Human Anatomy & Physiology: Vocabulary Blood Vessels Flashcards

form a closed delivery system that begins and ends at the heart.

the innermost tunic, in intimate contact with the blood in the lumen, forming a slick surface that minimizes friction as blood moves through the lumen.

in vessels larger than 1 mm, consisting of a basement membrane and loose connective tissue, supports the endothelium.

the middle tunic, mostly circularly arranged smooth muscle cells and sheets of elastin, the bulkiest layer in arteries, responsible for maintaining blood pressure and continuous blood circulation.

reduction in lumen diameter as the smooth muscle contracts

increase in lumen diameter as the smooth muscle relaxes

the outermost layer is composed largely of loosely woven collagen fibers protect and reinforce the vessel, and anchor it to surrounding structures.

carry blood away from the heart, “branch,” “diverge,” or “fork” as they form smaller and smaller divisions.

carry blood toward the heart, “join,” “merge,” and “converge” into the successively larger vessels approaching the heart.

have intimate contact with tissue cells and directly serve cellular needs. Exchanges between the blood and tissue cells occur primarily through the gossamer-thin capillary walls.

conducting, thick-walled arteries near the heart—the aorta and its major branches.

distributing arteries, which deliver blood from elastic arteries to specific body organs

smallest of the arteries delivers blood from the muscular arteries to the capillaries

abundant in the skin and muscles, are most common. They are continuous in the sense that their endothelial cells provide an uninterrupted lining, adjacent cells being joined laterally by tight junctions.

are similar to the continuous variety except that some of the endothelial cells in fenestrated capillaries are riddled with oval pores, or fenestrations

are highly modified, leaky capillaries found only in the liver, bone marrow, spleen, and adrenal medulla.

interweaving networks of capillaries

The flow of blood from an arteriole to a venule—that is, through a capillary bed

are formed when capillaries unite.

the smallest venules, consist entirely of endothelium around which pericytes congregate. They are extremely porous and fluid and white blood cells move easily from the bloodstream through their walls.

feeds the capillary bed

a vessel structurally intermediate between an arteriole and a capillary

intermediate between a capillary and a venule.

number 10 to 100 per capillary bed, depending on the organ or tissues served. They usually branch off the metarteriole

surrounds the root of each true capillary at the metarteriole and acts as a valve to regulate blood flow into the capillary

is the heaviest wall layer, Consisting of thick longitudinal bundles of collagen fibers and elastic networks

are formed from folds of the tunica intima, and resemble the semilunar valves of the heart in both structure and function

such as the coronary sinus of the heart and the dural venous sinuses of the brain, are highly specialized, flattened veins with extremely thin walls composed only of endothelium.

interconnections where vascular channels unite

one arterial branch meets another supplying the same area.

anastomoses provide alternate pathways

the metarteriole–thoroughfare channel shunts of capillary beds that connect arterioles and venules.

veins connect

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

the force per unit area exerted on a vessel wall by the contained blood, is expressed in millimeters of mercury (mm Hg).

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

friction encountered in the peripheral (systemic) circulation, well away from the heart

the internal resistance to flow that exists in all fluids and is related to the thickness or “stickiness” of a fluid.

the relationship between total blood vessel length and resistance is straightforward: the longer the vessel, the greater the resistance.

is the pressure peak, averages 120 mm Hg in healthy adults. Blood moves forward into the arterial bed because the pressure in the aorta is higher than the pressure in the more distal vessels

the aortic valve closes, preventing blood from flowing back into the heart, and the walls of the aorta (and other elastic arteries) recoil, maintaining sufficient pressure to keep the blood flowing forward into the smaller vessels. During this time, aortic pressure drops to its lowest level (approximately 70 to 80 mm Hg in healthy adults).

the pressure that propels the blood to the tissues. Diastole usually lasts longer than systole, so the MAP is not simply the value halfway between systolic and diastolic pressures. Instead, it is roughly equal to the diastolic pressure plus one-third of the pulse pressure.

