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