Bolus
In digestive physiology, a bolus is a cohesive mass of chewed food mixed with saliva and formed in the mouth for swallowing. As food is chewed, it is mechanically broken into smaller pieces and mixed with …
Browse the journal
Knowledge
Follow journal articles connected to Alpekin knowledge topics.
376
published entries
Explore articles
Knowledge
Bone Resorption
Bone resorption is the physiological process by which existing bone tissue is broken down and removed. It is carried out primarily by osteoclasts, large multinucleated cells derived from the monocyte-macrophage lineage. Bone resorption is a normal …
Borg RPE Scale
The Borg Rating of Perceived Exertion scale, or Borg RPE scale, is a 15-point scale used to rate how hard physical exercise feels. Developed by Gunnar Borg, it ranges from 6, representing no exertion, to 20, …
Brainstem
The brainstem is the part of the brain that connects the diencephalon and other higher brain regions with the spinal cord. It lies in front of the cerebellum and consists of three major regions: the midbrain, …
Butyrate
Butyrate, also called butanoate, is the negatively charged conjugate base of butyric acid, a four-carbon short-chain fatty acid. In the human colon, butyrate is produced mainly by members of the gut microbiota during anaerobic fermentation of …
Calcitriol
Calcitriol is the principal hormonal form of vitamin D, chemically known as 1,25-dihydroxyvitamin D. It is produced after vitamin D undergoes two hydroxylation steps. Vitamin D is first converted mainly in the liver to 25-hydroxyvitamin D, …
Calcium Homeostasis
Calcium homeostasis is the set of physiological processes that keeps the concentration of calcium in extracellular fluid, especially ionized calcium in blood, within a narrow range. This regulation is essential because calcium is required for functions …
Capillarization
Capillarization refers to the extent of the capillary network supplying a tissue. In skeletal muscle physiology, it describes the number and distribution of capillaries in relation to muscle fibers. These microscopic blood vessels provide an important …
Carbohydrate Loading
Carbohydrate loading, also called glycogen loading, is a pre-exercise nutrition strategy designed to increase the amount of glycogen stored in skeletal muscle before prolonged endurance exercise. Glycogen is the stored form of glucose in muscle and …
Carbohydrate-Electrolyte Drink
A carbohydrate-electrolyte drink is a water-based beverage containing carbohydrates together with dissolved electrolytes. These drinks are commonly formulated for use during or after exercise, when fluid, carbohydrate, and electrolytes may need to be replaced together. Sodium …
Carbohydrates
Carbohydrates are a broad class of organic compounds that includes monosaccharides, oligosaccharides, polysaccharides, and compounds derived from them. Monosaccharides are basic carbohydrate units and include molecules such as glucose. They can be joined through glycosidic bonds …
Cardiac Muscle
Cardiac muscle is the specialized muscle tissue that forms the myocardium, the contractile middle layer of the heart wall. It is one of the three major types of muscle tissue, alongside skeletal and smooth muscle. Its …
Cardiometabolic
Cardiometabolic is an adjective describing the interconnected metabolic and cardiovascular aspects of health, risk, and disease. It is commonly used in terms such as cardiometabolic health, cardiometabolic risk, and cardiometabolic disease. The concept reflects links between …
Cardiomyocytes
Cardiomyocytes, also called cardiac myocytes, are the specialized muscle cells of the heart. They form the contractile component of the myocardium and generate the force that pumps blood. Most working cardiomyocytes are elongated, striated cells containing …
Cardiorespiratory Endurance
Cardiorespiratory endurance is the capacity to sustain rhythmic, large-muscle exercise through the integrated transport and use of oxygen. It is a component of physical fitness and is closely related to concepts such as cardiorespiratory fitness, aerobic …
Cardiovascular Drift
Cardiovascular drift is the gradual change in cardiovascular responses that occurs during prolonged, steady-intensity exercise. It is characterized mainly by a progressive rise in heart rate together with a decline in stroke volume, even though the …
Cariogenicity
Cariogenicity is the capacity of a substance, food, or dietary exposure to promote the development of dental caries. In nutrition and dentistry, the term is commonly used to describe the caries-promoting potential of foods and carbohydrates. …
Carotenoids
Carotenoids are a large family of naturally occurring pigments characterized by an extended system of conjugated double bonds. They are produced by plants, algae, and many microorganisms and contribute yellow, orange, and red coloration to many …
Carotid Bodies
The carotid bodies are small, paired sensory organs located near the bifurcation of the common carotid arteries in the neck. They are the principal peripheral chemoreceptor organs for monitoring the chemical composition of arterial blood and …
Catabolism
Catabolism is the part of metabolism that breaks down larger or more complex molecules into smaller products. Catabolic pathways include the degradation of carbohydrates, fats, and amino acids. These reactions often release free energy, some of …
Celiac Disease
Celiac disease is a chronic immune-mediated disorder in which eating gluten triggers an abnormal immune response that damages the lining of the small intestine in genetically susceptible people. Gluten is a group of proteins found in …
Central Chemoreceptors
Central chemoreceptors are chemosensitive cells and neural circuits within the brain that help regulate breathing by detecting changes related to carbon dioxide and acidity. They are located primarily within the brainstem, particularly the medulla oblongata. The …
Central Nervous System
The central nervous system, or CNS, is the part of the nervous system composed of the brain and spinal cord. It serves as a major center for receiving and integrating sensory information, generating motor commands, and …
Cerebral Edema
