neuro objectives 6-8 - Sheet1 Flashcards
(28 cards)
What percentage of total cardiac output does the brain require despite making up only 2% of body mass?
15-20%
Through which arteries does blood reach the brain?
Internal carotid arteries and vertebral arteries
What percentage of the body’s oxygen and glucose does the brain use?
20% of oxygen and 25% of glucose
What is the primary regulator of blood flow within the CNS?
Carbon dioxide (CO2), a potent vasodilator
How does high CO2 (hypercapnia) affect cerebral blood flow?
High CO2 increases blood flow to the brain, raising intracranial pressure and potentially causing mental changes.
What happens when O2 levels drop below 60 mmHg in the brain?
Blood vessels vasodilate, increasing intracranial pressure as more oxygen is delivered.
How does acidosis (increased hydrogen ion concentration) affect cerebral blood flow?
Acidosis causes vasodilation, increasing cerebral blood flow.
Why is the brain extremely sensitive to hypoxia?
Hypoxic damage to the brain becomes irreversible after only a few minutes.
Through which veins does blood leave the brain?
Cerebral veins -> venous plexuses and dural sinuses -> internal jugular veins
What happens when blood backs up in the brain?
Increased intracranial pressure
What is intracranial pressure (ICP)?
Hydrostatic force measured in the cerebrospinal fluid (CSF) compartment in the brain.
What is the normal ICP range?
0-15 mmHg
What ICP level and duration is considered a medical emergency?
ICP of 20 mmHg for more than 5 minutes.
How is ICP measured?
Through a lumbar puncture (LP/spinal tap) or ventriculostomy.
What are the three components in the skull that affect ICP?
Brain tissue, blood, and CSF.
What factors influence increased ICP?
Cerebral edema, hypercapnia, hypoxemia, increased metabolic demands, increased intra-abdominal and intra-thoracic pressure, venous outflow obstruction, and excessive CSF production.
What are classic signs of elevated ICP?
Projectile vomiting, pounding headache, blurred vision, confusion, decline in LOC, pupillary changes, unrelieved crying in babies, bulging fontanels, speech changes.
What formula determines Cerebral Perfusion Pressure (CPP)?
CPP = MAP - ICP (where MAP is Mean Arterial Pressure).
What is the normal MAP range?
60-100 mmHg
At what CPP does cerebral ischemia occur?
CPP < 30 mmHg is incompatible with life.
What is cerebral edema?
Net accumulation of water in the brain tissue due to trauma, infection, hemorrhage, tumor, ischemia, infarct, or hypoxia.
What harmful effects can cerebral edema cause?
Distortion of blood vessels, displacement of brain tissues, and herniation.
What is hydrocephalus?
A condition characterized by excess CSF within the cranial vault or subarachnoid space, leading to increased ICP.
What are signs of hydrocephalus in children?
Megamind (enlarged head), bulging fontanelles.
