A Power Program for Student Review
A Review of Teaching Highlights from Last Month
The 6-Month Program
- Biophysics Of Obesity
- Obesity...The Metabolic Syndrome
- Obesity...Insulin Resistance...Diabetes
- Diabetes Complications: Glycoproteinopathies
- Obesity...Feeling Sick and Liverish
Last Month’s Daily Teaching Patient Focus (on Twitter): Cholesterol & Atheroma…is reviewed in this Countdown.
Imagine for a moment you’re a red blood cell…a tiny package of oxygen-carrying hemoglobin inside a fragile shell. You’re pummeled and pushed, choked and channeled, squeezed and squirted…endlessly swept out and back through miles of blood vessels in a closed, recycling pumping system…called the circulation.
Gathered up in the heart’s ventricle for less than a second of rest, you travel through a narrowing maze of tubes, eventually into ones so fine that you can only get through them single file. That’s where you give up your oxygen, and take up tissue carbon dioxide. Back and forth you travel in a brief existence that survives intact in the average circulation for about 4 months.
You live within the body’s blood vessels: its arteries, veins and capillaries. All of them lined by a delicate skin, as tough and translucent as food wrap. It is a glass-smooth surface formed from flat cells, like a flagstone walk. Its job is to contain the blood and keep it flowing, while allowing molecules like oxygen and nutrients to leave at their destinations. All the while it must protect you, a red cell, from damage while doing your oxygen/carbon dioxide pick-up & delivery job.
The tubing of the circulation is composed of 3 tissue layers, but blood cells like you normally contact only the inner glistening lining. Outside the lining is a muscular layer for artery strength and resilience. The outermost third layer is fibrous tissue holding blood vessels in place through the body. The lining or intima, is in contact with all blood molecules. Cholesterol can penetrate it and stay there…especially if damaged by hypertension or diabetes or smoking. Heart attacks commonly complicate such situations because they damage heart intima.
Cholesterol circulates in the blood in a protein wrapper, like a rolled taco, called lipoprotein cholesterol…3 types are most common and were first separated by centrifuge, hence their names: HDL, LDL and VLDL…Very Lo Density Lipoprotein being the least friendly. It slips too easily through the intima into artery walls. At first, in a two way process, coming and going, eventually to stay as a deposit which arteries hate.
An artery regards cholesterol as you would a splinter in your finger. It treats a cholesterol deposit like a foreign body, calling for immune pus cells to come and digest it. But cholesterol is indigestible. Once gobbled up by pus cells, it sits all cosy inside, choking them and becoming a resident foreign body. The frustrated artery then tries to isolate it by weaving a web of fiber around the deposit. This creates an atheroma.
Unless defensive dietary steps are taken, artery cholesterol deposits persist and grow, lumping up into the artery’s tunnel and slowing its flow of blood. Over the months and years, as they age, their fiber wrap stiffens and cracks which exposes raw edges to the streaming blood. Raw edges attract circulating cells called thrombocytes whose job is to form clots that can plug up an artery.
Circulating thrombocytes evolved to seal holes in arteries against blood loss, an early defense against bleeding to death. But the raw edges of a cracked atheroma pose no such threat of blood loss, so their ancient function is inappropriate and creates a blocking thrombus…for a modern medical emergency that was years in the making.
A thrombus in a coronary artery causes a heart attack. Heart muscle downstream loses its blood supply and may die, ending a life. A thrombus in cerebral artery threatens a brain part, say the motor function of an arm, leg or both, causing a stroke. People take aspirin these days to prevent their thrombocytes from collecting on the recurring fresh cracks of the atheromas scattered in all their arteries.
A thrombus in the leg causes pain below the knee…pulses at the foot are absent or diminished…toes are whitened and can darken from gangrene. In the dairy country of Denmark, men over 40 are told to begin lifetime dosing with a statin drug. It’s a cost saving move for their National Health Plan. It’s a market preserver for their butter, eggs, cream and cheese production.
This Month’s Daily Teaching Patient Focus: The Metabolic Syndrome.