much stronger than usual
*Repolarization
- after Na+ ions have rushed into the cell, K+ ions rush out of the cell to restore the balance and the original polarity
Cheyne-Stokes Respirations
- aka CSR - repeated cycle of increased rate & depth of breathing, then creased rate & depth of breath (cycle of hyperventilation & apnea) - happens in a number of conditions
Epidural Hematomas
- aka extradural hematomas - 90% have skull fracture - almost always arterial bleeds (85%); meningeal vein or dural sinus injury (15%) - most involve the middle meningeal artery in the temporal fossa - bood accumulates quickly & the individual is in imminent danger of death if not diagnosed & treated expediently
*Infarction
- an area of dead cells as a result of oxygen deprivation
Hyperalgesia
- an exaggerated sense of pain
Cerebral Edema
- an increase in the fluid content of brain tissues - a net accumulation of water within the brain - leads to increased intracranial pressure
*Gangrene
- an infected necrotic area (bacterial) - can be wet or dry depending on location (such as intestines or limb) - removed surgically to prevent spread of infection
Sensory Pathways
- anterior spinothalamic - lateral spinothalamic - posterior (dorsal): 3 neuron chain, ipsilateral transmission (on the same side), contralateral transmission (on the opposite side)
*Contusion
- bleeding into the skin or underlying tissues as a consequence of a blow
Subarachnoid Hemorrhage
- blood escapes from defective or injured vasculature into the subarachnoid space - manifestations: meningeal irritation & inflammation causing neck stiffness (nuchal rigidity); photophobia, blurred vision, irritability, restlessness & low-gradefever *positive Kernig sigh: straightening the knee w/ the hip & knee in a flexed position produces pain in the back & neck regions *Brudzinksi sign: passive flexion of the neck produces neck pain & increased rigidity may appear
Hemoprotein Accumulations
- caused by excessive storage of iron, which is transferred to the cells from the bloodstream
Vasogenic Edema
- caused by the increased permeability of the capillary endothelium of the brain after injury to the vascular structure - leads to increased ICP
*Membrane Transport: Cellular Intake & Output
- cell membranes act as a barrier to most, but not all molecules - cell membranes are semi-permeable barriers separating the inner cellular environment from the outer cellular environment - In general, the mechanisms of cellular exchange (intake and output) can be divided into passive & active movement across the cell membrane
*Hypoxic Injury
- cellular injury mechanism; single most common cause of cellular injury - ischemia (decrease of blood flow into vessels that supply oxygen & nutrients - anoxia (total lack of oxygen) - cellular responses: decrease in ATP (metabolic failure), causing failure of sodium-potassium pump and sodium-calcium exchange --> cellular swelling (Na+ influxes the cell and K+ outfluxes, water comes into the cell with the Na+ & the cell swells) --> cell death - dissolution of all cellular membranes is occurring simultaneously - reperfusion injury: return of blood to the site of injury, which can cause inflammation
Hindbrain (metencephalon)
- cerebellum - pons: the nuclei of cranial nerves V through VIII are located in the pons
*Hypopolarization
- changes membrane potential toward the point of threshold potential (less negative), promoting the excitatory effect of propagation of the impulse or neuron firing
Spinal Cord Trauma (tissues)
- chemical & metabolic changes in tissues * release of toxic excitatory amino acids, accumulation of endogenous opiates, lipid hydrolysis w/ production of active metabolites & local free radical release * produce further ischemia, vascular damage & necrosis of tissues * necrosis consumes 40% of cross-secetional cord w/in 4 hours of trauma & 70% w/in 24 hours * cord swelling increases degree of dysfunction; distinguishing functions to be lost permanently from those that are impaired temporarily become difficult; in the cervical region, cord swelling may be life threatening
*Neurotransmitters
- chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse
Blunt Brain Trauma
- close, non-missile - head strikes hard surface or rapidly moving object strikes the head - the dura remains intact; brain tissues not exposed to the environment - causes focal (local) or diffuse (general) brain injuries
Epidural hematoma
- collection of blood between the inner surface of the skull and the dura - caused by a torn artery & is almost always associated w/ a skull fracture
*Hematoma
- collection of blood in soft tissues or an enclosed space
Spinal Cord Trauma
- commonly occurs from vertebral injuries: simple fracture, compressed fracture & comminuted fracture - traumatic injury of vertebral & neural tissues to compressing, pulling or shearing forces - most common locations: C1,C2,C4-C7 & T1-L2 lumbar vertebrae; in the cervical region, S.C. swelling may be life threatening due to possible impairment of the diaphragm function (phrenic nerves C3-C5) - older adults are particularly at risk for minor trauma resulting in serious s.c. injury from falls, etc - manifestations: complete loss of reflex function in all segments below the level of the lesion; severe impairment below the level of the lesion is obvious; paralysis & flaccidity in muscles, absence of sensation, loss of bladder & rectal control, transient drop in BP & poor venous circulation
Brain Trauma
- compound fractures - basilar skull fracture - subdural & epidural (extradural) hematomas
Hemosiderosis
- condition in which excess iron is stored as hemosiderin in the cells of many organs & tissues
*Peripheral Nervous System
- consists of the 12 pairs of cranial nerves: sensory, motor & mixed - cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal), X (vagus) contain parasympathetic nerves - consists of 31 spinal nerves: afferent (ascending:sensory to spinal) & efferent (descending: enervate effector) pathways - names correlate w/ the vertebral level from which they exit; mixed nerves; arise from the anterior & posterior horn cells of the spinal cord - densely packed cell bodies are called ganglia
Midbrain
- corpora quadrigemina (tectum): superior & inferior colliculi - tegmentum: red nucleus & substantia nigra - basis pedunculi
*Ischemia
- deficit of oxygen in the cells as a result in a decrease in blood supply to the tissues - can lead to necrosis
*Free Radicals
- difficult to control and initiate chain reactions - can cause: lipid peroxidation or destruction of unsaturated fatty acids, alteration of proteins & alterations in DNA - "steal" electrons or give one up to become stable & thus hurt the "normal population" of cells; capable of injurious chemical bond formation w/ proteins, lipids, carbohydrates- key molecules in membranes & nucleic acids - i.e. ALS, cancer, heart disease and function decliness associated w/ aging - emerging date indicates that reactive oxygen species play major roles in the initiation & progression of cardiovasuclar alterations associated w/ hyperlipidemia, DM, hypertension, ischemic heart disease & chronic heart failure - antioxidants: react with oxidants to disarm them (vit C)
*Cellular Damage Secondary to Accumulations
- due to osmosis, cells may shrink or swell which result in impaired function - accumulations of pigments, lipids, calcium, enzymes etc also occurs in multiple disorders can alter the cell's ability to function properly
Pain Tolerance
- duration of time or intensity of pain that a person will endure (tolerate) before initiating pain responses - influenced by cultural perceptions, expectations, role behaviors & physical & mental health - decreased w/ repeated pain, fatigue, anger, boredom, apprehension & sleep deprivation - generally increased by alcohol consumption, persistent used of pain medication, hypnosis, warmth, distracting activities & strong beliefs or fain - varies greatly among people & in the same person over time
Autonomic Hyperreflexia
- dysreflexia - massive, uncompensated cardiovascular response to stimulation of the sympathetic nervous system - stimulation of the sensory receptors below the level of the cord lesion - visceral distention, spinothalamic tract to level of lesion, reflex stimulus to sympathetic outflow, increase BP stimulation of carotid sinus receptors, cranial & vagus nerve stimulation, bradycardia & autonomic response to hypertension
Upper Motor Neurons
- efferent pathways primarily relaying information from the cerebrum to the brainstem or spinal cord - synapse w/ interneurons - destruction= partial recovery -upper motor neurons (i.e. corticospinal tract) are the classfication of motor pathways completely contained w/in the CNS; their primary roles include directing, influencing, & modifying spinal reflex arcs, lower-level control centers, & motor (and some sensory) neurons
