Category: Biology Dictionary E

Exocrine Glands Definition Exocrine glands are cellular sub-structures, organs, in a body that provide a system to secrete substances out and external to the body. They are distinct from the other type of gland, endocrine, in that exocrine gland secretions end up external to the body, while endocrine secretions go into the bloodstream/internal. Exocrine glands […]

Definition of Exergonic Reaction An exergonic reaction is a reaction that releases free energy. Because this type of reaction releases energy rather than consuming it, it can occur spontaneously, without being forced by outside factors. In chemistry terms, exergonic reactions are reactions where the change in free energy is negative. Free energy measures the total […]

Exercise Physiology Definition Exercise physiology is the study of the body’s responses to physical activity. These responses include changes in metabolism and in physiology of different areas of the body like the heart, lungs, and muscles, and structural changes in cells. The word exercise comes from the Latin exercitus, “to drive forth,” while physiology comes from […]

Excretory System Definition The excretory system consists of organs which remove metabolic wastes and toxins from the body. In humans, this includes the removal of urea from the bloodstream and other wastes produced by the body. The removal of urea happens in the kidneys, while solid wastes are expelled from the large intestine. Overview The […]

Excretion Definition Excretion is the process that biological organisms use to expel or eliminate the waste products produced by their metabolisms. In order for cells to survive, they need to perform certain biochemical reactions, as these reactions take place, some byproducts are formed which can be toxic or lethal to the cells if they are […]

Euthymic Definition Euthymic is the state of being in euthymia, which is a relatively neutral mood that is neither extremely happy nor extremely sad. It comes from the Greek words eu, meaning good, and thymos, meaning spirit. It is usually used in the context of mental health, especially when referring to bipolar disorder, which is […]

Euphoria Definition Euphoria refers to an affective state characterized by feelings of intense pleasure, happiness, contentment, and excitement. A state of euphoria can be naturally induced (e.g., in response to exercise, social activities, romance/sexual response, and artistic endeavours), chemically induced (e.g., recreational drug use), or the result of a neurological condition (e.g., mania). Types of […]

Definition A eukaryotic cell contains membrane-bound organelles such as a nucleus, mitochondria, and an endoplasmic reticulum. Organisms based on the eukaryotic cell include protozoa, fungi, plants, and animals. These organisms are grouped into the biological domain Eukaryota. Eukaryotic cells are larger and more complex than prokaryotic cells found in domains Archaea and Bacteria. Overview A […]

Eukaryote Definition Eukaryotes are organisms whose bodies are made up of eukaryotic cells, such as protists, fungi, plants and animals. Eukaryotic cells are cells that contain a nucleus and organelles, and are enclosed by a plasma membrane. Organisms with eukaryotic cells are grouped into the biological domain Eukaryota (also sometimes called Eukarya). The other two […]

Euchromatin Definition Euchromatin is a form of chromatin that is lightly packed—as opposed to heterochromatin, which is densely packed. The presence of euchromatin usually reflects that cells are transcriptionally active, i.e. they are actively transcribing DNA to mRNA. Euchromatin is found in the nucleus of eukaryotes and represents more than 90% of the human genome. […]