Notes on Cardiovascular and Pulmonary Physiology

Cardiovascular Physiology

Chambers, Valves, Blood Flow

  • Main Structures:
    • Arteries that supply head and arms
    • Right pulmonary artery & veins
    • Aorta
    • Left pulmonary artery & veins
  • Heart Chambers:
    • Right atrium
    • Right ventricle
    • Left atrium
    • Left ventricle
  • Valves:
    • Tricuspid valve: between right atrium and right ventricle
    • Mitral (Bicuspid) valve: between left atrium and left ventricle
    • Pulmonary semilunar valve: between right ventricle and pulmonary trunk
    • Aortic semilunar valve: between left ventricle and aorta
  • Structural Features:
    • Chordae tendineae & papillary muscle help in valve functioning
    • Interventricular septum divides left and right ventricles
  • Heart Layers:
    • Myocardium: muscular layer
    • Epicardium: outer layer
    • Pericardium: protective sac around the heart with pericardial fluid

Blood Supply and Infarctions

  • Understanding Infarctions:
    • Inferior/Posterior: RCA involvement; moderate-sized infarcts with AV blocks common
    • Anterior/Septal: LADA; high risk for heart failure, sudden cardiac death; termed "Widow maker" due to severity
    • Superior/Lateral: smallest percentage, least complications

Nervous System Control

  • Parasympathetic Nervous System (PSNS):
    • Uses Vagus nerves
    • Ach (Acetylcholine) as the neurotransmitter influencing heart rate
  • Sympathetic Nervous System (SNS):
    • Utilizes thoracic spinal nerves
    • Norepinephrine & Epinephrine increase heart rate and contractility

Electrical Conduction in the Heart

  • Key Components:
    • Sinoatrial (SA) node: natural pacemaker
    • Atrioventricular (AV) node: receives impulse from SA node
    • Bundle of His splits into right and left bundle branches
    • Purkinje fibers distribute impulses throughout ventricles
  • Action Potential Phases:
    • Atrial excitation, followed by atrial relaxation
    • Ventricular excitation followed by relaxation
  • ECG Segments:
    • P wave: atrial depolarization
    • QRS complex: ventricular depolarization
    • T wave: ventricular repolarization

Pulmonary Physiology and Breathing Mechanics

  • Respiratory Anatomy:
    • Upper and Lower Tract components: Nose, Pharynx, Larynx, Trachea, Bronchi, Lungs
  • Muscles of Breathing:
    • Inspiration:
    • Sternocleidomastoid, Scalenes, External intercostals, Diaphragm
    • Forced Expiration:
    • Internal intercostals, Rectus abdominis, External abdominal oblique
  • Lung Volumes and Capacities:
    • Tidal Volume (TV): 500 mL
    • Inspiratory Reserve Volume (IRV): 3000 mL
    • Expiratory Reserve Volume (ERV): 1200 mL
    • Residual Volume (RV): 1200 mL
    • Total Lung Capacity (TLC): 5900 mL

Gas Exchange

  • Mechanisms at the Alveoli:
    • O2 and CO2 diffusion between alveolar air and capillary blood
  • Oxygen-hemoglobin Dissociation Curve:
    • Each hemoglobin can bind 4 O2 molecules
    • Relationship of PaO2 to SpO2 values indicates tissue oxygenation levels

Acidosis vs. Alkalosis

  • Definitions:
    • Acidosis: Lower pH due to retained CO2 (Respiratory) or excess organic acid (Metabolic)
    • Alkalosis: Higher pH due to reduced CO2 (Respiratory) or excess bicarbonate (Metabolic)
  • Effects and Symptoms:
    • Symptoms can range from mild (dyspnea) to severe (cardiac arrest) depending on pH levels

Interaction of Kidneys and Lungs

  • Both systems regulate blood pH balance
  • Compensation mechanisms:
    • Respiratory acidosis and alkalosis lead to corresponding renal responses
  • Overall Coordination:
    • Efficient management of acid-base homeostasis is vital for bodily functions

Immune and Pulmonary Pathology

  • Key Cellular Components:
    • Mast cells, T-cells, B-cells, Alveolar macrophages involved in inflammation and immune response
  • Pathological Conditions:
    • Asthma, COPD, pulmonary hypertension, and fibrosis can lead to impaired gas exchange and lung function