UC 8022 Exam 5 practice questions

Cold Injuries

• A skin injury from exposure to extreme cold temperatures, affecting fingers, toes, ears, nose, and cheeks
• Burning reaction caused by alternating cycles of vasoconstriction and vasodilation
• Inflammation and reperfusion are part of the pathophysiology
• Clinical manifestations: skin appears white or yellowish, waxy, and firm to the touch

Burns

• A cutaneous injury resulting from thermal, chemical, or electrical causes
• Multisystem injuries with interactions with shock, inflammation, and immunocompromised state
• Burn wound depths:
  • Partial-thickness injury: involves only the epidermis, no injury to underlying dermal and subcutaneous tissue
  • Clinical manifestations: local pain, erythema, and no blisters until 24 hours after injury
  • Superficial partial-thickness injury: thin-walled, fluid-filled blisters develop within minutes after injury
  • Deep partial-thickness injury: involves the entire dermis, sparing skin appendages
  • Clinical manifestations: waxy white skin, surrounding margins of superficial partial-thickness injury
  • Full-thickness injury: entire epidermis, dermis, and subcutaneous tissue destroyed
  • Clinical manifestations: burn color is white, cherry, red, or black; blisters are rare

Burn Shock

• Consequences of a major burn injury, leading to a life-threatening hypovolemic shock
• Phenomenon consisting of both hypovolemic and cardiovascular components, and cellular components
• Capillary seal indicates the end of burn shock

Types of Cells

• Neuron:
  • Primary information/communication cell of the nervous system
  • Variable size and structure throughout the nervous system
  • Primary fuel is glucose, no insulin required for cellular glucose uptake in CNS
  • Cell body (soma) located mainly in the CNS
  • Dendrites carry nerve impulses toward the cell body
  • Axons carry nerve impulses away from the cell body
  • Myelin: segmented layer of lipid material, insulating substance
  • Functional classification: sensory, associational, and motor neurons

Synapses

• Region between adjacent neurons
• Impulses transmitted across the synapse by chemical and electrical conduction
• Presynaptic neurons: proximal to the synapse, relay impulses toward the synapse
• Postsynaptic neurons: distal to the synapse, relay impulses away from the synapse
• Neurotransmitters formed in the neuron, stored in synaptic knobs or boutons

Central Nervous System (CNS)

• Reticular Formation: network of connected nuclei regulating vital reflexes
• Forebrain (telencephalon):
  • Cerebrum: largest portion of the brain
  • Cerebral cortex: gray matter, organized into columns perpendicular to the surface
  • White matter: numerous tracts, composed of myelinated nerve fibers
  • Lobes: frontal, parietal, occipital, and temporal
  • Functions: voluntary motor, sensory, and cognitive processes

Brain Stem (Hindbrain)

• Midbrain: relay center for motor and sensory tracts
• Cerebellum: maintains balance and posture
• Pons: important center for control of respiration
• Medulla oblongata: lowest portion of the brainstem, controls reflex activities

Cranial Nerves (Peripheral Nervous System)

• CN I: Olfactory (sensory)- smell
• CN II: Optic (sensory)- vision
• CN III: Oculomotor (motor)- pupil reaction, extraocular movement
• CN IV: Trochlear (motor)- extraocular movement, superior oblique muscles
• CN V: Trigeminal (motor & sensory)- mastication, face sensation
• CN VI: Abducens (motor)- EOM, lateral rectus
• CN VII: Facial (motor & sensory)- facial expression, taste on anterior of tongue
• CN VIII: Vestibulocochlear (sensory)- hearing
• CN IX: Glossopharyngeal (motor & sensory)- motor fibers serve pharynx and salivary glands
• CN X: Vagus (motor & sensory)- motor and sensory for pharynx, parasympathetic motor fiber
• CN XI: Spinal Accessory (motor)- sternocleidomastoid and trapezius muscles
• CN XII: Hypoglossal (motor)- tongue muscles

Spinal Cord

• Lies within the vertebral canal, protected by the vertebral column
• Connects the brain and the body, conducts somatic and autonomic reflexes
• Modulates sensory and motor function
• Regions: cervical, thoracic, lumbar, sacral, and coccygeal
• Conus medullaris: end of the spinal cord
• Cauda equina: nerve bundle at the end of the spinal cord

