Glossary for OTEP

the part of the sarcoplasmic reticulum, a striated muscle specialized organelle, that is adjacent to the terminal cisternae and sequesters Ca²⁺ for release when the muscle is activated.

describing stimulation or a contraction resulting from sequential activations of a muscle without sufficient time for complete relaxation between activations. A tetanic contraction can be incompletely fused if some relaxation is evident between sequential activations or completely fused if the frequency of activation is sufficient that no relaxation occurs between sequential activations.

a contraction resulting from the fusion of contractile responses to sequential activations; see tetanic.

heat generated in the digestive and absorptive processes.   Also known as specific dynamic action. The net caloric benefit of a food is the caloric content of the food minus the thermic effect of the food.

the process by which an organism keeps its body temperature within certain boundaries, even when the surrounding temperature is very different.  

thermoregulatory (adjective):

describing the purpose of a control mechanism like sweating. The purpose is to regulate temperature.

thermoregulate (verb):

to control the temperature within narrow limits by generation of heat to warm the body or by sweating and increasing skin blood flow to dissipate heat

protein filaments composed primarily of myosin, forming the A-band region of the sarcomere within the myofibrils of muscle. The length of the thick filaments appears to be constant across the animal kingdom.

protein filaments composed primarily of actin, extending from the Z-disk towards the middle of the sarcomere. The length of the thin filaments varies to some degree between animal species.

the amount or size of a measurable phenomonon that results in a change in structure, membrane voltage, metabolic pathway contribution or other.  

threshold voltage

the membrane potential that, when passed results in a change in ion channel function

anaerobic threshold

the highest intensity of exercise that can be sustained by aerobic metabolism. See more

aerobic threshold

the highest intensity of exercise that can be sustained while maintaining close to resting blood lactate concentration

ventilatory threshold

the intensity of exercise above which ventilation increases in proportion to oxygen uptake; a second ventilatory threshold occurs at the intensity of exercise above which ventilation increases relative to carbon dioxide output

the amount of air moved in or out of the lungs in one breath. Typically, about 500 ml at rest (but this varies with body size) and increasing to about 50 % of vital capacity at maximal exercise.  

the time needed for an exponential relationship to change by 1-1/e or ~63.2 % of the original value (where e = Euler’s number ~2.71828182846).   

a physical challenge (often a form of locomotion like running or cycling) against the clock, rather than directly against a competitor. A time-trial typically will be a fixed distance and the competitor will attempt to complete the distance in as short a time as possible. Alternatively, some research involves a task that must be completed in a fixed amount of time.  Wikipedia

gigantic muscle protein that spans the sarcomere, beginning at the M-line (middle of the sarcomere) and following the thick filament but extending beyond that to the Z-disk. Titin has the ability to bind Ca²⁺ and actin. Wikipedia

the highest level of a micronutrient that has been shown to have no adverse side effects in humans.  

the willingness or a capacity to tolerate a disturbance to homeostasis. Tolerance relates to the ability or willingness of an athlete to push their physiological limits in the hopes of improving physical performance.  

heat tolerance

the ability to maintain close to normal body temperature when exposed to high environmental temperatures. 

proteins, typically found on macrophages or dendritic cells that bind to chemicals on the surface of microorganisms, allowing the immune system to recognize these invading organisms.   Wikipedia

the volume of air in the lungs after full inspiration. When the vital capacity is exhaled, residual volume remains in the lungs. TLC is the sum of vital capacity and residual volume.

resistance is the ratio of delta pressure to Flow (DP·R^-1) . Total peripheral resistance is the resistance across the full circulatory system or the difference in pressure from the aorta to the right atrium divided by cardiac output. 

the sum of all weak acids in the body; a weak acid will partially retain H⁺ attached to the molecule under physiological conditions.  In contrast, a strong acid will lose its H⁺ in solution.  A measure of the strength of an acid is the pK or negative log concentration of the substance at which 50% of the substance is still bound to H⁺.  Lactic acid is a weak acid.

