Definition Hip abduction refers to the movement of the hip joint as the leg is moved away from the midline of the body. As the hip is composed of a ball and socket joint, a degree of rotation is also present during this motion. A group of muscles contribute to hip abduction; the most important … Read more
Gland Definition A gland is a group of cells or a “secreting organ” that excretes a chemical substance. This substance can take the form of hormones, sweat, saliva, mucus, or acids (i.e. HCl acid in gastric glands). Glands are tasked with helping create the substance that they then secrete for further use or total elimination … Read more
Nephron Definition A nephron is the basic unit of structure in the kidney. A nephron is used separate to water, ions and small molecules from the blood, filter out wastes and toxins, and return needed molecules to the blood. The nephron functions through ultrafiltration. Ultrafiltration occurs when blood pressure forces water and other small molecules … Read more
Intercostal Muscles Definition The intercostal muscles are a group of muscles found between the ribs which are responsible for helping form and maintain the cavity produced by the ribs. The muscles assist with expansion and contraction during breathing. The intercostal muscles consist of 11 muscle trios in humans. Intercostal Muscles Overview In humans, the muscles … Read more
Thoracic Cavity Definition The thoracic cavity, also called the chest cavity, is a cavity of vertebrates bounded by the rib cage on the sides and top, and the diaphragm on the bottom. The chest cavity is bound by the thoracic vertebrae, which connect to the ribs that surround the cavity. The thoracic cavity is actually … Read more
ATP Synthase Definition ATP synthase is an enzyme that directly generates adenosine triphosphate (ATP) during the process of cellular respiration. ATP is the main energy molecule used in cells. ATP synthase forms ATP from adenosine diphosphate (ADP) and an inorganic phosphate (Pi) through oxidative phosphorylation, which is a process in which enzymes oxidize nutrients to … Read more
Epistasis Definition Epistasis is the interaction between genes that influences a phenotype. Genes can either mask each other so that one is considered “dominant” or they can combine to produce a new trait. It is the conditional relationship between two genes that can determine a single phenotype of some traits. At each locus are two … Read more
Nucleoid Definition In a prokaryotic cell, the nucleoid contains the genetic information called the genophore. The prokaryotes are divided into bacteria and archaea, both of which are unicellular organisms without membrane-bound organelles. Also, the nucleoid does not have a membrane surrounding it. Attached to the cell membrane, it is in direct contact with the cytoplasm. … Read more
Genetic drift, gene flow, and natural selection may sound similar or even confusing to some. All three are mechanisms in the evolutionary process that have to do with alleles and/or gametes, but there are several significant differences. Discussions about genes and natural selection usually include the term allele. An allele is just one version of … Read more
Petiole Definition A petiole is the stalk that attaches a leaf to the stem of a plant. People often refer to it as a stem, which is incorrect. In contrast to stems, which support the plant and produce nodes and roots, petioles do not produce nodes or roots. The nodes in the picture below are … Read more