NURS-340: Pathophysiology 1 (Exam 3)

What is the functional unit of the nervous system?

The neuron

What is the primary function of neurons?

To generate and transmit bioelectrical impulses throughout the body

What type of response do neurons generate when conducting impulses?

An “all-or-none” response (either fully fires or not at all)

Can neurons divide and regenerate after damage?

No - once neurons are damaged, it’s generally permanent (except in cases of limited regeneration in the hippocampus and olfactory bulb)

True or False: Sometimes when neurons in one part of the brain die, other parts of the brain can assume those functions over time.

True

What are the three major structural components of a neuron?

Dendrites, cell body (soma), and axon

What is the function of the dendrites?

They receive incoming signals

What type of signals do dendrites and the cell body receive?

Afferent signals

What is the function of the axon?

To carry impulses away from the cell body

What type of signals do axons carry?

Efferent signals

What is the role of the myelin sheath?

It insulates axons and increases conduction speed

What are the nodes of Ranvier?

Gaps in between myelin segments that allow for rapid inpulse conduction

What is the function of axon terminals?

They convert electrical action potentials into chemical signals (drugs act here)

What is the primary function of neuroglial cells?

To support, protect, and assist with neural repair

What structural role do neuroglial cells provide?

They form scaffolding for nervous tissue

What is the difference between neurons and neuroglial cells?

Neurons transmit impulses; glial cells support and protect neurons

What structures make up white matter?

Myelinated axons and glial cells (i.e., “cables” in a network)

What structures make up gray matter?

Neuronal cell bodies (i.e., “computers” in a network)

Which brain tissue uses most of the brain’s oxygen supply?

Gray matter (~95%)

Neurotransmitters interact with the postsynaptic membrane by binding to a…

Receptor

What are the three steps of synaptic transmission?

1. Impulse travels down the axon

2. Neurotransmitter is released from the axon terminal

3. Neurotransmitter binds to a receptor on a postsynaptic cell

What can happen when a neurotransmitter binds to a postsynaptic cell?

• Muscle contracts or relaxes

• Glands increase or decrease secretion

• Neurons fire more or less frequently

How does synaptic transmission affect body systems overall?

It controls movement, secretion, and neural signaling

What happens after neurotransmitters cross the synapse?

They are either degraded or reabsorbed for reuse in the next impulse transmission

Why is neurotransmitter removal important?

It prevents continuous stimulation of the postsynaptic cell

What two substances does the brain require continuously?

Oxygen and glucose

What symptoms occur with hypoxia or hypoglycemia in brain tissue?

Lethargy, confusion, and combativeness

What is the most common cause of brain inflammation?

Infection

What structure is affected in meningitis?

Meninges

What structure is affected in encephalitis?

Brain parenchyma

What structure is affected in myelitis?

Spinal cord

What structure is affected in encephalomyelitis?

Brain and spinal cord

What are the two major types of meningitis?

Acute purulent (bacterial) and acute lymphocytic (viral)

What are classic clinical manifestations of meningitis?

Fever, chills, headache, muscle aches, nuchal rigidity, nausea, and vomiting

What additional severe manifestations may occur with meningitis?

Seizures, cranial nerve palsies, petechial rash, delirium, and coma

How do viral meningitis symptoms compare to bacterial meningitis?

Viral symptoms are typically milder

What diagnosis test confirms meningitis?

Lumbar puncture with cerebrospinal fluid (CSF) analysis

What cerebrospinal fluid (CSF) findings will present in cases of bacterial meningitis?

• Increased neutrophils

• Increased protein

• Decreased glucose

What cerebrospinal fluid (CSF) findings will present in cases of viral meningitis?

• Increased lymphocytes

• Mildly increased protein

• Normal glucose

What treatment is used for bacterial meningitis?

Broad-spectrum antibiotics

What treatment is used for viral meningitis?

Symptom management (except in cases of herpes simplex virus type 2 (HSV-2) → IV acyclovir)

What are the two major types of stroke?

Ischemic and hemorrhagic

Which type of stroke is more common?

Ischemic stroke

Which type of stroke is most frequently fatal?

Hemorrhagic stroke

Why is stroke considered a time-dependent emergency?

Early intervention limits irreversible brain injury

What are modifiable risk factors for stroke?

Hypertension, smoking, diabetes, hyperlipidemia, obesity, inactivity, alcohol use, cocaine use, coagulation disorders, carotid artery disease (CAD), and heart disease

What are nonmodifiable risk factors for stroke?

Age, gender, race, and heredity

What causes ischemic stroke?

Thrombosis or embolism blocking cerebral blood flow

Why is ischemic stroke compared to myocardial infarction?

Both involve ischemia due to blocked blood flow

What area surrounds the infarct core in ischemic stroke?

The penumbra (ischemic but salvageable tissue)

What determines whether penumbra cells survive?

• Speed of restoring circulation

• Amount of toxic substances released

What is the most common cause of ischemic stroke?

Thrombotic occlusion from atherosclerosis

What happens in thrombotic stroke?

