WGU Pathophysiology D236 Comprehensive Study Guide

Body Defense Systems and Infectious Pathologies

  • General Body Response to Infection: The body utilizes a multi-step immune response where T cells produce cytokines. These cytokines then stimulate B cells, which are responsible for producing antibodies to target the pathogen.

  • Innate vs. Adaptive Immunity:

    • Innate Immunity: Serves as the body’s first line of defense against pathogens. It is characterized as general and non-specific, meaning it does not differentiate between various types of pathogens.

    • Adaptive Immunity: This type of immunity is developed over time through exposure to specific diseases or through vaccinations.

  • Injury Response Process: The body releases cytokines, which produce inflammatory cells or chemokines directly at the affected site to stimulate healing. Simultaneously, vasodilation occurs to facilitate the quicker and easier movement of inflammatory cells to the area. This combined process results in the cardinal signs of redness, swelling, heat, and pain.

  • Lyme Disease: A tick-borne illness caused by the spirochete known as Borrelia burgdorferi.

  • West Nile Virus: Transmitted through the bite of an infected mosquito. Severe signs and symptoms include a high fever, headache, and a stiff neck.

  • Erythema Infectiosum (’Fifth Disease’): A febrile upper respiratory illness occurring in children, followed by the sudden appearance of red, flushed cheeks.

  • Communicable vs. Infectious Disease:

    • Communicable Disease: A disease that can be spread from one person or species to another.

    • Infectious Disease: A disease caused by a pathogen that can be spread from one individual to another.

Genetic and Congenital Pathophysiology

  • Genetic and Chromosomal Abnormalities: Congenital abnormalities result from mutations in genes or chromosomal abnormalities. These disruptions in development are primarily caused by alterations of DNA.

  • Sickle Cell Disease Probability: In a scenario with two heterozygous carriers (possessing one dominant and one recessive gene), there is a 50%50\% chance the offspring will have sickle cell disease.

  • Spina Bifida:

    • Etiology: Results from the failure of the neural tube to close.

    • Risk Factors: Obesity and diabetes in the mother are identified risk factors.

    • Clinical Sign: Presence of a fluid-filled sac on the lower back.

  • Hematologic Genetics: Hemophilia is noted to be more common in males.

  • Prenatal Alcohol Exposure: Consequences of exposure include Neurodevelopmental Disorder Associated with Prenatal Alcohol Exposure (ND-PAE), decreased brain function, and Fetal Alcohol Syndrome (FAS).

  • Huntington’s Disease: A genetic disorder caused by a dominant allele that leads to progressive deterioration of brain cells. Symptoms usually do not manifest until approximately the age of 3030 and involve involuntary muscle movements.

Fluid, Electrolyte, and Acid-Base Homeostasis

  • Homeostasis and Wellbeing: Disruptions in homeostasis (e.g., fluid and electrolyte shifts) significantly affect wellbeing, potentially causing symptoms like nausea, vomiting (n/vn/v), or dysrhythmias.

  • Renin-Angiotensin-Aldosterone System (RAAS):

    1. Reduced blood flow triggers the kidneys to release renin.

    2. Renin facilitates the production of Angiotensin I.

    3. Angiotensin I is converted into Angiotensin II.

    4. Angiotensin II causes systemic vasoconstriction and triggers the release of aldosterone.

    5. Aldosterone causes the kidneys to conserve sodium and water.

    6. Result: Reduced water loss in urine and maintenance of blood pressure.

  • Acid-Base Imbalances and Compensations:

    • Alkalosis: The kidneys compensate by retaining HH ions and excreting HCO3HCO_3.

    • Acidosis: If left untreated, leads to an increase in potassium levels (K+K^+).

    • Diabetic Ketoacidosis (DKA): Characterized by an increased anion gap and decreased HCO3HCO_3. Hallmarks include lipolysis with ketone formation; it can lead to cerebral edema.

  • Electrolyte Indicators:

    • Trousseau’s Sign: Arm or carpal spasm associated with hypocalcemia.

    • Hypernatremia (High Sodium): Signs include the mnemonic SALT: S (Skin flushed), A (Agitation), L (Low grade fever), T (Thirst).

    • Hypervolemia (Fluid Volume Excess): Signs and symptoms include muscle/chest pain, weakness, n/vn/v, and palpitations.

  • Starling’s Law of Capillary Forces: Fluid movement due to filtration across the capillary wall depends on the balance between the hydrostatic pressure gradient and the pressure gradient across the capillary. Edema occurs when water is retained in the tissues rather than the vascular system.

  • Blood Glucose Balance: Homeostatic balance is vital because glucose is the primary energy source for the brain and is not synthesized by the brain, making it essential for brain and motor functions.

Integumentary and Musculoskeletal Pathophysiology

  • Integumentary Disorders:

    • Dermatitis: General inflammation of the skin.