Diencephalon
- epithalamus - thalamus - hypothalamus: functions in maintenance of a constant internal environment & implementation of behavioral patterns - subthalamus
*Fat necrosis
- fatty tissue is broken down into fatty acids
Central Nervous System
- forebrain: cerebral hemispheres - midbrain: corpora quadrigemina, tegmentum & cerebral peduncles - hindbrain (brain stem): cerebellum, pons & medulla
Diffuse Axonal Injury
- formerly called primary brainstem injury or brainstem contusion - involves severe mechanical disruption of many axons in both cerebral hemispheres & those extending in the diencephalon & brainstem
Embolic Stroke
- fragments that break from a thrombus formed outside of the brain - high-risk sources for the onset of embolic stroke are atrial fibrillation (15 to 25% of strokes, left ventricular aneurysm or thrombus, left atrial thrombus, recent myocardial infarction, rheumatic valvular disease, mechanical prosthetic valve, nonbacterial thrombotic endocarditis, patent foramen ovale & primary intracardiac tumors - moving from another area of body; like DVT - arterial defibrillation = irregular contraction of atria; many Ps before QRS
*Parasympathetic Nervous System
- functions to conserve & restore energy- "rest or digest/repose response" - receives innervation from cell bodies located in the cranial nerve nuclei & sacral region of the spinal cord (craniosacral) - preganglionic neurons travel to ganglia close to the organs they innervate
Parasympathetic Nervous System
- functions to conserve and restore energy - cell bodies are located in the cranial nerve nuclei & the sacral region o the spinal cord - division of the ANS that is most active in ordinary conditions; it counterbalances the effects of the sympathetic system by restoring the body to a restful state after a stressful experience
Sympathetic Nervous System
- functions to mobilize energy stores in time of need - aka "Fight or Flight" response - prepares the body for emergencies and stress by increasing the breathing rate, heart rate, and blood flow to muscles - cell bodies located from T1 to L of the spinal cord - mediated by epinephrine & norepinephrine
*Phagocytic cells
- ingest & digest bacteria and cellular particulate - immunologic & inflammatory injury
*Cell Injury
- initial cell damage leads to loss of cell function (less oxygen to the area as well as ATP --> less function) - the damage can be reversible, if not, structural changes occur => cell death
*Action Potential
- initiated when adequate positive stimulus is applied to the cell - cellular membrane poteintial exists due to the ionic concentration difference across the membrane's permeability characteristics & active transport systems that maintain the ion concentration acorss the membrane; in the resting state, the inside of the cell membrane is negative w/ respect to the outside - the voltage arises from differences in concentration of the electrolyte ions K+ & Na+
Cerebral Death
- irreversible coma - death of the cerebral hemisphere exclusive of the brainstem & cerebellum - no behavioral or environmental responses - the brain can continue to maintain normal respiratory & cardiovascular functions, temperature control, & GI function - Survivors: remain in coma; emerge into a vegetative (wakeful unconscious) state; progress into a minimal conscious state: akinetic mutism (AK) & locked-in syndrome
Motor Pathways
- lateral corticospinal - corticobulbar - basal ganglia - vestibulospinal
Clinical Manifestations of Alterations in Arousal
- level of consciousness changes - pattern of breathing: posthyperventilation apnea and Cheyne-Stokes respirations - Pupillary changes: consensual reaction- when pupil will react due to other reacting - oculomotor responses (Doll's eyes) - motor responses - normal ICP is 10-15 mmHg - when neural control at this center is lost as consciousness decreases, the lower brainstem centers regulated the breathing pattern by response only to changes (increases) in PaCO2 levels; result is the irregular breathing associated w/ PHVA - rhythmic breathing returns when the PaCO2 returns to normal - vomiting is associated particularly w/ CNS injuries that: (1) involve the vestibular nuclei (located in the lower pons & medulla oblongata) or their immediate projections, particularly when double vision (diplopia) is also present
*Axons
- long threadlike extensions of motor neurons, which travel bundled within nerves , to muscle cells they serve; ends are called axon terminals - Nodes of Ranvier: regular interruptions of the myelin sheath - saltatory conduction: flow of ions between segments o myeline rather than along the entire length of the axon - divergence: ability of branching axons to influence many neurons - convergence: branches of numerous neurons converging on one for a few neurons
*Anoxia
- loss of oxygen
prefrontal lobe
- mediates several cognitive functions including vigilance, reasoning, & executive functions
Myelencephalon
- medulla oblongata: makes up the myelencephalon & is the lowest portion of the brainstem; reflex activities, such as heart rate, respiration, blood pressure, coughing, sneezing, swallowing, & vomiting - the nuclei of cranial nerves IX through XII are located here
*Sympathetic Nervous System
- mobilized energy stores in time of need- "fight or flight" response - receives innervation from he cell bodies located from the 1st thoracic thru the 2nd lumbar (thoracolumbar division) - sympathetic (paravertebral) ganglia
preganglionic neurons
- myelinated neurons with cell bodies located in the CNS - axons terminate in the autonomic ganglia.
Depolarization
- net movement of Na+ into the cell causes the membrane potential to decrease from a negative value to zero - the depolarized cell is more positively charged & its polarity is neutralized
Reticular Formation
- network of connected nuclei that regulate vital reflexes, such as cardiovascular & respiratory function - together w/ the cerebral cortex is referred to as the reticular activating system - the reticular formation is a large network of neurons w/in the brainstem that is essential for maintaining wakefulness
Lower Motor Neurons
- neurons having direct influence on muscle - cell bodies originate in gray matter of spinal cord, but their axons extend into the PNS - destruction=permanent paralysis
Spinal Shock
- normal activity of the s.c. ceases at & below the level of injury - sites lack continuous nervous discharges from the brain - complete loss of reflex function (skeletal, badder, bowel, sexual, thermal control; autonomic control) - indications of termination: reappearance of reflex activity, hyperreflexia, spasticity, & reflex emptying of the bladder
Intracranial Pressure
- normal: 5 to 15mmHG - increases caused by an increased intracranial content: tumor growth, edema, excessive CSF or hemorrhage
Focal Brain Injury
- observable brain lesion - cerebral edema - coup injury or contrecoup injury - force of impact typically produces contusions - contusions can cause: epidural hemorrhage or hematoma; subdural hematoma; intracerebral hematoma; clinical manifestations of contusion
*Active Transport
- occurs across membranes that have receptors that are capable of binding w/ the substances to be transported - other molecules cannot be driven across the plasma membrane solely by forces of diffusion, hydrostatic pressure, or osmosis b/c they are too large or are ligands that have bound w/ receptors on the cell's plasma membrane - protein mediated; active transport pumps; transport by vesicle formation (endocytosis-pinocytosis, phagocytosis, potocytosis)
*Coagulative Necrosis
- occurs primarily in the kidneys, heart, & adrenal glands - cell proteins are altered or denaturation - commonly results from hypoxia caused by severe ischemia or hypoxia caused by chemical injury (esp. mercuric chloride)
*Necrosis
- occurs when a group of cells die (autolysis) - includes liquefaction necrosis, coagulative, fat, caseous, and Infarction- lack of oxygen (MI) - an area of dead cells lose function, blood can not be pumped effectively & scar tissue replaces the cells
Action Potential
- occurs when a nerve or muscle cell receive a stimulus that exceeds the membrane threshold value causing a rapid change in the resting membrane potential - carries signals along the cell & conveys info from one cell to another
Brainstem Death
- occurs when brain damage is so extensive that the damage is irreversible & the brain has not potential for recovery - the brain has lost reflex function & body cannot maintain internal homeostasis - criteria: completion of all appropriate, therapeutic procedures; unresponsive coma (absence of motor & reflex responses); no spontaneous respirations (apnea); no cephalic (ocular or caloric) reflexes; isoelectric EEG & EKG; persistence for 1 hour & 6 hours after onset - apnea is viewed as a criterion of brainstem death, whereas vegetative state, coma & Locked in Syndrome reflect cerebral death