Upper and Lower Motor Neurons

• Upper Motor Neurons:
  • Motor pathways completely contained within the CNS
  • Efferent pathways primarily relaying information from the cerebrum to the brainstem or spinal cord
  • Disruptions result in initial paralysis, followed by partial recovery
• Lower Motor Neurons:
  • Neurons having direct influence on muscles
  • Cell bodies originate in the gray matter of the spinal cord
  • Destruction leads to permanent paralysis

Meninges

• Protective membranes surrounding the brain and spinal cord
• Dura mater, arachnoid, and pia mater
• Falx cerebri: dips between the two cerebral hemispheres along the longitudinal fissure
• Form potential and real spaces important in understanding functional and pathologic mechanisms

Blood Supply to the Brain

• Blood supplied by two pairs of large blood vessels: carotid arteries and vertebral arteries
• Circle of Willis: anterior, middle, and posterior cerebral arteries
• ACA: supplies blood to the frontal lobe
• MCA: supplies blood to the middle part of the brain
• PCA: supplies blood to the back of the brain

Blood Brain Barrier

• Cellular structures that selectively inhibit certain substances from entering the brain or CSF
• Functions: protects the brain, maintains a constant biochemical environment
• Increases permeability or breakdowns: hypertension, dilutional hyponatremia, high doses of anesthetics, vasodilation, and hypercapnia

Peripheral Nervous System (PNS) and Autonomic Nervous System (ANS)

• PNS: cranial nerves and spinal nerves, peripheral nerve pathways
• ANS: motor and sensory pathways regulating the body's internal environment
• Somatic Nervous System: motor and sensory pathways regulating voluntary motor control of skeletal muscle
• Autonomic Nervous System: motor and sensory pathways regulating the body's internal environment
• Sympathetic Nervous System: mobilizes energy stores, increases HR and BP, and diverts blood from gut to skeletal muscle
• Parasympathetic Nervous System: conserves and restores energy, promotes visceral activity and repose

Neuroanatomy of Pain

• Nociception: transduction, transmission, perception, and modulation
• Primary-order neurons: nociceptors, bare nerve endings responding to chemical, mechanical, and thermal stimuli
• Second-order neurons: interneurons in the dorsal horn of the spinal cord
• Third-order neurons: afferent neurons in the spinothalamic tract
• Types of pain: somatic, visceral, referred, and neuropathic pain

Types of Acute Pain

• Somatic pain: superficial, arises from connective tissue, muscle, bone, and skin
• Visceral pain: internal, transmitted by sympathetic afferents, poorly localized
• Referred pain: present in an area distant from its origin, supplied by the same spinal segment

Chronic Pain and Neuropathic Pain

• Chronic pain: persistent or intermittent, no physiological signs, significant behavior and psychological changes
• Neuropathic pain: result of trauma or disease of the PNS and CNS, leads to abnormal central pain processing
• Conditions: myofascial pain syndromes, chronic postoperative pain, low back pain, and chronic pain associated with cancer
• Peripheral neuropathic pain: injured nerves become hyperexcitable
• Central neuropathic pain: caused by lesion or dysfunction in brain or spinal cord
• Clinical manifestations: paroxysmal with hyperesthesia and paresthesia, burning, shooting, or stabbing sensations### Temperature Regulation
• Achieved through precise balancing of heat production, heat conservation, and heat loss
• Mediated by the hypothalamus
• Body temperature is maintained around 37°C (98.6°F)
• Varies in response to: location, activity, environment, circadian rhythm, and gender
• Peripheral thermoreceptors in the skin and central thermoreceptors in the hypothalamus, spinal cord, and abdominal organs provide information about skin and core temperatures

Fever

• Triggered by release of pyrogens from leukocytes and other cells involved in the immune response (endogenous pyrogens) and bacteria (exogenous pyrogens)
• Both a symptom of a disease and a normal immunologic mechanism
• Involves resetting of the hypothalamic thermostat to a higher level
• Benefits of fever:
  • Kills many microorganisms
  • Decreases serum levels of iron, zinc, and copper needed for bacteria replication
  • Promotes lysosomal breakdown and auto-destruction of cells
  • Increases lymphocytic and phagocyte motility
  • Augments antiviral interferon production and phagocytosis