    • Eczema: A noninfectious inflammatory disease featuring redness, blisters, scabs, and itching.

    • Decubitus Ulcer: A sore resulting from prolonged pressure (lying down for long periods).

    • Vitiligo: Localized loss of pigmentation resulting in milk-white patches.

    • Albinism: A genetic alteration resulting in decreased pigment in the skin, hair, and eyes.

    • Fungal Infections: Superficial localized conditions or deep tissue infections caused by exposure to spores; transmission varies.

  • Skin Cancers:

    1. Basal Cell Carcinoma: Most common and least severe; characterized by light or pearly nodules. Usually appears on the face due to sun exposure and rarely metastasizes.

    2. Squamous Cell Carcinoma: More serious than basal cell; presents as scaly red crusted papules or firm nodules.

    3. Melanoma: The most serious form; typically appears as black or brown lesions. Caucasian males are at the highest risk.

  • Burns:

    • Superficial (1st degree): Redness and pain.

    • Partial-thickness (2nd degree): Wet, pink, and painful.

    • Full-thickness (3rd degree): White, swollen, and painless.

  • Musculoskeletal Tissue Classification:

    • Connective Tissue Disorders: Rheumatoid Arthritis (RA), Scleroderma, Lupus.

    • Muscle Tissue Disorders: Multiple Sclerosis (MS), Muscular Dystrophy, Myasthenia Gravis.

  • Bone and Joint Conditions:

    • Osteoporosis: Loss of bone mass (often age-related) making bones porous, brittle, and prone to fractures. It can be treated with Denosumab, an antibody that blocks a protein to suppress bone-breaking cells.

    • Osteomalacia: Softening of bones due to calcium and Vitamin D deficiency.

    • Rickets: Vitamin D deficiency in children leading to soft bones.

    • Paget Disease: Chronic inflammation causing thickening and softening of bones, most common in the long bones of the legs, pelvis, lower spine, and skull.

    • Degenerative Disk Disease: Loss of intervertebral disk integrity due to wear and tear, age, or injury.

    • Bursa: Fluid-filled sac facilitating joint movement.

    • Myoglobin: Red pigment storing oxygen in muscle cells.

  • Bone Biology:

    • Bone Remodeling: Osteoclasts destroy old cells; Osteoblasts build new cells; Osteocytes (housed in lacunae) maintain bone mass through anabolic activities and facilitate the process by retaining calcium.

    • Articular Degeneration (Osteoarthritis): Primarily involves macrophages which induce inflammation.

  • Fractures and Complications:

    • Comminuted Fracture: Bone splintered into many pieces.

    • Compartment Syndrome: Occurs when blood flow is restricted to an area (usually extremities) for an extended time.

    • Rhabdomyolysis: Recognized by muscle pain and decreased urinary output; clinical confirmation is made via the creatine kinase laboratory test.

Neurological and Sensory Pathophysiology

  • Cerebrovascular Conditions:

    • Ischemic CVA: Caused by a clot. Predisposing factors include atrial fibrillation (a fib), carotid stenosis, and cerebral arteriosclerosis.

    • Hemorrhagic CVA: Caused by bleeding (blood).

    • Transient Ischemic Attack (TIA): Result of temporary cerebral artery blockage and decreased blood flow.

    • Cerebral Stroke (CVA): Complete artery blockage leading to brain cell death and permanent functional loss.

  • Brain Injuries and Disorders:

    • Subdural Hematoma: Blood collection under the dura mater.

    • Cerebral Contusion: Brain bruising from the brain bouncing against the skull. Symptoms: ringing in ears, severe headache, $n/v$.

    • Alzheimer’s Disease: Primarily affects language and memory.

    • Parkinson’s Disease: Affects all executive functioning.

    • Multiple Sclerosis (MS): Chronic, irreversible CNS damage to the myelin sheath. Plaques in the brain/spinal cord cause tremors, weakness, incoordination, and vision/speech disturbances.

    • Myasthenia Gravis: Autoimmune attack on Ach receptors. Causes skeletal muscle weakness, ptosis, double vision, and dysphagia (difficulty swallowing).

  • Sensory Loss:

    • Glaucoma: Loss of peripheral vision.

    • Cataracts: Cloudy vision.

    • Retinal Detachment: Characterized by floaters, flashes, and ’curtain vision.’ Vision loss occurs because the detached areas lose blood supply.

    • Meniere’s Disease: Fluid changes in the inner ear causing vertigo and imbalance.

    • Otitis Media: Middle ear infection.

  • Spinal Anatomy: Kyphosis is the excessive outward curvature of the spine leading to hunching.

Cardiovascular and Hematological Pathophysiology

  • Vascular Conditions:

    • Aneurysm: Ballooning of a weakened arterial wall.

