patho exam 2
Esophagus
Sphincters:
Upper Esophageal Sphincter: Prevents air entry during respiration.
Lower Esophageal Sphincter: Prevents gastric reflux.
Gastroesophageal Reflux Disease (GERD): Incompetence of the lower sphincter leads to this condition.
Peristalsis
Definition: Involuntary wave-like contractions that move food to the stomach (takes about 5-10 seconds).
Stomach Phases
Cephalic Phase:
Triggered by sight, smell, and thought of food.
Mediated by the vagus nerve, it prepares the stomach.
Gastric Phase:
Occurs when food enters the stomach.
Release of gastrin increases acid production and motility.
Intestinal Phase:
Chyme enters the duodenum, slowing gastric emptying for digestion.
Stress can inhibit the cephalic phase, affecting digestion.
High-fat foods delay gastric emptying; liquids accelerate it.
Patients are advised to drink liquids to alleviate constipation.
Dysphagia
Definition: Difficulty swallowing, often following a stroke affecting cranial nerves IX (Glossopharyngeal) and X (Vagus).
Types:
Oropharyngeal Dysphagia: Trouble initiating the swallow.
Esophageal Dysphagia: Feeling of food getting stuck.
Red Flags: Coughing or choking during eating, gurgling voice post-swallowing, pocketing food.
Aspiration: Entry of food or liquids into the airways; can lead to aspiration pneumonia.
Prevention: Keep head elevated 30-90 degrees during and after meals.
Consult Speech Therapy for safe swallowing strategies and thickened liquids (nectar, honey, pudding consistency). Avoid thin liquids (water, coffee).
Small Intestine Anatomy
Parts of the Small Intestine
Duodenum:
Length: 10-12 inches.
Secretion of secretin stimulates pancreatic bicarbonate to neutralize stomach acid.
Jejunum:
The site of nutrient absorption, malabsorption can lead to significant malnutrition.
Ileum:
Absorbs vitamin B12 in conjunction with intrinsic factor.
Bile acid reabsorption prevents diarrhea.
Ileal Resection: Requires lifelong B12 injections due to malabsorption; Crohn's disease commonly affects this area.
Pathophysiology of GI Disorders
Functions: Ingest, digest, absorb, and eliminate waste.
Dumping Syndrome: Rapid gastric emptying leads to malabsorption; symptoms include diarrhea, cramping, and hypoglycemia.
Gastroparesis: Slow gastric emptying causes nausea and vomiting, increasing aspiration risk.
Leaky Gut: Inflammation impacts motility and absorption; causes electrolyte imbalances (potassium, magnesium, calcium).
Conditions Related to Dysphagia
Aspiration Pneumonia
Major complication; caused by food or liquid entering the lungs during dysphagia.
Hernias
Definition: A portion of the small intestine bulges through a weakness in the abdominal muscle.
Types:
Reducible: Can be pushed back into place.
Incarcerated: Trapped, cannot be pushed back.
Strangulated: Blood supply cut off, leading to ischemia—a medical emergency (nausea, vomiting).
Celiac Disease
Definition: Autoimmune disorder triggered by gluten (wheat, barley, rye).
Symptoms: Chronic diarrhea, bloating, weight loss, fatigue, failure to thrive in children.
Villi Damage: Leads to poor nutrient absorption; presents as steatorrhea (fatty, foul-smelling stools).
Diagnosis: Biopsy during endoscopy to confirm villi damage.
Management: Read food labels to avoid gluten (can hide in medications, personal care products), and prevent cross-contamination.
Large Intestine Anatomy & Disorders
Structure & Function
Main Function: Absorbs water and nutrients (1-2 liters daily).
Parts include: Cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal.
Transit Time: 12-48 hours for contents to pass.
Colon Motility
Types of Movements
Mixing Movements: Occur 2-3 times a minute for water and electrolyte absorption.
Propulsive Movements: Large contractions occur 1-3 times a day post-meals, promoting defecation.
Gastrocolic Reflex: Stomach distension triggers increased colonic activity.
Medications Affecting Motility:
Opioids slow bowel movements; stool softeners are often prescribed.
Metoclopramide can accelerate motility, causing diarrhea.
Neural Control of the GI Tract
Autonomic Nervous System (ANS): Modulates the intrinsic nervous system controls.
Myenteric Plexus: Controls motility between muscle layers.
Submucosal Plexus: Governs secretion and absorption, local blood flow.
Vagus Nerve (parasympathetic): Increases colon motility, relaxes sphincters for defecation.
Sympathetic Nervous System: Decreases bowel activity, tightens sphincters, and reduces blood flow during stress.
