science

Vasomotor center

Vasomotor center 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 Vasomotor center rather than just read about it. In short: The vasomotor center (VMC) is a portion of the medulla oblongata. Together with the cardiovascular center and respiratory center, it regulates blood pressure.

Key takeaways

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

Reference excerpt

The vasomotor center (VMC) is a portion of the medulla oblongata. Together with the cardiovascular center and respiratory center, it regulates blood pressure. It also has a more minor role in other homeostatic processes. Upon increase in carbon dioxide level at central chemoreceptors, it stimulates the sympathetic system to constrict vessels. This is opposite to carbon dioxide in tissues causing vasodilatation, especially in the brain. Cranial nerves IX (glossopharyngeal nerve) and X (vagus nerve) both feed into the vasomotor centre and are themselves involved in the regulation of blood pressure.

Structure The vasomotor center is a collection of integrating neurons in the medulla oblongata of the middle brain stem. The term "vasomotor center" is not truly accurate, since this function relies not on a single brain structure ("center") but rather represents a network of interacting neurons. This center is located in the Rostral ventrolateral medulla.

Afferent fibres The vasomotor center integrates nerve impulses from many places via the solitary nucleus:

central chemoreceptors aortic body chemoreceptors, which send impulses via the vagus nerves carotid body chemoreceptors, which send impulses via the glossopharyngeal nerves aortic arch and brachiocephalic artery high-pressure baroreceptors, which send impulses via the aortic nerve carotid sinus high-pressure baroreceptors, which send impulses via the glossopharyngeal nerves

Efferent fibres The vasomotor center gives off sympathetic fibres through the spinal cord and sympathetic ganglia, which reach vascular smooth muscle.

Function The vasomotor center changes vascular smooth muscle tone. This changes local and systemic blood pressure. A drop in blood pressure leads to increased sympathetic tone from the vasomotor center. This acts to raise blood pressure.

Clinical significance Methyldopa acts on the vasomotor center, leading to selective stimulation of α2-adrenergic receptor. Guanfacine also causes the same stimulation. This reduces sympathetic tone to vascular smooth muscle. This reduces heart rate and vascular resistance. Digoxin increases vagal tone from the vasomotor centre, which decreases pulse. G-series nerve agents have their most potent effect in the vasomotor center. Unlike other parts of the body, where continued stimulation of acetylcholine receptors leads to recoverable paralysis, overstimulation of the vasomotor center is often causes a fatal rise in blood pressure.

History The localization of vasomotor center was determined by Filipp Ovsyannikov in 1871.

See also Rostral ventrolateral medulla cardiovascular center

References

Worked examples

Example 1 — a first encounter with Vasomotor center

Start with the simplest possible case. Write down what Vasomotor center 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 Vasomotor center 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 Vasomotor center 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 Vasomotor center

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

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

Frequently asked questions

What is Vasomotor center in simple terms?

The vasomotor center (VMC) is a portion of the medulla oblongata. Together with the cardiovascular center and respiratory center, it regulates blood pressure.

Why does Vasomotor center 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 Vasomotor center?

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 Vasomotor center.