6 Changes Inside Your Arteries That Can Affect Blood Pressure

Blood pressure is often reduced to two numbers.

But those numbers are partly determined by what is happening inside the arteries carrying blood away from the heart.

Healthy arteries are not rigid tubes. Their walls stretch as the heart pumps blood forward and recoil between beats. Smaller arteries can also widen or narrow to control how much resistance the blood encounters.

Changes to either function can influence blood pressure.

Researchers in the Framingham Offspring Study followed 1,759 adults for approximately seven years and measured several indicators of vascular stiffness.

Greater aortic stiffness at the beginning of the study was associated with higher systolic blood pressure later.

The relationship can also move in the opposite direction. Higher pressure places additional mechanical stress on artery walls, which can contribute to further structural and functional changes.

That creates an important cycle: changes inside the arteries can influence blood pressure, while elevated blood pressure can place additional strain on the arteries.

1. Elastic Fibers Can Begin To Break Down

Large arteries contain elastic fibers that allow the vessel wall to stretch when blood is pushed out of the heart.

One of the most important proteins in those fibers is elastin.

Elastin works alongside collagen, another structural protein that provides strength to the artery wall.

The balance matters.

Elastin allows the artery to stretch and recoil. Collagen is considerably less flexible and helps prevent the vessel from overstretching.

With aging and repeated vascular stress, elastic fibers can gradually fragment and degrade.

At the same time, more of the mechanical load can shift toward the stiffer collagen fibers.

The result is an artery that requires more pressure to expand during each heartbeat.

Instead of absorbing part of the force created when the heart contracts, a stiffer artery transmits more of that pressure forward.

This is one reason arterial stiffness is particularly connected with increases in systolic blood pressure—the top number in a blood-pressure reading.

Researchers have described this change as a shift in the balance between elastin and collagen inside the arterial wall. [1]

2. The Endothelium May Produce Less Available Nitric Oxide

The innermost layer of an artery is called the endothelium.

It is only a thin layer of cells, but it plays a major role in controlling how the vessel behaves.

One of its important functions is producing nitric oxide.

Nitric oxide sends a signal to the smooth muscle surrounding the blood vessel, encouraging that muscle to relax.

As the muscle relaxes, the vessel can widen and allow blood to move through with less resistance.

This system can become less effective when endothelial function declines.

Oxidative stress, inflammation, metabolic changes, smoking, aging, and elevated blood pressure itself have all been studied for their effects on endothelial function and nitric oxide availability.

When less nitric oxide is available, the balance can shift away from vasodilation.

The artery may have more difficulty relaxing appropriately when greater blood flow is needed.

Researchers have found that inhibiting nitric oxide production can increase both blood pressure and peripheral vascular resistance, demonstrating how closely this signaling system is connected to pressure regulation.

Endothelial dysfunction and high blood pressure can also reinforce one another, making it difficult to identify a single starting point in every person. [2]

3. Smooth Muscle Can Keep The Artery More Constricted

Beneath the endothelium sits a layer containing vascular smooth muscle.

These muscle cells continuously adjust the diameter of the vessel.

When they relax, the vessel widens.

When they contract, the opening becomes smaller.

That difference can have a surprisingly large effect on resistance.

Small resistance arteries—generally those with an internal diameter below about 300 micrometers—play an especially important role in controlling blood pressure.

Researchers describe vessel diameter as one of the most important determinants of vascular resistance because even relatively small changes in radius can substantially change the resistance blood encounters.

Several biological systems influence this contraction.

Calcium signaling inside smooth-muscle cells, the sympathetic nervous system, the renin-angiotensin-aldosterone system, oxidative stress, inflammatory signaling, and other mechanisms can all alter vascular tone.

When the balance favors greater contraction, the opening available for blood becomes smaller.

The heart is then pumping against greater resistance.

That does not necessarily mean there is a physical blockage inside the artery. The artery itself may simply be maintaining a more constricted state. [3]

4. The Artery Wall Can Remodel Around A Smaller Opening

Temporary constriction is one thing.

Over time, some smaller arteries can also undergo structural remodeling.

Instead of simply contracting and then relaxing again, components of the vessel wall can physically reorganize.

One pattern researchers observe in hypertension is called inward remodeling.

Material in the artery wall becomes arranged around a smaller internal opening, or lumen.

In other situations, smooth-muscle cells and other components of the wall can increase in size or number, contributing to a thicker vessel wall.

Both changes can increase the wall-to-lumen ratio.

Why does that matter?

Blood must travel through the lumen.

When that opening becomes smaller, vascular resistance increases.

Research on hypertension has identified increased peripheral resistance as a central hemodynamic abnormality, with structural changes in smaller arteries contributing to the reduced lumen diameter.

High blood pressure can encourage remodeling, but the resulting narrower vessel can then create additional resistance.

Once again, the relationship can become a cycle rather than a single cause-and-effect event. [4]

5. Calcium Can Accumulate Within The Artery Wall

Calcium belongs in many places in the body.

It helps build bone, participates in muscle contraction, and supports nerve signaling.

But calcium can also accumulate within blood-vessel walls.

This process is known as vascular calcification.

It is not simply calcium circulating through the bloodstream and sticking to an artery. Vascular calcification is an active biological process involving cells and signaling mechanisms within the vessel wall.

One form, called medial arterial calcification, develops within the middle layer of the artery.

Unlike a plaque that can obstruct blood flow, medial calcification may stiffen the artery without necessarily blocking the opening.

That distinction is important.

An artery can remain open while becoming considerably less flexible.

When calcium deposits make the arterial wall more rigid, the vessel has greater difficulty expanding as the heart ejects blood.

Research has connected medial calcification with increased arterial stiffness.

Calcification becomes more common with aging and has also been associated with conditions including diabetes and chronic kidney disease.

The pressure problem, therefore, does not always come from something physically blocking blood flow. Sometimes it comes from the artery losing its ability to absorb the force of each heartbeat. [5]

6. Collagen Can Become More Rigid Through Glycation

The collagen inside an artery can change even when the amount of collagen stays the same.

One way this happens involves compounds called advanced glycation end products, or AGEs.

AGEs can form when sugars react with proteins over time.

Because collagen is a long-lived protein, it can accumulate these modifications.

AGEs can create additional chemical cross-links between collagen molecules.

Think of those cross-links as additional connections tying neighboring collagen fibers together.

More cross-linking makes the collagen less flexible.

Inside an artery wall, that can translate into greater stiffness and less ability to expand when pressure rises.

AGE-related changes can also affect elastin and interfere with nitric oxide availability, meaning the effect is not limited to collagen alone.

AGE accumulation occurs with normal aging but can be accelerated when blood glucose remains elevated.

Research has connected collagen cross-linking by AGEs with arterial stiffening and reduced vascular compliance.

This creates another example of how metabolic health and vascular health can intersect inside the artery itself. [6]

What These Six Changes Have In Common

Not every person with elevated blood pressure will have the same combination of vascular changes.

One person may have greater arterial stiffness.

Another may have changes in endothelial function or vascular tone.

Another may have several processes happening simultaneously.

And high blood pressure itself can accelerate some of the same changes that contribute to higher pressure.

That is why blood pressure is more than a number produced by the heart.

It also reflects how effectively the vascular system can expand, relax, and accommodate blood as it moves throughout the body.

The artery wall is constantly responding to each heartbeat.

When its elasticity, signaling, muscle tone, structure, or composition changes, the amount of resistance encountered by the blood can change with it.

Understanding those changes gives the numbers on a blood-pressure monitor much more context.