Chapter 19: The Cardiovascular System: Blood Vessels

Flashcards about the Cardiovascular System: Blood Vessels

Blood Vessels

Delivery system of dynamic structures that begins and ends at the heart; works with the lymphatic system to circulate fluids.

Arteries

Carry blood away from the heart; typically oxygenated, except in pulmonary circulation and umbilical vessels of the fetus.

Capillaries

Direct contact with tissue cells; directly serve cellular needs.

Veins

Carry blood toward the heart; typically deoxygenated, except in pulmonary circulation and umbilical vessels of the fetus.

Lumen

The central blood-containing space in a blood vessel.

Tunica Intima (Interna)

The innermost tunic of a blood vessel, consisting of endothelium, basement membrane, and internal elastic lamina.

Tunica Media

The middle tunic of a blood vessel, consisting of circular smooth muscle and elastic fibers.

Tunica Externa

The outermost tunic of a blood vessel, consisting of elastic and collagen fibers.

Elastic Arteries (Conducting Arteries)

Large diameter arteries with more elastic fibers and less smooth muscle; function as pressure reservoirs.

Muscular Arteries (Distributing Arteries)

Medium diameter arteries with more smooth muscle and fewer elastic fibers; capable of vasoconstriction and vasodilation to adjust blood flow.

Arterioles (Resistance Arteries)

Smallest of all arteries; control flow into capillary beds via vasodilation and vasoconstriction.

Capillaries

Microscopic vessels with very thin walls; function in the exchange of gases, nutrients, wastes, hormones, etc., between blood and interstitial fluid.

Continuous Capillaries

Capillaries abundant in skin, muscles, lungs, and CNS; form the blood-brain barrier in the brain.

Fenestrated Capillaries

Capillaries found in areas involved in active filtration, absorption, or endocrine hormone secretion; contain fenestrations (pores) for increased permeability.

Sinusoid Capillaries

Capillaries with fewer tight junctions, larger intercellular clefts, and incomplete basement membranes; found in the liver, bone marrow, spleen, and adrenal medulla.

Capillary Bed

Interwoven network of capillaries between arterioles and venules.

Microcirculation

Flow of blood through a capillary bed from arteriole to venule.

Venules

Capillaries that unite to form postcapillary venules; very porous and allow fluids and WBCs into tissues.

Veins

Carry blood toward the heart; have thinner walls and larger lumens compared with corresponding arteries; function as capacitance vessels (blood reservoirs).

Varicose Veins

Dilated and painful veins due to incompetent (leaky) valves.

Anastomoses

Interconnections of blood vessels that provide alternate pathways for blood flow.

Blood Flow

Volume of blood flowing through a vessel, organ, or entire circulation in a given period.

Blood Pressure (BP)

Force per unit area exerted on the wall of a blood vessel by blood.

Resistance (Peripheral Resistance)

Opposition to flow; measurement of the amount of friction blood encounters with vessel walls.

Systolic Pressure

Pressure exerted in the aorta during ventricular contraction.

Diastolic Pressure

Lowest level of aortic pressure when the heart is at rest.

Pulse Pressure

Difference between systolic and diastolic pressure.

Vital Signs

Pulse and blood pressure, along with respiratory rate and body temperature.

Pressure Points

Areas where arteries are close to the body surface and can be compressed to stop blood flow.

Muscular Pump

Contraction of skeletal muscles that “milks” blood back toward the heart.

Respiratory Pump

Pressure changes during breathing that move blood toward the heart.

Sympathetic Venoconstriction

Under sympathetic control, smooth muscles constrict, pushing blood back toward the heart.

Hypertension

Sustained elevated arterial pressure of 140/90 mm Hg or higher.

Hypotension

Low blood pressure below 90/60 mm Hg.

Circulatory Shock

Condition where blood vessels inadequately fill and cannot circulate blood normally.

Blood Velocity

Speed of blood flow in cm/sec; inversely related to cross-sectional area.

Capillary Exchange

Movement of materials in & out of a capillary via diffusion, transcytosis, and bulk flow.

Diffusion (Capillary Exchange)

Movement of substances down a concentration gradient across a capillary wall.

Transcytosis (Capillary Exchange)

Passage of material across endothelium in tiny vesicles by endocytosis and exocytosis.

Bulk Flow (Capillary Exchange)

Passive process in which large numbers of ions, molecules, or particles in a fluid move together in the same direction.

Hydrostatic Pressure (HP)

Force exerted by fluid pressing against a wall.

Colloid Osmotic Pressure (Oncotic Pressure, OPc)

“Sucking” pressure created by nondiffusible plasma proteins pulling water back into the capillary.

Net Filtration Pressure (NFP)

Net filtration pressure; comprises all forces acting on a capillary bed.

Edema

Abnormal increase in the amount of interstitial fluid.