This is a living post! We will add to it as we come across words that we think would be useful to explain to you!
Adaptive Immune System: Is a subset of the overall immune system and one of the two main immune strategies found in vertebrate animals (the other being the innate immune system). The adaptive immune system creates immunological memory after an initial response to a specific pathogen, this enables an enhanced response to a subsequent encounter with the same pathogen. This system is the basis of vaccination.
Atrophy: Atrophy is the wasting away of a tissue or an organ. It can occur in disease and then is termed pathological atrophy but it also occurs as part of normal developmental processes or as a result of disuse (muscle for example atrophies without frequent use).
Bone Density: bone density is the amount (mass) of bone mineral in a given volume of bone tissue.
Cognition: at the simplest level cognition refers to thinking. A broader definition would be all the mental actions or processes of acquiring knowledge and understanding though thought, experience and our senses. Cognition is the ability we have to evaluate and assimilate all the information we receive from different sources and involves different processes like learning, attention, memory, language and reasoning.
DNA: DNA stands for deoxyribonucleic acid. It is the molecule that carries all the genetic instructions used in the growth, development and function of living organisms.
Light-intensity physical activity: This is an activity that is classified as < 3 METs (see below). These activities involve light effort with a small increase in rate of breathing or heart rate above rest. Examples are slow casual walking, stretching, light house work, standing at a work-station.
Mediate: In a biological context this refers to bringing about a physiological effect.
MET: MET stands for metabolic equivalent and one MET is defined as the amount of oxygen consumed while sitting at rest (resting metabolic rate) and is equal to 3.5 ml oxygen per kg body weight per minute. The MET concept is a simple procedure for expressing the energy cost of physical activities as a multiple of resting metabolic rate. An activity that is 4 METs has an energy cost that is 4 times resting metabolic rate. See light- moderate-and vigorous-intensity activities for more information.
Mitochondrial Biogenesis: Is a rather fancy name for the process by which cells increase mitochondrial mass; this can include an increase in number (by division of mitochondria) or an increase in size and mass of individual mitochondria.
Moderate-intensity physical activity: These are activities that require a moderate mount of effort and noticeably accelerate the heart rate. Activities with a MET (see above) of between 3 and 6 fall into this category. Examples are brisk walking, dancing, carrying moderate loads and gardening.
Molecular Pathway: is a series of actions among molecules in a cell that leads to a certain product or a change in the cell. A molecular pathway can trigger the assembly of new molecules, such as a fat or protein, turn genes on and off, or result in cell movement.
Organelle: an organelle is a tiny structure within a cell. Analogous to organs within the body, organelles perform specific functions with a cell. Examples are the nucleus (which contains DNA and controls cell growth and reproduction) and the mitochondria (the cell’s power generators).
RNA: RNA stands for ribonucleic acid. There are various forms within the cell and they are essential for the regulation and expression of genes.
Telomeres: A telomere is a region of repetitive DNA at the end of each chromosome which protects the rest of the chromosome from deterioration or from fusion with neighbouring chromosomes. During chromosome replication (required for cell division) the enzyme that duplicates the DNA cannot fit right to the end of the chromosome. This means at each cell division a bit of the end of the chromosome is lost. The telomere acts as a buffer to protect the genes on the chromosomes from being lost.
Senescent Cell: A senescent cell is one which has ceased dividing in response to a DNA-damage signal resulting from either a critical shortening of the telomeric DNA on the ends of chromosomes or from another significant DNA damage event (as a result of excessive oxidative stress for example). Senescent cells are associated with a Senescence Associated Secretory Phenotype (SASP) consisting of several classes of inflammatory molecules. The SASP is associated with many age-related diseases.
Systemic: This term means relating to a system rather than a part and in physiology means that the effect is generally on the whole body and not just a part of it. The opposite would be a local effect.
Upregulate: In a biological context, upregulation is the process by which a cell increases the amount of a cellular component (usually a protein or RNA) in response to an external stimulus. The complementary process is of course downregulation where the amount of the cellular component decreases.
Vigorous-intensity Physical Activity: These activities require a large amount of effort, rapid breathing and a substantial increase in heart-rate. Activities with METs (see above) of > 6 fall into this category. Examples are running, uphill fast hiking, carrying very heavy loads, fast swimming.
WHO (World-Health-Organization): The World Health Organization is an agency of the United Nations that is concerned with international public health.