Doll's Eyes
- oculomotor response - a clinical sign for evaluating brainstem function in a comatose patient - in a normal person, as the head is turned rapidly to one side (contraindicated if there is a possibility of brainstem injury) the eye conjugately deviate in the direction opposite to the head's movement - loss of this reflex implies dysfunction of brainstem or oculomotor nerves - inferolateral deviation of the eyes in combination w/ pupillary dilation implies dysfunction of the 3rd cranial nerve, possibly due to tentorial herniation
Neurotransmitters & Neuroreceptors
- one NT can have different effects in different postsynaptic cells; one type of NT can bind to several types of receptors in the postsynaptic PM, each type producing different effects when stimulated - sympathetic nervous system w/ the NT norepinephrine and alpha & beta receptors - the exceptions; for example, Beta receptors in the conductive tissues of the heart mimic alpha effects - sympathetic preganglionic fibers: acetylcholine & cholinergic receptors - sympathetic postganglionic fibers: norepinephrine & adrenergic receptors - parasympathetic pre- and postganglionic fibers: acetylcholine & cholinergic receptors (spinal cord or brain -->(ACh) @ peripheral ganglion --> (ACh) @ organ: post-ganglionic)
*Membrane Transport Mechanisms: Osmosis and Diffusion
- osmosis involves the body's attempts to maintain the same concentration of solvent (water) to solute (sodium) across all 3 body fluid compartments (intracellular, vascular, interstitial) - Ex: if hydrogen moves into the cell, a K+ moves out of the cell so that the electrolyte make up of all the cell remains neutral; it is compensatory, but ultimately can cause problems such as high blood potassium in acidosis as K+ moves out of the cell to "make room" for H+ inside the cell - when water osmoses into or out of the cell in excess, the cell will or shrink
Cerebellum
- part of the hindbrain in the brain steam - the cerebellum is responsible for conscious & unconscious muscle synergy & for maintaining balance & posture
* Mediated (Protein) Transport
- passive & active - involves integral or transmembrane proteins with receptors having a high degree of specificity for the substance being transport - inorganic anions & cations (Na+, K+, etc) & charged & uncharged organic compounds (e.g. amino acids, sugars) require specific transport systems to facilitate movement through different cellular membranes - Ex: in type 2 DM, the cell membrane protein (receptor) for insulin is deficient in # or function; many drugs increase the # of receptors for insulin
Open Brain Trauma
- penetrating, missile - injury breaks the dura & exposes the cranial contents to the environment - causes primarily focal injuries
Repolarization
- period in which the negative polarity of the resting membrane potential is reestablished - as voltage-gated Na+ channels begin to close, voltage-gated K+ channels open - membrane permeability to Na+ decreases & K+ permeability increases w/ an outward movement of K+ ions - Na+ gates close & w/ outward movement of K+, the membrane potential becomes negative - the Na+-K+ pump then returns the membrane to resting potential by pumping K+ back into the cell & Na+ out of the cell
Temperature Regulation
- peripheral thermoreceptors - hypothalamic control - heat production & conservation: chemical reactions of metabolism, skeletal muscle contraction, chemical thermogenesis, vasoconstriction, voluntary mechanisms
Frontal lobe
- prefrontal: goal-oriented behavior i.e. ability to concentrate, short-term or recall memory & the elaboration of though & inhibition of the limbic (emotional areas) - premotor: basal ganglia-Parkinson disease & Huntington disease are conditions associated w/ defects of the basal ganglia - primary motor area: Brodmann area 4 is located along the precentral gyrus forming the primary voluntary motor area. Electrical stimulation of specific areas of this cortex causes specific muscles of the body to move - Broca speech area: responsible for the motor aspects of speech. articulation of words
Occipital lobe
- primary visual cortex (Brodmann area 17) - receives input from the retinas - visual association
Multiple Sclerosis
- progressive, inflammatory, demyelinating, autoimmune disorder of the CNS - degeneration of the myelin sheath in CNS neuron & loss of axons
Sympathetic Stimulation
- promotes responses that are concerned w/ the protection of the individual that would include increased blood sugar levels & temperature & BP - the primary response from norepinephrine (levophed) is stimulation of alpha1-adrenergic receptors that cause vasoconstriction
Heat Loss
- radiation - conduction - convection - vasodilation - decreased muscle tone - evaporation - increased respirations - voluntary measure - adaption to warmer climates
*Hypoxia
- reduced oxygen in tissues - the single most common cause of cellular injury - can lead to anoxia
Aging & Pain
- research studies are conflicting - increase in pain threshold: peripheral neuropathies, skin thickness changes - decrease in pain tolerance -alteration in metabolism of drugs & metabolites
*Liquefactive Necrosis
- results from ischemia injury to neurons & glial cells in the brain - dead cells liquefy due to release of hydrolytic enzymes
Spinal Cord
- secretions: cervical, thoracic, lumbar & sacral - horns: posterior, lateral, anterior - blood supply provided by the vertebral arteries (anterior & posterior spinal arteries) & aorta
Parkinson's Disease
- severe degeneration of the basal ganglia (corpus striatum) involving the dopaminergic nigrostriatal pathway - manifestations: rigidity, bradykinesia, tremor; postural abnormalities; autonomic & neuroendocrine symptoms; cognitive-affective symptoms
Parietal lobe
- somatic sensory input
Forebrain
- telecephalon: cerebrum --> gyric, sulci, & fissures; gray matter & white matter - cerebral nuclei (basal ganglia)
*Plasma Membrane Transport
- the PM is a barrier to many solutes - a solute has a greater likelihood of crossing the plasma membrane if one or more of the following criteria are met: small molecular size, neutrally charged, lipid soluble, or presence of a specific transport protein - water soluble substances cannot get through the hydrophobic cell membrane without help; the fatty cell membrane repels water
Supratentorial
- the area located above the tentorium cerebellum - contains the cerebrum
Infratentorial
- the area of the brain located below the tentorium cerebelli, the infratentorial region contains the cerebellum - disease process include compression of the brainstem resulting from hematomas, hemorrhage & aneurysm as well as cerebellar hemorrhage, infarcts, abscesses, enoplamsa & demyelinating disorders
Synapses
- the binding of the NT at the receptor site changes the permeability of the postsynaptic neuron & consequently, its membrane potential
*Central Nervous System
- the brain and spinal cord - densely packed cell bodies are nuclei
Blood Supply to the Brain
- the brain receives approx. 20% of the cardiac output or 800 to 1000 ml of blow flow per minute - CO2 is the primary regulator for CNS blood flow internal carotid & vertebral arteries - arterial circle (circle of Willis): a structure credited w/ the ability to compensate for reduced blood low from any one of the major contributors (collateral blood flow) - the choroid plexuses, structures that produce CSF, arise from the pia mater - CSF is reabsorbed by means of a pressure gradient btw the arachnoid villi & the cerebral venous sinuses
Blood-Brain Barrier
- the capillary walls of the brain serve as barriers for the movement of selected chemicals & molecules from the blood to the brain tissue - an example of a set of sieves w/ different gauges of mesh helps illustrate how some substances are allowed to pass through & others are not, depending on the composition & size of the substance in relation to the mesh size of the sieve
Resting Membrane Potential
- the difference in electrical charge/voltage across the plasma membranes as a result of differences in ionic composition of ICF and ECF (-70 mV to -85mV) - Na+ have a higher conc in the ECF and K+ in the ICF; the concetration diff. is maintained by active transport of Na+ and K+
*Threshold potential
- the electrical charge or potential difference at which an action potential will occur
*Filtration
- the greater the force of blood flow (hydrostatic pressure) within a capillary, the greater the filtration out of the capillary
Threshold intensity
- the intensity @ which a stimulus (eg. heat, pressure) beings to evoke pain - so if a hotplate on your skin begins to hurt at 107degF, then it is the pain threshold temp for that bit of skin at that time
Relative Refractory Period
- the latter phase of the action potential, when permeability to K+ increases, a stronger-than-normal stimulus can evoke an action potential
