D236 Pathophysiology Final Exam Study Guide

Grace J.
November 11, 2025November 11, 2025
BSN, D236, Western Governors University

Student Name

Western Governors University

D236 Pathophysiology

Prof. Name

Date

Clinical Case Review and Physiological Interpretations

1. Acid–Base Imbalance and Respiratory Compensation

Question:
A patient suffering from a viral infection combined with severe vomiting presents with an elevated carbon dioxide (CO₂) level and a blood pH of 7.53. The patient is also exhibiting a slow respiratory rate. What is the most likely diagnosis?

Respiratory acidosis
Respiratory alkalosis
Metabolic acidosis
Metabolic alkalosis

Answer:
The diagnosis is metabolic alkalosis.

Explanation:
This patient’s blood pH is elevated, indicating alkalosis, and the CO₂ level is also increased, which suggests respiratory compensation rather than the cause. Vomiting causes loss of hydrogen ions and chloride, leading to a rise in blood pH (alkalosis). In response, the respiratory system slows breathing (hypoventilation), causing CO₂ retention to help correct the alkalosis by increasing carbonic acid levels.

Table 1
Summary of Acid–Base Imbalance and Compensatory Mechanisms

Condition	pH	CO₂	Primary Cause	Compensation Mechanism
Metabolic Alkalosis	↑	↑	Acid loss (vomiting)	Hypoventilation to retain CO₂

2. Fluid Balance and Hormonal Response in Dehydration

Question:
In the setting of dehydration, what changes occur in antidiuretic hormone (ADH) levels and the renin-angiotensin-aldosterone system (RAAS)?

ADH decreases and RAAS activates
ADH decreases and RAAS deactivates
ADH increases and RAAS deactivates
ADH increases and RAAS activates

Answer:
ADH levels increase, and RAAS is simultaneously activated.

Explanation:
Dehydration elevates plasma osmolality, detected by hypothalamic osmoreceptors, triggering the release of ADH from the posterior pituitary. ADH promotes water reabsorption in the kidneys, conserving fluid. Concurrently, reduced renal perfusion stimulates RAAS, causing sodium and water retention and vasoconstriction to restore blood volume and pressure.

3. Mechanism of ACE Inhibitors

Question:
How do angiotensin-converting enzyme (ACE) inhibitors contribute to lowering blood pressure?

Answer:
ACE inhibitors block the conversion of angiotensin I to angiotensin II, a powerful vasoconstrictor. This blockage leads to vasodilation, reduced aldosterone secretion, decreased sodium and water retention, and ultimately a drop in blood pressure.

Table 2
Impact of ACE Inhibition on Blood Pressure Regulation

Step	Normal RAAS Function	Effect of ACE Inhibition
Angiotensin I → II	Vasoconstriction	Vasodilation
Aldosterone Secretion	↑ Sodium & water retention	↓ Sodium & water retention
Overall Effect	Increased blood pressure	Lowered blood pressure

4. Anion Gap in Diabetic Ketoacidosis (DKA)

Question:
What happens to the anion gap in diabetic ketoacidosis?

Answer:
In DKA, the anion gap increases due to the consumption of bicarbonate (HCO₃⁻) as it buffers accumulating ketone acids.

Explanation:
Ketone bodies produced in DKA consume bicarbonate during buffering, lowering plasma bicarbonate levels and elevating the anion gap, which is calculated by the difference between measured cations and anions.

Table 3
Anion Gap Calculation and Changes in DKA

Formula	Normal Range	Effect in DKA
(Na⁺ + K⁺) – (Cl⁻ + HCO₃⁻)	8–16 mEq/L	Increased due to decreased HCO₃⁻

5. Potassium Regulation in Dialysis

Question:
For patients with end-stage renal disease, what is the recommended potassium concentration of the dialysate during dialysis?

Answer:
The dialysate should have a lower potassium concentration than the patient’s blood to facilitate diffusion of potassium out of the bloodstream.

Explanation:
Dialysis removes excess potassium via diffusion. A dialysate low in potassium creates a concentration gradient that promotes potassium movement from blood into the dialysate, helping prevent hyperkalemia and associated cardiac complications.

