Covered in 5.5:

The heart is the commander of the vascular system; it has has 4 chambers
Half of the heart pumps blood into the lungs for the cleanout process of oxygen to CO2
Half of the heart sends that oxygen rich blood through the rest of the body via the arteries
Arteries carry oxygen-rich blood to our tissues
Veins carry oxygen-depleted blood back to the heart
The difference in structure between arteries and veins and why this matters in our inversion practice
If we’re standing, the blood pressure in our legs is stronger than the blood pressure in our heart
In inversions, this reverses: blood pressure in the head increases as blood rushes down to the head due to the force of gravity
Our baroreceptors respond to this change is pressure by telling the heart rate to slow down; this is why for longtime practitioners, inversions can slow the heart rate and reduce blood pressure over time
An inversion is any pose in which your head is below your heart (this is also why some students may get dizzy when they simply fold forward)
When your head is below your heart, your veins don’t have to work as hard to bring to bring deoxygenated blood from the lower half of the body to the heart and lungs
This can also help with swelling in the feet and ankles (gravity assists venous blood return) and relaxes the nervous system