Pain Threshold
- the point at pain beings to be felt; entirely subjective; the intensity @ which a stimulus (e.g. heat, pressure) beings to evoke pain is the threshold intensity - does not vary significantly among people or in the same person over time - the intensity @ which a stimulus beings to evoke pain varies from individual to individual & for a given individual - intense pain @ one location may cause an increase in the threshold in another location
*Depolarization
- the process during the action potential when sodium is rushing into the cell causing the interior to become more positive
Absolute Refractory Period
- the time during the action potential in which the plasma membrane cannot respond to an additional stimulus - related to changes in permeability to Na+
Direct Excitation
- threshold depolarization from direct stimuli
Indirect Excitation
- threshold depolarization from inflammatory mediators after tissue injury - increased sensitivity due to inflammatory mediators - i.e. sunburn
Thrombotic Stroke
- type of ischemic stroke - arterial occlusions caused by thrombi formed in arteries supplying the brain or in intracranial vessels - transient ischemic attacks (for short period of time; decrease blood supply) - blockage in brain
postganglionic neurons
- unmyelinated - ANS neurons that exist outside the brain and spinal cord and innervate the major organ systems -- ACh used as a transmitter in parasympathetic postganglionic neurons
Subdural Hematomas
- venous bleeds that can be acute (w/in 48 hours, often located at the top of the skull) or chronic (develops over weeks to months-older adults, alcohol abuse) - chronic: complain of chronic headaches & have tenderness at site of injury - 10 to 20% of person w/ traumatic brain injury - MVAs are the most common cause - also occur due to falls (older adults, substance abuse) - usually located in the top of the skull & most often resulting from tearing of the bridging veins - 50% associated w/ skull fractures - may need surgical removal, depending on their size
Consciousness
- viewed as having 2 distinct components: arousal & awareness - arousal: an attentional system, is the state of awakens that an individual exhibits; level of arousal - mediated by the reticular activating system -awareness: all the cognitive functions that embody awareness of self, environment, & affective states (i.e. moods) - content of
*Passive Transport
- water and small electrically uncharged molecules move easily through pores in the plasma membrane's lipid bilayer; occurs naturally through any semipermeable barrier - driven by osmosis , hydrostatic pressure & diffusion - does not require energy expenditure & substances move down a concentration or pressure gradient by diffusion, osmosis, filtration & carrier-mediated facilitated diffusion - the most widely referred to passive transport system is that for glucose in erythrocytes
*What causes the rapid change in the resting membrane potential that initiates an action potential?
- when a resting cell is stimulated through voltage-regulated channels, the cell membranes become more permeable to Na+. There is a net movement of Na+ into the cell & membrane potential decreases. - Na+ gates open & Na+ rushes into the cell, changing the membrane potential from negative to positive (depolarization) - when it becomes sufficiently positive, the Na+ channels close & the K+ channels open - Now K+ leaves the cell, & the membrane potential becomes more negative (repolarization) - Hyperpolarization (undershoot) - the return of the membrane potential to the resting level is completed by the Na+/K+ pump, which exchanges the inside Na+ for the outside K+
*Hyperpolarization
- when axon is repolarizing, more K+ ions leave the cell, causing the cell to become MORE polarized than before it started
*Membrane Potential
- when the cell is inactive, its a resting potential - at resting state the inside of the cell membrane is negative (-70mV to 90 mV) - to balance positive charges, the inside of the cell contains proteins that have a negative charge & are too large to pass thru the cell membrane easily
Hyperpolarization
- when the membrane potential is more negative than normal, the cell is in a less excitable state - a larger-than-normal stimulus is required to reach the threshold potential & generate an action potential - occurs as K+ continues to leave the cell, after the Na+ gates have close, and (undershoots) causing a drop in membrane potential
Hypopolarization
- when the membrane potential is more positive than normal - a more excitable than normal state & a smaller-than-normal- stimulus is required to reach the theshold potential
Hemorrhagic stroke
-ICH - lacunar stroke: a microinfarct smaller than 1 cm in diameter; b/c of the subcortical location & small area of infarction, these strokes may have pure motor & sensory deficits - cerebral infarction -cerebral hemorrhage
Explain the fourth different type of tissues
Ans: (1) Epithelial tissue is found on most internal & external surfaces of the body. B/c of their different locations, epithelial tissues have different functions. Ex: the epidermis provides protection from outside trauma. Epithelial cells found in the respiratory passages assist in moving particles out of the body. (2) connective tissue: provides strength in binding different types of tissues & organs together. As opposed to the epithelial tissue, connective tissue contains an enormous amount of extracellular matrix & is classified as either dense or loose. (3) Muscle tissue is made up of long, slim fibers that highly contract. there are different types of muscle tissue: skeletal, cardiac & smooth. (4) Neural tissue is composed of highly specialized cells that quickly receive & transmit nerve impulses across synapses. The total number of neurons is determined at birth.
What specific mechanisms could be targeted by a drug that would block the transmission of impulses across a synapse?
Ans: A drug could block the release of the neurotransmitter, block the binding of the neurotransmitter to the postsynaptic neuron, or encourage the removal of the neurotransmitter from the synaptic cleft. All three of these mechanism could block the transmission of an impulse across a synapse
What are the causes and risk factors associated with a hemorrhagic stroke?
Ans: A hemorrhagic stroke has several causes. These include hypertension (56% to 81%), ruptured aneurysm, vascular malformations, bleeding into the tumor, hemorrhage linked to bleeding disorders or anticoagulation, head trauma, and illegal drug use. The risk factors include hypertension, previous cerebral infarct, coronary artery disease, and diabetes mellitus
Mr. Black was working in his garage when one of the shelves gave way & landed on his head. He was brought to the ER & was diagnosed w/ a subarachnoid hemorrhage. What causes subarachnoid hemorrhage?
Ans: A subarachnoid hemorrhage occurs when there is trauma to the inter cranial vessels. Signs & symptoms include neck stiffness, Kernig sign, & low back pain
Discuss why proteins & lipids in plasma membranes are dynamic & asymmetrically distributed.
Ans: According to the fluid mosaic model, biologic membranes are dynamic & change in response to cell needs. Lipids are very fluid & mobile in the PM. They are not asymmetrically distributed but are also capable of fairly free lateral & rotational mobility. Asymmetric distribution of lipid changes plasma fluidity, which affects the flexibility & curvature of membranes. The type of fatty acid & the length of the fatty acid chains affect fluidity. For example, cholesterol, a small molecule w/ a small OH head group occurs @ he bilayer surface, decreasing fluidity & increasing the mechanical strength & stability of the membrane. Proteins define the specific function of the membrane b/c they are asymmetrically distributed. They can be either integral (intrinsic) or peripheral & float either singly or in an aggregate w/in the membrane. Integral proteins are associated directly w/ the lipid bilayer. Peripheral membrane proteins are associated ionically w/ hydrophilic lipid molecule heads or other proteins
Describe decrease in voluntary movement
Ans: Akinesia Exp: Akinesia is an absence, poverty, or lack of control of associated & voluntary muscle movements. There is a disturbance in time it takes to perform a movement
Two individuals come to the emergency department with head injuries. One, 25 years old, has just been in a motor vehicle accident (MVA) and has a temporal lobe injury. The other, 65 years old, has increasing confusion after a fall that happened earlier in the week. How could you clinically differentiate between the individual with the extradural hematoma and the individual with the subdural hematoma? Which one of these individuals requires priority surgical treatment?
