The Transit System of the Body
From bib. source
Arteries are the plumbing that carries oxygenated blood to your muscles and organs, but unlike pipes in a house, your arteries are responsive and dynamic. Arteries can shunt more blood to where it is needed the most such as working muscles; they dilate in response to exercise (lowering resistance and increasing flow); and they assist forward movement of the blood by pulsating with muscular walls.
Arteries are like pipes, except that they are also like the stems or branches of a plant or tree insofar as they “are responsive and dynamic,” shunting “more blood to where it is needed the most” (LeMond 2015, 23). Just as plants and trees move their stems so that leaves may face the sun more directly, arteries can migrate or move to where fuel and reactants are most in demand. They also “dilate in response to exercise,” “lowering resistance and increasing flow” (Ibid). This means that (Ibid):
From bib. source
Even though the heart pumps more forcefully during exercise, the arteries dilate and reduce resistance thus lowering blood pressure.
That is, forceful pumping of the heart is expected to increase pressure against the arterial walls from the stronger force of the flow of blood, but this is counteracted by the dilation of the arteries. This makes it so that blood increases without increasing blood pressure. After all, arterial health is related to the quality of blood flow and the allocation of arterial termini, but it should not be reflected in high blood pressure. Since arteries are pipes comprised of muscular walls that “assist forward movement of the blood by pulsating,” that which applies to healthy muscle applies to arteries (Ibid).
In addition (Ibid):
From bib. source
The arteries are lined with a delicate and metabolically active lining (the endothelium) which when healthy is thin, pliable and smooth, but when diseased becomes thickened, hardened and covered with plaques.
“The first arteries from the heart” that “supply blood to the heart,” called the coronary arteries, “are especially prone to plaque formation” (Ibid). Blockages from plaque–called atherosclerosis–can result in (Ibid):
- Weakened heart muscle
- Heart attacks
- Muscular cramps, especially in the legs (e.g., claudication), during kinesis
- Disability or mortality due to all the previously enlisted
To avoid atherosclerosis, and thereby these symptoms and effects, it is important to exercise and control cholesterol as produced by the liver (LeMond 2015, 16-17):
From bib. source
The liver makes cholesterol. […] cholesterol is a vital part of our cell membranes and several key hormones. […] What is important to cardiovascular health is the balance and form of cholesterol. Low-density lipoprotein (LDL, known as “bad cholesterol”) delivers cholesterol from the liver to the rest of the body, where in excess it can cause plaques and arterial narrowing. On the other hand, high-density lipoprotein (HDL, known as “good cholesterol”) removes cholesterol from the body and brings it back to the liver. The liver uses this cholesterol to make bile that aids in the digestion of fat.
So, having some level of cholesterol is important for maintaining the integrity of cells that make up organ tissue, but different types of cholesterol have different downstream impacts on blood flow (Ibid):
- High-density lipoprotein (i.e., HDL), or “good” cholesterol, leads to the diverting of cholesterol from the body and into the liver, and the liver then gets to use that cholesterol for bile production. The bile is needed for fat digestion, and gets reabsorbed and recycled by the intestines.
- Low-density lipoprotein (i.e., LDL), or “bad” cholesterol, leads to the diverting of cholesterol from the liver and into the rest of the body, and an excess of this cholesterol can lead to plaque formation.
Consequently, cholesterol control involves lowering the cholesterol in circulation through the vascular system so that it remains in a Goldilocks zone amount of availability to the liver with minimal clogging or arterial wall damage: “the liver draws more cholesterol from the blood stream thus lowering cholesterol in the body” (Ibid). There are four ways to get the liver to do this (Ibid):
- Fiber consumption, as such fiber soaks up and eliminates bile from the intestines wherein it has been recycled, leading to a need for a renewed bile supply. Since bile production by the liver relies on cholesterol, this causes the liver to shift more cholesterol–especially if it is HDL–from the blood stream and into itself.
- Consuming “good” cholesterol, i.e. food with high-density lipoprotein / HDL, as this makes it easier or more likely for cholesterol to be re-diverted from the blood stream and into the liver.
- Engaging in exercise, which may so-to-speak “activate” the liver due to its involvement in the blood sugar regulatory system, which is relevant to fuel storage and use for producing energy. The increased liver activity in response to exercise may tap into bile generation to gain nutrients from the gastrointestinal tract for this purpose. In addition, effects on cardiac efficiency and muscular performance can also make blood flow more effective.
In addition, reducing consumption of heavily greasy meat may aid in reducing independent cholesterol intake. In any case, what is decidedly harmful in that it can lead to cholesterol build-up or risk a venous clot (i.e., deep vein thrombosis / DVT) given excess cholesterol is “[i]nactivity such as prolonged bed rest and long distance driving or air travel” (LeMond 2015, 23). This can escalate to “limb swelling and dangerous blockage of lung arteries,” the latter known as pulmonary emboli (LeMond 2015, 23-24).
Fiber + low-grease good cholesterol + frequent exercise = efficient blood flow
Ways to increase quality blood flow are then to eat some regular amount of fiber in one’s diet while avoiding excess consumption of highly greasy meats, and where meat or other cooked food is involved, making sure to use oils or fat comprised of “good” cholesterol (i.e., high-density lipoprotein). In the final analysis, though, what is important to avoiding clots is “staying active and maintaining good muscle tone” (LeMond 2015, 24).
biology cardiovascular_system cardiology vascular_science organ_system organ_systems physiology biological_economics blood_flow leaf reactant pipe stem branch plante terminus blood_pressure resting_blood_pressure coronary_artery coronary_arteries atherosclerosis muscle_cramp muscle_cramps myology endocrinology hormone cytology hepatology low-density_lipoprotein LDL HDL high-density_lipoprotein Goldilocks_zone intestine digestive_system digestive_tract gastrointestinal_tract blood_stream deep_vein_thrombosis embolus embolism pulmonary_embolism pulmonary_emboli pulmonary_embolus limb limbs lungs
bibliography
- “The Human Machine.” In The Science of Fitness: Power, Performance, and Endurance, 9–38. Waltham, MA: Academic Press, 2015.