    • Thrombus: A clot within the arteries.

    • Embolus: A dislodged traveling clot that blocks blood flow.

    • Atherosclerosis: Hardening/narrowing of arteries via cholesterol plaques. Steps: 1. Endothelial injury, 2. Foam cell formation, 3. Fatty streak formation.

    • Hypertension:

    • Benign: Chronic vascular damage due to sodium retention (’essential hypertension’).

    • Malignant: Acute vascular damage due to renin release.

    • Hypertensive Crisis: Defined as a systolic BP > 180\,mmHg.

  • Heart Disorders:

    • Angina Pectoris: Chest pain potentially radiating to the left arm and jaw due to insufficient oxygen supply.

    • Stable Angina: Predictable pain on exertion, relieved by rest or nitroglycerin.

    • Myocardial Infarction (MI): Heart attack caused by coronary artery occlusion. Damage can affect the brain, retina, heart, and kidneys. Key biomarkers: troponin and creatine kinase.

    • Right-sided Heart Failure: Often presents with Jungular Venous Distension (JVD).

    • Cor Pulmonale: Right-sided heart failure resulting from chronic lung disease.

    • Endocarditis: Inflammation of the inner heart lining; may cause valve dysfunction. Treated with antibiotics or valve repair.

    • Pericarditis: Inflammation of the sac surrounding the heart. Can compress the heart (tamponade) and is treated with NSAIDs, steroids, or pericardiocentesis.

  • Hematological and Lymphatic Systems:

    • Anemia Types:

    • Aplastic: Missing or decreased RBC production.

    • Iron Deficiency.

    • Folic Acid Deficiency.

    • Vitamin B12 Deficiency / Pernicious.

    • Hemolytic: RBC breakdown exceeds production rate.

    • Sickle Cell: Shortage caused by early RBC death.

    • Leukemia: Cancer originating in the bone marrow.

    • Hodgkin’s Lymphoma: Identified by the presence of Reed-Sternberg cells.

    • Non-Hodgkin’s Lymphoma: Lymphomas where Reed-Sternberg cells are absent.

    • Lymphocytosis: Asymptomatic abnormal increase in lymphocytes.

    • Lymphatic Anatomy: Lymph nodes filter interstitial fluid; Peyer’s patches are lymphoid tissue in the small intestine involved in antigen immunity.

Respiratory Pathophysiology

  • Infections:

    • Upper Respiratory (URI): Common cold, laryngitis, croup, pharyngitis, rhinitis, sinusitis, tonsillitis.

    • Lower Respiratory (LRI): Pneumonia, bronchitis, tuberculosis.

  • Chronic Obstructive Pulmonary Disease (COPD):

    • Etiology: Smoking, asthma, dust, chemicals, genetics.

    • Emphysema: Characterized by the overdistention of alveoli resulting in the inability to remove CO2CO_2.

  • Specific Lung Conditions:

    • Pneumonia: Inflammation caused by infection (bacteria, viruses, fungi, parasites) or aspiration. Clinical signs: crackles and rhonchi.

    • Asthma: Treatment-resistant bronchospasm; categorized under COPD.

    • Pneumothorax: Air in the pleural cavity caused by lung or chest wall puncture.

    • Coal Worker’s Pneumoconiosis (’Black Lung’): Caused by carbon dust; massive exposure leads to diffuse fibrosis.

    • Pulmonary Embolism (PE): Blood clot lodged in a pulmonary artery; treated with anticoagulants.

    • Fat Embolism (FE): Clot of fat cells (usually post-bone fracture); no specific treatment.

Gastrointestinal and Hepatic Pathophysiology

  • General Digestive Symptoms:

    • Chronic (Celiac, Crohn’s, Colitis): Abdominal pain, weight loss, changes in waste elimination, bleeding.

    • Acute (GERD, IBS, Hiatal Hernia): Abdominal pain, bleeding, bloating, heartburn, n/vn/v.

  • Specific GI Disorders:

    • GERD: Caused by the failure of the lower esophageal sphincter to close.

    • Crohn’s Disease: Chronic inflammation of the digestive tract lining; symptoms include diarrhea, sores, fistulas, and weight loss.

    • Ulcerative Colitis: Autoimmune/inflammatory bowel disease causing chronic colon inflammation and ulcers.

    • Diverticulitis: Inflammation of diverticula (usually colon). Pain is relieved by bowel movements; enemas and colonoscopies are advised against during acute phases.

    • Colon Cancer: Signs include right-sided iron deficiency anemia, left-sided obstruction, ’apple core’ lesions on barium enema, pencil-thin stools, hematochezia (bright red blood), and colicky pain.

  • Hepatobiliary and Pancreatic:

    • Cholecystitis: Gallbladder inflammation, usually associated with gallstones; features RUQ pain radiating to the back.

