Heart Function

• Heart
• Blood vessels
• 5 L of blood

Entering: oxygen, nutrients and water

Within: nutrients, immune cells, chemical messengers

Exiting: metabolic wastes, heat and carbon dioxide

Diffusion is slow and the area to volume ratio.

have more oxygen than pulmonary arteries

have less oxygen then systemic veins

• Body
• De-oxygenated blood

blood gets oxygenated

• L/R ventricles contract
• AV valves close (immediately)
• Semilunar valves open (brief delay)

• L/R ventricles relax
• Semilunar valves close (immediately)
• AV valves open (brief delay)

ventricular blood pushes AV valves closed

papillary muscles contract against ventricular wall and chordae tendinae, preventing prolapse of AV valves (opening wrong way)

Pressurized blood pushes against the aortic and pulmonary valve cusps, opening the valves and ejecting blood out of the ventricles

• Closes immediately.
• Both ventricles relax and blood in ventricle has almost no positive pressure.
• Blood in aorta and pulmonary trunk is still under positive pressure, closing semilunar valves.

• Brief delay.
• Blood coming into L/R atria under positive pressure, which opens the AV valves and allows the ventricles to fill

70 mL for resting heart rate

• autorhythmic
• CNS regulates rate through sympathetic and parasympathetic nervous systems.
• 2 cells contractile (99%) (does the work) and autorhythmic (set the pace)

pacemaker cells

set the beat for the contractile cells, which actually do the work of the heart