What is the expansion and contraction of the arteries?

What is the expansion and contraction of the arteries?

The pulse, which can be felt over an artery lying near the surface of the skin, results from the alternate expansion and contraction of the arterial wall as the beating heart forces blood into the arterial system via the aorta.

What do you call the rhythmic expansion of an artery that may be felt with the finger?

Pulse, rhythmic dilation of an artery generated by the opening and closing of the aortic valve in the heart. A pulse can be felt by applying firm fingertip pressure to the skin at sites where the arteries travel near the skin’s surface; it is more evident when surrounding muscles are relaxed.

What is the contraction of an artery called?

Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles.

What is stretching of the artery walls called?

Aneurysms are the result of weakening and thinning of the artery wall. When a portion of the arterial wall stretches and swells to more than 50 percent of the original diameter, this is called an aneurysm.

Where in the systemic circulation is the blood flow the slowest?

Blood Flow Away from the Heart In the aorta, the blood travels at 30 cm/sec. From the aorta, blood flows into the arteries and arterioles and, ultimately, to the capillary beds. As it reaches the capillary beds, the rate of flow is dramatically (one-thousand times) slower than the rate of flow in the aorta.

Is systole a contraction or relaxation?

Systole is the contraction phase of the cardiac cycle, and diastole is the relaxation phase. At a normal heart rate, one cardiac cycle lasts for 0.8 second.

What causes arteries to constrict?

Vasoconstriction is narrowing or constriction of the blood vessels. It happens when smooth muscles in blood vessel walls tighten. This makes the blood vessel opening smaller.

What is the path of systemic circulation?

Systemic circulation carries oxygenated blood from the left ventricle, through the arteries, to the capillaries in the tissues of the body. From the tissue capillaries, the deoxygenated blood returns through a system of veins to the right atrium of the heart.

What happens when your diastolic and systolic numbers are close together?

If systolic pressure goes up — even if the diastolic pressure stays the same — the patient is at risk for developing serious cardiovascular conditions. What Is Pulse Pressure? The term pulse pressure might be new to you — it’s the difference between your systolic pressure and your diastolic pressure.

What are the 4 stages of cardiac cycle?

The cardiac cycle involves four major stages of activity: 1) “Isovolumic relaxation”, 2) Inflow, 3) “Isovolumic contraction”, 4) “Ejection”.

What happens when arteries constrict?

Vasoconstriction is the narrowing (constriction) of blood vessels by small muscles in their walls. When blood vessels constrict, blood flow is slowed or blocked. Vasoconstriction may be slight or severe. It may result from disease, drugs, or psychological conditions.

capillaries
As the total cross-sectional area of the vessels increases, the velocity of flow decreases. Blood flow is slowest in the capillaries, which allows time for exchange of gases and nutrients.

How does vasoconstriction affect the diameter of blood vessels?

Contraction and relaxation of the circular muscles decrease and increase the diameter of the vessel lumen, respectively. Specifically in arteries, vasoconstriction decreases blood flow as the smooth muscle in the walls of the tunica media contracts, making the lumen narrower and increasing blood pressure.

How is the pressure of an artery related to heart activity?

Key Terms. Arterial pressure varies between the peak pressure during heart contraction, called the systolic pressure, and the minimum or diastolic pressure between contractions, when the heart expands and refills. This pressure variation within the artery produces the observable pulse that reflects heart activity.

How does elasticity of the arteries keep blood pressure constant?

Arterial elasticity gives rise to the Windkessel effect, which through passive contraction after expansion helps to maintain a relatively constant pressure in the arteries despite the pulsating nature of the blood flow from the heart.

When does blood pressure change during a heart contraction?

Arterial pressure varies between the peak pressure during heart contraction, called the systolic pressure, and the minimum or diastolic pressure between contractions, when the heart expands and refills. This pressure variation within the artery produces the observable pulse that reflects heart activity.

Contraction and relaxation of the circular muscles decrease and increase the diameter of the vessel lumen, respectively. Specifically in arteries, vasoconstriction decreases blood flow as the smooth muscle in the walls of the tunica media contracts, making the lumen narrower and increasing blood pressure.

What makes up the media of the artery wall?

The thickness of a normal media layer is between 125 and 350 μm (average 200 μm). However, the media in an atherosclerotic site is thinner and ranges between 16 and 190 μm (average 80 μm) [ 3]. The adventitia is made up of fibrous tissue, which is mostly elastin and collagen fibers, and fibroblasts.

What is the WSS of the artery wall?

Regions of the vessel wall experiencing low WSS (<0.2Pa), secondary flow, and oscillatory WSS are more likely to develop atherosclerotic lesions ( Ku et al., 1985; Zarins et al., 1983; Friedman and Fry, 1993 ).

What causes a narrowing of the artery wall?

As a consequence of plaque formation, the vascular lumen narrows and produces a stenosis. The latter may cause an acute decrease of the blood flow in a downstream part of the vascular network either due to a significant occlusion or due to a plaque rupture and associated clot formation and embolization.