NR-283 Pathophysiology - Set 5 - Part 1

Correct Answer: Fat embolism syndrome arising from marrow contents

Marrow fat enters torn venous sinusoids after a long bone fracture and lodges in lung capillaries, where released fatty acids injure endothelium. Hypoxemia, mental status change and a petechial rash follow within days. Option b is incorrect because a clot from the leg veins typically arrives later, is tied to immobility and calf findings, and produces no petechial rash over the shoulders and trunk. Option c is incorrect because wound sepsis brings fever, spreading erythema, purulent drainage and falling blood pressure. Nothing in this picture points to an infected incision, and petechiae are not a septic hallmark here. Option d is incorrect because compartment syndrome stays confined to the injured limb, announcing itself with unrelenting thigh pain and a rigid compartment. It does not cause confusion, rapid breathing or a rash on the chest.

Correct Answer: A soft cartilaginous callus bridging the fracture ends

Mesenchymal cells in the granulation tissue differentiate into chondrocytes and fibroblasts, laying a collagen rich cartilaginous bridge across the fracture. This soft callus precedes ossification into hard callus and clinical union. Option a is incorrect because remodeling is the final stage, running for months to years. It replaces woven bone with mature lamellar bone long after the callus stage this client has just entered. Option b is incorrect because hematoma formation happens within hours of the break, when torn vessels bleed and clot. That scaffold has already been cleared here, so the sequence cannot return to it. Option d is incorrect because hard callus requires endochondral ossification of a cartilage bridge that has not yet been built. Skipping straight to calcified woven bone leaves no template for mineral deposition.

Correct Answer: Urate crystals triggering an intense neutrophil response

Purine rich alcohol raises serum urate, and the cool peripheral first metatarsophalangeal joint lets monosodium urate crystallize. Neutrophils engulf the crystals and release inflammatory signals that produce sudden, severe redness, heat and swelling. Option b is incorrect because septic arthritis looks nearly identical and must be excluded, yet it usually brings high fever and rigors and follows bacteremia or a joint puncture rather than an alcohol binge. Option c is incorrect because degenerative cartilage loss develops slowly and produces aching that tracks with activity. It never explodes overnight into a scarlet, boiling hot joint that cannot tolerate light touch. Option d is incorrect because autoimmune synovitis of rheumatoid disease builds over weeks in several small joints on both sides. A single scorching toe after a drinking weekend points to crystal disease.

Correct Answer: Absent knee and ankle deep tendon reflexes

Molecular mimicry after infection sends antibodies against Schwann cell myelin, so nerve roots and peripheral nerves demyelinate. Conduction along the reflex arc fails, which makes areflexia a required feature of Guillain Barre syndrome. Option a is incorrect because brisk reflexes and clonus mark an upper motor neuron lesion in brain or cord. Peripheral demyelination does the reverse, silencing the reflex arc rather than releasing it from cortical restraint. Option b is incorrect because strength that returns after rest describes myasthenia gravis, where receptors at the endplate are blocked. Rest changes nothing here, since the myelin itself is under attack and conduction stays impaired. Option d is incorrect because a crisp sensory level points to a cord lesion such as compression or transverse myelitis. This illness spreads through peripheral nerves diffusely and produces patchy paresthesias without any sharp boundary.

Correct Answer: Bacterial meningitis requiring immediate antibiotic therapy

Bacteria and the neutrophil flood they attract consume glucose, and purulent exudate clouds the fluid while protein climbs. Low glucose with neutrophil predominance is the signature pattern, and treatment starts before cultures return. Option a is incorrect because viral disease leaves the fluid clear, the glucose normal, and lymphocytes as the dominant cell. Every value reported here runs the other direction, which rules that milder illness out. Option b is incorrect because healthy spinal fluid is clear and colorless with only a handful of lymphocytes, low protein and glucose near two thirds of serum. Cloudiness alone already excludes a normal result. Option c is incorrect because inflammation of brain substance shows a lymphocytic picture with normal glucose, and altered behavior dominates the presentation. A purulent sample with consumed glucose points squarely at bacteria in the subarachnoid space.

