science

Local hormone

Local hormone is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Local hormone rather than just read about it. In short: Local hormones are a large group of signaling molecules that do not circulate within the blood. Local hormones are produced by nerve and gland cells and bind to either neighboring cells or the same type of cell that produced them.

Key takeaways

Local hormone belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Local hormone to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Local hormone from memory before moving on to harder problems.

Reference excerpt

Local hormones are a large group of signaling molecules that do not circulate within the blood. Local hormones are produced by nerve and gland cells and bind to either neighboring cells or the same type of cell that produced them. Local hormones are activated and inactivated quickly. They are released during physical work and exercise. They mainly control smooth and vascular muscle dilation. Strength of response is dependent upon the concentration of receptors of target cell and the amount of ligand (the specific local hormone). Eicosanoids (ī′kō-să-noydz; eicosa = twenty, eidos = formed) are a primary type of local hormone. These local hormones are polyunsaturated fatty acid derivatives containing 20 carbon atoms and fatty acids derived from phospholipids in the cell membrane or from diet. Eicosanoids initiate either autocrine stimulation or paracrine stimulation. There are two main types of eicosanoids: prostaglandins and leukotrienes, which initiate either autocrine stimulation or paracrine stimulation. Eicosanoids are the result of a ubiquitous pathway which first produces arachidonic acid, and then the eicosanoid product. Prostaglandins are the most diverse category of eicosanoids and are thought to be synthesized in most tissues of the body. This type of local hormone stimulates pain receptors and increases the inflammatory response. Nonsteroidal anti-inflammatory drugs stop the formation of prostaglandins, thus inhibiting these responses. Leukotrienes are a type of eicosanoids that are produced in leukocytes and function in inflammatory mediation. Paracrines (para- = beside or near) are local hormones that act on neighboring cells. This type of signaling involves the secretion of paracrine factors, which travel a short distance in the extracellular environment to affect nearby cells. These factors can be excitatory or inhibitory. There are a few families of factors that are very important in embryo development including fibroblast growth factor secreted them. Juxtacrines (juxta = near) are local hormones that require close contact and act on either the cell which emitted them or on adjacent cells.

Classification According to structural and functional similarity, many local hormones fall into either the gastrin or the secretin family.

Gastrin family The Gastrin family is a group of peptides evolutionarily similar in structure and function. Commonly synthesized in antroduodenal G-cells. Regulate gastric function along with gastric acid secretion and mucosal growth.

Gastrin Cholecystokinin (CCK)

Secretin family The Secretin family are peptides that act as local hormones which regulate activity of G-protein coupled receptors. Most often found in the pancreas and the intestines. Secretin was discovered in 1902 by E. H. Starling. It was later linked to chemical regulation and was the first substance to be deemed a hormone.

Secretin Glucagon Glicentin (GLI) Vasoactive intestinal peptide (VIP) Gastric inhibitory polypeptide (GIP)

Others Motilin Neurotensin Substance P Somatostatin Bombesin Serotonin Angiotensin Nitric Oxide Kinins Histamine

References

Mark H. Whitnall, William G. Haynes, David J. Webb (1997). Principles of Medical Biology. Salmon JA, Higgs GA (April 1987). "Prostaglandins and leukotrienes as inflammatory mediators". Br. Med. Bull. 43 (2): 285–96. doi:10.1093/oxfordjournals.bmb.a072183. PMID 2825898. SF Gilbert. (2000). Developmental Biology 6th Edition. Jan M. Keppel Hesselink.(2016). "Autacoids: A New Fundament for Pain Medicine of the 21th Century". McKinley, Michael P., et al. Anatomy & Physiology: an Integrative Approach. McGraw-Hill Higher Education, 2012 Rehfeld JF1, Friis-Hansen L, Goetze JP, Hansen TV. (2007). "The biology of cholecystokinin and gastrin peptides". Curr Top Med Chem. 2007;7(12):1154-65. Henriksen JH, de Muckadell OB. (2000). "Secretin, its discovery, and the introduction of the hormone concept.". Scand J Clin Lab Invest. 2000 Oct;60(6):463-71.

Worked examples

Example 1 — a first encounter with Local hormone

Start with the simplest possible case. Write down what Local hormone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Local hormone before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Local hormone ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Local hormone

In research: Local hormone appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Local hormone in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Local hormone is common in secondary-school and first-year university syllabi. It links to neighbouring topics Endocrine system, Hormones, Signal transduction, so understanding it makes those chapters shorter.
In everyday life: Look for Local hormone outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Local hormone in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Local hormone means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Local hormone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Local hormone in simple terms?

Why does Local hormone matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Local hormone?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Local hormone.