6. Genetic Probability in Hemophilia

Question:
If a woman is a carrier for hemophilia, what is the likelihood her male child will inherit the disorder?

Answer:
There is a 50% chance her son will have hemophilia.

Explanation:
Hemophilia is an X-linked recessive disorder. Males receive their single X chromosome from their mother; if she carries the mutated gene, there is a 50% probability that her son will inherit it and express the disease.

7. Sickle Cell Disease and Gene Therapy

Question:
What causes sickle cell anemia, and how might gene therapy offer treatment?

Answer:
Sickle cell anemia arises from a mutation in the β-globin gene, producing abnormal hemoglobin S (HbS). Gene therapy aims to reactivate fetal hemoglobin (HbF) production, which does not sickle, thereby improving oxygen delivery and reducing disease severity.

8. Effects of Alcohol on Fetal Brain Development

Question:
How does prenatal alcohol exposure affect fetal brain development?

Answer:
Alcohol consumption during pregnancy results in reduced brain volume, particularly affecting structures such as the corpus callosum, cerebellum, and frontal lobes, leading to cognitive and behavioral impairments characteristic of fetal alcohol spectrum disorders (FASD).

9. Down Syndrome Etiology

Question:
What genetic abnormality causes Down syndrome?

Answer:
Down syndrome results from the presence of an extra copy of chromosome 21 (trisomy 21), leading to typical physical features and developmental delays.

10. Blood Loss and Hormonal Response

Question:
Following significant blood loss, how does the body respond hormonally?

Answer:
ADH secretion increases to promote water reabsorption in the kidneys, aiding in blood volume restoration and maintaining blood pressure.

11. Respiratory Rate and pH Balance During Exercise

Question:
How does increased breathing during exercise maintain acid-base balance?

Answer:
An elevated respiratory rate removes excess CO₂ generated by increased metabolism, reducing carbonic acid formation and preventing acidosis, thereby maintaining pH homeostasis.

12. Arterial Blood Gas Imbalance in ICU Patient

Question:
An ICU patient presents with low pH, low CO₂, and increased respiratory rate. What condition does this indicate?

Metabolic acidosis
Metabolic alkalosis
Respiratory alkalosis
Respiratory acidosis

Answer:
The patient has metabolic acidosis.

Explanation:
Low pH with low CO₂ and increased breathing rate reflects a primary metabolic acidosis with respiratory compensation via hyperventilation to reduce CO₂ and raise pH.

13. Dialysis and Home-Based Kidney Management

Question:
Which dialysis method allows patients to manage their treatment at home?

Answer:
Peritoneal dialysis (PD).

Explanation:
PD utilizes the patient’s peritoneal membrane as a natural filter for waste removal and electrolyte balance, enabling home-based therapy and greater patient autonomy.

Table 4
Comparison of Dialysis Modalities

Feature	Hemodialysis	Peritoneal Dialysis
Location	Hospital/Clinic	Home
Filtration Membrane	Artificial dialyzer	Peritoneal membrane
Patient Independence	Moderate	High

14. Compensation for Pulmonary Edema

Question:
How does the body compensate for elevated CO₂ levels caused by pulmonary edema?

Answer:
The kidneys respond by excreting hydrogen ions and conserving bicarbonate to counteract respiratory acidosis, helping restore pH balance.

15. Inflammatory Response Mechanisms

Question:
A patient stung by a bee shows redness and swelling. Which physiological process is unlikely?

Vasodilation
Increased capillary permeability
Vasoconstriction causing fluid buildup

Answer:
Vasoconstriction is unlikely; inflammation is characterized by vasodilation.

Explanation:
Histamine release causes vasodilation and increased capillary permeability, allowing immune cells and plasma proteins to infiltrate tissues, leading to redness and swelling.

16. Function of Helper T Cells

Question:
What is the role of helper T cells in the immune response?

Answer:
Helper T cells produce cytokines that activate B cells to produce antibodies and stimulate cytotoxic T cells to eliminate infected or malignant cells, orchestrating adaptive immunity.

