KNOW HOW & KNOWLEDGE

Glossary

Macula

An oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. The macula is specialized for high acuteness or clearness of vision. It absorbs excess light that enters the eye and acts as natural sunglasses.

Mediterranean diet

A dietary style based on food patterns typical of Greece (Crete) and southern Italy in the early 1960s: abundant plant foods, fresh fruit as the typical daily dessert, olive oil as the principal source of fat, dairy products (principally cheese and yogurt), fish and poultry consumed in low to moderate amounts, zero to four eggs consumed weekly, red meat consumed in low amounts, and wine consumed in low to moderate amounts. Total fat in this diet is 25% to 35% of calories, with saturated fat at 8% or less of calories. The Mediterranean diet consists of a healthier balance between (higher) omega-3 and (lower) omega-6 fatty acids (compared to the Western diet).

Research has shown that people who follow this diet are less likely to develop cardiovascular diseases (e.g., heart disease).

Membrane

The barrier that separates the contents of a cell from its outside environment and controls what moves in and out of the cell. A human cell membrane consists of two lipid layers with embedded proteins and cholesterol. Some functional subunits (organelles) within the cell, such as mitochondria, contain own lipid membranes.

Membrane potential

The electrical potential difference across a membrane. The membrane potential is a result of the concentration differences between potassium ions (K+) and sodium ions (Na+) across cell membranes which are maintained by ion pumps in the cell membrane, pumping sodium out of the cell in exchange for potassium. A large proportion of the body's resting energy expenditure (20%–40% in a typical adult) is devoted to maintaining the membrane potential, which is critical for nerve impulse transmission, muscle contraction, heart function, and the transport of nutrients and metabolites in and out of cells.

Meta-analysis

A statistical technique that combines the results of several studies addressing a set of related research hypotheses. The results of the included studies are analyzed as if they were the results of one large study.
 
The quality of a meta-analysis strongly depends on the quality (methodological soundness) of the included studies. A (good) meta-analysis of poorly designed studies will result in bad statistics, results, and conclusions.

 
Some (bad) meta-analyses can be misleading as they inaccurately pool data from primary prevention (disease prevention in healthy people) and secondary prevention (slowing down disease progression in patients) studies.

 
Additionally, a meta-analysis can be strongly biased by the scientists’ heavy reliance on published studies: as non-convincing (significant) studies often end up not getting published, the authors may tend to “select” data to get significant publishable results.

Metabolism

A set of physical and chemical reactions that occur in living organisms in order to maintain life, such as digesting food and nutrients, eliminating waste through urine and feces, circulating blood, and breathing. The chemical reactions can be catabolic (catabolism) ─ breaking down organic molecules (e.g., nutrients) to generate energy ─ or anabolic (anabolism) ─ using energy to construct components of cells such as proteins and nucleic acids.

Mitochondria

Energy-producing structures within cells. Among other critical functions, mitochondria convert nutrients into energy.

Myocardial infarction (MI)

Death (necrosis) of heart muscle tissue due to an interruption in its blood supply. Commonly known as a heart attack, an MI usually results from the obstruction of a coronary artery by a clot in people who have coronary atherosclerosis (heart disease).

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