A closed delivery system that begins and ends at the heart

Blood Vessels

The 3 major types of blood vessels are

• Arteries
• Capillaries
• Veins

A blood vessel that carries blood AWAY from the heart

Arteries

A blood vessel that carries blood TOWARD to the heart

Veins

The innermost tunic of a blood vessels, that contains endothelium, is called

Tunica Intima

The middle tunic of a blood vessel, which is mostly circularly arranged smooth muscle cells and sheets of elastin, is called

Tunica Media

Narrowing of blood vessels

Vasoconstriction

Relaxation of the smooth muscles of the blood vessels, producing dilation

Vasodilation

The bulkiest layer of the blood vessels

Tunica Media

The outermost layer of a blood vessel wall, which is composed largely of loosely woven collagen fibers that protect and reinforce the vessel is called

Tuncia Externa

Arteries can be divided into three groups

• Elastic Arteries
• Muscular Arteries
• Arterioles

The thick-walled arteries near the heart, such as the aorta and its major branches

Elastic Arteries

Arteries that deliver blood to specific body organs

Muscular Arteries

The smallest of the arteries

Arterioles

The smallest blood vessels

Capillaries

The average length of capillaries are

1mm

There are three types of capillaries

• Continuous
• Fenestrated
• Sinusoid

These capillaries are the most abundant in the skin and muscles

Continuous Capillaries

Similar to continuous capillaries, these capillaries are riddled with oval pores, or fenestrations

Fenestrations

Leaky capillaries found only in the liver, bone marrow, spleen, and adrenal medulla

Sinusoid Capillaries

Form interweaving networks of capillaries

Capillaries Bed

The flow of blood from an arteriole to a venule

Microcirculation

A short vessel that directly connects the arteriole and venule at opposite ends of the bed

Vascular Shunt

Actual exchange vessels

True Capillaries

A small vein

Venule

A minute artery

Arteriole

Blood vessesls that carry blood from the capillary beds toward the heart

Veins

Valves formed from folds of the tunica intima of veins

Venous Valves

Special interconnections formed by blood vessels

Vascular Anastomoses

Merged arteries that supply the same area of an organ

Arterial Anastomoses

The volume of blood flowing through a vessel, an organ, or the entire circulation in a given period (ml/min)

Blood Flow

The force per unit area exerted on a vessel wall by the contained blood; expressed in mm Hg

Blood Pressure

The opposition to flow and is a measure of the amount of friction blood encounters as it passes through the vessel

Resistance

There are three important sources of resistance

• Blood Viscosity - the thickness or "stickiness" of blood
• Vessel Length - the longer the blood vessel, the greater the resistance
• Vessel Diameter - the smaller the diameter of a blood vessel, the greater the resistance

When blood pressure increase

blood flow speeds up

When peripheral resistance increase

blood flow decrease

Formula for blood flow

Systemic blood pressure is highest

in the aorta

Arterial blood pressure reflects two factors

• How much the elastic arteries close the heart can stretch
• The volume of blood forced into them at any time

Pressure exerted by blood on the blood vessel walls during ventricular contractions

Systolic Pressure

Period when either the ventricles or the atria are contracting

Systole

Period of the cardiac cycle when either the ventricles or the atria are relaxing

Diastole

Arterial blood pressure reached during or as a result of diastole;

Diastolic Pressure

The difference between the systolic and diastolic pressures

Pulse Pressure