BP104T Unit 3 – Skeletal System & Articulations (Joints)
Unit 3 provides exhaustive coverage of cardiovascular anatomy, blood composition, the coagulation cascade, intrinsic cardiac conduction, the cardiac cycle, 12-lead ECG waveforms, and the pathophysiology of major cardiovascular disorders (Hypertension, Atherosclerosis, Angina Pectoris, Myocardial Infarction, and Congestive Heart Failure).
📋 Prescribed Syllabus Topics
📖 Detailed Lecture Notes & Solved Examples
11. Blood Composition & The Secondary Hemostatic Coagulation Cascade
Dedicated Webpage➔Blood is a liquid connective tissue accounting for approx. 8% of total body weight (5-6 liters in adult males). It consists of 55% liquid Plasma (water, albumin, globulins, fibrinogen, electrolytes) and 45% Formed Elements (Erythrocytes/RBCs, Leukocytes/WBCs, Thrombocytes/Platelets). Hemostasis is the physiological sequence that stops bleeding from an injured vessel. Secondary hemostasis involves a multi-enzyme amplification cascade culminating in the conversion of soluble plasma Fibrinogen into an insoluble cross-linked Fibrin polymer mesh that stabilizes the primary platelet plug.Khoon me 55% Plasma aur 45% Blood cells (RBC, WBC, Platelets) hote hain. Chot lagne par Coagulation Cascade chalu hota hai jisme Thrombin enzyme soluble Fibrinogen ko insoluble Fibrin jaal me badal deta hai jisse bleeding rukti hai. Warfarin dawai Vitamin K dependent factors (II, VII, IX, X) ko rok kar khoon patla karti hai.
▶The Classic Coagulation Cascade: Extrinsic, Intrinsic & Common Pathways
Biochemical activation cascade of clotting factors.
- •Erythrocyte Life Span: Approx. 120 days; phagocytosed in spleen and liver reticuloendothelial system.
- •Hematocrit (Packed Cell Volume - PCV): Percentage of total blood volume occupied by RBCs (Normal: 40-50% in males, 36-46% in females).
- •Vitamin K Dependent Clotting Factors: Factors II (Prothrombin), VII, IX, and X (Inhibited by oral anticoagulant Warfarin).
- •Heparin Mechanism: Accelerates Antithrombin III activity by 1000-fold, rapidly neutralizing Thrombin (IIa) and Factor Xa.
22. Cardiac Anatomy, Conduction System, Cardiac Cycle & ECG Waveforms
Dedicated Webpage➔The heart is a four-chambered muscular pump enclosed within the pericardial sac. Myocardial auto-rhythmic pacemaker cells spontaneously generate periodic action potentials without neural input. The cardiac conduction hierarchy originates at the Sinoatrial (SA) Node (the primary pacemaker, firing at 60-100 bpm), spreads across atria via internodal tracts to the Atrioventricular (AV) Node (where a physiological 0.1-second delay occurs allowing ventricular filling), travels down the Bundle of His, branches into Left and Right Bundle Branches, and terminates in Purkinje Fibers, triggering synchronous ventricular systole.SA Node dil ka natural pacemaker hai jo 72 beats/min generate karta hai. ECG me P wave Atria ke contract hone ko dikhati hai, QRS complex Ventricles ke fast contraction ko dikhata hai, aur T wave Ventricles ke relaxation ko dikhati hai. Dil ke valves band hone par S1 (LUB) aur S2 (DUB) aawaz aati hai.
▶Correlation of Cardiac Cycle Phases with Standard 12-Lead ECG
Electrophysiological events and their surface ECG representation.
- •Cardiac Output ($CO$): $CO = \text{Heart Rate (HR)} \times \text{Stroke Volume (SV)}$ (Normal resting $CO \approx 70 \text{ bpm} \times 70 \text{ mL} = 4.9 \text{ to } 5.0 \text{ L/min}$).
- •Frank-Starling Law of the Heart: The force of cardiac contraction is directly proportional to the initial resting length of the myocardial fibers (End-Diastolic Volume / Preload).
- •Ejection Fraction (EF): $EF = \frac{SV}{EDV} \times 100$ (Normal healthy EF is 55% to 70%).
33. Pathophysiology of Major Cardiovascular Disorders
Dedicated Webpage➔Cardiovascular diseases are the leading cause of global mortality. Understanding the cellular and hemodynamic pathophysiological mechanisms of Hypertension, Atherosclerosis, Ischemic Heart Disease (Angina & Myocardial Infarction), and Heart Failure is essential for rational pharmacotherapy.Atherosclerosis me arteries ke andar cholesterol (LDL) jamta hai jise Macrophages khakar Foam Cells banate hain. Jab ye plaque phatata hai, toh khoon ka thakka bankar artery block ho jati hai jisse Heart Attack (Myocardial Infarction) hota hai. Iski confirm janch Cardiac Troponin I test se hoti hai.
▶Mechanistic Overview of 4 Primary Cardiovascular Pathologies
Cellular mechanisms, clinical symptoms, and drug targets.
| Disorder | Core Hemodynamic Defect | Key Diagnostic Biomarkers / Signs | First-Line Pharmacotherapy Classes |
|---|---|---|---|
| Hypertension | Elevated SVR and arterial stiffening | BP >= 140/90 mmHg, LVH on ECG | ACE inhibitors, ARBs, CCBs, Thiazide diuretics |
| Atherosclerosis | Intimal fibro-fatty plaque accumulation | Elevated hs-CRP, LDL-C > 100 mg/dL | HMG-CoA reductase inhibitors (Statins), Aspirin |
| Myocardial Infarction | Transmural ischemic myocyte necrosis | ST elevation, Elevated Cardiac Troponin I / CK-MB | Thrombolytics (tPA), Antiplatelets, Beta-blockers, PCI |
| Congestive Heart Failure | Inadequate cardiac output (EF < 40%) | Elevated BNP / NT-proBNP, pulmonary rales | ARNI (Sacubitril/Valsartan), Beta-blockers, SGLT2i, Spironolactone |
- •Cardiac Biomarkers for MI: Cardiac Troponin I (cTnI) and Troponin T (cTnT) are highly specific and remain elevated for 7-10 days; CK-MB peaks at 24 hours.
- •Atherosclerosis Progression: Endothelial injury $\rightarrow$ LDL Oxidation $\rightarrow$ Macrophage Foam Cells $\rightarrow$ Fatty Streak $\rightarrow$ Fibrous Cap Plaque $\rightarrow$ Rupture & Thrombosis.
- •Systolic Heart Failure: Reduced ejection fraction ($EF < 40\%$) due to impaired contractility.
- In a 10-mark question on Myocardial Infarction and Atherosclerosis, draw the step-by-step diagram of plaque formation from endothelial injury to foam cells and rupture.
- List the coagulation cascade pathways (Intrinsic, Extrinsic, Common) with factor names.