substances that are poisonous to the body, at low concentrations. Toxins can be ingested or get into the body through the skin or by ventilation.  

the process by which genetic information of a gene is copied into a messenger RNA (mRNA).

transcription factor

A protein found in the nucleus that binds DNA to regulate RNA polymerase activity, and thereby control transcription of a gene.

also known as T4 (inactive) and T3 (active).  T4 is a peptide released by the thyroid hormone, and it is converted to T3 to activate it. T3 regulates metabolism. Thyroid hormone is important for growth and development and increases basal metabolic rate.

a contrived region of the lungs represented by the airways of the lung where gas exchange can occur. The transitional zone can be considered the airways representing the transition from simply conducting the air to those that can contribute to gas exchange and include several branches of bronchioles, and the alveolar ducts.

genetically modified animals used for research. Transgenic animals are genetically modified to introduce a foreign gene into their genome. Transgenic animals are commonly used to study the physiological effect of specific proteins by altering their gene expression. Most common transgenic animals used in research are mice. 

the process of synthesizing new proteins. The DNA information transcribed into the messenger RNA is translated via ribosomes and transfer RNA to produce new proteins.

 a periodic invagination of the surface membrane (plasmalemma) forming a tube that goes deep into the myocyte, encircling myofibrils as it goes.  The transverse tubule conducts the action potential deep into the cell, signaling the release of Ca²⁺from the terminal cisternae.

structure of the transverse tubule seen in microscopic cross-section, flanked by two terminal cisternae.  The triad occurs at the Z-line in amphibian muscle and about 500 nm from the Z-line in mammalian muscle.  This means there are twice as many transverse tubules in mammalian muscle as in amphibian muscle.

a common fat molecule, a glyceride molecule with 3 fatty acids bound. Triglycerides are hydrolyzed to release the fatty acids for metabolism

a filamentous protein bound to the thin filament and positioned to prevent binding of the myosin head to actin. The position of tropomyosin is regulated by troponin; when troponin-C has Ca²⁺ bound to it, troponin-T moves the tropomyosin away from the myosin binding locations.

troponin is a 3-part molecule bound to the thin filaments in skeletal and cardiac muscle. Troponin-C is a Ca²⁺ binding protein. Troponin-I inhibits muscle activation until Ca²⁺ binds to troponin-C. Troponin-T binds tropomyosin, permitting troponin to regulate the position of tropomyosin relative to the myosin binding sites on actin.  When Ca2+ binds to troponin-C, the troponin complex reorganizes and pulls the troponin out of the groove between the strands of actin forming the thin filament.  This movement exposes the myosin binding sites on the actin monomers.

the contractile response to a single activation; the rise and fall of force in a muscle fibre, motor unit, or whole muscle. A single action potential will follow all branches of a given motoneuron and transfer a single activation to all muscle fibres associated with that motor unit. The subsequent contraction of all these muscle fibres is called a twitch.

Twitch interpolation:

An electrical impulse is applied to the motor nerve or muscle during a voluntary contraction to see if an extra contractile response can be obtained. This method is applied in an effort to calculate the voluntary activation ratio. The twitch interpolation(Twint) is followed by electrical stimulation after relaxation has been achieved. This stimulation will cause a twitch contraction (Twrest). The voluntary activation ratio (VAR) is calculated as:

VAR = 1 - Twint/Twrest

inadequate insulin secretion due to failure of the pancreas to synthesize or secrete sufficient amount of this hormone.  Also known as juvenile diabetes because this form of diabetes usually manifests early in life.

also known as adult onset or insulin independent diabetes; blood glucose increases in spite of insulin presence in the blood because insulin has become less effective at mobilizing glucose transporters to the surface of adipose and muscle cells. Physical exercise is still capable of mobilizing these transporters (GLUT4). Wikipedia

vaguely defined as extremely long distance events; running, cycling, cross-country skiing. Usually considered much longer than a marathon and can take several hours to days to complete

an image, created by comparing the nature of reflection of ultrasound (echo) from tissues. The echo varies, based on the density of the underlying tissue, creating darker and lighter elements of the image.  Ultrasound imaging is used to follow the development of a fetus and also has been used extensively for cardiac diagnostics and evaluation of skeletal muscle dynamics.

