B2W1 Trans Phys Flashcards
Brain weight, blood, and oxygen percentage
Brain is 2% body weight
Blood flow 15%
Oxygen 20%
What maintains basal tone in cerebral vessels?
Autoregulation
Absolute blood flow of the brain
Brain always needs 750 mL of blood
Autoregulation
Ability for tissue to adjust vascular resistance and maintain blood flow despite changes in mean arterial pressure.
Achieved by changing myogenic tone
Homeostatic mean arterial pressure
60 - 160 mmHg
Blood brain barrier and its type movement
Structures within the brains vascular system that limits and controls what can and cannot enter the brain.
-Water soluble agents
-Lipid soluble agents via transcellular pathways
-Transport proteins
-Receptor mediated endocytosis
Neurovascular unit
Blood vessel surrounded, in order from closest to farthest, endothelial cell, basement membrane, pericyte, smooth muscle, astrocyte endfeet, microglia, and neurons.
Cerebrovascular Autoregulation patterns
Increase in MAP -> Increased Vessel Resistance = BF Maintained
Decrease in MAP -> Decreased Vessel Resistance = BF Maintained
MAP and Resistance are directly correlated
Sympathetic Outflow of Cerebral Vessel Tone
Alpha 1 & 2 cause vasoconstriction and prefer Norepinephrine
Beta 1 & 2 cause vasodilation and prefer Epinephrine
Parasympathetic innervation
Via Muscarinic Receptors
NOS - Produces NO Nitric Oxide
Parasympathetic Vasodilators
Nitric Oxide
Acetylcholine
Lipid-Soluble Substances
CO2, O2, and Ethanol
CO2 Concentration and CBF
Increased pCO2 -> Vasodilation -> increased CBF
Decreased pCO2 -> Vasoconstriction -> decreased CBF
H+ Concentration and CBF
Increased H+ -> Vasodilation -> increased CBF
Decreased H+ -> Vasoconstriction -> increased CBF
O2 Concentration and CBF
Increased pO2 -> Vasoconstriction -> Decreased CBF
Decreased pO2 -> Vasodilation -> increased CBF
Migraine Symptoms
Nausea
Loss of Vision
Unilateral Headache
Extreme Sensitivity to Sound
Migraine Stages
Prodrome - Days to hours
Aura - Right Before
Attack (Headache) - During
Postdrome - After
Main cause of Migraines
Vasospasms
Vasospasms
Significant, short, unattenuated contraction, followed by relaxation, ending with flaccid vessel tone
Migraine Treatment
Beta Blocker
Vascular Smooth Muscle Cell Migraine Pathway
Calcium enters through L-Type Calcium Channel -> Calcium introduction causes intracellular stores of calcium in the sarcoplasmic reticulum -> Increase in intracellular calcium concentration -> Calcium attaches with Calmodulin to form Ca-Calmodulin -> Ca-Calmodulin activates MLCK or Myosin Light Chain Kinase -> MLCK phosphorylates myosin which inhibits myosin and stops crossbridge formation -> Causes VSMC relaxation
Role of Beta Blockers in the Vascular Smooth Muscle Pathway
Beta blocker or beta receptor agonist or epinephrin bind to Beta 1 or Beta 2 receptors -> Activate Gs alpha subunit -> Converts ATP to cAMP which inhibits MLCK thus allowing myosin to form crossbridge and for vascular tone to be established.
Neuroplasticity in recovery
Structural changes
- Increase in cortical thickness
- Dendritic Growth
- Formation of New Synapses
- Angiogenesis
Mechanisms of Functional Recovery
Macroscopic
- Restructuring of functional networks
- Other Brain areas substitute for lost function
Morphological Changes
- Neurogenesis
- Synaptogenesis
- Axonal Sprouting
Molecular Changes
- Gene Activation
- Protein Synthesis
- Nerve, vascular growth factor production
Rehab Recovery Test
Time difference to do various arm related everyday tasks pre and post treatment
Repetitive Transcranial Magnetic Stimulation
Usage of magnetic fields to induce electrical change in specified brain areas
Advantage of rTMS
Non-invasive, feasible and safe, no systemic side effects, focal effects
Inhibitory frequency of rTMS
Inhibitory 1 Hz
Facilitative frequency of rTMS
Facilitative 5-10 Hz
Usage of inhibitory rTMS
Healthy region of the brain can send inhibitory signals to damaged areas of the brain which prevents the damaged area from getting used.
Inhibition of the healthy region can stop that inhibitory signaling
Usage of Facilitative rTMS
Stimulation of damaged areas of the brain to increase neuroplasticity