Cardiovascular System: Arteries, Veins, Capillaries, and Hemostasis

What is the primary function of arteries?

Carry blood away from the heart toward capillaries.

What makes arteries suitable for high pressure?

Thick smooth muscle and elastic fibers.

What is the primary site of vascular resistance?

Arterioles.

What is the function of veins?

Carry blood from capillaries toward the heart.

Why are veins considered high compliance vessels?

They stretch easily and store ~50% of total blood volume.

What prevents backflow in veins?

One-way valves.

What is the role of capillaries?

Site of gas exchange and nutrient delivery.

How do substances cross capillary walls?

Hydrophilic via intercellular passages; lipid-soluble via endothelial membranes.

What drives lymph flow?

"Skeletal muscle pump, smooth muscle contractions, and one-way valves."

What do lymphatic vessels absorb?

"Fluid, proteins, and bacteria."

Define compliance.

Compliance = Δ Volume / Δ Pressure.

Which vessels have high compliance?

Veins.

Which vessels have low compliance?

Arteries.

What governs blood flow direction?

Blood flows from high to low pressure.

What is the relationship between flow and resistance?

Flow ∝ 1 / Resistance.

What is perfusion pressure?

MAP - CVP.

What is the equation for MAP?

MAP = (1/3 × SBP) + (2/3 × DBP).

What is cardiac output (CO)?

CO = HR × SV.

What is the average CO in an adult male?

~5 L/min.

Characteristics of laminar flow?

"Smooth, quiet, low resistance."

Characteristics of turbulent flow?

"Chaotic, audible, high resistance."

What predicts turbulence?

High Reynolds number.

What is the primary site of resistance?

Arterioles.

How does radius affect resistance?

Resistance ∝ 1 / radius⁴.

Effect of vasoconstriction?

"↑ resistance, ↓ flow."

Effect of vasodilation?

"↓ resistance, ↑ flow."

What are the 3 components of hemostasis?

"Vascular spasm, platelet plug formation, coagulation."

What stimulates vascular spasm?

Thromboxane A₂.

What activates platelets?

Exposed collagen.

What forms the fibrin net?

Coagulation cascade.

What are the 3 risk factors for clotting?

"Endothelial injury, stasis, hypercoagulability."

What does PT/INR test?

"Factors V, VII, X, fibrinogen, prothrombin."

What does PTT test?

"Factors VIII, IX, XI, XII, fibrinogen."

What does TEG evaluate?

"Clot formation, stability, platelet function, fibrinolysis."

What does D-dimer indicate?

"Fibrin degradation (sensitive, not specific)."

Effect of alpha-1 stimulation on veins?

"↓ compliance, ↑ pressure, ↑ venous return."

Effect on arterioles?

"↑ resistance, ↓ flow to gut/extremities, ↑ perfusion pressure."

Why are large catheters preferred for rapid fluid administration?

Poiseuille's law: flow ∝ radius⁴.

Normal arterial BP?

100-130 / 60-80 mmHg.

Normal CVP?

2-10 mmHg.

Normal MAP?

90-100 mmHg.

Normal CO?

~5 L/min.