Cerebral edema is an abnormal accumulation of water in brain tissue that increases brain volume. The excess water may accumulate inside brain cells, in the extracellular space between cells, or both, depending on the underlying mechanism. …
Chemiosmosis
Chemiosmosis is the coupling of cellular work to the energetically favorable movement of ions down an electrochemical gradient across a membrane, most notably during ATP synthesis. In many biological energy-conversion systems, the relevant ion is the …
Chylomicrons
Chylomicrons are large, triglyceride-rich lipoprotein particles produced by absorptive cells of the small intestine, called enterocytes. Their main function is to transport lipids absorbed from food, particularly triglycerides, through the lymph and bloodstream. They also carry …
Chyme
Chyme is the semifluid mixture of partially digested food and digestive secretions that forms in the stomach during digestion. After swallowed food, called a food bolus, enters the stomach, it is mixed and mechanically broken down …
Chymotrypsin
Chymotrypsin is a digestive enzyme that hydrolyzes peptide bonds within proteins and peptides in the small intestine. It belongs to the serine protease family and is an endopeptidase, meaning that it cleaves peptide bonds within a …
Circuit Training
Circuit training is an exercise-training method in which several different exercises or stations are performed sequentially, usually with relatively short rest periods between them. After completing the stations, the sequence may be repeated for additional circuits. …
Clavicle
The clavicle, or collarbone, is an S-shaped long bone that extends horizontally across the upper front of the chest between the sternum and the scapula. Together with the scapula, it forms the pectoral, or shoulder, girdle. …
Coccyx
The coccyx, commonly called the tailbone, is the small, triangular bone at the lowest end of the vertebral column, immediately below the sacrum. It develops from coccygeal vertebral segments, with three to five segments commonly reported …
Colonic Fermentation
Colonic fermentation is the anaerobic microbial breakdown of substrates in the large intestine. It occurs mainly when dietary components escape digestion and absorption in the small intestine and reach the colon, where resident microorganisms can use …
Colonocytes
Colonocytes are the absorptive epithelial cells found in the lining of the colon, or large intestine. They form part of the single layer of epithelial cells that separates the intestinal contents from underlying tissues. Colonocytes arise …
Complete Protein
The term complete protein is commonly used for a dietary protein that supplies all of the indispensable, or essential, amino acids in proportions that meet a human reference amino acid pattern. Humans require nine indispensable amino …
Contractile Tissue
Contractile tissue is tissue containing cells specialized to generate mechanical force through contraction. In standard human anatomy and physiology, the term most commonly refers to muscle tissue, one of the body's four primary tissue types. Human …
Creatine
Creatine is a nitrogen-containing organic compound involved in rapid cellular energy transfer. The body obtains creatine through both endogenous synthesis and the diet. It is synthesized from amino-acid-derived precursors, principally arginine and glycine, with a methyl …
Cross-Bridge Cycle
The cross-bridge cycle is the repeating sequence of molecular interactions between myosin and actin that generates force during muscle contraction. A cross-bridge forms when a myosin head on a thick filament attaches to actin on a …
Cross-contamination
Cross-contamination is the transfer of harmful microorganisms from a contaminated food, surface, object, or person to another food or food-contact surface. In food safety, the term commonly describes the spread of disease-causing microorganisms such as bacteria …
DXA
DXA, or dual-energy X-ray absorptiometry, is an imaging technique that uses low-dose X-rays at two different energy levels to assess bone mineral and estimate body composition. As the X-rays pass through the body, bone and soft …
De Novo Lipogenesis
De novo lipogenesis (DNL) is the metabolic process by which cells synthesize new fatty acids from acetyl-CoA rather than obtaining those fatty acids directly from dietary or stored fat. Acetyl-CoA can be generated from several metabolic …
Dehydrogenase
A dehydrogenase is an enzyme that catalyzes an oxidation-reduction reaction in which a substrate is oxidized and electrons, often transferred together with hydrogen, are passed to an electron acceptor. Dehydrogenases belong to the broad enzyme class …
Detraining
Detraining is the partial or complete loss of physiological and performance adaptations previously gained through exercise training because the training stimulus has been substantially reduced or stopped. It can occur during periods of injury, illness, inactivity, …
Diaphragm
The diaphragm is a dome-shaped sheet of skeletal muscle and tendon that separates the thoracic cavity, containing the lungs and heart, from the abdominal cavity. It forms the floor of the thorax and the roof of …
Dietary Fiber
Dietary fiber is a group of substances that resist digestion and absorption in the human small intestine. It includes nondigestible carbohydrates that are intrinsic and intact in plant foods, together with lignin, a noncarbohydrate component associated …
Dipeptides
Dipeptides are peptides composed of two amino-acid residues. In a typical linear dipeptide, the carboxyl group of one amino acid is joined to the amino group of another by a peptide bond. This leaves one amino …
Drop Set
A drop set is a resistance-training technique in which an exercise is typically performed to, or close to, muscular failure, the load is then reduced, and additional repetitions are performed immediately with little or no rest. …
Duodenum
The duodenum is the first and shortest section of the small intestine. It begins at the pylorus, where the stomach empties, and continues to the jejunum at the duodenojejunal junction. In adults, it is roughly 25 …
Dynamic Knee Valgus
Dynamic knee valgus is a movement pattern in which the knee moves medially relative to the hip and foot during a weight-bearing task such as squatting, landing, running, or changing direction. Although it is often recognized …