Circulation and vessels Flashcards
What is the periphery circulatory organization?
Arterial System: High-pressure vessels distributing oxygenated blood.
Capillaries: Thin-walled vessels for gas/nutrient exchange.
Venous System: Low-pressure vessels returning deoxygenated blood to the heart.
What is the blood vessel wall structure?
Arteries: Thick walls with elastic fibres and smooth muscle for high-pressure flow.
Capillaries: Single endothelial layer for diffusion.
Veins: Thin walls with valves to prevent backflow under low pressure.
What are the pressures like in different arteries?
Highest in arteries, drops across arterioles and capillaries, lowest in veins.
How do you measure blood pressure and flow?
Blood Pressure: Sphygmomanometer and auscultation (Korotkoff sounds).
Blood Flow: Doppler ultrasound or plethysmography
define flow vs velocity
Flow: Volume of blood per unit time (e.g., L/min).
Velocity: Speed of blood through a vessel (e.g., cm/s).
what are the types of flow?
Laminar: Smooth, organised layers.
Turbulent: Disorganised, occurs at high velocities or obstructions.
what is resistance to laminar flow?
Determined by vessel radius (major factor), length, and blood viscosity (Poiseuille’s law).
what are the resistance circuits?
Series: Total resistance = sum of individual resistances.
Parallel: Reduces overall resistance (e.g., capillary networks
compliance in arteries and veins
Arteries: Low compliance, maintain pressure.
Veins: High compliance, act as volume reservoirs
what forces are on vessel walls
Arteries: High pressure and pulsatile forces.
Capillaries: Low pressure, driven by hydrostatic/osmotic gradients.
Veins: Low pressure, assisted by valves and skeletal muscle pumps.
what is the structure and function of microcirculation?
Includes arterioles, capillaries, and venules.
Facilitates exchange of gases, nutrients, and waste between blood and tissues.
What is autoregulation?
Myogenic Mechanism: Vessel constriction/dilation in response to pressure changes.
Metabolic Regulation: Vasodilation in response to local metabolites (e.g., CO₂, lactate).
What is fluid exchange?
Driven by Starling forces:
Hydrostatic Pressure: Pushes fluid out of capillaries.
Oncotic Pressure: Pulls fluid into capillaries via plasma proteins.