tolerable upper limit

when muscle fibres are oriented at an angle with respect to the line of action of a muscle, the muscle is called pennate. When all fibres are oriented at a similar angle, the muscle is unipennate in contrast where fibres are oriented at more than one angle, the muscle is bipennate (2 angles) or multipennate.

consists of the anatomical structures of the: nose, mouth, pharynx, and larynx.

a measure of the variability of a measurement among a group of subjects. Variance is obtained by taking the average of the squared differences from the mean:  variance = sum((xx-x)²)×n ^-1  where xx is sample value and x is mean value.

the relative state of contraction of the smooth muscle cells in the walls of a blood vessel.  

vascular (adjective)

having to do with blood vessels

the resistance to blood flow through a blood vessel, expressed as delta P×flow^-1. where delta P is the difference in pressure across the vascular system of interest.  Wikipedia

the act of constricting or reducing radius of a blood vessel or tubular structure. 

vascular smooth muscle contraction resulting in narrowing of the lumen of a blood vessel. Vasoconstriction results in increased vascular resistance and if blood pressure does not increase, there will be a decrease in blood flow. Wikipedia

the act of relaxing smooth muscle in the wall of blood vessel or tubular structure, resulting in decreased vascular radius.

relaxation of vascular smooth muscles in the walls of blood vessels, leading to increased vessel diameter and decreased vascular resistance. Wikipedia

blood vessel that conducts blood towards the heart.  Veins can be quite large and have relatively little smooth muscle in the walls.  

the rate of flow of venous blood from all sources returning to the right side of the heart.

the movement of air into and out of the lungs. Quantified over 1 min, this is called minute ventilation. Ventilation is comprised of tidal volume and breathing frequency and is expressed as a volume of air per minute.  The movement of air into (VI) and out of (VE) the lungs is often expressed relative to time; minute ventilation (VdotI or VdotE):  Wikipedia

Alveolar Ventilation (VdotA)

The amount of air moving into or out of the alveolar space each minute

inspiratory volume (VI)

the volume of air inhaled, often expressed per min.

expiratory volume (VE)

the volume of air exhaled, often expressed per min.

normally, the volume of air delivered to an alveolar space is equal to about 80% of the volume of blood delivered in the same amount of time. Under this circumstance, the ratio of ventilation to perfusion is equal to 0.8.  When this ratio is different from the normal value, this area has a ventilation perfusion mismatch.  A small mismatch is inconsequential, as is a high ventilation relative to the blood flow, but if the ventilation is markedly lower than the blood flow, then the blood flowing through this area of the lung will not be adequately oxygenated.  Hypoxia is the result.

ventilation-perfusion ratio (VdotA/Qdot)

the ratio of volume of air taken into the lungs in a given period of time to the blood flow through the lungs in the same time. The ventilation-perfusion ratio can be applied to subsections of the lungs including localized to small areas or regions.

a specific change in the minute ventilation relative to either oxygen uptake or Carbon dioxide output as exercise intensity increases.  There are two identifiable ventilatory thresholds.  The first is usually identified as the intensity where the ratio of ventilation to oxygen uptake increases while the ratio of ventilation to carbon dioxide output does not. This is often referred to as ventilatory threshold 1 or Gas Exchage Threshold. The second ventiltory threshold is when the ratio of ventilation to carbon dioxide increases. This is also called the Respiratory Compensation Point.

ventilatory sinus arrhythmia

a oscillation of the heart rate, in tandem with ventilation. Heart rate increases during inspiration and decreases during expiration. This is usually considered a normal response.

blood vessel connecting capillaries to veins.  Venules are small, and serve to conduct blood from the capillaries where exchange of O₂, CO₂, ions, water and several small molecules can occur to the veins, on route to the heart.

an intensity of exercise approaching maximal oxygen uptake.  

