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
, WGU D236 pathophysiology Exam A+
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 homeostatic 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, metabolic 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 tin 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 in 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.
7. Why is it important to maintain a homeostatic balance of
glucose in the blood (ie describe the pathogenesis of
diabetes)?
Insulin is the hormone responsible for initiating the uptake of glucose by the
cells. Cells use glucose to produce energy (ATP). In a normal individual, when blood
, WGU D236 pathophysiology Exam A+
glucose increases, the pancreas is signaled to produced in insulin, which binds to insulin
receptors on a cells surface and initiates the uptake of glucose. Glucose is a very
reactive molecule and if left in the blood, it can start to bind to other proteins and lipids,
which can lead to loss of function. AGEs are advanced glycation end products that are a
result of glucose reacting with the endothelial lining, which can lead to damage in the
heart and kidneys.
8. Compare and contrast Type I and Type II Diabetes
Type I diabetes is caused by lack of insulin. With out insulin signaling, glucose will
not be taken into the cell and leads to high blood glucose (hyperglycemia). Type I is
usually treated with insulin injections. Type II diabetes is caused by a desensitization to
insulin signaling. The insulin receptors are no longer responding to insulin, which also
leads to hyperglycemia. Type II is usually treated with drugs to increase the sensitization
to insulin (metformin), dietary and life-style changes or insulin injections.
9. Describe some reasons for a patient needing dialysis AEIOU-
acidosis. Electrolytes, Intoxication/Ingestion, overload, uremia. Patients with kidney
or heart failure. A build up of phosphates, urea and magnesium are removed
from the blood using a semi-permeable membrane and dialysate. AEIOU: A—acidosis; E
—electrolytes principally hyperkalemia; I—ingestions or overdose of medications/drugs;
O—overload of fluid causing heart failure; U—uremia leading to encephalitis/pericarditis.
10. Compare and contrast hemodialysis and peritoneal dialysis.
What are some reasons for a patient choosing one over the
other?
Hemodialysis uses a machine to pump blood from the body in one tube while
dialysate (made of water, electrolytes and salts) is pumped in the separate tube in the
opposite direction. Waste from the blood diffuses through the semipermeable
membrane separating the blood from the dialysate. Peritoneal Dialysis does not use a
machine, but instead injects a solution of water and glucose into the abdominal cavity.
The peritoneum acts as the membrane instead of dialysis tubing. The waste products
diffuse into the abdominal cavity and the waste solution is then drained from the body.
Peritoneal dialysis offers continuous filtration and is less disruption to the patient’s daily
routines. However, it does require some training of the patient and is not recommended
for individuals who are overweight or have severe kidney failure. Hemodialysis provides
medical care, but 3 times a week for several hours sitting at a hospital or clinic.
Individuals with acute kidney failure are recommended to use hemo
11. Essential Question: How does homeostasis and maintaining
optimal physiological health impact your wellbeing?
, WGU D236 pathophysiology Exam A+
Homeostasis acts to create a constant and stable environment in the body
despite internal and external changes. Proteins and other cellular processes require
optimal conditions in order to carry out their functions. Alterations in pH, salt
concentration, temperature, glucose levels, etc. can have negative effects on health, so
it is vital for mechanisms that regulate homeostasis to function properly for maintaining
good health.
Lesson 2: Cellular Response and
Adaptation
1. Differentiate between Innate Immunity and Adaptive
Immunity.
The innate immune system encompasses physical barriers and chemical and
cellular defenses. Physical barriers protect the body from invasion. These include things
like the skin and eyelashes. Chemical barriers are defense mechanisms that can destroy
harmful agent. Examples include tears, mucous, and stomach acid. Cellular defenses of
the innate immune response are non-specific. These cellular defenses identify
pathogens and substances that are potentially dangerous and takes steps to neutralize
or destroy them. Adaptive immunity is an organism’s acquired immunity to a specific
pathogen. As such, it’s also referred to as acquired immunity. Adaptive immunity is not
immediate, nor does it always last throughout an organism’s entire lifespan, although it
can. The adaptive immune response is marked by clonal expansion of T and B
lymphocytes, releasing many antibody copies to neutralize or destroy their target
antigen.
2. What is a way that Adaptive Immunity can recruit innate
immunity?
The innate immune response to microbes stimulates adaptive immune responses
and influences the nature of the adaptive responses. Conversely, adaptive immune
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