It’s one of the tiniest machines on the planet — about a hundred times smaller than the average cell. It’s so small that no scientist can spot it through a typical light microscope. Only with an electron microscope can we see its spiky surface. It’s not alive, and it’s not what most of us would think of as “dead.” This teensy machine seems to survive in a kind of purgatory state, yet it has traveled across continents and oceans from host to host, and brought hundreds of nations to a standstill. Despite its diminutive size, the novel coronavirus, dubbed SARS-CoV-2, has seemingly taken the world by surprise with its virulence.
The pulmonary circuit oxygenates and the systemic arterial circuit circulates several Liters of blood per minute. As this blood trickles through the capillaries, some of it oozes out through the thin endothelial lining, becoming interstitial fluid.
Most of this flud gets back into the capillaries and returns to the heart in the venous return. About 20% of the fluid drains into the LYMPHATIC SYSTEM, through the Lymph nodes, and back into the thoracic duct, into the vena cava, and eventually back into the general blood supply, which recirculates.
The Return of the residual interstitial fluid by the Lymphatic vessels back to the general circulation is important, and if BLOCKED by such things as surgery and parasites, produces a swelling known as LYMPHEDEMA.
But the major importance of the lymphatic vessels is their characteristic cells, LYMPHOCYTES, and their accessory structures, The THYMUS, SPLEEN, LYMPH NODES, AND LYMPHATIC TISSUES is in the development and training of the IMMUNE SYSTEM. The THYMUS can be regarded as an organ to TRAIN Lymphocytes to be functional members of the immune system.
SomeT-cells operate to Help B-cells to produce antibody. These are called Th-4 cells. Others, called Th-8 cells. function to delete cells,
The thymus POSITIVELY selects cells that are prepared to recognize pathogens, and gets rid of cells (NEGATIVELY selects) cells that recognize the body’s own cells.
Failure to do so would result in “horror autotoxicus”, or AUTOIMMUNITY. The Thymus performs most of its functions when we are young.
The LYMPH NODES act as a type of filter for the Lymphatic channels, and intercept most bacteria and other pathogens coming through the lymphatic channes to keep them out of the blood stream. Lymph nodes are present at predictable locations throughout the body.
The Spleen acts as a big lymph node to filter the blood directly, and can intercept organisms that have escaped the lymph nodes. The Spleen can enlarge with certain infections, as with the EB Virus that causes mononucleosis.
Rupture of the spleen is not uncommon with direct blunt trauma to the abdomen. Removal of the spleen can increase susceptibility to blood stream infection. Lymph tissue is scattered throughout the body, like in the Tonsils, adenoids and Intestinal tract.
This Lymphocyte-containing tissue can expand with exposure to infection, and can become cancerous with Lymphomas. It can also enlarge enough to produce local Blockage, as with Adenoids. Lymph tissue should not be removed wantonly, since it may provide protection. There are 2 arms of our immune system.
I have been discussing the ADAPTIVE immune system which recognizes the pathogen, and stores memory of this interaction in “memory T-cells”. The helper T-cells( Th-4) start to multiply and stimulate the B-cells to “clonally” proliferate and differentiate into Antibody-producing Plasma Cells. The Cytotoxic T-cells, which can directly kill Pathogens, also multiply.
The first time this happens with a new Pathogen, Like SARS CoV-2, this adaptive process takes a week or so. But if the same Pathogen comes later, The adaptive immune system is ready, via the Memory T-cells, and springs rapidly into action. The 2nd arm of our immune system, shared with all of our vertebrate relatives, is the INNATE immune system.
The innate system is prepared IMMEDIATELY to recognize certain foreign molecules common to many invaders, and foreign our own bodies. It usually does not have the Power of the innate immune system, but in healthy people does an amazingly good job.
Some people just don’t get sick very often. Do the best you can to be one of these healthy people by getting proper SLEEP, DIET. AND EXERCISE!
The idea of “METS” as a unit of energy expenditure is interesting and practical. I agree that EXERCISE IS IMPORTANT.
Frank Wilczek, in an article on Dyson Freeman, talked about another unit that I find even more interesting . He proposed that 100 Watts be the unit of energy expenditure. This is (approximately) the energy used in an old 100 Watt incandescent light bulb. It is also the amount of energy used by the “average” human on a 2000 Calorie diet.
Using this unit, the average U.S. Citizen uses 95 units, compared to a 25 unit world average. The suns output is 5 X ten to the fourteenth power, of which 1X ten to the fourth power units lands on earth. Good cocktail information.
I also read that a professional cyclist has an output of only 400 watts, vs. the 14 Mets mentioned in the article.but when I read that the human body is only 20-25% efficient in converting Calories to Watts of Output, 14 Mets made more sense.
Philips Virtual Care Station, inspired by the VA’s ATLAS program, is a community-based telehealth solution designed to expand access to high-quality care by connecting patients and providers remotely through a secure, clinical-grade environment.
“The findings of this study are promising and reinforce what we’ve seen in other studies — fasting diets are a viable option for people who want to lose weight, especially for people who do not want to count calories or find other diets to be fatiguing,” Varady said.
…participants in both daily fasting groups reduced calorie intake by about 550 calories each day simply by adhering to the schedule and lost about 3% of their body weight. The researchers also found that insulin resistance and oxidative stress levels were reduced among participants in the study groups when compared with the control group.
Two daily fasting diets, also known as time-restricted feeding diets, are effective for weight loss, according to a new study published by researchers from the University of Illinois at Chicago.
The study reported results from a clinical trial that compared a 4-hour time-restricted feeding diet and a 6-hour time-restricted feeding diet to a control group.