Anal Sphincter Function
Internal Anal Sphincter: Involuntary; relaxes under parasympathetic control.
External Anal Sphincter: Voluntary; can be controlled; potential damage during childbirth or spinal injuries.
Reflex Bowel: May occur with injuries above S2-S4 resulting in spastic bowel; below these levels, flaccid bowel requiring manual disimpaction.
Absorption & Electrolyte Control
Primary Function: Absorbs water via osmosis; regulates electrolytes (sodium, chloride).
Secretions: Alkaline mucus protects the intestinal lining and neutralizes bacterial acids.
Gut Microbiome: Influences digestion, flora balance, susceptible to disruption by antibiotics leading to conditions like C. Diff.
Defecation Process
Triggers for Defecation: Stretch receptors, parasympathetic signals, rectal contraction, internal sphincter relaxation.
Bowel Sounds Assessment:
Hyperactive bowel sounds indicate increased activity (gastroenteritis, obstruction).
Hypoactive or absent sounds suggest ileus or late obstruction; they may indicate constipation if quiet.
Normal bowel sounds are gurgling or intermittent air-related noises.
Common Disorders of the Large Intestine
Obstructive Disorders
True Obstruction: Physical blockage preventing stool passage.
Symptoms: Cramping, distention, vomiting, absence of bowel movement/gas.
Pseudo Obstruction: No physical blockage; typically neuromuscular dysfunction post-surgery or electrolyte imbalance.
Constipation
Definition: Less than three stools per week; hard stools; straining.
Fecal Impaction: Hard stool is stuck leading to paradoxical diarrhea.
Common Causes: Immobility, dehydration, low fiber diets, certain medications (opioids, anticholinergics).
Inflammatory Bowel Disease (IBD)
Difference from IBS: IBD involves inflammation, IBS does not.
Conditions: Crohn's Disease (can affect any part of the GI, skip lesions, fistulas present) and Ulcerative Colitis (limited to the colon, continuous inflammation).
Symptoms of UC: Bloody diarrhea, abdominal pain, fever, and fatigue.
Diverticular Disease
Diverticulosis: Presence of diverticula; typically asymptomatic until inflamed.
Diverticulitis Symptoms: Fever, elevated WBC, and left lower quadrant pain.
Management: Importance of monitoring for perforation risk due to potential sepsis.
Hemorrhoids
Definition: Swollen veins in the rectum/anus; types include internal (painless, may bleed) and external (itchy, painful).
Risk Factors: Age (45-65), pregnancy, straining during bowel movements.
Management Strategies: High fiber diet, hydration, sitz baths, topical medications (witch hazel, hydrocortisone).
Diverticular Disease Overview
Diverticulosis vs. Diverticulitis
Prevention: High fiber diet, hydration, exercise.
Symptoms of Diverticulitis: Fever, LLQ pain, potential for infection and complications.
Conclusion: Proper dietary and lifestyle modifications are crucial in the management of diverticular diseases.
Oxyhemoglobin Dissociation Curve
Right Shift:
Decreased affinity for oxygen due to:
Increased CO₂
Increased temperature
Increased acid (lower pH)
Left Shift:
Increased affinity for oxygen.
CBC Interpretation
Hgb Normal Ranges: Typically 12-16 g/dL for women and 14-18 g/dL for men.
Hct Normal Ranges: 38-46% for women and 42-54% for men.
RBC Count: Normal range is approximately 4.5-5.5 million cells per microliter.
Platelet Count: Normal range is 150,000-450,000 platelets per microliter.
WBC Basics: Standard range is about 4,500-11,000 cells per microliter; important for infection response and immune system function.
Coagulation Labs
PT / INR (Prothrombin Time / International Normalized Ratio): Used to monitor patients on anticoagulants; normal PT: 11-13.5 seconds.
aPTT (Activated Partial Thromboplastin Time): Evaluates the intrinsic clotting pathway; normal range: 30-40 seconds.
Fibrinogen: Levels reflect clotting ability; normal range: 200-400 mg/dL.
D-dimer: Used to rule out thrombosis; normal is typically less than 250 ng/mL.
Clot Dissolution
Plasmin: Enzyme that breaks down fibrin in blood clots.
Fibrinolysis: Process of breaking down fibrin and resolving a blood clot.
Control of Breathing
CO₂: Primary driver for the urge to breathe; elevated levels increase respiratory rate.
Central vs Peripheral Chemoreceptors:
Central: Located in the brain, sensitive to CO₂ levels.
Peripheral: Located in the carotid and aortic bodies, sensitive to O₂ and CO₂ levels.
COPD: Patients may rely on hypoxic drive due to chronically elevated CO₂ levels.
