WGU D236 Pathophysiology Exam 2023
Questions and Answers
1. What is Starling's Law of Capillary forces?
How does this explain why a nutritionally deficient child would have edema?
: Starling's Law describes how fluids move across the capillary
membrane. There are two major opposing forces that act to balance
each other, hydrostatic pressure (pushing water out of the capillaries)
and osmotic pressure (including oncontic pressure, which pushes fluid
into the capillaries).
Both electrolytes and proteins (oncontic pressure) in the blood affect
osmotic pressure, high electrolyte and protein concentrations in the
blood would cause water to leave the cells and interstitial space and
enter the blood stream to dilute the high concentrations.
On, the other hand, low electrolyte and protein concentrations (as
seen in a nutritionally deficient child) would cause water to leave the
capillaries and enter the cells and interstitial fluid which can lead to
edema.
2. How does the RAAS (Renin-Angiotensin-Aldosterone System) result in
,increased blood volume and increased blood pressure?: A drop in blood
pressure is sensed by the kidneys by low perfusion, which in turn
begins to secrete renin.
Renin then triggers the liver to produce angiotensinogen, which is
converted to Angiotensin I in the lungs and then angiotensin II by the
enzyme
Angiotensin-converting enzyme (ACE). Angiotensin II stimulates
peripheral arterial vasoconstriction which raises BP.
Angiotensin II is also stimulating the adrenal gland to release
aldosterone, which acts to increase sodium and water reabsorption
increasing blood volume, while also increased potassium secretion in
urine.
3. How can hyperkalemia lead to cardiac arrest?: Normal levels of
potassium are between 3.5 and 5.2 mEq/dL. Hyperkalemia refers to
potassium levels higher that 5.2 mEq/dL.
A major function of potassium is to conduct nerve impulses in
muscles. Too low and muscle weakness occurs and too much can
cause muscle spasms.
,This is especially dangerous in the heart muscle and an irregular
heartbeat can cause a heart attack
4. The body uses the Protein Buffering System, Phosphate Buffering
System, and Carbonic Acid-Bicarbonate System to regulate and maintain
homeosta- tic pH, what is the consequence of a pH imbalance: Proteins
contain many acidic and basic group that can be affected by pH
changes. Any increase or decrease in blood pH can alter the structure
of the protein (denature), thereby affecting its function as well
5.Describe the laboratory findings associated with metabolic acidosis,
meta- bolic alkalosis, respiratory acidosis and respiratory alkalosis. (ie
relative pH and CO2 levels).: Normal ABGs (Arterial Blood Gases) Blood
pH: 7.35-7.45 PCO2: 35-45 mm Hg PO2: 90-100 mm Hg HCO3-: 22-26
mEq/L SaO2: 95-100%
Respiratory acidosis and alkalosis are marked by changes in PCO2.
Higher = acidosis and lower = alkalosis
Metabolic acidosis and alkalosis are caused by something other than
abnormal CO2 levels. This could include toxicity, diabetes, renal
failure or excessive GI losses.
Here are the rules to follow to determine if is respiratory or metabolic
, in nature. -If pH and PCO2 are moving in opposite directions, then it is
the pCO2 levels that are causing the imbalance and it is respiratory in
nature.
-If PCO2 is normal or is moving in the same direction as the pH, then
the imbalance is metabolic in nature.
6. The anion gap is the difference between measured cations (Na+ and
K+) and measured anions (Cl- and HCO3-), this calculation can be useful
in determining the cause of metabolic acidosis.
Why would an increased anion gap be observed in diabetic ketoacidosis or
lactic acidosis?: The anion gap is the calculation of unmeasured anions i
the blood.
Lactic acid and ketones both lead to the production of unmeasured
anions, which remove HCO3- (a measured anion) due to buffering of
the excess H+ and therefore leads to an increase in the AG.
Questions and Answers
1. What is Starling's Law of Capillary forces?
How does this explain why a nutritionally deficient child would have edema?
: Starling's Law describes how fluids move across the capillary
membrane. There are two major opposing forces that act to balance
each other, hydrostatic pressure (pushing water out of the capillaries)
and osmotic pressure (including oncontic pressure, which pushes fluid
into the capillaries).
Both electrolytes and proteins (oncontic pressure) in the blood affect
osmotic pressure, high electrolyte and protein concentrations in the
blood would cause water to leave the cells and interstitial space and
enter the blood stream to dilute the high concentrations.
On, the other hand, low electrolyte and protein concentrations (as
seen in a nutritionally deficient child) would cause water to leave the
capillaries and enter the cells and interstitial fluid which can lead to
edema.
2. How does the RAAS (Renin-Angiotensin-Aldosterone System) result in
,increased blood volume and increased blood pressure?: A drop in blood
pressure is sensed by the kidneys by low perfusion, which in turn
begins to secrete renin.
Renin then triggers the liver to produce angiotensinogen, which is
converted to Angiotensin I in the lungs and then angiotensin II by the
enzyme
Angiotensin-converting enzyme (ACE). Angiotensin II stimulates
peripheral arterial vasoconstriction which raises BP.
Angiotensin II is also stimulating the adrenal gland to release
aldosterone, which acts to increase sodium and water reabsorption
increasing blood volume, while also increased potassium secretion in
urine.
3. How can hyperkalemia lead to cardiac arrest?: Normal levels of
potassium are between 3.5 and 5.2 mEq/dL. Hyperkalemia refers to
potassium levels higher that 5.2 mEq/dL.
A major function of potassium is to conduct nerve impulses in
muscles. Too low and muscle weakness occurs and too much can
cause muscle spasms.
,This is especially dangerous in the heart muscle and an irregular
heartbeat can cause a heart attack
4. The body uses the Protein Buffering System, Phosphate Buffering
System, and Carbonic Acid-Bicarbonate System to regulate and maintain
homeosta- tic pH, what is the consequence of a pH imbalance: Proteins
contain many acidic and basic group that can be affected by pH
changes. Any increase or decrease in blood pH can alter the structure
of the protein (denature), thereby affecting its function as well
5.Describe the laboratory findings associated with metabolic acidosis,
meta- bolic alkalosis, respiratory acidosis and respiratory alkalosis. (ie
relative pH and CO2 levels).: Normal ABGs (Arterial Blood Gases) Blood
pH: 7.35-7.45 PCO2: 35-45 mm Hg PO2: 90-100 mm Hg HCO3-: 22-26
mEq/L SaO2: 95-100%
Respiratory acidosis and alkalosis are marked by changes in PCO2.
Higher = acidosis and lower = alkalosis
Metabolic acidosis and alkalosis are caused by something other than
abnormal CO2 levels. This could include toxicity, diabetes, renal
failure or excessive GI losses.
Here are the rules to follow to determine if is respiratory or metabolic
, in nature. -If pH and PCO2 are moving in opposite directions, then it is
the pCO2 levels that are causing the imbalance and it is respiratory in
nature.
-If PCO2 is normal or is moving in the same direction as the pH, then
the imbalance is metabolic in nature.
6. The anion gap is the difference between measured cations (Na+ and
K+) and measured anions (Cl- and HCO3-), this calculation can be useful
in determining the cause of metabolic acidosis.
Why would an increased anion gap be observed in diabetic ketoacidosis or
lactic acidosis?: The anion gap is the calculation of unmeasured anions i
the blood.
Lactic acid and ketones both lead to the production of unmeasured
anions, which remove HCO3- (a measured anion) due to buffering of
the excess H+ and therefore leads to an increase in the AG.