“This is the first human clinical trial to compare the effects of two popular forms of time-restricted feeding on body weight and cardiometabolic risk factors,” said Krista Varady, professor of nutrition at the UIC College of Applied Health Sciences and corresponding author of the story.
Time-restricted eating brought my weight down from 142 pounds to 136, which is close to what was found on the study; not much, but every pound counts. The improved insulin resistance was reassuring but I am surprised they didn’t find any effects on the HDL, LDL and triglycerides.
The most detailed study on time restricted eating and fasting in general was in the New England Journal of Medicine in December 26, 2019. That excellent article went into all kinds of metabolic pathways that are benefited by fasting.
Good sleep, diet and exercise can be very helpful.
DR. C REVIEWS MAJOR HEALTH AND TELEMEDICAL NEWS FOR THE WEEK ENDING JULY 19, 2020.
Dizziness, Fainting, Falls, Orthostatic Hypotension, Heart rate and rhythm, Cardiac output and Perfusion, The Autonomic Nervous system,
Falls and Injury are all very interconnected. They all tend to accumulate as we age, but the young are not immune to these conditions. In all of these discussions,
I make the ASUMPTION that you have these conditions in an undramatic, infrequent, moderate way, and are not burdened by Risk factors such as diabetes and hypertension. Stroke is always a worry lingering in the background, and will be discussed at the end of the series.
I will begin with DIZZINESS AND FAINTING. The amazing thing is that we are able to walk upright all day without falling. We can surprisingly lie on our backs, suddenly get up and run away seamlessly, or at least we were able to do these things, most of the time. Our bodies almost magically supply our brains and balance mechanisms with the right amount of blood and nourishment ALMOST all of the time.
Everybody gets dizzy if they spin around enough, and even young people can faint if they stand long enough in one place. Dizziness and fainting is usually considered normal if there is a good explanation. It is when they are too sudden, too severe, last too long, or happen too frequently that we seek medical Help.
Dizziness can mean “lightheadedness” without the room spinning. This is often more concerning than Vertigo, since it more often is due to a lessening of blood flow to the brain. When we get up suddenly from a sitting or lying position, the blood may pool in our abdomen and legs, with consequent insufficient pumping of blood to the brain.
This happens at 1G to civilians, but it takes about 5Gs for young jet pilots to need their “blackout” suits. Instead of blackout suits, we can use support-hose, or even a constricting pants-suit which includes our lower abdomen.
I have also been using a buzzer-timer which reminds me to walk every 10 minutes, to keep me from staying in my comfortable lazy-boy too long. I try to walk rapidly and breathe deeply, and believe this helps keep my body “toned up” and responsive for when I stand up rapidly.
The other way to adapt would be to “baby” my body, and stand up more slowly. There are always the opposite ways to respond: go easy, or push the body and expect it to adapt. If you are worried, your Family Doctor can help you and suggest a path forward .
Perhaps you are overmedicated, need medication, or some tests would help clarify the situation. Vertigo is where the room seems to be spinning. You might be able to tell whether it is spinning clockwise or counterclockwise.
The most common cause is BPPV, or benign periodic positional vertigo, and you can wait it out. Look it up on the internet for parameters. Persistent Vertigo can also be due to inner ear (labyrinth) problems. which an ENT Doctor can address.
For more details, I have included a couple of good articles. A discussion of Falls is next in this series.
Folic acid has a secure place in my medicine cabinet, and is there for one of the best reasons. In screening for possible causes for heart disease, my doctor ordered a HOMOCYSTEINE LEVEL. The Laboratory value came back elevated.
The treatment given was folic acid. Some background is necessary. Homocysteine is a rather toxic amino acid that can cause heart disease and neurological problems, among other things. If you do not get enough folic acid in your diet with green vegetables, legumes, nuts, eggs and the like (it is hard to be deficient with a good diet), your Homocysteine may become elevated.
You need folic acid to convert Homocysteine to the essential amino acid, Methionine. 10-15% of the population, and up to 30% of older people have elevated Homocysteine levels. Stiffness, slow gait, and heart disease can be related to these elevated levels.
Since I have a good diet, I assume that I have a weak form of an enzyme called Tetrahydrofolate Reductase, which is the rate limiting enzyme in converting Homocysteine to Methionine. A weak enzyme needs more folic acid to do its job. The MDR of Folic acid is 0.4 mg./day. I started supplementing with 1 mg. Daily, without effect on the Homocysteine level. I doubled the dose to 2 mg., and my blood level was still above the upper limits of normal, 15 micromoles/L.. I doubled it again to 4 mg., 2 mg. Twice daily.
Finally my level became normal at 10, This was a decade ago. Recently, I have been doing some research on Alzheimer’s Disease, because a Friend is losing her short term memory. I talked to a neurologist to see if a medical evaluation was mandatory, and found that he has recently BEEN GIVING FOLIC ACID supplements to his AD Patients.
Folic acid deficiency is now being suspected as being a factor in AD! This story is similar to the Vitamin D conundrum. Should I take Vitamin D or not? Am I a “believer” or not. The resolution is easy. You get a Vitamin D blood level.
The lab test will report “normal” if your level is above 20 ng,/ml. I prefer 50, which I achieve with 4000 i.u. Daily supplement. The NFL likes their players to be above 50 to be in best shape. The point is, take a measurement, and then decide.
If you chose to take a Folic acid supplement, I would suggest checking both your Folic acid blood level, and Homocysteine blood level as a reference.
Also, if you take folic (B9) supplements, you should also take extra B12, and B6, since they are involved in the same metabolic pathways. Balance is necessary in metabolism.
What should you expect when you schedule a telehealth appointment with our physicians? John Carmichael, MD, and Sirisha Mohan, MD, walk you through the process and offer helpful tips on how to make the most of the experience.