Exam Pack For;
Physiology Exam 1
** Expert-Verified Explanation
** Questions with Verified Answer
** New Edition |Updated
** Guaranteed Pass
** 100% Correct Answers | Graded A+
,Cerebral metabolic rate (CMR) how much energy the brain uses to work and keep cells alive
How much of the body's total oxygen does the brain 20%
normally consume?
2 components of measuring brain oxygen content 1. ABG
2. pulse ox
Pulse ox tells the % of oxygen bound to hemoglobin
ABGs in regards to brain oxygen tells us % of oxygen physically dissolved in plasma
What part of ABGs tells us the amount of dissolved O2 PaO2
-partial pressure of oxygen dissolved in plasma
What is the driving force for O2 diffusion into the brain? PaO2, dissolved oxygen in plasma
Because of relatively high oxygen consumption, unconsciousness
interruption of cerebral perfusion results in
Neurons use _________ as their primary source glucose
Average cerebral blood flow (CBF) 50ml/100g/min
Blood flow is a volume over period of time and is affected pressure (numerator)
by changes in resistance (denominator)
Cerebral perfusion pressure (CPP) formula CPP = MAP-ICP (or CVP)
Define auto regulation of cerebral blood flow automatic alteration in diameter of cerebral blood vessels with changes in blood
pressure, to maintain constant blood flow to brain
Normal MAP range that autoregulation works between 50-150 mmHg
What happens to CBF when MAP is below 50 mmHg? vessels are dilated, CBF falls, causes ischemia
What happens to CBF when MAP is above 150 mmHg? vessels are constricted, CBF rises, can cause edema or hemorrhage
, How does anesthesia affect BP and the autoregulation anesthesia lowers BP, but if a pt has chronic hypertension and their
curve? body/autoregulation curve is already adjusted and used to this, the lowered BP
can cause ischemia
How does the autoregulation curve shift with chronic rightward
hypertension?
What happens to CBF below the autoregulation curve? CBF directly depends on MAP, pressure dependent
(MAP < 50 mmHg) If MAP drops, CBF drops
What is the most important extrinsic factor of respiratory PaCO2
gas tension & CBF
Why is PaCO2 such a good extrinsic regulator of CBF? CO2 crosses the BBB easily, where it dissociates into H+ and HCO3-. H+ then
goes on to affect the pH of cerebral vessels (acidosis or alkalosis)
How does an increase in H+ affect cerebral vessels? acidosis, vasodilates vessels and increases CBF
How does a decrease in H+ affect cerebral vessels? alkalosis, vasoconstrictor and decreases CBF
How does hyperventilation affect PaCO2? decreases it, causing vasoconstriction and a decease in CBF/ICP
How does hypoventilation affect PaCO2? increases it, causing vasodilation and an increase in CBF/ICP
What is the main ion that does NOT cross the BBB? sodium
What is the key driver of water shifts across the BBB? serum osmolality, sodium does not cross the BBB (stays in plasma and ECF)
why?
What drugs cause an increase in PaCO2? opioids, induction meds
What happens to the brain during hypernatremia? water leaves brain cells to try dilute the high sodium in blood, shrinkage
What happens to the brain during hyponatremia? water enters brain cells, swelling
What is the major factor affecting viscosity? hemoglobin
What happens to viscosity when a patient is anemic? less blood viscosity and improved CBF
Physiology Exam 1
** Expert-Verified Explanation
** Questions with Verified Answer
** New Edition |Updated
** Guaranteed Pass
** 100% Correct Answers | Graded A+
,Cerebral metabolic rate (CMR) how much energy the brain uses to work and keep cells alive
How much of the body's total oxygen does the brain 20%
normally consume?
2 components of measuring brain oxygen content 1. ABG
2. pulse ox
Pulse ox tells the % of oxygen bound to hemoglobin
ABGs in regards to brain oxygen tells us % of oxygen physically dissolved in plasma
What part of ABGs tells us the amount of dissolved O2 PaO2
-partial pressure of oxygen dissolved in plasma
What is the driving force for O2 diffusion into the brain? PaO2, dissolved oxygen in plasma
Because of relatively high oxygen consumption, unconsciousness
interruption of cerebral perfusion results in
Neurons use _________ as their primary source glucose
Average cerebral blood flow (CBF) 50ml/100g/min
Blood flow is a volume over period of time and is affected pressure (numerator)
by changes in resistance (denominator)
Cerebral perfusion pressure (CPP) formula CPP = MAP-ICP (or CVP)
Define auto regulation of cerebral blood flow automatic alteration in diameter of cerebral blood vessels with changes in blood
pressure, to maintain constant blood flow to brain
Normal MAP range that autoregulation works between 50-150 mmHg
What happens to CBF when MAP is below 50 mmHg? vessels are dilated, CBF falls, causes ischemia
What happens to CBF when MAP is above 150 mmHg? vessels are constricted, CBF rises, can cause edema or hemorrhage
, How does anesthesia affect BP and the autoregulation anesthesia lowers BP, but if a pt has chronic hypertension and their
curve? body/autoregulation curve is already adjusted and used to this, the lowered BP
can cause ischemia
How does the autoregulation curve shift with chronic rightward
hypertension?
What happens to CBF below the autoregulation curve? CBF directly depends on MAP, pressure dependent
(MAP < 50 mmHg) If MAP drops, CBF drops
What is the most important extrinsic factor of respiratory PaCO2
gas tension & CBF
Why is PaCO2 such a good extrinsic regulator of CBF? CO2 crosses the BBB easily, where it dissociates into H+ and HCO3-. H+ then
goes on to affect the pH of cerebral vessels (acidosis or alkalosis)
How does an increase in H+ affect cerebral vessels? acidosis, vasodilates vessels and increases CBF
How does a decrease in H+ affect cerebral vessels? alkalosis, vasoconstrictor and decreases CBF
How does hyperventilation affect PaCO2? decreases it, causing vasoconstriction and a decease in CBF/ICP
How does hypoventilation affect PaCO2? increases it, causing vasodilation and an increase in CBF/ICP
What is the main ion that does NOT cross the BBB? sodium
What is the key driver of water shifts across the BBB? serum osmolality, sodium does not cross the BBB (stays in plasma and ECF)
why?
What drugs cause an increase in PaCO2? opioids, induction meds
What happens to the brain during hypernatremia? water leaves brain cells to try dilute the high sodium in blood, shrinkage
What happens to the brain during hyponatremia? water enters brain cells, swelling
What is the major factor affecting viscosity? hemoglobin
What happens to viscosity when a patient is anemic? less blood viscosity and improved CBF
