Anatomy & Physiology: Cardiovascular System

Components: Heart and blood vessels.
Functions:
- Transport blood (O2, nutrients) and remove waste (CO2).
- Maintain adequate perfusion (blood delivery per time per tissue).

Two Sides:
- Right side: Receives deoxygenated blood, pumps to lungs.
- Left side: Receives oxygenated blood, pumps to body.
Chambers:
- Atria: Superior chambers receive blood.
- Ventricles: Inferior chambers pump blood away.

Types:
- Arteries: Carry blood away from heart (mostly oxygenated).
- Veins: Carry blood to heart (mostly deoxygenated).
- Capillaries: Sites for gas exchange.

Superior and Inferior Vena Cava: Drain deoxygenated blood into right atrium.
Pulmonary Trunk: Transports blood from right ventricle; splits into pulmonary arteries.
Pulmonary Veins: Drain oxygenated blood into left atrium.
Aorta: Transports blood from left ventricle.

Types:
- Atrioventricular (AV) valves: Control flow between atria and ventricles.
- Right: Tricuspid valve.
- Left: Bicuspid (mitral) valve.
- Semilunar valves: Control flow from ventricles to arteries.
- Pulmonary: Between right ventricle and pulmonary trunk.
- Aortic: Between left ventricle and aorta.

Pulmonary: Right heart to lungs for gas exchange.
Systemic: Left heart to body tissues for nutrient and gas exchange.
Flow Pattern: Right heart → lungs → left heart → systemic tissues → right heart.

Systole: Contraction phase (ventricular ejection).
Diastole: Relaxation phase (ventricular filling).
Events:
- Atrial contraction fills ventricles.
- Isovolumetric contraction raises pressure.
- Ejection phase when pressure exceeds arterial pressure.
- Isovolumetric relaxation when all valves are closed.

Congestive Heart Failure: Impaired pumping ability, leading to edema.
Coronary Heart Disease: Plaque buildup reduces blood flow, can lead to heart attacks.

Components: The system consists of the heart (a muscular pump) and blood vessels (a closed network of tubes).
- Heart Wall Layers:
  1. Epicardium: The outer visceral layer of the serous pericardium.
  2. Myocardium: The middle, thickest layer composed of cardiac muscle tissue responsible for contraction.
  3. Endocardium: The inner lining of the heart chambers and valves, composed of simple squamous epithelium.
Functions:
- Transport: Delivery of O_2, nutrients, and hormones to tissues.
- Waste Removal: Removal of CO_2 and metabolic byproducts (e.g., urea) for excretion.
- Perfusion: Maintenance of adequate blood delivery per unit of time per gram of tissue (mL/min/g).

General Anatomy:
- Located in the mediastinum, slightly rotated to the left.
- Enclosed by the pericardium, a double-walled sac that reduces friction and prevents overfilling.
Chambers:
- Atria: Thin-walled superior chambers that function as receiving rooms. Separated by the interatrial septum.
- Ventricles: Thick-walled inferior chambers that function as the primary pumps. Separated by the interventricular septum. The left ventricle is significantly thicker than the right to generate higher pressure for systemic circulation.

Tunic Layers:
- Tunica Intima: Inner layer (endothelium).
- Tunica Media: Middle layer containing smooth muscle and elastin; controls vasodilation and vasoconstriction.
- Tunica Externa: Outer protective layer of connective tissue.
Vessel Diversity:
- Arteries: High-pressure vessels. Elastic arteries (conductance) lead to muscular arteries (distribution) and then to arterioles (resistance).
- Capillaries: Composed only of tunica intima to facilitate rapid diffusion of gases and nutrients.
- Veins: Low-pressure vessels containing valves to prevent backflow as blood returns to the heart against gravity.

Atrioventricular (AV) Valves:
- Prevent backflow into atria during ventricular contraction.
- Tricuspid (Right) and Bicuspid/Mitral (Left).
- Chordae Tendineae and Papillary Muscles: These structures anchor the valve cusps to prevent them from prolapsing into the atria during systole.
Semilunar Valves:
- Prevent backflow from great vessels into ventricles during relaxation.
- Pulmonary Valve and Aortic Valve.

Electrical Conduction:
1. SA Node: The natural pacemaker (60-100 bpm).
2. AV Node: Delays the impulse to allow atria to finish contracting.
3. Bundle of His and Purkinje Fibers: Distribute the impulse through the ventricular myocardium.
Mechanical Events:
- Systole: Ventricular contraction. Includes isovolumetric contraction (all valves closed) and the ejection phase.
- Diastole: Ventricular relaxation. Includes isovolumetric relaxation and ventricular filling.
Heart Sounds: S1 ("lub") from AV valves closing and S2 ("dub") from semilunar valves closing.

Formula: CO = HR \times SV
- Stroke Volume (SV): The amount of blood ejected per beat (SV = EDV - ESV).
Factors Affecting SV:
- Preload: Degree of stretch of the cardiac muscle cells before they contract (Frank-Starling Law).
- Contractility: Contractile strength at a given muscle length (influenced by Ca^{2+} levels).
- Afterload: The pressure that must be exceeded before ejection of blood from the ventricles can occur.
Autonomic Regulation:
- Sympathetic: Releases norepinephrine to increase HR and contractility.
- Parasympathetic: Via the Vagus nerve, releases acetylcholine to decrease HR.

Coronary Artery Disease (CAD): Atherosclerosis in coronary arteries reducing blood flow to the myocardium (Ischemia).
Myocardial Infarction: Complete blockage leading to tissue death (heart attack).
Congestive Heart Failure (CHF): Occurs when the heart cannot pump enough blood; left-side failure leads to pulmonary edema, while right-side failure leads to systemic edema.