Ans: An extradural hematoma or epidural hemorrhage is a rapidly accumulating arterial bleed occurring between the skull and dura mater. Injuries to the temporal lobe are often associated with extradural hematomas because the middle meningeal artery runs in a groove on the surface before entering the skull. Extradural hematomas are most commonly caused by MVAs and are frequently associated with temporal lobe injuries. An epidural hemorrhage is characterized by loss of consciousness at the time of injury, followed by a lucid period. Within a few hours symptoms progress from severe headache, vomiting, and drowsiness to confusion, seizures, ipsilateral pupillary dilation, and contralateral hemiparesis. An extradural hematoma is always a medical emergency, so the individual in the MVA requires priority surgical treatment...A subdural hematoma is a venous bleed occurring between the dura mater and the arachnoid mater. Subdural bleeds occur more slowly, ranging from hours to weeks. The range in the delay depends on how many veins were torn, the size of the epidural space, and the amount of compression on the bleeding veins. Once a vein is torn, it will bleed and compress the brain. As intracranial pressure increases, the bleeding veins are compressed, slowing the amount of bleeding. A subdural hematoma can also be caused by an MVA but is commonly the result of falls in older adults, in whom the symptoms vary from a chronic headache and drowsiness to slowed cognition, confusion, progressive dementia, and paratonia (generalized rigidity). A subdural hematoma requires surgery to evacuate the clot but does not take priority over the individual with the extradural hematoma.
A right hemisphere emoblic cerebrovascular accident has resulted in left-sided paralysis & reduced sensation of the left foot & leg. The vessel most likely affected by the emobli is the right ___artery.
Ans: Anterior cerebral Exp: Symptomatology of an embolic stroke in the right anterior cerebral artery would include left-sided contralateral paralysis or paresis (greater in foot and thigh) and mild upper extremity weakness with mild contralateral lower extremity sensory deficiency with loss of vibratory and/or position sense and loss of two-point discrimination.
Explain how a deep-sea diver develops decompression sickness ("the bends")
Ans: As a diver descends, the pressure of gases in the body increases & more gas goes into solution. If the diver surfaces too quickly, the gases dissolved in the blood bubble out of solution. Oxygen dissolves very quickly back into solution but nitrogen does not. The gases form gaseous emboli that can obstruct blood vessels & cause ischemia. The gases can also accumulate in the joints & muscles. causing the diver to double up in pain, thus causing the bends.
What pathologic alteration produces tremors at rest, rigidity akinesia, & postural abnormalities?
Ans: Atrophy of neurons in the substantia nigra that produce dopamine Exp: The hallmark characteristics of Parkinson disease are a result of a loss of dopaminergic pigmented neurons in the substantia nigra (SN) pars compacta w/ dopaminergic deficiency in the putamen portion of the striatum includes the putamen & caudate nucleus
Why is autonomic dysreflexia dangerous?
Ans: Autonomic dysreflexia is a condition that occurs after spinal shock has resolved. A stimulus of the sympathetic nervous system causes a severe, uncompensated cardiovascular response. It is considered life threatening and requires immediate response. This syndrome occurs mainly in lesions at the T6 level or above. Signs and symptoms include paroxysmal hypertension (300 mmHg systolic), pounding headache, blurred vision, sweating that occurs above the lesion level, skin flushing, nasal congestion, nausea, piloerection, and bradycardia (30 to 40 beats/minute).
What complication is occurring for a person who has a spinal cord injury above T6 & is experiencing paroxysmal hypertension as well as piloerection & sweating above the spinal cord lesion?
Ans: Autonomic hyperreflexia Exp: Individuals most likely to be affected have lesions at the T6 level or above. Autonomic hyperreflexia is characterized by paroxysmal hypertension (up to 300 mmHg systolic), a pounding headache, blurred vision, sweating above the level of the lesion w/ flushing of the skin, nasal congestion, nausea, pilorection caused by pilomotor spasm, & bradycardia (30 to 40 beats/minute)
Of the following people, who is at the highest risk for a cerebrovascular accident (CVA)?
Ans: Black women older than 70 years age Exp: 50% of CVAs occur in persons older than 70 years. Strokes, however, do occur in a 3:10 ration (28%) in individuals younger than 65 years. Stroke tends to run in families. The incidence of stroke 2.5x higher in blacks in whites. Stroke prevalence in 2005 for black mean was 2.3 million compared to 3.4 million in black women. The risk of first ever stroke in blacks is almost twice of whites
Bobby, an energetic 10 year old is swinging on his swing set when he suddenly falls to the ground, shaking uncontrollably. His family lives out in the country & 40 min have gone by before the rescue team arrives. His mother who saw the incident said that he never stopped shaking the entire time. What happened to him?
Ans: Bobby is suffering from status epilepticus It occurs due to failing to take anti-seizure medications as scheduled or it may be due to not being effectively treated for epilepsy. It is considered a medical emergency because of the complication of cerebral hypoxia. In addition, Bobby is at risk for mental retardation, dementia, other types of brain injuries, aspiration & even death.
Define Expressive Dysphasia
Ans: Broca dysphasia Exp: Broca dysphasia is an expressive dysphasia of speech & writing but with retention of comprehension
Explain how cells are connected to form tissues & organs.
Ans: Cells can be bound together via the extracellular matrix that the cells secrete around themselves. It is an intricate network of fibrous proteins embedded in a watery gel-like substance composed of complex carbohydrates. It is like glue, but it provides a pathway for diffusion of nutrient wastes & other water-soluble traffic between the blood & tissue cells. Interwoven w/in the matrix are 3 types of protein fiber: (1) collagen: forms cable-like fibers or sheets that provide tensile strength or resistance to longitudinal stress; (2) elastin: a rubber-like protein fiber that is most abundant in tissues that are capable of stretching & recoiling; (3) fibronectin: promotes cell adhesion & cell anchorage..The matrix is not just for cellular attachment, it also helps regulate the functions of cell w/ which it interacts. The matrix helps regulate cell growth & differentiation.
How does the variety of cells differ in cell division?
Ans: Cells differ in variety of ways. First, adult cells from the nerves, lens of the eye, & muscle cells cannot replicate & divide. However, epithelial cells found in the intestine. lung, & skin can divide. These types of cells rapidly divide & complete the cycle in less than 10 hours.
Mr. Smith is suffering from head trauma due to a severe car accident. The computed tomography (CT) scan indicated that he has cerebral edema. Why is cerebral edema dangerous?
Ans: Cerebral edema is the fluid that accumulates in the brain. Once the trauma occurs on the brain, there is an increase of extracellular or intracellular tissue volume to the area. Cerebral edema can also cause infection, hemorrhage, tumor, ischemia, infarct or hypoxia. The dangerous effects are caused by blood vessel distortion, brain tissue displacement, & herniation of brain tissue from one brain compartment to another.
How do cells receive communication from the extracellular fluid surrounding them?
Ans: Chemical messengers such as ligands Exp: Channel opening & closing can be initiated in 1 of 3 ways: (1) by binding a ligand to a specific membrane receptor that is closely associated w/ the channel (G-proteins); (2) by changes in electric current in the plasma membrane, altering flow of Na+ & K+; & (3) by stretching or other chemical deformation of the channel
What effect does fetal alcohol syndrome (FAS) have on infants?
Ans: Cognitive impairment & facial anomalies Exp: FAS can lead to growth restriction, cognitive impairment, facial anomalies, & ocular disturbances
Sally, a nurse, injured her lower back while helping a nursing assistant get Mr. Pod from his chair back into bed. He weighs 300 pounds and was not steady on his feet in the transfer. Sally's diagnosis was a herniated L4 disk. What are her treatment options?
Ans: Conservatively, treatment options include traction, bed rest, heat and ice to painful areas, and effective analgesic anti-inflammatory medications. Surgical interventions may be needed if severe compression is apparent or if the conservative approach is not successful
What causes stage 1 of intracranial hypertension? Stage 1 intracranial hypertension is caused by the:
Ans: Displacement of cerebrospinal fluid (CSF) followed by compression of the cerebral venous system Exp: If intracranial pressure remains high after CSF displacement out of the cranial vault, cerebral blood volume is altered, which causes state 1 intracranial hypertension. Vasoconstriction & external compression of the venous system occur in an attempt to further decrease intracranial pressure
Clinical manifestations of Parkinson disease are cause by a deficit in which neurotransmitter?
