Lecture on Arteries and Arterioles

Vocabulary flashcards covering structural features, functional terms, and regulatory concepts for elastic arteries, muscular arteries, and arterioles.

Elastic arteries

Largest arteries (e.g., aorta) with abundant elastic fibers in the tunica media; serve mainly to conduct blood and exhibit strong elastic recoil.

Muscular arteries

Medium-sized "distributing" arteries with a tunica media rich in smooth muscle and fewer elastic fibers; capable of moderate vasoconstriction/dilation.

Arterioles

Microscopic vessels whose ring-like smooth muscle layers provide the main control of resistance and blood flow into capillary beds.

Conducting arteries

Another name for elastic arteries, emphasizing their role in simply passing blood forward rather than regulating lumen size.

Distributing arteries

Alternate term for muscular arteries, reflecting their function of routing blood toward individual organs and tissues.

Tunica media

Middle layer of a blood vessel wall; in arteries it contains smooth muscle and, in elastic arteries, large amounts of elastic fibers.

Tunica adventitia

Outer connective-tissue coat of a blood vessel; thin in arterioles, thicker in larger arteries.

Compliance (vascular)

The degree a vessel stretches for a given internal (distending) pressure; elastic arteries have low compliance, veins high compliance.

Distending pressure

Inside pressure (blood pressure) that stretches a vessel wall; graphed against vessel volume to assess compliance.

Elastic recoil

Forceful snap-back of a low-compliance vessel (e.g., aorta) after stretch, helping maintain arterial pressure during diastole.

Low-compliance vessel

Vessel that stretches only slightly under pressure (e.g., elastic arteries), producing strong recoil.

High-compliance vessel

Vessel that stretches easily under pressure (e.g., veins), storing large blood volumes with little recoil.

Vasoconstriction

Narrowing of a vessel’s lumen due to smooth muscle contraction, increasing resistance to flow.

Vasodilation

Widening of a vessel’s lumen due to smooth muscle relaxation, decreasing resistance to flow.

Metarteriole

Short arterial branch that traverses the center of a capillary bed, equipped with smooth-muscle sphincters.

Precapillary sphincter

Ring of smooth muscle at a capillary entrance that regulates blood entry into individual capillaries.

Arteriolar sphincter

General term for the circular smooth muscle bands in arterioles and metarterioles that modulate lumen size.

Capillary bed

Interlacing network of capillaries supplied by an arteriole (via metarterioles) and drained by a venule.

Total peripheral resistance (TPR)

Sum of all systemic vascular resistances; chiefly influenced by arteriolar diameter and determines MAP.

Mean arterial pressure (MAP)

Average arterial pressure driving blood into tissues; maintained partly by arteriolar control of TPR.

Metabolic (intrinsic) regulation

Arteriolar dilation driven by local increases in CO₂/H⁺ and decreases in O₂ to match blood flow to tissue metabolic demand.

Myogenic response

Intrinsic arteriolar constriction triggered by stretch; stabilizes capillary flow when perfusion pressure rises.

Perfusion pressure

Blood pressure within a vessel (especially an arteriole) that drives flow through downstream capillaries.

Boyle’s law (vascular context)

Principle that decreasing vessel volume (via elastic recoil) raises internal pressure, aiding diastolic blood flow.

Vascular smooth muscle

Muscle in vessel walls controlling lumen size; densely packed in muscular arteries and arterioles.

Compliance curve

Graph of vessel volume versus distending pressure; illustrates low compliance of arteries versus high compliance of veins.