CNS Semester 1: Cerebrospinal Fluid
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Questions and Answers

What type of injury is characterized by damage to brain tissue on the side opposite to the initial impact?

  • Cerebral contusion
  • Depressed skull fracture
  • Contrecoup injury (correct)
  • Concussion

    • Which component is NOT found in high concentration in cerebrospinal fluid (CSF) compared to blood?

  • Protein (correct)
  • Sodium
  • Glucose
  • Chloride

    • What is one of the key functions of cerebrospinal fluid (CSF)?

  • Transport oxygen
  • Maintain thermal balance
  • Remove waste products (correct)
  • Protect against bacterial infection

    • Which of the following solutes is present in cerebrospinal fluid at lower concentrations than in blood?

    <p>Protein</p> Signup and view all the answers

    What type of skull fracture occurs when bone is driven into brain tissue?

    <p>Depressed skull fracture</p> Signup and view all the answers

    Which electrolyte is present in cerebrospinal fluid at a higher concentration than in blood?

    <p>Sodium (Na+)</p> Signup and view all the answers

    Which of the following is NOT considered a function of cerebrospinal fluid (CSF)?

    <p>Support neuronal regeneration</p> Signup and view all the answers

    Which of these substances is primarily found in higher concentrations in cerebrospinal fluid but lower in blood?

    <p>Lactate</p> Signup and view all the answers

    What facilitates the movement of larger water-soluble solutes across the cell membrane?

    <p>Specific transporter</p> Signup and view all the answers

    What property allows lipid soluble molecules to easily traverse the cell membrane?

    <p>Lipid solubility</p> Signup and view all the answers

    Which component's concentration is typically lower in cerebrospinal fluid (CSF) compared to plasma?

    <p>Potassium</p> Signup and view all the answers

    What role does ATP play in the function of P-glycoprotein?

    <p>Drives the efflux pump</p> Signup and view all the answers

    What is the typical sodium concentration range in plasma?

    <p>135-145 mmol/L</p> Signup and view all the answers

    What happens to P-glycoproteins when they interact with lipid-soluble molecules?

    <p>They change shape and expel the molecules</p> Signup and view all the answers

    Which of these ions typically has a higher concentration in CSF compared to plasma?

    <p>Chloride</p> Signup and view all the answers

    What is the characteristic of permeability at the choroid plexus compared to the blood-brain barrier?

    <p>Similar permeability to water-soluble substances</p> Signup and view all the answers

    What does the opening pressure of cerebrospinal fluid (CSF) indicate?

    <p>The pressure within the CSF system</p> Signup and view all the answers

    Which characteristic is typical of a normal cerebrospinal fluid (CSF) sample?

    <p>Colorless and clear fluid</p> Signup and view all the answers

    In a sub-arachnoid hemorrhage, what change is expected in CSF composition?

    <p>Discoloration and yellowish appearance</p> Signup and view all the answers

    What is NOT a characteristic of the blood-brain barrier (BBB)?

    <p>Allows unrestricted movement of water-soluble substances</p> Signup and view all the answers

    What is a primary function of the blood-brain barrier?

    <p>To separate circulating blood from the brain and extracellular fluid</p> Signup and view all the answers

    In cases of bacterial infection, which of the following changes occur in the CSF?

    <p>Increase in lactate levels</p> Signup and view all the answers

    How do endothelial cells in the blood-brain barrier differ from those in peripheral capillaries?

    <p>They are tightly packed with tight junctions</p> Signup and view all the answers

    What happens to CSF lactate levels in cases of CNS infections?

    <p>They increase</p> Signup and view all the answers

    What is the primary cause of increased CSF pressure leading to hydrocephalus?

    <p>Obstruction to CSF circulation</p> Signup and view all the answers

    Which condition is characterized by the swelling of the optic disc due to increased intracranial pressure?

    <p>Papilledema</p> Signup and view all the answers

    What condition results from the brain becoming flattened against the skull due to increased CSF volume?

    <p>Hydrocephalus</p> Signup and view all the answers

    What is a common cause of hydrocephalus in older adults?

    <p>Clogged arachnoid granulations</p> Signup and view all the answers

    At what pressure is CSF typically measured in healthy individuals?

    <p>10 mm Hg</p> Signup and view all the answers

    What is one of the associated conditions that can cause hydrocephalus in infants?

    <p>Neural tube defects</p> Signup and view all the answers

    Which imaging techniques are typically used for diagnosing hydrocephalus?

    <p>CT scan and MRI</p> Signup and view all the answers

    What is the goal of cerebral perfusion?

    <p>Maintain a constant supply of oxygen and nutrients</p> Signup and view all the answers

    What primarily determines the pressure gradient driving cerebral blood flow?