MAP = diastolic pressure + (pulse pressure)/3

During inhalation, abdominal pressure increases, squeezing the local veins and forcing blood toward the heart. At the same time, the pressure in the chest decreases, entry into the right atrium.

consisting of skeletal muscle activity. As the skeletal muscles surrounding the deep veins contract and relax, they “milk” blood toward the heart, and once blood passes each successive valve, it cannot flow back.

The neural center that oversees changes in the diameter of blood vessels, a cluster of neurons in the medulla.

postganglionic visceral efferent fibers innervating the smooth muscles of vessel walls.

state of moderate constriction the arterioles are almost always in

neural receptors located in the carotid sinuses (dilations in the internal carotid arteries, which provide the major blood supply to the brain).

slowing of the heart beat on pressure on the carotid artery at the level of the cricoid cartilage.

help maintain adequate blood pressure in the systemic circuit as a whole.

in the aortic arch and large arteries of the neck transmit impulses to the cardioacceleratory center, which then increases cardiac output, and to the vasomotor center, which causes reflex vasoconstriction. The rise in blood pressure that follows speeds the return of blood to the heart and lungs.

during periods of stress, the adrenal gland releases norepinephrine (NE) and epinephrine to the blood, NE has a vasoconstrictive action. Epinephrine increases cardiac output and promotes generalized vasoconstriction.

when blood pressure or blood volumes are low, the kidneys release the hormone renin. Renin acts as an enzyme, ultimately generating angiotensin II that stimulates intense vasoconstriction, promoting a rapid rise in systemic blood pressure

Causes blood volume and blood pressure to decline.

stimulates the kidneys to conserve water. It is not usually important in short-term blood pressure regulation, but when blood pressure falls to dangerously low levels (as during severe hemorrhage), much more ADH is released and helps restore arterial pressure by causing intense vasoconstriction.

pulse, blood pressure, respiratory rate and body temperature

pressure wave that is transmitted through the arterial tree.

clinically important arterial pulse points because they are compressed to stop blood flow into distal tissues during hemorrhage.

or low blood pressure, is a systolic pressure below 100 mm Hg.

high blood pressure.

Blood flow through body tissues

the automatic adjustment of blood flow to each tissue in proportion to the tissue’s requirements at any instant.

is a powerful vasodilator which acts via a cyclic GMP second-messenger system.

are among the most potent vasoconstrictors known.

refers to the dramatically increased blood flow into a tissue that occurs after the blood supply to the area has been temporarily blocked.

When muscles become active, blood flow increases

is the force exerted by a fluid pressing against a wall.

the pressure exerted by blood on the capillary walls.

acting outside the capillaries and pushing fluid in

the force opposing hydrostatic pressure, is created by the presence in a fluid of large nondiffusible molecules, such as plasma proteins, that are unable to cross the capillary wall.

which results from large-scale loss of blood, as might follow acute hemorrhage, severe vomiting or diarrhea, or extensive burns. If blood volume drops rapidly, heart rate increases in an attempt to correct the problem. Thus, a weak, “thready” pulse is often the first sign of hypovolemic shock.

blood volume is normal, but circulation is poor as a result of an abnormal expansion of the vascular bed caused by extreme vasodilation.

or pump failure, occurs when the heart is so inefficient that it cannot sustain adequate circulation.

complex network of blood vessels

routes blood through a long loop to all parts of the body before returning it to the heart

is the short loop that runs from the heart to the lungs and back to the heart.

Arteries run deep while veins are both deep and superficial.

Venous pathways are more interconnected.

The brain and digestive systems have unique venous drainage systems.

The endothelial lining of blood vessels is formed by mesodermal cells, which collect in little masses

Pulmonary Trunk

Pulmonary Arteries
Right & Left

Pulmonary Veins

Right & Left
Superior & Inferior