    • Pancreatitis: Pancreas inflammation; can be caused by gallstones blocking the common bile duct. Hallmarked by Cullen’s sign (umbilical ecchymosis).

    • Hepatitis Types:

    • Hepatitis A & E: Spread via fecal-oral route.

    • Hepatitis B, C, & D: Spread via blood and bodily fluids.

    • Hepatitis C: Specifically targets the liver.

    • Jaundice (Liver Dysfunction):

    1. Pre-hepatic: Excessive RBC breakdown.

    2. Hepatic: Liver loses ability to regulate bilirubin.

    3. Post-hepatic: Result of blockage or obstruction.

Renal and Urinary Pathophysiology

  • Manifestations of Kidney Disease:

    • Pyelonephritis: Bacterial infection (commonly E. Coli) causing inflammation of the renal pelvis and kidney.

    • Glomerulonephritis: Inflammation of kidney glomeruli.

    • Renal Calculi (Kidney Stones): Crystallized minerals; large stones can obstruct the ureter.

    • Acute Kidney Injury (AKI): Rapid loss of renal function.

    • End-Stage Renal Disease (ESRD): Little to no remaining function; requires dialysis or transplant. Symptoms: AMS, HTN, fatigue, chest pain.

  • Critical Renal Care:

    • Continuous Renal Replacement Therapy (CRRT): Circulates blood through a hemofilter 24 hours/day24\,\text{hours/day}. Benefits include slower electrolyte shifts compared to standard dialysis.

    • GFR (Glomerular Filtration Rate): Primary tool used to stage chronic renal disease.

  • Renal/Bladder Oncology:

    • Renal Cell Carcinoma: Originates in kidney tubule cells; features flank pain, hematuria, and an abdominal lump. Risk factors: smoking, obesity, HTN.

    • Bladder Cancer: Highest risk factor is smoking. Other factors: exposure to dyes (benzenes, aromatic amines), history of UTI, urologic disorders, pelvic irradiation, or analgesic abuse.

  • Nephron Anatomy:

    • Glomerulus: Filters blood.

    • Bowman’s Capsule: Filters blood from glomerulus capillaries.

    • Juxtaglomerular Apparatus: Maintains blood pressure and flow.

    • Proximal Tubule: Reabsorbs filtrate.

    • Loop of Henle: Reabsorbs salt and water.

    • Distal Tubule / Collecting Duct: Reabsorbs ions/water for homeostasis.

Endocrine and Reproductive Pathophysiology

  • Thyroid and Pituitary Disorders:

    • Graves Disease: Hyperthyroidism (autoimmune); features goiter, exophthalmos (protruding eyes), tachycardia, insomnia, and weight loss.

    • Hypothyroidism: Low T3T_3 and T4T_4 with high TSH. Symptoms: chronic fatigue, brittle nails, constipation.

    • Thyroid Cancer: Papillary carcinoma presenting as a neck lump, dysphagia, and voice changes.

    • Acromegaly: Pituitary hypersecretion of growth hormone leading to enlarged extremities.

  • Adrenal and Metabolic Disorders:

    • Addison’s (General Endocrine Symptoms): Dark skin spots, low BP, fatigue, n/v/dn/v/d.

    • Cushing’s Disease: Mnemonic UP, UP, UP, DOWN, UP for Hypernatremia, Hypertension, Increased fluid volume, Hypokalemia, and Hyperglycemia.

    • Diabetes Mellitus:

    • Type 1: Autoimmune destruction of pancreatic beta cells (usually in children/teens).

    • Type 2: Insulin resistance (body fails to respond to insulin); linked to being overweight.

    • Gestational: Hormonal changes during pregnancy rising glucose levels.

    • Diabetes Insipidus (DI): Deficiency in Antidiuretic Hormone (ADH) or kidney resistance to ADH.

  • Reproductive Health:

    • Polycystic Ovary Syndrome (PCOS): Elevated androgens and follicle cysts. Signs: infertility, irregular periods, hirsutism, insulin resistance.

    • Endometriosis: Endometrial tissue grows outside the uterus.

    • Pelvic Inflammatory Disease (PID): Infection of pelvic organs; causes pain during sex/urination and discharge.

    • Oncology: Triple negative breast cancer lacks estrogen/progesterone receptors (requires chemo). Prostate/testicular cancer may require orchiectomy or cryotherapy.

    • Therapy Effects: Antiandrogen therapy (Spironolactone/Flutamide) can cause erectile dysfunction, hot flashes, or decreased bone density.

  • Infections (STIs):

    • Gonorrhea: Bacterial; causes PID and burning urination. Can be passed via birth canal.

    • Chlamydia: Bacterial; causes penile discharge and uncomfortable walking. Can be passed via birth canal; also a cause of epididymitis.