Cardiovascular System – Blood Vessels Vocabulary

Vocabulary flashcards covering key terms, structures, mechanisms, and pathologies related to blood vessels and cardiovascular physiology as presented in Chapter 19.

Artery

Blood vessel that carries blood away from the heart; usually oxygenated except in pulmonary and umbilical circulation.

Vein

Blood vessel that carries blood toward the heart; functions as a capacitance vessel with valves and large lumens.

Capillary

Microscopic vessel with a one-cell-thick wall where exchange of gases, nutrients, wastes, and hormones occurs.

Tunica Intima (Interna)

Innermost blood-vessel layer composed of endothelium; lines the lumen.

Tunica Media

Middle muscular and elastic layer of a vessel wall; controls vasoconstriction and vasodilation.

Tunica Externa (Adventitia)

Outer connective-tissue layer of a vessel wall containing collagen fibers and elastic networks.

Lumen

Central blood-containing space within a vessel surrounded by the tunics.

Vasa Vasorum (what is it)

Small vessels that nourish the outer layers of large blood-vessel walls; literally “vessels of the vessels.”

Elastic (Conducting) Artery

Thick-walled artery near the heart (e.g., aorta) rich in elastin; acts as a pressure reservoir.

Muscular (Distributing) Artery

Medium-sized artery with thick smooth-muscle media; delivers blood to specific body organs and actively constricts.

Arteriole

Smallest artery leading into capillary beds; key regulator of blood flow via diameter changes.

Pericyte

Contractile cell scattered along capillaries that stabilizes the wall and regulates permeability.

Continuous Capillary

Most common capillary type; uninterrupted endothelium with tight junctions; forms blood-brain barrier in the CNS.

Fenestrated Capillary

Capillary with pores (fenestrations) that increase permeability; found in kidneys, endocrine glands, and intestines.

Sinusoidal Capillary (Sinusoid)

Leaky, large-lumen capillary with few tight junctions; allows passage of large molecules and cells; present in liver, bone marrow, spleen.

Precapillary Sphincter

Ring of smooth muscle surrounding a true capillary that regulates blood entry into the bed.

Venule

Small vessel formed when capillaries unite; allows fluid and white-blood-cell passage into tissues.

Capacitance Vessel

Alternate term for veins, highlighting their ability to hold ~65 % of the blood volume.

Arterial Anastomosis

Connection between arterial branches providing collateral circulation if one pathway is blocked.

Blood Flow

Volume of blood moving through a vessel, organ, or entire circulation per minute; equals cardiac output systemically.

Blood Pressure (BP)

Force per unit area exerted by blood on vessel walls; expressed in mm Hg and measured in arteries near the heart.

Resistance (Peripheral Resistance)

Opposition to blood flow caused by friction; determined mainly by blood viscosity, vessel length, and vessel diameter.

Blood Viscosity

“Stickiness” of blood due to formed elements and plasma proteins; a constant factor influencing resistance.

Systolic Pressure

Arterial pressure during ventricular contraction (highest level).

Diastolic Pressure

Lowest arterial pressure during ventricular relaxation.

Respiratory Pump

Mechanism by which breathing-induced pressure changes propel venous blood toward the heart.

Muscular Pump

Contraction of skeletal muscles that “milks” venous blood toward the heart; valves prevent backflow.

Vasoconstriction

Narrowing of blood-vessel diameter, usually caused by smooth-muscle contraction.

Vasodilation

Widening of vessel diameter caused by smooth-muscle relaxation.

Vasomotor Center

Part of the cardiovascular center in the medulla that adjusts vessel diameter via sympathetic output.

Chemoreceptor

Receptor sensitive to blood levels of oxygen or carbon dioxide; prominent in carotid and aortic bodies.

Norepinephrine / Epinephrine

Adrenal-medulla hormones that raise BP by vasoconstriction and increasing cardiac output.

Antidiuretic Hormone (ADH / Vasopressin)

Hormone that conserves water and, in extreme low BP, causes intense vasoconstriction.

Angiotensin II

Potent vasoconstrictor generated from renin release by kidneys; increases BP.

Atrial Natriuretic Peptide (ANP)

Atrial hormone that lowers blood volume and BP by promoting sodium and water loss.

Nitric Oxide (NO)

Short-lived, potent vasodilator released from endothelial cells; decreases BP locally.

Hypotension

Chronically low BP with systolic < 100 mm Hg; may indicate good fitness or underlying problems.

Hypertension

Sustained arterial pressure ≥ 140/90 mm Hg; risk factor for heart failure, stroke, renal disease.

Autoregulation

Intrinsic adjustment of blood flow to a tissue based on its metabolic needs.

Angiogenesis

Long-term autoregulatory process of forming new blood vessels or enlarging existing ones when demand persists.

Mean Arterial Pressure (MAP)

Average pressure propelling blood to tissues; roughly diastolic pressure plus one-third pulse pressure.

Peripheral Resistance (PR)

Collective resistance of the systemic circulation; heavily influenced by arteriolar diameter.

Blood-Brain Barrier

Tight continuous-capillary junctions in the brain that strictly regulate substance passage from blood to neural tissue.

Turbulence

Disrupted, swirling flow often caused by abrupt vessel diameter changes or atherosclerotic plaques; raises resistance.

Cardiac Output (CO)

Amount of blood the heart pumps per minute; product of heart rate and stroke volume.

Circulatory Shock

Condition where blood vessels are inadequately filled or blood cannot circulate properly, failing to meet tissue needs.

Hypovolemic Shock

Type of shock from large-scale blood or fluid loss.

Vascular Shock

Shock due to extreme vasodilation and decreased peripheral resistance, e.g., anaphylactic reaction.

Cardiogenic Shock

Shock resulting from the heart’s inability to maintain adequate circulation, typically after severe myocardial damage.