Atelectasis
Definition: Collapse of lung tissue; a common postoperative complication.
Symptoms: Diminished breath sounds and potential hypoxemia.
Hypoxemia vs Hypoxia
Hypoxemia: Defined as low partial pressure of oxygen (PaO₂).
Hypoxia: Defined as insufficient oxygen at the tissue level.
Pulmonary Edema
Symptoms:
Pink frothy sputum
Crackles upon auscultation
Fluid accumulation in alveoli
Pleural Effusion
Symptoms:
Decreased breath sounds
Dullness to percussion
Thoracentesis may be required for diagnosis and treatment.
Bilirubin Breakdown (High Yield)
Unconjugated (Indirect): Formed from the breakdown of hemoglobin; fat-soluble and not excreted by the liver.
Conjugated (Direct): Water-soluble; excreted in bile.
Types of Jaundice:
Prehepatic: Caused by hemolysis of red blood cells.
Hepatic: Due to liver dysfunction.
Posthepatic: Obstruction of the bile ducts.
Liver Functions
Protein Metabolism:
Albumin production, maintains oncotic pressure.
Production of clotting factors for hemostasis.
Carbohydrate Metabolism:
Glycogen storage for energy reserves.
Gluconeogenesis for glucose production during fasting.
Fat Metabolism:
Bile production is essential for fat digestion and absorption.
Liver Failure Signs
Signs Include:
Ascites
Portal hypertension
Varices (enlarged veins)
Asterixis (flapping tremor)
Elevated ammonia levels leading to hepatic encephalopathy.
Hepatitis A–E Differences
Transmission Differences:
A and E: Fecal-oral transmission.
B, C, and D: Bloodborne; B and C can become chronic.
Vaccines Available:
Vaccines for Hepatitis A and B.
Hepatitis D requires the presence of Hepatitis B.
Hepatitis C often leads to chronic conditions.
Electrical Conduction System
Components:
The heart's electrical conduction pathway includes the SA node, the AV node, the Bundle of His, and the Purkinje fibers.
Baroreceptors
Function:
Detect changes in blood pressure and help regulate cardiovascular response.
RAAS (Renin-Angiotensin-Aldosterone System)
Role:
Regulates blood pressure and fluid balance.
Antidiuretic Hormone (ADH)
Function:
Promotes water reabsorption in the kidneys to maintain blood volume.
Natriuresis
Definition:
Excretion of sodium in urine, often in response to volume overload.
Angina Pathophysiology
Understanding:
Due to myocardial ischemia and insufficient blood flow to the heart muscle.
Hyperlipidemia Pathophysiology
Understanding:
Elevated levels of lipids in the blood; significant risk factor for cardiovascular diseases.
RAAS Mechanism
Steps: Low BP → Kidney releases renin → Angiotensin I → ACE (lungs) → Angiotensin II →
Vasoconstriction
Aldosterone → Na & water retention
↑ BP
ACE-Inhibitor Connection: Important in hypertension management.
ADH Trigger
Released when:
↑ serum osmolality
↓ blood volume
Baroreceptors Location
Location:
Carotid sinus
Aortic arch
Electrical Conduction of the Heart
Sequence of Events:
SA → AV → Bundle of His → R/L bundle branches → Purkinje
Important for understanding heartbeat regulation.
Hepatic Encephalopathy Mechanism
Mechanism:
Ammonia crosses the BBB
Alters neurotransmission
Causes confusion → asterixis → coma
Portal Hypertension Consequences
Consequences:
Portal pressure ↑ → blood backs up →
Esophageal varices
Splenomegaly
Caput medusae
COPD Hypoxic Drive
Clarification:
High oxygen in COPD can suppress respiratory drive → CO₂ retention.
Oxyhemoglobin Dissociation Curve
2,3-BPG Impact:
Right shift also occurs with ↑ 2,3-BPG (chronic hypoxia).
Dumping Syndrome
Symptoms:
Early:
Cramping
Diarrhea
Tachycardia
Late:
Hypoglycemia
Additional Considerations
Important points not previously mentioned:
Peptic ulcer disease
Gastritis
Variceal bleeding emergency
Hepatitis labs (ALT/AST)
Albumin low → edema
Pathophysiology of GI Disorders
Functions: Ingest, digest, absorb, and eliminate waste.
Dumping Syndrome: Rapid gastric emptying leads to malabsorption; symptoms include diarrhea, cramping, and hypoglycemia.
Gastroparesis: Slow gastric emptying causes nausea and vomiting, increasing aspiration risk.
Leaky Gut: Inflammation impacts motility and absorption; causes electrolyte imbalances (potassium, magnesium, calcium).