Blood vessels become occluded, cutting off blood supply upstream

What brain areas are commonly affected in thrombotic stroke?

The cortex

What are common clinical manifestations of thrombotic stroke?

• Aphasia

• Neglect

• Visual field deficits

What causes cardiogenic embolic stroke?

A traveling clot from the heart or carotids

Where do emboli commonly originate?

• Left side of the heart

• Carotid artery plaques

What conditions increase risk for embolic stroke?

Atrial fibrillation and endocarditis

How does embolic stroke typically present?

Sudden onset with immediate maximum deficit

What imaging rules out hemorrhagic stroke first?

CT scan

What imaging identifies vascular blockages?

Computed tomography angiography (CTA) or magnetic resonance angiography (MRA)

How is ischemic stroke treated?

Via tPA, a “clot-buster” used in emergency medicine to dissolve blood clots - certain criteria must be met in order to use as it can cause severe bleeding

What is a transient ischemic attack (TIA)?

Temporary neurological dysfunction caused by focal brain ischemia without permanent infarction

How long do symptoms of a transient ischemic attack (TIA) typically last?

A few minutes up to 24 hours

What causes transient ischemic attacks (TIAs)?

The same mechanisms as ischemic stroke (thrombus or embolus)

Why is a transient ischemic attack (TIA) considered a medical warning sign?

It indicates high risk for a future stroke

What is the key clinical significance of recognizing transient ischemic attacks (TIAs) early?

Early intervention can prevent progression to ischemic stroke

What causes hemorrhagic stroke?

Rupture of a cerebral blood vessel

What occurs when a cerebral vessel ruptures during hemorrhagic stroke?

Hematoma formation, edema, and compression of surrounding brain tissue

What secondary vascular complication can occur near a hemorrhage site?

Vasospasm of adjacent blood vessels

What are the most common predisposing factors for hemorrhagic stroke?

Age and hypertension

What are some other predisposing factors for hemorhagic stroke?

Trauma, tumors (can erode nearby blood vessels), vasculitis, certain medications (increase bleeding tendency), and structural abnormalities (e.g., vascular malformations, aneurysms)

What early symptoms are commonly seen in hemorrhagic stroke?

Headache and vomiting

Why does vomiting occur in hemorrhagic stroke?

Increased intracranial pressure (ICP)

What neurologic deficit commonly results from basal ganglia hemorrhage?

Contralateral hemiplegia

How does muscle tone typically change after basal ganglia hemorrhage?

Initial flaccidity progresses to spasticity

Why can hemorrhagic stroke rapidly become fatal?

Expanding hematoma and edema increase intracranial pressure and compress vital brain structures

What level of consciousness change often develops as hemorrhagic stroke worsens?

Progression to coma

Why is blood pressure control critical in hemorrhagic stroke?

It slows ongoing bleeding and supports clot formation

What medications may be used to promote clotting in hemorrhagic stroke?

Vitamin K and prothrombin complex concentrates

When is surgery indicated in hemorrhagic stroke?

To relieve increased intracranial pressure

What rehabilitation therapies are commonly needed after hemorrhagic stroke?

Physical therapy, occupational therapy, and speech-language pathology

What is the difference between primary and metastatic brain tumors?

Primary tumors originate in brain tissue; metastatic tumors spread from cancers elsewhere in the body

True or False: Primary brain tumors are more common than metastatic brain tumors.

False

What are the most common sources of metstatic brain tumors?

Lung, breast, melanoma, kidney, and colon cancers

How do brain tumors cause neurologic symptoms?

Increased intracranial pressure (ICP), tissue compression, and local tissue destruction

Why does tumor location matter clinically?

Symptoms depend on the brain region affected

What is a classic early symptom of brain tumors?

Headache (often worse in the morning)

Why are headaches worse in the morning with brain tumors?

Increased intracranial pressure while lying down overnight

What cognitive changes may occur with brain tumors?

Personality changes, confusion, and memory impairment

What are some other symptoms of brain tumors?

Seizures, papilledema (edema of the optic disc), visual disturbances, alterations in sensory/motor function, nausea, and vomiting

Why do brain tumors cause seizures?

Irritation of cortical neurons

What imaging is most commonly used to diagnose brain tumors?

MRI

What treatments are used for brain tumors?

Surgery, radiation therapy, chemotherapy (must cross the blood-brain barrier), and corticosteroids (to reduce edema)

What drug administration routes cross the blood-brain barrier?

Intravenous and intraarterial

What drug administration routes cannot cross the blood-brain barrier?

Intrathecal and intraventricular

What are upper motor neurons (UMNs)?

Neurons that originate in the brain’s motor cortex, traveling down to the spinal cord or brainstem to control movement

What are lower motor neurons (LMNs)?

Neurons that start in the spinal cord/brainstem and directly innervate muscles

What does upper motor neuron (UMN) damage cause?

Spasticity and hyperreflexia

What does lower motor neuron (LMN) damage cause?

Flaccid paralysis and atrophy