1. Introduction to the CVS Flashcards
Functions of the CVS
- Pump blood through lungs and carry oxygen
- Transport nutrients to muscles & organs
- Circulates hormones & immune mediators
- Connection to lymphatic system
- Human reproduction
- Temperature regulation
How does the CVS move blood?
Through convection (movement by pressure gradient)
What is cardiac output?
CO = Heart rate (bpm) x Stroke volume (ml/beat)
What three things control cardiac output?
- Filling pressure (Starling’s Law)
- Sympathetic and parasympathetic autonomic nerves
- Chemical factors & hormones (adrenaline)
What is blood flow?
Blood flow = (Pressure of the artery - Pressure of the vein)/Resistance
Describe total cross sectional area of blood vessels from aorta to venae cavae
The total cross-sectional area increases as the arteries diverge into arterioles and capillaries then decreases back into venules and veins.
Describe velocity of blood in blood vessels from aorta to venae cavae
The mean velocity decreases once the blood is in the capillaries but it increases once the blood is back in the veins, but not to the previous speed.
Why does velocity decrease in capillaries?
To allow gaseous/nutrient exchange to occur
What are elastic vessels?
Arteries - large arteries accommodate stroke volume and convert intermittent ejection to continuous flow
What are resistance vessels?
Arterioles - control arterial BP and regulate local blood flow
What are exchange vessels?
Capillaries - Nutrient delivery to cells, water and lymph formation and removal of metabolic waste
What are capacitance vessels?
Venules and veins - control filling pressure and provide reservoir of blood
