Secretion in the context of "Gulping"

Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell. For example, placental mammals expel urine from the bladder through the urethra, which is part of the excretory system. Unicellular organisms discharge waste products directly through the surface of the cell.

During life activities such as cellular respiration, several chemical reactions take place in the body. These are known as metabolism. These chemical reactions produce waste products such as carbon dioxide, water, salts, urea and uric acid. Accumulation of these wastes beyond a level inside the body is harmful to the body. The excretory organs remove these wastes. This process of removal of metabolic waste from the body is known as excretion.

Prostaglandins (PG) are a group of physiologically active lipid compounds that have diverse hormone-like effects in animals. They are a subclass of eicosanoids and of the prostanoid class of fatty acid derivatives. Prostaglandins have been found in almost every tissue in humans and other animals. They are derived enzymatically from the fatty acid arachidonic acid. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring.

The structural differences between prostaglandins account for their different biological activities. A given prostaglandin may have different and even opposite effects in different tissues in some cases. The ability of the same prostaglandin to stimulate a reaction in one tissue and inhibit the same reaction in another tissue is determined by the type of receptor to which the prostaglandin binds. They act as autocrine or paracrine factors with their target cells present in the immediate vicinity of the site of their secretion. Prostaglandins differ from endocrine hormones in that they are not produced at a specific site but in many places throughout the human body.

The Golgi apparatus (/ˈɡɒldʒi/), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination. It resides at the intersection of the secretory, lysosomal, and endocytic pathways. It is of particular importance in processing proteins for secretion, containing a set of glycosylation enzymes that attach various sugar monomers to proteins as the proteins move through the apparatus.

The Golgi apparatus was identified in 1898 by the Italian biologist and pathologist Camillo Golgi. The organelle was later named after him in the 1910s.

Hemichordata (/ˌhɛmɪkɔːrˈdeɪtə/ HEM-ih-kor-DAY-tə) is a phylum which consists of triploblastic, eucoelomate, and bilaterally symmetrical marine deuterostome animals, generally considered the sister group of the echinoderms. They appear in the Lower or Middle Cambrian and include two main classes: Enteropneusta (acorn worms), and Pterobranchia. A third class, Planctosphaeroidea, is known only from the larva of a single species, Planctosphaera pelagica. The class Graptolithina, formerly considered extinct, is now placed within the pterobranchs, represented by a single living genus Rhabdopleura.

Acorn worms are solitary worm-shaped organisms. They generally live in burrows (the earliest secreted tubes) and are deposit feeders, but some species are pharyngeal filter feeders, while the family are free living detritivores. Many are well known for their production and accumulation of various halogenated phenols and pyrroles. Pterobranchs are filter-feeders, mostly colonial, living in a collagenous tubular structure called a coenecium.

Insulin (/ˈɪn.sjʊ.lɪn/ ; from Latin insula 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the insulin (INS) gene. It is the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats, and protein by promoting the absorption of glucose from the blood into cells of the liver, fat, and skeletal muscles. In these tissues the absorbed glucose is converted into either glycogen, via glycogenesis, or fats (triglycerides), via lipogenesis; in the liver, glucose is converted into both. Glucose production and secretion by the liver are strongly inhibited by high concentrations of insulin in the blood. Circulating insulin also affects the synthesis of proteins in a wide variety of tissues. It is thus an anabolic hormone, promoting the conversion of small molecules in the blood into large molecules in the cells. Low insulin in the blood has the opposite effect, promoting widespread catabolism, especially of reserve body fat.

Beta cells are sensitive to blood sugar levels so that they secrete insulin into the blood in response to high level of glucose, and inhibit secretion of insulin when glucose levels are low. Insulin production is also regulated by glucose: high glucose promotes insulin production while low glucose levels lead to lower production. Insulin enhances glucose uptake and metabolism in the cells, thereby reducing blood sugar. Their neighboring alpha cells, by taking their cues from the beta cells, secrete glucagon into the blood in the opposite manner: increased secretion when blood glucose is low, and decreased secretion when glucose concentrations are high. Glucagon increases blood glucose by stimulating glycogenolysis and gluconeogenesis in the liver. The secretion of insulin and glucagon into the blood in response to the blood glucose concentration is the primary mechanism of glucose homeostasis.

Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane, controlling the flow of ions across secretory and epithelial cells, and regulating cell volume. Ion channels are present in the membranes of all cells. Ion channels are one of the two classes of ionophoric proteins, the other being ion transporters.

The study of ion channels often involves biophysics, electrophysiology, and pharmacology, while using techniques including voltage clamp, patch clamp, immunohistochemistry, X-ray crystallography, fluoroscopy, and RT-PCR. Their classification as molecules is referred to as channelomics.

Autophagy (or autophagocytosis; from the Greek αὐτόφαγος, autóphagos, meaning "self-devouring" and κύτος, kýtos, meaning "hollow") is the natural, conserved degradation of a biological cell that removes unnecessary or dysfunctional components through a lysosome-dependent regulated mechanism. It allows the orderly degradation and recycling of cellular components. Although initially characterized as a primordial degradation pathway induced to protect against starvation, it has become increasingly clear that autophagy also plays a major role in the homeostasis of non-starved cells. Defects in autophagy have been linked to various human diseases, including neurodegeneration and cancer, and interest in modulating autophagy as a potential treatment for these diseases has grown rapidly.

Four forms of autophagy have been identified: macroautophagy, microautophagy, chaperone-mediated autophagy (CMA), and crinophagy. In macroautophagy (the most thoroughly researched form of autophagy), cytoplasmic components (like mitochondria) are targeted and isolated from the rest of the cell within a double-membrane vesicle known as an autophagosome, which, in time, fuses with an available lysosome, bringing its specialty process of waste management and disposal; and eventually the contents of the vesicle (now called an autolysosome) are degraded and recycled. In crinophagy (the least well-known and researched form of autophagy), unnecessary secretory granules are degraded and recycled.

Neuroendocrinology is the branch of biology (specifically of physiology) which studies the interaction between the nervous system and the endocrine system; i.e. how the brain regulates the hormonal activity in the body. The nervous and endocrine systems often act together in a process called neuroendocrine integration, to regulate the physiological processes of the human body. Neuroendocrinology arose from the recognition that the brain, especially the hypothalamus, controls secretion of pituitary gland hormones, and has subsequently expanded to investigate numerous interconnections of the endocrine and nervous systems.

The endocrine system consists of numerous glands throughout the body that produce and secrete hormones of diverse chemical structure, including peptides, steroids, and neuroamines. Collectively, hormones regulate many physiological processes. The neuroendocrine system is the mechanism by which the hypothalamus maintains homeostasis, regulating reproduction, metabolism, eating and drinking behaviour, energy utilization, osmolarity and blood pressure.