Correct Answer: Sodium moving inward through voltage gated channels

Reaching threshold opens voltage gated sodium channels, and sodium rushes down its gradient into the cell. That inward positive charge swings the interior from negative toward positive, which is the depolarization phase of the action potential. Option a is incorrect because potassium exit restores the negative interior rather than creating it. That outward flow defines repolarization, the recovery step that follows the sodium surge and precedes the brief hyperpolarization before the pump resets gradients. Option b is incorrect because calcium entry belongs at the synapse, where it triggers vesicles to dump neurotransmitter into the cleft. Its job is chemical signaling between neurons, not the electrical swing traveling along the axon. Option d is incorrect because chloride shifts push membrane voltage further from firing, adding to inhibition rather than excitation. Nothing in the sequence described here depends on chloride, so the impulse would never get started.

Correct Answer: Blood clogging the arachnoid villi and blocking absorption

Communicating hydrocephalus follows failed absorption. Blood breakdown products clog the arachnoid villi, so fluid still reaches the subarachnoid space but cannot drain into the venous sinuses, and every ventricle enlarges together as pressure builds. Option b is incorrect because aqueductal narrowing is a non communicating obstruction, and it would swell the lateral and third ventricles while leaving the fourth normal in size. Imaging here shows all four enlarged. Option c is incorrect because the choroid plexus almost never makes too much fluid. Production runs at a steady rate day after day, so hydrocephalus is nearly always a problem of blocked flow or failed reabsorption. Option d is incorrect because a mass at the fourth ventricle outlets is exactly what the imaging excludes. Such a lesion would also be a non communicating cause, whereas recent bleeding into the subarachnoid space fits this timeline.

Correct Answer: Avascular necrosis of the ischemic femoral head

Blood reaches the femoral head through a precarious retrograde supply that a neck fracture readily interrupts. The bone dies, loses structural support and collapses, which produces the progressive pain and the flattened joint surface. Option a is incorrect because delayed union simply means the fracture takes longer than expected before it finally knits. The bone eventually heals, and its articular surface stays intact rather than collapsing. Option b is incorrect because nonunion describes a fracture that never bridges, leaving persistent motion at the break and sometimes a pseudarthrosis. Imaging would show an unhealed gap, not a crushed articular dome. Option c is incorrect because malunion means healing occurred, but in a crooked position that shifts the mechanical axis. Deformity and later joint wear follow, yet the femoral head itself keeps its blood supply.

Correct Answer: Loss of dopamine producing neurons in the substantia nigra

Dopaminergic neurons of the substantia nigra project to the striatum and normally facilitate movement. As they die, acetylcholine becomes relatively excessive, basal ganglia output to the thalamus rises, and movement turns slow, small and hard to initiate. Option b is incorrect because antibodies against acetylcholine receptors describe myasthenia gravis, a neuromuscular junction disease. Its weakness builds with repeated effort and lifts after rest, a pattern nothing like the constant slowness of parkinsonism. Option c is incorrect because stripping myelin from central axons is what multiple sclerosis does. Conduction slows or fails along scattered tracts, producing visual loss, paresthesias and ataxia rather than rigidity with a resting tremor. Option d is incorrect because losing striatal inhibitory neurons is the Huntington lesion, and it frees movement instead of suppressing it. The result is chorea with excessive uncontrolled motion, the mirror image of what this client reports.

Correct Answer: Neurogenic shock from lost sympathetic outflow

Injury at or above the sixth thoracic level cuts sympathetic outflow while vagal tone continues. Vessels below dilate massively, pressure falls, and the heart cannot speed up, which is why bradycardia accompanies warm dry flushed skin. Option a is incorrect because spinal shock is a neurologic event, not a circulatory one. It explains the flaccid paralysis and vanished reflexes, yet by itself it does not move blood pressure or heart rate at all. Option b is incorrect because blood loss drives the pulse up and turns the skin cool, pale and clammy. The picture here runs the other way, although occult hemorrhage must still be ruled out in any trauma client. Option d is incorrect because sepsis takes time to develop and brings fever with a racing pulse. Hours after a fracture there has been no window for infection, and a slow heart rate argues strongly against it.