    <p>Mean arterial pressure (MAP)</p> Signup and view all the answers

    Which condition is likely to decrease cerebral perfusion pressure (CPP)?

    <p>Increased intracranial pressure (ICP)</p> Signup and view all the answers

    According to the Monro-Kellie Doctrine, what must occur if there is an increase in brain swelling?

    <p>Balancing change in another component</p> Signup and view all the answers

    What is the effect of elevated intracranial pressure (ICP) on the brain?

    <p>Can lead to brain ischemia</p> Signup and view all the answers

    For proper cerebral blood flow to occur, which condition must be true?

    <p>MAP must exceed ICP</p> Signup and view all the answers

    What does central venous pressure (CVP) reflect in relation to blood flow?

    <p>Pressure of blood exiting the brain</p> Signup and view all the answers

    What can an increase in cerebrospinal fluid (CSF) lead to within the skull?

    <p>Increased intracranial pressure (ICP)</p> Signup and view all the answers

    What primarily opposes blood flow into the brain?

    <p>Intracranial pressure (ICP)</p> Signup and view all the answers

    What is the relationship between ICP and CPP?

    <p>A decrease in CPP occurs when ICP approaches or exceeds MAP.</p> Signup and view all the answers

    What does a Cerebral Perfusion Pressure (CPP) of less than 50 mmHg indicate?

    <p>Cerebral ischemia due to insufficient blood flow.</p> Signup and view all the answers

    Which factor is NOT affected by high ICP?

    <p>Barometric pressure.</p> Signup and view all the answers

    What primary physiological adjustment does the body make when CPP is critically low?

    <p>Prioritizing blood perfusion to the brain.</p> Signup and view all the answers

    Which condition can lead to an increase in ICP?

    <p>Trauma.</p> Signup and view all the answers

    How does high ICP affect blood vessel function in the brain?

    <p>It compresses cerebral vessels, reducing blood flow.</p> Signup and view all the answers

    What happens when CPP exceeds 100 mmHg?

    <p>It signals potential tissue damage due to excessive perfusion.</p> Signup and view all the answers

    Which of the following best describes how the body responds to rising ICP?

    <p>Failure of autoregulation to maintain consistent blood flow.</p> Signup and view all the answers

    What is the primary site of cerebrospinal fluid (CSF) production?

    <p>Choroid plexus</p> Signup and view all the answers

    Which structure directly influences the circulation of CSF through the brain's ventricles?

    <p>Ependymal cells</p> Signup and view all the answers

    How often is cerebrospinal fluid (CSF) replaced in the human body?

    <p>Every 6-8 hours</p> Signup and view all the answers

    What is the approximate total volume of cerebrospinal fluid (CSF) at any given time?

    <p>140 mL</p> Signup and view all the answers

    What is the correct sequence of CSF flow from the lateral ventricles to the fourth ventricle?

    <p>Lateral ventricles → Third ventricle → Cerebral aqueduct → Fourth ventricle</p> Signup and view all the answers

    What is one of the primary consequences of increased intracranial pressure (ICP)?

    <p>Decreased blood flow to the brain</p> Signup and view all the answers

    Which manifestation is closely associated with a significant rise in ICP?

    <p>Cushing's triad</p> Signup and view all the answers

    Which of the following is NOT a typical cause of increased ICP?

    <p>Pulmonary embolism</p> Signup and view all the answers

    What role does cerebrospinal fluid (CSF) volume play in managing increased ICP?

    <p>Reducing CSF volume can lower ICP</p> Signup and view all the answers

    Which imaging technique is essential for diagnosing conditions associated with raised ICP?

    <p>CT or MRI</p> Signup and view all the answers

    What can happen to the brainstem if ICP rises excessively?

    <p>Loss of blood supply</p> Signup and view all the answers

    Which type of brain herniation is associated with compression of the temporal lobe?

    <p>Uncal herniation</p> Signup and view all the answers

    What is a critical concern when performing a lumbar puncture if elevated ICP is suspected?

    <p>Risk of herniation</p> Signup and view all the answers

    What is one major function of cerebrospinal fluid (CSF) that directly impacts brain protection?

    <p>Acts as a shock absorber</p> Signup and view all the answers

    Which characteristic best describes the relative impact of cerebrospinal fluid (CSF) on brain weight?

    <p>Decreases effective brain weight to approximately 50g</p> Signup and view all the answers

    Where is cerebrospinal fluid (CSF) primarily formed in the brain?

    <p>Choroid plexus</p> Signup and view all the answers

    What are the consequences of increased intracranial pressure (ICP) on the brain?

    <p>Decreased blood flow to the brain</p> Signup and view all the answers

    Which statement about cerebrospinal fluid (CSF) function as a cushion is true?