Hyperthermia

• Marked warming of core temperature
• Not mediated by pyrogens
• No resetting of the hypothalamic set point
• Consequences:
  • 41°C (105.8°F): nerve damage produces convulsions
  • 43°C (109.4°F): death results
• Forms of accidental hyperthermia:
  • Heat cramps
  • Heat exhaustion
  • Heatstroke (potentially lethal)
  • Malignant hyperthermia (potentially lethal)

Sleep

• Active, multiphase process
• Hypothalamus is the major sleep center
• Suprachiasmatic nucleus (SCN) controls the timing of the sleep-wake cycle
• Hypocreatins (orexins) promote wakefulness and REM sleep
• Two phases:
  • Rapid eye movement (REM) sleep (20% to 25% of sleep time)
  • Non-rapid eye movement (NREM) sleep (75% to 80% of sleep time)
• Stages of NREM sleep:
  • Stage N1: light sleep (3% to 8% of sleep time)
  • Stage N2: longest sleep (45% to 55% of sleep time)
  • Stage N3: slow-wave sleep (15% to 20% of sleep time)

Obstructive Sleep Apnea (OSAS)

• Disorder of breathing during sleep, related to upper airway obstruction
• Associated with reduced blood oxygen saturation and hypercapnia
• Risk factors: obesity, male gender, and age
• Clinical manifestations:
  • Loud snoring
  • Gasping
  • Intervals of apnea lasting 10-30 seconds
  • Fragmented sleep
  • Chronic daytime sleepiness

Age-Related Macular Degeneration (AMD)

• Drusen or retinal waste products accumulate in the deep retinal layers
• An eye disease that can blur central vision
• Happens when aging causes damage to the macula (the part of the eye that controls sharp, straight-ahead vision)
• Two types:
  • Dry AMD (atrophic AMD): loss of retinal pigment epithelium photoreceptors with overall atrophy of cells
  • Wet AMD (neovascular AMD): abnormal blood vessels grow in the back of the eye and damage the macula

Glaucoma

• Intraocular pressures above the normal pressures of 12 to 20 mmHg are maintained by the aqueous fluid
• Increased pressure that compresses and damages the optic nerve
• Clinical manifestations:
  • Eye pain
  • Pressures
  • Headaches
  • Rainbow-colored halos around lights
  • Low vision, blurred vision, narrowed vision (tunnel vision), or blind spots
  • Nausea and vomiting

Hearing Loss

• Types:
  • Conductive hearing loss: impaired sound conduction from the outer to inner ear
  • Sensorineural hearing loss: impairment of the organ of corti or its central connections
  • Mixed hearing loss: combination of conductive and sensorineural losses
  • Functional hearing loss: no organic reason, thought to be caused by emotional or psychologic factors
  • Tinnitus: ringing of the ears

Vertigo

• Sensation of spinning that occurs with inflammation of the ear's semicircular canals
• State of being awake
• Mediated by the reticular-activating system

Awareness

• Cognitive functions that embody awareness of self, environment, and affective states (moods)
• Content of thought

Coma

• No verbal response to the external environment or to any stimuli
• Noxious stimuli such as deep pain or suctioning yields motor movement
• Produced by either:
  • Bilateral hemisphere damage or suppression
  • Brainstem lesions or metabolic derangement that damages or suppresses the reticular activating system

Brain Death

• Brain has no potential for recovery and can no longer maintain the body's internal homeostasis
• State laws: entire brain, brainstem, and cerebellum stops functioning or has already autolyzed on postmortem examination### Cerebral Edema
• Increase in fluid (intracellular or extracellular) within the brain
• Harmful effects cause distortion of blood vessels, displacement of brain tissues, and eventual herniation of brain tissue from one compartment to another
• Results from infection, hemorrhage, tumor, ischemia, infarct, or hypoxia
• Types of cerebral edema:
  • Vasogenic: most clinically important, caused by increased permeability of the capillary endothelium of the brain after injury to the vascular structure
  • Cytotoxic: metabolic, toxic factors directly affect cellular elements of the brain parenchyma, causing failure of the active transport system
  • Interstitial: seen most commonly with non-communicating hydrocephalus

Hydrocephalus

• Excess fluid within the cranial vault, subarachnoid space, or both
• Caused by interference in CSF flow:
  • Decreased reabsorption: blockage of arachnoid villi (absorption) from SAH or infection
  • Increased fluid production: choroid plexus tumor
  • Obstruction within the ventricular system: tumor or congenital malformation
• Types of hydrocephalus:
  • Communicating (extraventricular) hydrocephalus: from impaired absorption, CSF can flow through ventricles
  • Non-communicating hydrocephalus: internal or intraventricular, blockage occurs along narrow pathways that connect the ventricular system
  • Normal pressure hydrocephalus: occurs mostly in middle-aged people, long-term presentation: memory decline, gait disturbance, and incontinence

