Cardiovascular system consists of the heart (cardio) and vessels (vascular).
Three types of vessels:
Arteries: Carry blood away from the heart.
Capillaries: Site of diffusion and material exchange.
Veins: Carry blood back to the heart.
Vessel Structure
All vessels have an inner endothelium (thin squamous type) to reduce friction.
Arteries
Structure:
Inner layer: Simple squamous epithelium.
Middle layer: Smooth muscle for structure and blood pressure regulation.
Outer layer: Fibers and loose connective tissue for stability.
Characteristics:
High pressure, requiring thicker walls.
Smaller diameter assists in blood movement.
Veins
Characteristics:
Thinner walls compared to arteries.
Larger in size, low pressure.
Reduce friction as blood returns to the heart.
Key Structures
Aorta: Largest artery; carries oxygenated blood from the left ventricle to the body.
Arterioles: Final branches of arteries; feed into capillary beds.
Capillary Network
Capillaries:
Thin to allow rapid diffusion.
Abundant where healthy tissue exists (6,000 square meters surface area).
Organized into capillary beds serving specific regions.
Function and Dynamics
Material Exchange: Oxygen, CO2, nutrients, and waste.
Blood flow to capillary beds varies based on tissue activity.
Digestive system active after eating, muscles during exercise.
Shunt (Atrial Venous Shunt): Bypass capillary beds when not active.
Circulation Pathway
Arterial blood flows under pressure, facilitating rapid nutrient and oxygen delivery.
Venules: Collect blood from capillaries, leading to larger veins and eventually back to the heart.
Diffusion Process
High oxygen in arterial blood diffuses into tissue.
High CO2 in tissue diffuses into blood to be carried back to the heart and lungs.
Conclusion
Understanding the structure and function of the cardiovascular system is crucial for comprehending how the body maintains homeostasis and efficiently distributes nutrients and gases.