    <p>CSF cushions the brain from both gravity and lateral impacts</p> Signup and view all the answers

    What role does cerebrospinal fluid (CSF) play in relation to the spinal cord?

    <p>Prevents contact with vertebral bones</p> Signup and view all the answers

    Cushing's reflex is a response to what condition within the cranial cavity?

    <p>Increased intracranial pressure (ICP)</p> Signup and view all the answers

    What is the primary purpose of the blood-brain barrier in relation to cerebrospinal fluid (CSF)?

    <p>To limit substances entering the brain from blood</p> Signup and view all the answers

    What is a potential consequence of untreated hydrocephalus?

    <p>Physical flattening of the brain against the skull</p> Signup and view all the answers

    How does increased intracranial pressure (ICP) typically affect a patient neurologically?

    <p>Confusion and drowsiness</p> Signup and view all the answers

    What is one common cause of aqueductal stenosis in infants?

    <p>Congenital neural tube defects</p> Signup and view all the answers

    What is a typical method for diagnosing increased cerebrospinal fluid (CSF) pressure?

    <p>Lumbar puncture</p> Signup and view all the answers

    What specific condition in older adults can lead to Normal Pressure Hydrocephalus (NPH)?

    <p>Clogged arachnoid granulations</p> Signup and view all the answers

    Which sign could indicate increased ICP during a clinical examination?

    <p>Papilledema</p> Signup and view all the answers

    What can the enlargement of the ventricles indicate in a neurological assessment?

    <p>Increased CSF volume leading to hydrocephalus</p> Signup and view all the answers

    Which of the following conditions could potentially lead to neural tube defects in infants?

    <p>Congenital aqueductal stenosis</p> Signup and view all the answers

    What primarily drives cerebral perfusion pressure (CPP)?

    <p>Mean arterial pressure (MAP)</p> Signup and view all the answers

    According to the Monro-Kellie Doctrine, what must happen when there is an increase in brain swelling?

    <p>There must be a decrease in another component such as blood volume.</p> Signup and view all the answers

    How does elevated intracranial pressure (ICP) affect cerebral perfusion pressure (CPP)?

    <p>It decreases CPP by reducing the pressure gradient.</p> Signup and view all the answers

    What role does mean arterial pressure (MAP) play in blood flow to the brain?

    <p>It is the pressure of blood entering the brain through arteries.</p> Signup and view all the answers

    What explains the relationship between mean arterial pressure (MAP) and intracranial pressure (ICP) for proper cerebral blood flow?

    <p>MAP must exceed ICP for cerebral blood flow to occur.</p> Signup and view all the answers

    Which component is NOT included in the determination of intracranial pressure (ICP)?

    <p>Mean arterial pressure (MAP)</p> Signup and view all the answers

    What could potentially result from a decrease in cerebral perfusion pressure (CPP)?

    <p>Brain ischemia and insufficient oxygen.</p> Signup and view all the answers

    What is the relationship between the pressure gradient and the components influencing cerebral blood flow?

    <p>The pressure gradient is influenced by both MAP and ICP.</p> Signup and view all the answers

    What physiological response characterizes Cushing’s Reflex as a reaction to increased intracranial pressure?

    <p>Elevation of arterial pressure to maintain cerebral perfusion</p> Signup and view all the answers

    Which of the following is NOT a component of Cushing’s Triad?

    <p>Hypotension</p> Signup and view all the answers

    What is the main danger associated with the manifestation of Cushing's Reflex in a patient?

    <p>It can lead to brain ischemia if not addressed promptly.</p> Signup and view all the answers

    What compensatory mechanism causes bradycardia during Cushing’s Reflex?

    <p>Response of baroreceptors to elevated blood pressure</p> Signup and view all the answers

    Which intervention is NOT typically used to manage increased intracranial pressure?

    <p>Medications to increase blood pressure</p> Signup and view all the answers

    What primary change occurs to respiration due to increased ICP as it compresses the brainstem?

    <p>Irregular breathing patterns develop</p> Signup and view all the answers

    What underlying problem must be addressed to manage Cushing's Reflex effectively?

    <p>Reducing intracranial pressure</p> Signup and view all the answers

    How does Cushing’s Reflex help maintain cerebral perfusion?