17. Genetic Basis of Red–Green Color Blindness

Question:
What type of genetic disorder is red–green color blindness?

Answer:
It is an X-linked recessive disorder affecting males more frequently.

18. Neurobehavioral Congenital Abnormality (ND-PAE)

Question:
What is the cause of ND-PAE?

Answer:
Prenatal alcohol exposure leads to neurobehavioral disorder associated with prenatal alcohol exposure (ND-PAE), resulting in cognitive and impulse control deficits.

19. Neural Tube Defect: Spina Bifida

Question:
What developmental anomaly characterizes spina bifida?

Answer:
Failure of the neural tube to close properly during embryogenesis causes protrusion of meninges or spinal cord tissue, visible as a sac on the lower back.

20. Fracture with Bone Fragments

Question:
An X-ray reveals multiple bone fragments after a hip injury. What fracture type is this?

Answer:
Comminuted fracture.

Explanation:
This fracture involves bone breaking into several pieces, often from severe trauma, requiring surgical intervention.

21. Ankle Sprain Severity

Question:
What type of ankle injury is characterized by swelling, bruising, and difficulty bearing weight?

Answer:
Grade II sprain, indicating partial ligament tears with moderate impairment.

22. Glucocorticoids and Bone Health

Question:
Why are glucocorticoid-treated patients prone to bone diseases like rickets?

Answer:
Glucocorticoids inhibit vitamin D–mediated calcium absorption, causing hypocalcemia and poor bone mineralization.

23. Cervical Degenerative Disc Disease

Question:
Which symptom is not associated with cervical degenerative disc disease?

Answer:
Low back pain is unrelated; cervical disease affects neck and upper limbs.

24. Compartment Syndrome After Tibial Fracture

Question:
What complication can arise due to elevated pressure in muscle compartments post-fracture?

Answer:
Compartment syndrome, requiring urgent decompression to avoid tissue death.

25. Melanoma Identification

Question:
What diagnosis fits an irregular, dark, flat lesion over 6 mm in diameter?

Answer:
Melanoma, a potentially deadly skin cancer.

26. Burn Classification After Sun Exposure

Question:
What burn type causes redness and pain without blisters?

Answer:
Superficial (first-degree) burn.

27. Burn Surface Area Estimation

Question:
If burns involve anterior face, neck, both arms, lower legs, and upper torso, what is the total body surface area (BSA) burned?

Answer:
Approximately 58.5% using the Rule of Nines.

28. Vitiligo and Skin Depigmentation

Question:
What causes smooth white patches of depigmented skin?

Answer:
Vitiligo, an autoimmune melanocyte destruction disorder.

29. Fungal Infection of the Scalp

Question:
What diagnosis fits a child with a scaly, itchy scalp lesion fluorescing yellow-green under Wood’s light?

Answer:
Tinea capitis, a fungal scalp infection.

30. Hemorrhagic Stroke Mechanism

Question:
What occurs during a hemorrhagic stroke?

Answer:
A ruptured cerebral blood vessel causes brain bleeding and ischemia.

31. Peripheral Neuropathy in Diabetes

Question:
What causes diabetic peripheral neuropathy?

Answer:
Microvascular damage to nerve blood supply (vasa nervorum) from chronic hyperglycemia.

32. Iron-Deficiency Anemia

Question:
What characterizes iron-deficiency anemia?

Answer:
Microcytic, hypochromic red blood cells due to insufficient iron for hemoglobin production.

Table 5
Common Anemias Characteristics

Type	RBC Size	Color	Cause	Lab Finding
Iron-deficiency	Microcytic	Hypochromic	Blood loss, low intake	↓ Ferritin
Pernicious (B₁₂)	Macrocytic	Normochromic	Autoimmune gastritis	↓ B₁₂, ↑ MCV
Aplastic	Normocytic	Normochromic	Bone marrow suppression	Pancytopenia

33. Pernicious Anemia

Question:
What vitamin deficiency causes pernicious anemia, and why?

Answer:
Vitamin B₁₂ deficiency due to lack of intrinsic factor from autoimmune destruction of gastric parietal cells.

