Cardiovascular System

Key Concepts

The cardiovascular system is responsible for transporting essential substances throughout the body and maintaining homeostasis. Understanding its structure and function is crucial for grasping human physiology.

• Vasodilation

  • Decreases blood pressure

  • Increases blood flow to tissues

  • Often occurs in response to heat or inflammation

• Primary Function of Cardiovascular System

  • Transport oxygen, nutrients, hormones, and waste

  • Maintain homeostasis (pH, temperature, fluid balance)

• Heart Anatomy and Function

  • Left ventricle pumps oxygenated blood to the body

  • Chambers and valves coordinate to maintain unidirectional flow

  • Autorhythmic cells initiate electrical signals for contraction

• Blood Flow Through Heart

  • Path: vena cava → right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta

• Blood Vessel Types and Functions

  • Arteries: thick walls, high pressure

  • Veins: low pressure, act as reservoirs, rely on valves and skeletal muscle pump

  • Capillaries: site of exchange

• Blood Pressure and Flow Equation

  • Flow = Pressure / Resistance

Blood and Plasma

Key Concepts

Blood is a connective tissue composed of plasma and formed elements, each with distinct functions in transport and defense.

• Plasma Composition

  • Mostly water (>90%)

  • Contains proteins (albumin, globulins, fibrinogen), electrolytes, nutrients

• Red Blood Cells (RBCs)

  • Function: oxygen transport via hemoglobin

  • Reticulocytes mature into RBCs (lose organelles/nucleus)

• White Blood Cells (WBCs)

  • Function: immune defense

  • Granulocytes include neutrophils, eosinophils, basophils

Cardiac and Skeletal Muscle Physiology

Key Concepts

Muscle physiology focuses on how cardiac and skeletal muscles contract and generate force, which is essential for movement and heart function.

• Excitation-Contraction Coupling in Cardiac Muscle

  • Involves calcium influx, triggering contraction

  • Calcium from extracellular fluid and sarcoplasmic reticulum

• Ion Movement

  • Calcium (Ca2+) initiates contraction in muscle fibers

  • Sodium (Na+) and potassium (K+) regulate action potentials

Respiratory System

Key Concepts

The respiratory system enables gas exchange and regulates blood pH, which is vital for cellular metabolism and homeostasis.

• Alveoli

  • Thin-walled sacs for gas exchange

  • Large surface area and short diffusion distance

• Pleural Fluid

  • Reduces friction

  • Helps lungs adhere to chest wall

• Gas Diffusion

  • Depends on surface area, membrane thickness, and partial pressure gradient

• Ventilation Mechanics

  • Diaphragm and intercostal muscles create pressure changes

  • Hyperventilation affects blood pH (e.g., respiratory alkalosis)

Renal (Kidney) Physiology

Key Concepts

The renal system filters blood, regulates water and electrolyte balance, and maintains acid-base homeostasis.

• Filtration

  • Occurs in the glomerulus

  • Blood cells and large proteins stay in blood; filtrate enters nephron

• Nephron Function

  • Loop of Henle concentrates urine

  • Collecting duct reabsorbs water (regulated by ADH)

• Glomerular Filtration Rate (GFR)

  • Affected by blood pressure and renal perfusion

  • Mesangial cells and juxtaglomerular apparatus regulate GFR

• Three Renal Processes

  • Filtration, reabsorption, secretion

• Water Balance & Alcohol

  • Alcohol inhibits ADH → reduced water reabsorption → dehydration

  • ADH creates osmotic gradient for water reabsorption when ADH returns

• Respiration and Kidney Function

  • Kidneys help compensate for respiratory pH imbalances by adjusting bicarbonate and H+ excretion

Matching Sections (Review Structures and Functions)

Key Concepts

Reviewing anatomical structures and their functions is essential for understanding physiological integration.

• Cardiac EC Coupling Events (diagram)

• Heart Chambers and Valves (matching diagram)

• Blood Vessel Types and Functions (matching diagram)

• Integration of respiratory and cardiovascular system: how they work to regulate low pO2 environments