Correct Answer: The first has myasthenia gravis, the second Guillain Barre

Fatigable ocular and bulbar weakness that lifts with rest marks antibody blockade of acetylcholine receptors in myasthenia gravis. Ascending symmetric weakness with areflexia one to three weeks after infection marks demyelination of peripheral nerve in Guillain Barre syndrome. Option a is incorrect because only the first presentation sits at the endplate. Lost reflexes and an ascending course after infection place the second client in the peripheral nerve, where myelin rather than a receptor is destroyed. Option c is incorrect because the two labels are swapped. Drooping lids that worsen through the day belong to the junction disorder, and weakness climbing from the feet with lost reflexes belongs to the post infectious neuropathy. Option d is incorrect because demyelination explains only one of these clients. Myasthenia gravis leaves myelin untouched and instead destroys receptors on the muscle side of the synapse, which is why reflexes and sensation stay normal.

Correct Answer: Absent blood supply to the necrotic segment

Inflammatory exudate inside rigid bone raises pressure, thromboses the intraosseous vessels and kills a segment called a sequestrum. Without circulation, neither antibiotics nor immune cells reach it, so debridement is usually required. Option a is incorrect because resistance would show up as a poor response despite good tissue penetration. Here the drug never arrives at all, since the dead fragment has lost its vascular connection to the rest of the bone. Option b is incorrect because kidney clearance affects the serum level, which is corrected by adjusting the dose or interval. That adjustment still cannot push drug into tissue that has no circulation at all. Option d is incorrect because absorption problems are bypassed entirely by the intravenous therapy used for bone infection. The obstacle in chronic osteomyelitis sits at the tissue, where dead bone shields the organisms.

Correct Answer: Immune complex deposition inflaming many organ systems

Lupus generates antibodies against nuclear material, and the resulting immune complexes lodge in connective tissue throughout the body. Complement activation and vasculitis then inflame skin, joints, pleura, kidney and other organs at once. Option a is incorrect because runaway collagen production belongs to scleroderma, which hardens and tightens the skin and narrows small vessels. That disease does not produce a photosensitive facial rash with kidney protein loss. Option b is incorrect because gouty inflammation is confined to joints and periarticular tissue, arriving in sudden monoarticular attacks. Pleurisy, a facial rash and protein in the urine have no place in it. Option c is incorrect because amplified pain processing describes fibromyalgia, where examination and laboratory studies stay normal. This client has objective organ damage, including inflamed pleura and a kidney leaking protein.

Correct Answer: Mild or early stage disease

Repetition, misplacing objects without being able to retrace steps, and getting lost in familiar surroundings are hallmark early findings. Recent memory and complex task performance fail first because hippocampal neurons degenerate before other cortical regions. Option b is incorrect because middle stage disease brings aphasia, apraxia and agnosia, wandering, sundowning and dependence for bathing and dressing. This woman still drives and manages her household, so those deficits have not arrived. Option c is incorrect because late disease strips away meaningful speech and the ability to walk, sit up or swallow. Family members go unrecognized, incontinence is constant, and pneumonia usually ends life at that point. Option d is incorrect because Alzheimer disease is graded as mild, moderate and severe rather than by a separate terminal label. Total care belongs to the severe phase, which this woman has clearly not reached.

Correct Answer: Osteoarthritis with cartilage wear and marginal osteophytes

Mechanical pain that worsens with use and settles with rest, together with Heberden nodes at the distal interphalangeal joints, marks degenerative cartilage loss rather than an inflammatory joint disease. Option a is incorrect because rheumatoid disease attacks small joints symmetrically, spares the fingertip joints, and loosens up as the person moves. Its stiffness lasts more than an hour each morning. Option b is incorrect because a gouty attack erupts suddenly in one exquisitely red, hot joint, most often the great toe. Chronic activity related knee soreness with bony nodules is a different story. Option d is incorrect because fibromyalgia produces widespread soft tissue pain, fatigue and unrefreshing sleep with normal joints on examination. Hard bony enlargement at specific finger joints does not belong to it.