A very small membrane-bound volume of fluid, often containing specialized molecules.  For example, transmitter vesicles contain neurotransmitters that can be excitatory or inhibitory.  Transmitter vesicles at the neuromuscular junction contain acetylcholine.  The membrane of vesicles contains special proteins that allow these vesicles to dock with the cell membrane to permit fusion and extrusion of vesicle contents into the extracellular fluid. 

exercise intensity above the aerobic threshold, but below the anaerobic threshold.  

a small rod-like protein found in mesenchymal cells including skeletal muscle that serves as an intermediate filament. Vimentin is one of the intermediate filaments that make up the Z-disk and along with actin and microtubules, contributes to the cytoskeleton. 

the maximal amount of air that can be expelled from the lungs after a maximal inhalation. Wikipedia

organic substances required for survival in relatively small amounts. Vitamins are typically obtained in the food we eat, but supplements are available that provide various amounts of these essential nutrients. There are 13 recognized vitamins.Medical News

 the highest rate of oxygen uptake achieved during an incremental exercise test, should be called VdotO₂peak unless it is confirmed that VdotO₂max has been reached.  The highest rate of VdotO₂ is equal to the VdotO₂max when an increase in exercise intensity does not result in an increase in oxygen uptake. Otherwise, the highest rate of oxygen uptake should be referred to as VdotO₂peak.

VCO₂

with the dot over the V, this refers to rate of carbon dioxide output. Without the dot, it is a volume of carbon dioxide output.

a channel is the pore of an ion channel protein, embedded in a plasmalemma. Normally, the channel will be closed; a structure that can be moved will be blocking the pore.  When the membrane potential changes from the normal resting potential (about -85 mV for nerve and muscle) to the threshold potential (about -50 mV for the fast sodium channel), the blocking structure moves, allowing the ions to move through the channel pore in the direction of the electrochemical gradient.

voltage-sensitive ion channel

a protein embedded in the membrane of an excitable cell (neuron or myocyte) that can be activated by a change in membrane potential.  see above

physical exercise with the intent to prepare for the best possible performance in competition. A warm-up is not simply to increase body temperature, but to increase cardiopulmonary readiness for exercise, prime the metabolic systems and rehearse the neural activation patterns. 

the relationship between water entering the body (consider all sources; fluids, food) versus water leaving the body (urine, feces, insensitive evaporation, sweat).  When the body is in water balance, the total amount of water in the body will remain constant.  

the concentration of an acid that partly dissociates (loses a hydrogen) in solution is a weak acid.  Atot is the total concentration of the acid and the dissociated base.

when speaking of the myosin bound to actin, the binding is initially weak (easily reversible to the unbound state), but once Pi is released it goes into a strong-bound, force-generating state. This state is not considered to be easily reversed to the weak-bound state or to the unbound state.

also simply Wingate test; a 30 s all-out cycling test yielding a measure of maximal power output, total work capacity and fatigue index.  Resistance is optimized for power output and total work.  This test was developed at the Wingate Institute, Israel.

an international organization that tracks health problems around the world and makes recommendations to ameliorate situations that create or worsen health problems. WHO

structural limit to the sarcomere formed by intermediate filaments and serves function of anchoring the thin filaments.  Also, the attachment site for costameres that join adjacent myofibrils.

The lowest metabolic rate in a true resting state. The BMR should be expressed in either oxgyen uptake equivalent or joules per second.  Measurement of BMR requires special conditions for accurate measurement: a thermally neutral environment, no food should be consumed in the prior 16 hours and the person who is being measured should lie supine for 30 min to minimize metabolism in muscles.

the ease with which flow occurs. In electrical current, conductance is the inverse of resistance.  in the case of blood flow, conductance is defined by the equation governing flow; conductance = flow/delta P.  

the impediment to flow. Resistance is calculated as R=delta P/flow.  Blood flow is impaired by a small diameter blood vessel. Such a vessel will have a high resistance.