Ans: Dopamine Exp: Parkinson disease is a commonly occurring degenerative disorder involving deficits of dopamine
What the difference between the absolute refractory period & the relative refractory period of the repolarization phase of impulse generation?
Ans: During the absolute refractory period the plasma membrane cannot respond to an excitatory stimulus, not matter how strong the stimulus is. The concentration of Na+ ions is too high w/in the cell to permit generation of an action potential. During the relative refractory period the cell is considered to be hyperpolarized or less excitable. Potassium ions are returning into the cell, & sodium ions are leaving. A stronger than normal excitatory stimulus can result in generation of an action potential
Mrs. Bronnell was brought to the E.R. department after suffering a seizure at home. Which diagnostic test is appropriate for this person & why?
Ans: Electroencephalography would be the appropriate test. The purpose of the test is to record electrical impulse impulses from the brain. It's helpful in determining the foci that caused the seizure activity.
Explain the role of electrolyes & non-electrolytes in body fluids.
Ans: Electrolytes consist of polarity in which they gravitate to a positive or negative pole. They are electrically charged ions make up 95% of the molecules of solute in body water. The concentrations of the anions & cations are responsible for how the electrical impulses transmit across the muscle & nerve cells
Which endogenous opioid is located in the hypothalamus & pituitary & is a strong mu-receptor?
Ans: Endorphins Exp: Endorphins were first discovered in the human PAG in 1979, b-endorphin being the best studied of the group. The synthesis & activity of b-endorphin are concentrated in the hypothalamus & pituitary gland
Describe lower motor neuron disorders
Ans: Flaccidity Exp: Lower motor neuron syndromes manifest with impaired voluntary & involuntary movements (i.e. hypotonia)
Brett reach into a clogged snowblower to clear the chute while it was still running. He completely severed one finger & partially severed another on hi left hand. AFter lengthy surgery to reattach his fingers, he has regained much of his motor ability but he has lost some of his sensory function. What factors are involved that affect the regeneration of Brett's neurons & neuron function?
Ans: For regeneration of neurons, the cell bodies must be intact. Cell bodies are in or near the CNS so Brett's injury did not involve the cell bodies. B/c his PNS neurons were involved, the chances of his neurons regenerating increases, but the Schwann cells must be functional. The newly created gap between the severed pieces cannot be too large or fill too rapidly w/ collaged fibers. Accumulation of collagen inhibits the excitability of the tissue.
A man was in an automobile accident in which his forehead struck the windshield. A blunt force injury to the forehead would result in a coup injury to the ___region.
Ans: Frontal Exp: The focal injury may be coup (directly below the point of impact). Objects striking the front of the head usually produce only coup injuries (contusions and fractures) because the inner skull in the occipital area is smooth.
What physiologic changes occur during heath exhaustion?
Ans: Hemoconcentration occurs because of the loss of salt & water. Exp: Heat exhaustion occurs when sufficient salt & water loss results in hemoconcentration.
Which mode of chemical signaling uses blood to transport communication to cells some distance away?
Ans: Hormone Signaling Exp: It involves specialized endocrine cells that secrete hormone chemicals (e.g. thyroid-stimulating hormone) released by one set of cells & travel though the tissue & through the bloodstream to produce a response in other sets of cells
Ms. Ellis has an annual Pap smear & gynecologic examination. 3 years ago, before her 3rd pregnancy, the pathology report of her Pap smear indicated she had hormonal hyperplasia. Her current Pap smear indicates she has atypical hyperplasia or dysplasia. What is the difference between these?
Ans: Hyperplasia- an increase in the # of normal cells. Ms. Ellis had normal hormonal hyperplasia cause by increased by increased cellular division. Estrogen was stimulating the uterine endometrium to grow & thicken in preparation for the ovum's implantation. Dysplasia or atypical hyperplasia-an abnormal change in the size, shape, or organization of mature cells. It most commonly occurs in epithelial membranes such as the uterus. It is strongly associated w/ neoplasia (malignant growth.) She will need more tests, eg biopsy.
Sally's husband has recently been diagnosed with late-onset familial Alzheimer disease (FAD). She wants to know what caused it and what the disease course will be.
Ans: In late-onset FAD there is a genetic defect on chromosome 19 that may be linked to aggregation & precipitation of insoluble amyloid (senile plaques) in brain tissue & blood vessels. The disease course varies from one individual to another, but eventually all persons affected with the disease will pass through 3 stages. IN stage 1, which lasts 1 to 3 years, her husband will seem apathetic, irritable or depressed, His memory will show impaired remote recall & defective new learning. He will have difficulty drawing simple pictures. His language will deteriorate, & he will be unable to recall the names of some objects. In stage 2, which lasts 2 to 10 years, her husband will seem indifferent & apathetic, will have a severely impaired recent & remote recall, will have fluent aphasia, will be unable to perform calculations or copy simple drawings, & will exhibit ideomotor apraxia. In stage 3, which lasts 8 to 12 years, her husband will have severely deteriorated intellectual functions, exhibit limb rigidity & flexion posture & be incontinent for urine & feces.
Why is cellular communication important to the survival of cells?
Ans: In order to maintain a stable environment, cells must have communication w/ each other. They communicate by forming protein channels that assemble nearby cell activities, activate receptors that affect the cells, & secrete chemicals that alert other cells of a change. Any discourse in cell communication leads to the onset of disease & affects the progression.
Where is the neurotransmitter norepinephrine secreted?
Ans: In the sympathetic postganglion Exp: Most postganglionic sympathetic fiber release norepinephrine (adrenaline). The remaining options do not reflect the correct site of norepinephrine secretion.
Mrs. Jones is 95 years old & is frustrated because of constant stiffness she suffers. What are some examples of a decrease in her tissue & systemic function as a result of her aging process?
Ans: Increase in peripheral resistance to blood flow is causing her stiffness; decrease in diffusion capacity of her lungs affects her breathing; decrease in renal plasma flow causing decreased production; muscle atrophy (decreased motor tone & contractility) affecting her mobilization
What are the characteristics if visceral pain?
Ans: It is perceived as poorly localized & is transmitted by the sympathetic nervous system Exp: Visceral pain refers to pain in the internal organs & the abdomen & is transmitted by sympathetic afferents. It is poorly localized b/c of fewer nociceptors in the visceral structures.
Joey is 16 & is the pitcher for the high school baseball team. In the 9th inning, Joey pitches a perfect knuckle ball. The batter swings hard & the ball hits him directly in the head. What kind of concussion did Joey experience?
Ans: Joey suffered a blow to the head. The injury will mirror the shape of the object. Bleeding will occur under the tissues b/c of the force of the injury which caused rupture of the blood vessels
What organs are affected by the type of necrosis that results from hypoxia caused by severe ischemia or caused by chemical injury?
Ans: Kidneys and heart Exp: Coagulative necrosis, which occurs primarily in the kidneys, heart & adrenal glands, commonly results from hypoxia caused by severe ischemia or hypoxia caused by chemical injury, especially ingestion of mercuric chloride
Which of the following transmit a never impulse at the highest rate?
Ans: Large myelinated axons Exp: If the myelin layer is tightly wrapped many times around the axon forming nodes of Ranvier, it increases conduction velocity & the neuron is referred to as myelinated. Larger myelinated axons transmit impulses at a faster rate
Which of the following is the most critical index of nervous system dysfunction?
Ans: Level of consciousness Exp: Level of consciousness is the most critical clinical index of nervous system function or dysfunction. An alteration in consciousness indicates either improvement or deterioration of a person's condition
What parts of the brain mediate the expression of affect, both emotional & behavioral states?
Ans: Limbic system & prefrontal cortex Exp: Expression of affect (emotional & behavioral states) is mediated by extensive connections w/ the limbic system & prefrontal cortex. The remaining options are not involve in these expressions
What are the major chemical components of the cell membranes?
