Excitation transmission from cell to cell – even from nerve cell to nerve cell – occurs through synapses. These are junctions between two nerve cells or between nerve cell and other tissue cells that are specialized for signal transmission and reception. In most cases, signal transmission occurs via so-called messenger substances (neurotransmitters); only in the … Excitation Transmission: Function, Task & Diseases
Nuclear division (mitosis) of cells of eukaryotic organisms with replication of DNA can be divided into four main phases. The second main phase is called metaphase, during which chromosomes contract in a spiral pattern and position themselves in the equatorial plane at approximately equal distances from both opposite poles. The spindle fibers, starting from both … Metaphase: Function, Tasks, Role & Diseases
Spermiogenesis is the term used to describe the remodeling phase of spermatids formed by spermatogenesis into mature spermatozoa capable of fertilization. During spermiogenesis, spermatids lose much of their cytoplasm and the flagellum forms, which serves active locomotion. On the head containing the nuclear DNA, opposite the point of attachment of the flagella, the acrosome is … Spermiogenesis: Function, Tasks, Role & Diseases
Dendritic cells are antigen-representing immune cells capable of T-cell activation. Thus, they trigger a specific immune response. Because of their sentinel position in the immune system, they have historically been implicated as therapeutic agents for diseases such as cancer and multiple sclerosis. What is the dendritic cell? Dendritic cells are part of the immune system. … Dendritic Cell: Structure, Function & Diseases
Klebsiella granulomatis is an unflagellated, Gram-negative, rod-shaped bacterium of the Enterobacteriaceae family. It lives facultatively anaerobically in the cytoplasm of large, mononuclear cells and is the causative agent of the venereal disease donovanosis. The bacterium does not form spores and therefore depends on direct human-to-human transmission, usually through sexual intercourse, for longer-term survival. What is … Klebsiella Granulomatis: Infection, Transmission & Diseases
Fibronectin is a glucoprotein and plays a major role in the cohesion of body cells or in blood clotting. In the organism, it performs many different functions related to its ability to form adhesive forces. Structural defects in the formation of fibronectin can lead to severe connective tissue weaknesses. What is fibronectin? Fibronectin represents a … Fibronectin: Structure, Function & Diseases
Myelin is the name given to a special, particularly lipid-rich, biomembrane that mainly acts as a so-called myelin sheath or medullary sheath, enclosing axons of nerve cells of the peripheral nervous system and the central nervous system and electrically insulating the contained nerve fibers. Because of regular interruptions of the myelin sheaths (Ranvier’s cord rings), … Myelin: Structure, Function & Diseases
Endolymph is a clear potassium-rich lymphoid fluid that fills the cavities of the membranous labyrinth in the inner ear. Separated by the Reissner membrane, the membranous labyrinth is surrounded by the sodium-rich perilymph. For hearing, the different ion concentration between perilymph and endolymph plays a major role, while the mechanical-physical properties (principle of inertia) are … Endolymph: Structure, Function & Diseases
The karyoplasm is the name given to the protoplasm within cell nuclei, which differs from the cytoplasm particularly in its electrolyte concentration. For DNA replication and transcription, the karyoplasm provides an optimal environment. In diabetic patients, nuclear inclusions of glycogen may be present in the karyoplasm. What is karyoplasm? Cell nuclei are located in the … Karyoplasm: Structure, Function & Diseases
In apocytosis, the membrane of a glandular cell is sequestered along with the secretion in containers. This is a secretory mode of apocrine glands that is a special form of exocytosis and primarily affects the mammary gland. Disorders of hormonal balance may alter apocytosis behavior. What is apocytosis? It is a secretion mode of apocrine … Apocytosis: Function, Role & Diseases
Apicomplexa, also called sporozoans, are unicellular parasites with nuclei whose reproduction alternates between asexual schizogony and sporozoites resulting from sexual fusion of gametes. As a rule, the alternation is associated with a host change typical of apicomplexa. The best-known representatives of apicomplexa belonging to the eukaryotes are Plasmodia (causative agent of malaria) and Toxoplasma gondii … Apicomplexa: Infection, Transmission & Diseases
West Nile virus is found in tropical as well as temperate areas, is from the Flaviviridae family, and was discovered in 1937. The virus primarily infects birds. If the virus is transmitted to a human, the so-called West Nile fever develops, a disease that causes no symptoms in 80 percent of cases. However, in less … West Nile Virus: Infection, Transmission & Diseases