    <p>By ensuring arterial pressure is above ICP</p> Signup and view all the answers

    Study Notes

    Course Information

    • Course: CNS
    • Year: 2
    • Semester: 1
    • Code: CNS
    • Title: Blood Brain Barrier, Cerebrospinal fluid, Intracranial Pressure
    • Lecturer: Dr. Melanie Föcking (RCSI-IE), Dr. Colin Greengrass (RCSI-BH)
    • Date: November 2024

    Cerebrospinal Fluid (CSF)

    • CSF is a clear, colorless fluid
    • Found in the brain and spinal cord
    • Acts as a cushion
    • Provides basic mechanical and immunological protection to the brain

    Functions of CSF

    • Buoyancy: Counteracts brain weight, ensuring it is neutrally buoyant, protecting from gravity injury
    • Protection: Acts as a cushion against impacts and blows
    • Cushioning: Allows the brain to withstand minor traumas of everyday living
    • Circulation: Transports and removes nutrients and waste products

    Formation of CSF

    • Primary site: Choroid plexus (tufts of capillaries in the ventricles)
    • Formed by tufts of capillaries and their associated membranes
    • Majority formed in the lateral ventricles (70%)
    • Remaining 30% produced by other brain capillaries

    Blood-CSF Barrier

    • Formed by choroid plexus and other brain capillaries
    • Regulates the entry of substances from blood into CSF
    • Transporters promote entry of some substances and restrict others
    • Maintains optimal ionic concentration for neuronal functioning
    • Helps in buffering pH and waste products

    CSF Components (Composition)

    • Primarily water (99.13%)
    • Organic solutes (0.87%): Glucose, albumin, urea, amino acids, globulins, immunoglobulins, lactate, enzymes, neurotransmitters etc
    • Inorganic solutes: Sodium(Na+), chloride (Cl-), potassium (K+), bicarbonate (HCO3-), calcium (Ca2+), magnesium (Mg2+), trace metals

    Intracranial Pressure (ICP)

    • Pressure exerted within the skull
    • Reflects pressure from brain tissue, blood, and CSF
    • Normal range: 7-15 mm Hg (in adults, supine)
    • Elevated ICP can compress cerebral vessels, reducing blood flow & causing cerebral ischemia

    Causes of Increased ICP

    • Traumatic brain injury
    • Brain tumours
    • Haemorrhage (e.g., subdural, epidural, intracerebral)
    • Hydrocephalus
    • Infections (e.g., meningitis, encephalitis)

    Consequences of Increased ICP

    • Brain herniation syndromes (e.g., uncal, central, tonsillar)
    • Compressed brainstem → Impaired consciousness and respiratory depression

    Clinical Relevance of ISF

    • Abnormalities in ISF formation/composition can cause neurological issues
    • Alzheimer's disease: Impaired ISF dynamics can lead to beta-amyloid accumulation
    • Oedema: Brain injury can disrupt the BBB, leading to abnormal ISF accumulation & swelling

    Abnormal Trauma

    • Abnormal trauma leads to brain injury
    • Examples: Contrecoup injury and depressed skull fracture

    CSF Circulation

    • CSF flows from the lateral ventricles through the interventricular foramina to the third ventricle, then through the cerebral aqueduct to the fourth ventricle to the subarachnoid space.
    • CSF circulates around the brain and spinal cord and is absorbed into venous blood via arachnoid granulations.

    Glymphatic System

    • The glymphatic system is a CSF-based waste clearance pathway that plays a significant role in waste removal.
    • CSF facilitates waste transportation.
    • Primarily active during sleep.

    Lumbar Puncture

    • A hollow needle is inserted between the 3rd/4th or 4th/5th lumbar vertebrae in such a way that the puncture site lies in the subarachnoid space.
    • Opening pressure is the initial CSF pressure reading from the subarachnoid area.

    Papilledema

    • Swelling of optic disk
    • A symptom of elevated ICP

    Hydrocephalus

    • An increase in CSF volume
    • Results in enlarged ventricles
    • Can cause brain flattening and damage

    CPP (Cerebral Perfusion Pressure)

    • Pressure gradient driving blood flow to brain tissue.
    • Ensures the delivery of oxygen and nutrients to brain tissue
    • CPP = MAP - ICP
    • Normal range: 60-80 mmHg
    • Low CPP can lead to brain ischemia.
    • High CPP can cause damage.

    Cushing's Reflex

    • A physiological response to increased intracranial pressure (ICP).
    • Mechanism: The body attempts to increase blood pressure and slow heart rate to maintain perfusion despite the reduced pressure gradient.
    • Elevated blood pressure with bradycardia, irregular respiration
    • Important clinical sign that can indicate rising ICP.

    Management of Raised ICP

    • Address the underlying causes (e.g., trauma, hemorrhage, tumour)
    • Reduce ICP: Medication, fluid removal, or surgical decompression.
    • Optimise blood flow.
    • Monitoring ICP

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    Test your knowledge on Cerebrospinal Fluid (CSF) and its functions, including buoyancy, protection, cushioning, and circulation. Discover how CSF is formed and its significance in the brain's mechanical and immunological protection. This quiz is designed for 2nd-year CNS students.

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