Ans: Lipids and Proteins Explanation: The major chemical components of all cell membranes are lipids and proteins, but the percentage of each varies among different membranes.
Explain the differences between bacterial meningitis, aseptic meningitis, fungal meningitis, and tubercular meningitis.
Ans: Meningitis in general is an infection of the meninges caused by bacteria, viruses, fungi, parasites, or toxins. Bacterial meningitis mainly affects the pia mater and arachnoid, subarachnoid space, ventricular system, and the CSF. Meningococcus and pneumococcus are the common causes. Aseptic meningitis is an inflammation thought to be limited to the meninges. This type is mainly caused by viruses such as enteroviruses, mumps, herpes simplex 1 and 2, West Nile virus, Epstein-Barr, Colorado tick fever, and influenzavirus types A and B. Fungal meningitis is a chronic condition and much less common. Some of the most common infections include histoplasmosis, candidiasis, and aspergillosis. It frequently occurs in people with immune response impairment or problems with normal body flora. Syphilis, tuberculosis, and Lyme disease are also associated with fungal meningitis. Tubercular meningitis is the common and dangerous form of CNS tuberculosis. Mycobacteria enter the CSF causing a hypersensitivity reaction that results in a purulent exudate that affects the basal meninges, cerebrum, and spinal nerves. Recovery is 90% effective if caught early and treated with appropriate medications.
Mr. Blane was driving his 1954 Chevy Impala to a Red Sox baseball game when a deer jumped out in front of him on the highway. He swerved his car and hit a telephone pole instead. His head hit the windshield and he suffered severe head trauma. What specific kind of head injury did he suffer?
Ans: Mr. Blane suffered a coup and contrecoup brain injury. As his car hit the telephone pole, it threw Mr. Blane's head forward (coup) breaking the windshield, and then his head went backward (contrecoup).
Which nerves are capable of regeneration?
Ans: Myelinated nerves in the peripheral nervous system Exp: Nerve regeneration is limited to myelinated fibers & generally only in the PNS.
Which neurotransmitters inhibit pain in the medulla & pons?
Ans: Norepinephrine & serotonin Exp: Norepinephrine & 5-hydroxytryptamine (serotonin) contribute to pain modulation (inhibition) in the medulla & pons.
Explain normal changes in the central nervous system occurring with aging.
Ans: Normal changes in the CNS that occur w/ aging are structural, cellular, & functional...Structural changes include decreased brain weight, decreased size of primarily the frontal hemispheres, adherence of the dura mater to the skull, fibrosis & thickening of the meninges, narrowed gyri, widened sulci, increased size of the subarachnoid space, aberrations in vascular structures of the basal ganglia & enlarged ventricles...Cellular changes include decreased number of neurons, changes in dendrite structure, lipofuscin deposition, & presence of neurofibrillary tangles, senile plaques, & Lewy bodies...The major functional change that results from the structural & cellular changes is a progressive slowing in response seen w/ aging
A blunt force injury to the forehead would result in a countercoup injury to the ___ region.
Ans: Occipital Exp: The focal injury may be coup (directly below the point of impact) or contrecoup (on the pole opposite the site of impact). Objects striking the back of the head usually result in both coup and contrecoup injuries because of the irregularity of the inner surface of the frontal bones.
Dilation of the ipsilateral pupil following uncial herniation is the result of pressure on which of the following cranial nerves?
Ans: Oculomotor (CN III) Exp: The oculomotor cranial nerve (CN III) is involved in this manifestation of pupil dilation
Explain why O2 can easily cross a plasma membrane, whereas Na+ are unable to cross a plasma membrane
Ans: Oxygen is able to easily cross the plasma membrane because oxygen is soluble in the lipid core of the plasma membrane. Na+ is insoluble in the lipid core of the membrane & thus is actively transported by a pump that uses ATP for energy
Which mode of chemical signaling uses local chemical mediators that are quickly taken up, destroyed or immobilized?
Ans: Paracrine Signaling Exp: In paracrine signaling, cells secrete local chemical mediators that are quickly taken up, destroyed, or immobilized
Describe abnormal involuntary movement
Ans: Paroxysmal dyskinesia Exp: Paroxysmal dyskinesias are abnormal, involuntary movements that occur as spasmas
What prevents water-soluble molecules from entering cells across the plasma membrane?
Ans: Phospholipid bilayer Exp: The bilayer's structure accounts for one of the essential functions of the plasma membrane-it is impermeable to most water-soluble molecules b/c they are insoluble in the oily core region. The bilayer serves as a barrier to the diffusion of water & hydrophilic substances while allowing lipid-soluble molecules, such as O2 and CO2 to diffuse through it readily
Which form of cell communication is used to communicate within the cell itself & with other cells in direct physical contact?
Ans: Plasma membrane-bound signaling molecules (involving receptors) Exp: Cells communicate in 3 ways: (1) they form protein channels (gap junctions) that directly coordinate the activities of adjacent cells; (2) they display plasma membrane-bound signaling molecules (receptors) that affect the cell itself & other cells in direct physical contact; & (3) (the most common means) they secrete chemicals that signal to cells some distance away
What organic compound facilitates transportation across cell membranes by acting as receptors, transport channels for electrolytes & enzymes to drive active pumps?
Ans: Proteins Explanation: Proteins act a (1) recognition & binding units (receptors) for substances moving in & out of the cell; (2)pores or transport channels for various electrically charged particles called ions or electrolytes & specific carriers for amino acids & monosaccharides; (3) specific enzymes that drive active pumps that promote concentration of certain ions, particularly K+, w/in the cell while keeping concentration of other ions, like Na+ below concentrations found in the extracellular environment
Neurotransmitters affect the postsynaptic membrane by binding to:
Ans: Receptors Exp: In each type of chemical signaling, the target cell receives the signal by first attaching to is receptors
Describe upper motor neuron disorders
Ans: Spasticity Exp: An upper motor neuron syndrom is characterized by paresis or paralysis, hypertonia (spasticity), & hyperreflexia
Why are spinal nerves called "mixed nerves"?
Ans: Spinal nerves are called mixed nerves b/c they have sensory & motor neurons.
What is spinal shock?
Ans: Spinal shock is a complete cessation of spinal cord functions below lesion of injury. Physical characteristics include complete flaccid paralysis, no reflexes & extreme disturbances of bowel & bladder function.
Dilated & sluggish pupils, widening pulse pressure & bradycardia are clinical findings evident of which stage of intracranial hypertension?
Ans: Stage 3 Exp: Stage 2 of intracranial hypertension presents clinical manifestations that include decreasing levels of arousal, Cheyne-Stokes respiration or central neurogenic hyperventilation, pupils that become sluggish & dilated, widened pulse pressure & bradycardia.
What sequence causes autonomic hyperreflexia-induce bradycaria?
Ans: Stimulation of the carotid sinus to the vagus nerve to the SA node. Exp: The intact autonomic nervous system reflexively responds w/ an arteriolar spasm that increases blood pressure. Baroreceptors in the cerebral vessels, the carotid sinus, & the aorta sense the hypertension & stimulate the parasympathetic system. The heart rate decreases, but the visceral & peripheral vessels do not dilate because efferent impulses cannot pass through the cord.
The ability of the eyes to track moving objects through a visual field is primarily a function of the ___ colliculi * voluntary & involuntary visual motor movements (e.g. the ability of the eyes to track moving objects in the visual field
Ans: Superior Exp: The superior colliculi are involved w/ voluntary & involuntary visual motor movements (e.g. the ability of the eyes to track moving objects in the visual field). This is not the primary function of the remaining options.
Ms. Spinosa has increased intracranial pressure of 30 mmHg caused by a massive closed head injury. Explain the process of increasing intracranial pressure & discuss possible complications if the pressure is not decreased.