Peptic Ulcer Disease (PUD):
H. pylori: Common cause of ulcers.
NSAIDs: A significant risk factor for the development of ulcers.
Risk of Bleeding: Signs include coffee-ground emesis and melena.
Conditions Related to Dysphagia
Aspiration Pneumonia: Major complication; caused by food or liquid entering the lungs during dysphagia.
Inflammatory Bowel Disease (IBD)
Crohn’s Disease vs. Ulcerative Colitis (UC):
Crohn’s Disease:
Fistulas
Transmural inflammation
Skip lesions
Ulcerative Colitis:
Continuous inflammation
Risk of toxic megacolon
Liver Labs
ALT/AST Levels:
AST > ALT: Suggests alcohol-related liver damage.
ALT > AST: Indicates viral hepatitis.
RAAS (Renin-Angiotensin-Aldosterone System)
Aldosterone Action Site: Acts at the distal tubule and collecting duct to regulate sodium and water balance.
Angina Types
Types of Angina:
Stable Angina: Triggered by exertion.
Unstable Angina: Occurs at rest.
Prinzmetal Angina: Caused by coronary vasospasm.
Hematology / Oxygen Transport
Erythrocytes (RBCs): carry oxygen to body tissues.
Hemoglobin + oxygen = oxyhemoglobin
Iron is required for hemoglobin formation.
Hemoglobin is composed of 4 polypeptide chains (2 alpha, 2 beta).
Transferrin: transports iron in blood.
Ferritin: stores iron (mainly in the liver).
Spleen: removes old red blood cells.
Hemoglobin Breakdown
Heme → biliverdin (green) → bilirubin
Jaundice: yellowing of skin/eyes (first visible in the sclera).
Blood Disorders
Thalassemia
A genetic disorder affecting hemoglobin production.
Severe form: Beta-thalassemia major
Leads to anemia.
Hemophilia
Hemophilia A: Factor VIII deficiency
Hemophilia B: Factor IX deficiency
Clotting factors are produced in the liver.
Hemostasis
Second phase of hemostasis: platelet plug formation.
Pulmonary & Respiratory Concepts
Pulmonary Embolism
Blood clots usually originate in the legs (DVT) and travel to the lungs.
Gas Exchange Measurements
PaO₂: arterial oxygen pressure in blood.
SaO₂: percentage of hemoglobin saturated with oxygen.
Respiratory Control
Phrenic Nerves
Stimulates the diaphragm for breathing.
Originates from C3–C5 (especially C4).
Breathing Mechanics
Inspiration: diaphragm moves down.
Expiration: diaphragm moves up.
Hypoxia Response
Erythropoietin
Hormone released during hypoxia
Stimulates RBC production.
Lung Ventilation Concepts
Shunt
Blood passes through the lungs without ventilation.
Dead Space
Ventilated but not perfused areas of the lung.
V/Q Mismatch
Imbalance between ventilation and circulation.
Lung Anatomy
Alveoli
Small air sacs where gas exchange occurs.
Airway Physiology
Bronchodilation
Relaxation of airway smooth muscle → airways open.
Dyspnea
Difficulty breathing or shortness of breath.
Intercostal Retractions
Chest wall pulling inward during breathing → sign of respiratory distress.
Larynx
Laryngitis
Inflammation of the vocal cords.
GI System Notes
Hernia
Incarcerated hernia: cannot be pushed back into the abdomen.
Stool Characteristics
Acholic stool
Pale, soft, greasy stool.
Caused by a lack of bile.
Bright red blood in stool
Usually hemorrhoids.
GI Hormones
Gastrin
Stimulates gastric acid secretion.
Cholecystokinin (CCK)
Stimulates bile release and pancreatic enzymes.
Intestinal Anatomy
Small Intestine
The final stage of digestion occurs here.
Sections:
Duodenum
Jejunum
Ileum
Large Intestine
Functions:
Absorbs water and nutrients
Forms stool.
Intestinal Layers
Mucosa – inner layer
Submucosa – middle layer
Muscularis
Serosa
GI Cells
Goblet Cells
Produce mucus in the GI tract.
Diverticular Disease
Diverticulitis: inflammation of diverticula.
Common location: sigmoid colon and rectum.
Irritable Bowel Syndrome (IBS)
Common symptoms:
Lower abdominal pain
Nausea
Pain is relieved after a bowel movement.
Aspiration Pneumonia
Occurs when food/liquid enters the lungs.
VentilatioN
Movement of air into and out of the lungs.
Gas exchange involves:
Oxygen (O₂)
Carbon dioxide (CO₂)
Diagnostic Test
ABG (Arterial Blood Gas)
Blood test used to evaluate ventilation and oxygenation.