Correct Answer: Inflamed synovium proliferating into invasive pannus

Autoantibodies and cytokines drive chronic synovitis, and the swollen synovium grows into a tumor like tissue called pannus. Pannus creeps over cartilage and digests it, then erodes the bone at the joint margins. Option a is incorrect because bone spurs are the repair response of osteoarthritis, forming where cartilage has worn thin. They add bone at the rim instead of hollowing out the erosions seen here. Option b is incorrect because urate deposits belong to gout, where tophi and punched out lesions with overhanging edges appear. Rheumatoid destruction is driven by immune cells, not by crystals precipitating in tissue. Option c is incorrect because subchondral cysts sit under a degenerating cartilage surface and accompany joint space narrowing in wear and tear disease. They do not explain ulnar drift or margin erosion.

Correct Answer: Reactivation of varicella virus in a sensory ganglion

Varicella virus stays latent in a dorsal root ganglion after chickenpox. When cell mediated immunity wanes it travels down one sensory nerve, so the rash and the preceding burning pain follow a single dermatome. Option a is incorrect because a first exposure to this virus causes chickenpox, a generalized crop of lesions at different stages scattered over the whole body. A strictly one sided band is not how primary disease appears. Option c is incorrect because pemphigus arises when autoantibodies break the bonds holding epidermal cells together, so flaccid blisters start in the mouth and spread widely. Nerve territory means nothing to an antibody mediated process. Option d is incorrect because mast cell degranulation produces itchy wheals that come and go within hours anywhere on the body. Histamine driven swelling neither respects a dermatome nor announces itself with days of burning pain.

Correct Answer: Immunoglobulin E triggered mast cell histamine release

Hives are a type one reaction. Antigen cross links immunoglobulin E on mast cells, histamine floods the dermis, and fluid leaks into it, raising transient wheals that resolve as the histamine is cleared. Option b is incorrect because sensitized lymphocytes need hours to days to produce a rash, and that rash sits exactly where the substance touched skin. An eruption arriving within an hour of a meal is far too fast. Option c is incorrect because deposited immune complexes damage vessel walls, giving palpable purpura that lasts for days and often leaves staining. Fixed, bruise like lesions are the opposite of the fleeting swellings described. Option d is incorrect because a caustic or abrasive agent injures skin only where it lands, producing burning and scaling confined to that spot. Something swallowed reaches the skin through the bloodstream and needs an immune trigger.

Correct Answer: Large touch fibers inhibit the nociceptive transmission cells

Rubbing floods that spinal segment with fast input from large touch and pressure fibers. Their traffic inhibits the transmission cells in the dorsal horn, closing the gate on slower pain fibers arriving behind them. Option a is incorrect because prostaglandins and bradykinin are cleared by the circulation over hours, and cold or an anti inflammatory drug is what limits them. Relief arriving in seconds cannot come from that route. Option b is incorrect because shifting attention does modify pain, but it works high up in the cortex through descending fibers. The question asks what happens at the segment where the injured nerves enter. Option d is incorrect because endogenous opioids act centrally at dorsal horn and brainstem synapses, not on receptors out in the skin, and their release builds over minutes. Their site and their timing both fail to match.

Correct Answer: Stupor with return to unresponsiveness

Stupor sits between obtundation and coma. The client can be roused, but only by vigorous repeated painful stimulation, and drops back immediately once the stimulus stops, which separates it from lighter and deeper states. Option a is incorrect because a lethargic client wakes to a spoken name, answers appropriately though slowly, and then drifts off. Pain is never needed to get a response at that level of arousal. Option c is incorrect because obtundation still allows limited drowsy conversation once the client is roused with repeated stimulation. Interaction is possible, whereas this client offers nothing beyond a brief reaction to a painful stimulus. Option d is incorrect because coma means no arousal by any stimulus whatever, with no eye opening, no speech and no purposeful movement. Some response is present here, so the description stops short of that endpoint.