Ans: Supratentorial processess that cause a decreased level of consciousness are caused by injury somewhere above the tentorium. In this case, Ms. Spinosa suffered diffuse bilateral cortical dysfunction that caused widespread injury throughout the cerebral cortex & in the subcortical white matter. IN Ms. Spinosa's injury, her intracranial pressure increased from a normal 5 to 15 mmHg because of intracerebral hemorrhage or edema. The brain tissue is displaced, & the blood vessels are distorted...In stage 1 the increasing pressure forces the cerebrospinal fluid out of the cranial vault, compresses the intracranial veins, & increases venous vasoconstriction. Often intracranial pressure will not change during this stage b/c blood volume & CSF volumes are reduced...Stage 2 occurs when pressure is not relieved. Arterial blood vessels constrict, compromising oxygen supply. The systemic arterial system will also constrict to increase BP. There elevated system BP is an attempt to overcome the intracranial pressure...When intracranial pressure increases & approaches arterial pressure, stage 3 intracranial hypertension occurs. During the stage tissue hypoxia, hypercapnia, & acidosis occur. Autoregulation of blood vessel diameter is lost. Hypercapnia causes local vasodilation w/ subsequent increasing capillary permeability. As increasing cerebral edema occurs., ICP increases. Small changes in volume cause dramatic increases in pressure w/ decreased cerebral perfusion pressure...Stage 4 is characterized by herniation of the brain from the compartment of greater pressure to one of lower pressure. In Ms. Spinosa's case, the brain herniated downward (supratentorial herniation), causing central or uncal herniation. Blood supply & brain tissue are markedly compromised or completely cut off, causing further ischemia, hypoxia & hemorrhage in the herniated portion of the brain. When mean systolic pressure equals ICP, the blow to the brain sops
Compare & Contrast the sympathetic (SNS) & parasympathetic nervous (PNS)
Ans: The SNS is the "fight or flight" system & when activated produces a generalized & widespread response that mobilizes energy stores...Sympathetic stimulation promotes responses that are concerned w/ protection of the individual. The single most important function of this system is regulation of vasomotor tone, allowing it to shunt blood to areas of highest need in the body...In contrast, the PNS can be thought as the "rest and digest" system. It lacks the general widespread response of the sympathetic nervous system & functions to conserve & restore energy store...The actions of the two systems are usually antagonistic. However, exception to this include unopposed parasympathetic control of the shape of the lens of the eye for near vision & unopposed sympathetic regulation of vasomotor tone
Injury to the extrapyramidal motor system does not cause paralysis of voluntary movement & general spasticity. Explain why, & discuss the major motor symptoms seen in extrapyramidal motor disorders.
Ans: The extrapyramidal motor system includes all motor pathways in the brain & brainstem that are not part of the corticospinal or pyramidal motor pathways. This system includes the basal ganglia, reticular formation, & parts of the cerebellum. Disorders are classified as either basal ganglia motor or cerebellar motor syndroms. Both are characterized by little or no paralysis of voluntary movement; normal or slightly increased tendon reflexes; presence of tremor, chorea, athetosis, or dystonia; & rigidity or intermittent rigidity. Muscle tone & equilibrium are also affected
Mr. Crane has suffered an acute myocardial infarction. Describe the cellular process of this disease
Ans: The gradual narrowing of the arteries has occurred over the years. Suddenly, there is an obstruction of the coronary artery that may cause cell death of the myocardium if the blood supply is not recovered
Why does a person who has a spinal cord injury experience faulty control of sweating?
Ans: The hypothalamus is unable to regulate body heat as a result of sympathetic nervous system damage. Exp: The condition also results in disturbed thermal control b/c the hypothalamus is unable to regulate a damaged sympathetic nervous system. This damage causes faulty control of sweating & radiation through capillary dilation.
How do the 31 pairs of spinal nerves correspond to the to the vertebral column?
Ans: The names of the spinal nerves are derived from where they exit at the vertebral location. ONly the first cervical vertebra has the nerve exit above it. The remaining spinal nerves exit below the appropriate vertebrae.
A physician suspects that her 23-year-old patient has either bacterial or viral (aseptic) meningitis. What diagnostic information does she need to make her decision?
Ans: The physician will likely order a complete blood count (CBC), a white cell differential, and cerebrospinal fluid (CSF) analysis to include culture, Gram stain, cell count, and protein and glucose levels....Both types of meningitis demonstrate an increased white cell count, but the physician will look for a neutrophilic (bacterial) versus a lymphocytic (viral) response to help her make the decision. CSF cell counts should also show a neutrophilic response in bacterial meningitis and a lymphocytic response in viral...Gram-stain testing should reveal a bacterial organism with bacterial meningitis. Neisseria meningitidis is a common organism based on the age of this person...CSF protein levels increase in both types, but the increase is usually greater in bacterial meningitis because of the greater intensity of inflammation present in bacterial meningitis...Because of the consumption of glucose by the bacteria for metabolism and reproduction, the CSF glucose result will be out of the normal range on the low end. Viruses do not use the glucose present in the CSF, so the CSF glucose result will likely be in the normal range.
A bacterium is producing a toxin that causes flaccid paralysis. How might this toxin be the cause of this condition?
Ans: The toxin could block the release of an acetylcholine; block acetylcholine receptors, thus limiting the effects of acetylcholine; or increase the production of acetylcholinesterase
A bacterial toxin is producing a toxin that causes large groups of skeletal muscle to contract at the same time. How might this toxin be causing this condition?
Ans: The toxin could block the release or action of acetylcholinesterase, block inhibitory neurotransmitters to antagonistic muscles so antagonists contract w/ prime movers, or mimic the action of acetylcholine on postsynaptic receptors.
A victim of poisoning present with cherry-red appearance. How wold you determine what type of poisoning this victim has?
Ans: Toxins, eg, carbon monoxide, hydrogen sulfide, & hydrogen cyanide, directly interfere w/ cellular respiration; carbon monoxide & hydrogen cyanide cause a cherry-red appearance; to differentiate, lab tests must be done-presence of carboxyhemoglobin is diagnostic for carbon monoxide, drug test for cyanide.
Define Receptive Dysphasia
Ans: Wernicke aphasia Exp: Wernicke dysphasia is a disturbance in understanding all language-verbal & reading comprehension
Mr. White, 39, a construction worker, was admitted to the E.R. w/ a ruptured disk. He & another worker were carrying a 125-pound bag of concrete when his partner tripped on a rock & fell. Mr. White tried to hold the bag but felt excruciating pain in his lower back. The x-ray revealed a ruptured disk in L4. What happened to Mr. White?
Ans: When Mr. White's partner let go of the bag of concrete, it caused undo stress on his lower back. The disk ruptured & protruded through the spinal canal. The action caused the spinal cord to compress.
Using the fluid mosaic model, a cell is actively capable of protecting itself against injurious agents by:
Ans: altering the number & patterns of receptors to bacteria, antibodies & chemicals Exp: Hormones, bacteria, viruses, drugs, antibodies, chemicals that transmit nerve impulses, & other substances attach to the plasma membrane by means of receptor molecules on its outer layer. The number of receptors present may vary @ different times, and the cell is capable of modulating the effects of injurious agents by altering receptor # and pattern. This aspect of the fluid mosaic model has drastically modified previously held concepts concerning the onset of disease
The ___ is the membrane that separates the cerebellum from the cerebrum.
Ans: tentorium cerebelli Exp: The tentorium cerebelli is a membrane that separates the cerebellum below from the cerebral structures above. The remaining options do not perform the function described in the stem
Ms. Evans has a flexion injury with resultant incomplete spinal cord transection at level C4-C5. What symptoms would you expect Ms. Evans to have 1 month after her injury?
She would have Brown-Séquard syndrome with (1) ipsilateral paralysis below C4-5 with return of Babinski reflexes and ankle and knee reflexes; (2) ipsilateral loss of touch, pressure, vibration, and proprioception with possible paresthesia below the level of transection; and (3) contralateral loss of pain and temperature. She may experience autonomic hyperreflexia (dysreflexia). She may also have some reappearance of defecation and urination reflexes.
