science

Pylorus

Pylorus 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 Pylorus rather than just read about it. In short: The pylorus ( or ) connects the stomach to the duodenum. The pylorus is considered as having two parts, the pyloric antrum (opening to the body of the stomach) and the pyloric canal (opening to the duodenum).

Key takeaways

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

Reference excerpt

The pylorus ( or ) connects the stomach to the duodenum. The pylorus is considered as having two parts, the pyloric antrum (opening to the body of the stomach) and the pyloric canal (opening to the duodenum). The pyloric canal ends as the pyloric orifice, which marks the junction between the stomach and the duodenum. The orifice is surrounded by a sphincter, a band of muscle, called the pyloric sphincter. The word pylorus comes from Greek πυλωρός, via Latin. The word pylorus in Greek means "gatekeeper", related to "gate" (Greek: pyle) and is thus linguistically related to the word "pylon".

Structure

The pylorus is the furthest part of the stomach that connects to the duodenum. It is divided into two parts, the antrum, which connects to the body of the stomach, and the pyloric canal, which connects to the duodenum.

Antrum

The antrum also called the gastric antrum or the pyloric antrum is the initial portion of the pyloric region. It is near the bottom of the stomach, proximal to the pyloric sphincter, which separates the stomach and the duodenum. It may temporarily become partially or completely shut off from the remainder of the stomach during digestion by peristaltic contraction of the prepyloric sphincter; it is demarcated, sometimes, from the pyloric canal by a slight groove.

Canal The pyloric canal (Latin: canalis pyloricus) is the opening between the stomach and the duodenum. The wall thickness of the pyloric canal is up to 3 millimeters (mm) in infants younger than 30 days, and up to 8 mm in adults.

Sphincter The pyloric sphincter, surrounding the pyloric orifice is a strong ring of smooth muscle at the end of the pyloric canal which lets food pass from the stomach to the duodenum. It acts as a valve, controlling the outflow of gastric contents into the duodenum and release of chyme. Its function is modulated by both the central and enteric nervous systems. It receives sympathetic innervation from the celiac ganglion.

Histology

Under microscopy, the pylorus contains numerous glands, including gastric pits, which constitute about half the depth of the pyloric mucosa. They consist of two or three short closed tubes opening into a common duct or mouth. These tubes are wavy, and are about one-half the length of the duct. The duct is lined by columnar cells, continuous with the epithelium lining the surface of the mucous membrane of the stomach, the tubes by shorter and more cubical cell which are finely granular. The glands contain mucous cells and G cells that secrete gastrin. The pylorus also contains scattered parietal cells and neuroendocrine cells. These endocrine cells include D cells, which release somatostatin, responsible for shutting off acid secretion. (There is a second hormone-sensitive population near the fundus.) Unstriated muscles, which are entirely involuntary, are located at the pylorus.

Function The pylorus is one component of the gastrointestinal tract. Food from the stomach, as chyme, passes through the pylorus to the duodenum. The pylorus, through the pyloric sphincter, regulates entry of food from the stomach into the duodenum.

Clinical significance In such conditions as stomach cancer, tumours may partly block the pyloric canal. A special tube can be implanted surgically to connect the stomach to the duodenum so as to facilitate the passage of food from one to the other. The surgery to place this tube is called a gastroduodenostomy.

Stenosis

Pyloric stenosis refers to a pylorus that is narrow. This is due to congenital hypertrophy of the pyloric sphincter. The lumen of the pylorus is narrower, and less food is able to pass through. This problem is often detected in the early weeks of life. When it is present, a newborn baby may projectile vomit after eating, but despite vomiting remain hungry. Pyloric stenosis may be managed by the insertion of a stent, or through surgical cutting of the pyloric sphincter, a pyloromyotomy.

Other Pyloric tumors Pyloric gland adenoma

Additional images

Illustrations

Pylorus: Diagram from cancer.gov:1. Body of stomach2. Fundus3. Anterior wall4. Greater curvature5. Lesser curvature6. Cardia9. Pyloric sphincter10. Pyloric antrum11. Pyloric canal12. Angular incisure13. Gastric canal14. Rugal folds — Diagram from cancer.gov:1. Body of stomach2. Fundus3. Anterior wall4. Greater curvature5. Lesser curvature6. Cardia9. Pyloric sphincter10. Pyloric antrum11. Pyloric canal12. Angular incisure13. Gastric canal14. Rugal folds

Worked examples

Example 1 — a first encounter with Pylorus

Start with the simplest possible case. Write down what Pylorus 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 Pylorus 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 Pylorus 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 Pylorus

In research: Pylorus 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 Pylorus 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: Pylorus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Digestive system, Stomach, so understanding it makes those chapters shorter.
In everyday life: Look for Pylorus 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 Pylorus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pylorus 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 Pylorus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pylorus in simple terms?

Why does Pylorus 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 Pylorus?

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 Pylorus.