34. Leukemia and Bone Marrow Function

Question:
How does leukemia affect hematopoiesis?

Answer:
Uncontrolled proliferation of immature white cells crowds out normal blood cell production, causing anemia and immunodeficiency.

35. Disseminated Intravascular Coagulation (DIC)

Question:
What is DIC?

Answer:
A pathological state of widespread clotting that depletes clotting factors, paradoxically causing bleeding.

36. Hypertension Pathophysiology

Question:
What physiological change underlies primary hypertension?

Answer:
Increased systemic vascular resistance from chronic vasoconstriction.

37. Atherosclerosis Development

Question:
What are the stages leading to atherosclerosis?

Answer:
Endothelial injury → LDL infiltration → foam cell formation → fibrous plaque → plaque rupture causing thrombosis.

Table 6
Stages of Atherosclerosis

Stage	Key Process	Outcome
Endothelial Injury	Shear stress, toxins	LDL entry
Fatty Streak	Foam cell accumulation	Early lesion
Fibrous Plaque	Smooth muscle proliferation	Arterial narrowing
Complicated Lesion	Plaque rupture	Thrombosis

38. Myocardial Infarction (MI)

Question:
What causes the chest pain in MI?

Answer:
Ischemia leads to anaerobic metabolism and lactic acid accumulation, irritating nerve endings.

39. Heart Failure

Question:
Why do patients with left-sided heart failure have pulmonary symptoms?

Answer:
Blood backs up into the lungs, increasing hydrostatic pressure and causing pulmonary edema.

40. Right-Sided Heart Failure

Question:
What clinical signs indicate right-sided heart failure?

Answer:
Peripheral edema, ascites, and jugular vein distension due to systemic venous congestion.

41. Shock States

Question:
How does shock cause cellular injury?

Answer:
Reduced perfusion causes hypoxia, leading to anaerobic metabolism and energy failure.

Table 7
Types of Shock

Type	Cause	Example
Hypovolemic	Blood/fluid loss	Hemorrhage
Cardiogenic	Pump failure	Myocardial infarction
Distributive	Vasodilation	Septic/anaphylactic
Obstructive	Physical blockage	Pulmonary embolism

42. Deep Vein Thrombosis (DVT)

Question:
What three factors predispose to DVT?

Answer:
Venous stasis, endothelial injury, and hypercoagulability (Virchow’s triad).

43. Pulmonary Embolism (PE)

Question:
What is the physiological effect of a large PE?

Answer:
Impaired gas exchange and increased pulmonary artery pressure, risking right heart failure.

44. Endocarditis

Question:
How does infective endocarditis develop?

Answer:
Bacteria colonize damaged heart valves, forming vegetations that impair function and cause emboli.

45. Rheumatic Heart Disease

Question:
What causes heart valve damage in rheumatic fever?

Answer:
Autoimmune cross-reactivity between streptococcal and cardiac tissue proteins leads to inflammation and scarring.

46. Peripheral Arterial Disease (PAD)

Question:
Why does PAD cause intermittent claudication?

Answer:
Ischemia during exercise causes muscle pain due to inadequate oxygen supply.

47. Varicose Veins

Question:
What causes varicose veins?

Answer:
Valve incompetence leads to venous pooling and vein dilation.

48. Aneurysm Formation

Question:
What predisposes arteries to aneurysm?

Answer:
Degeneration of the tunica media weakens vessel walls, promoting dilation.

49. Hypertensive Crisis

Question:
Why is hypertensive crisis dangerous?

Answer:
Sudden blood pressure elevation damages endothelium, risking encephalopathy or renal failure.

50. Raynaud’s Phenomenon

Question:
What triggers Raynaud’s phenomenon?

Answer:
Cold or stress-induced vasospasm of small arteries reduces blood flow, causing color changes and numbness.

References

Guyton, A. C., & Hall, J. E. (2020). Textbook of Medical Physiology (14th ed.). Elsevier.

Ganong, W. F. (2019). Review of Medical Physiology (26th ed.). McGraw-Hill Education.