Upper Motor Neuron Syndromes

• Spastic paresis or paralysis:
  • Hemiparesis or hemiplegia: upper and lower extremities on one side
  • Paraparesis or paraplegia: affects lower extremities
  • Quadriparesis or quadriplegia: all 4 extremities
• Associated with hyperreflexia, pyramidal motor syndrome
• Spinal shock: complete cessation of spinal cord functions below the lesion, flaccid paralysis, absence of reflexes, and marked disturbances of bowel and bladder function

Lower Motor Neuron Syndromes

• Flaccid paresis or paralysis:
  • Caused by dysfunction of lower motor neurons (anterior horn cells and motor nuclei of the brainstem)
  • Impairs voluntary and involuntary movement
  • Degree of paralysis or paresis proportional to the number of lower motor neurons affected
  • Associated with areflexia or hyporeflexia

Huntington Disease

• Autosomal dominant hereditary degenerative disorder
• Severe degeneration of the basal ganglia (caudate nucleus) and frontal cerebral atrophy
• Clinical manifestations:
  • Abnormal movement (chorea)
  • Progressive dysfunction of intellectual processes (dementia)
  • Thought processes mark the onset of the disease
  • Choreiform movements begin in the face and arms and progresses to the rest of the body
  • Symptoms of frontal lobe dysfunction: executive attention deficits, short-term memory loss, reduced capacity to plan, organize, and sequence, bradyphrenia, and apathy
  • Euphoria and depression may be present

Parkinson Disease

• Degeneration of the dopaminergic pathway to the basal ganglia
• Results in inhibition of the motor cortex, manifested with bradykinesia and rigidity
• Hallmark pathologic features of PD: loss of dopaminergic pigmented neurons in the substantia nigra pars compacta with dopaminergic deficiency in the putamen
• Clinical manifestations:
  • Insidious onset of symptoms
  • Classic motor manifestations: bradykinesia, tremor at rest, muscle rigidity, hypokinesia, and stooped posture
  • Non-motor symptoms: hyposmia, fatigue, pain, autonomic dysfunction, sleep fragmentation, depression, and dementia with or without psychosis

Focal Brain Injuries

• Contusion: bruising of the brain
• Laceration: tearing of brain tissue
• Extradural (epidural) hematoma: accumulation of blood above the dura mater
• Subdural hematoma: blood between the dura mater and arachnoid membrane
• Intracerebral hematoma: bleeding in the brain
• Open head trauma: skull fracture with exposure of the cranial vault to the environment

Diffuse Brain Injuries

• Result from the effect of head rotation or shaking
• Brain experiences shearing stresses, resulting in axonal damage
• Pathophysiology can only be seen with a microscope
• Oxygen free radicals contribute to secondary injury

Concussions

• Temporary axonal disturbance causing attention and memory deficits
• Grade I: confusion, disorientation, and momentary amnesia, no loss of consciousness
• Grade II: momentary confusion and retrograde amnesia, no loss of consciousness
• Grade III: confusion with retrograde and anterograde amnesia, loss of consciousness for seconds to minutes
• Grade IV: disconnection of cerebral systems from the brain stem and reticular activating system, loss of consciousness for more than 24 hours

Spinal Cord Trauma

• Most commonly occurs due to vertebral injuries
• Traumatic injury of vertebral and neural tissues, resulting in compression, pulling, exerting tension on tissue, or shearing tissues
• Often causes spinal shock with cessation of all motor, sensory, reflex, and autonomic functions below the transected area
• Loss of motor and sensory function depends on the level of injury

Cerebrovascular Accident (Stroke)

• Thrombotic stroke: arterial occlusions caused by thrombi formed in arteries supplying the brain or in intracranial vessels
• Embolic stroke: fragments that break from a thrombus formed outside the brain
• Hemorrhagic stroke: bleeding into the brain, can occur secondary to TBI
• Lacunar stroke: microinfarct smaller than 1cm in diameter, involves small perforating arteries, predominantly in the basal ganglia, internal capsules, and pons