Blood Vessels and Circulation 4e NOTES Fall 2022 (1)

Circulatory System

System responsible for the transport of blood, nutrients, oxygen, carbon dioxide, and hormones throughout the body.

Arteries

Blood vessels that carry oxygen-rich blood away from the heart.

Veins

Blood vessels that carry oxygen-poor blood back to the heart.

Capillaries

Smallest blood vessels where the exchange of substances between blood and tissues occurs.

Tunica intima

Innermost layer of the blood vessel wall, composed of endothelium and subendothelial layer.

Tunica media

Middle layer of the blood vessel wall, primarily composed of smooth muscle and elastic fibers to regulate blood vessel diameter.

Tunica externa

Outermost layer of the blood vessel wall, made of connective tissue, anchors vessels to surrounding structures.

Sphincters

Muscle structures that regulate blood flow through capillaries by controlling whether capillaries are open or closed.

Net Filtration Pressure (NFP)

The pressure that drives fluid out of the capillary, calculated as the difference between hydrostatic and osmotic pressures.

Blood pressure

Force exerted by circulating blood on the walls of blood vessels.

Atherosclerosis

A disease characterized by the buildup of fatty deposits and plaque on the arterial walls.

Vasoconstriction

Narrowing of blood vessels due to contraction of muscular walls, which increases blood pressure.

Vasodilation

Widening of blood vessels, resulting from relaxation of the muscular walls, which decreases blood pressure.

Portal Systems

Circulatory routes where blood flows through two capillary beds before returning to the heart.

Anastomoses

Connections or junctions between blood vessels that provide alternative routes for blood flow.

Blood Hydrostatic Pressure (HPb)

Force of blood inside the capillaries pushing fluid out into the interstitial space.

Colloid Osmotic Pressure (COP)

Pressure exerted by proteins in blood plasma that attracts water into the circulatory system.

Pulmonary circulation

Pathway of circulating blood from the heart to the lungs for gas exchange.

Systemic circulation

Pathway of circulating blood from the heart to the rest of the body and back.

Erythrocytes

Red blood cells responsible for transporting oxygen and removing carbon dioxide.

Venous return

The process of blood returning to the heart through the veins.

Blood flow

Volume of blood that circulates through a blood vessel, organ, or entire circulation in a minute.

Cardiac output (CO)

The volume of blood pumped by the heart per minute, determined by heart rate and stroke volume.

Vasa vasorum

Small blood vessels that supply blood to the walls of larger blood vessels.

Capillary Beds

Networks of capillaries supplying blood to a specific tissue area for exchange.

Diastolic pressure

The lowest pressure in the arteries during the relaxation phase of the heart.

Systolic pressure

The highest pressure in the arteries during the contraction phase of the heart.

Hypertension

Chronically elevated blood pressure.

Hypotension

Chronically low blood pressure.

Perfusion

The flow of blood through the capillaries of a tissue.

Angiogenesis

The formation of new blood vessels, typically in response to tissue needs.

Vasoconstrictors

Substances that cause constriction of blood vessels and increase blood pressure.

Vasodilators

Substances that cause dilation of blood vessels and decrease blood pressure.

Endothelium

Thin layer of cells lining the blood vessels, playing a key role in regulating blood flow and pressure.

Aneurysm

A localized dilation of an artery caused by weakening of the arterial wall.

Fetal circulation

Circulation in a fetus, involving unique pathways that divert blood away from the lungs and liver.

Ductus arteriosus

A fetal blood vessel connecting the pulmonary artery to the aorta, allowing bypass of the lungs.

Foramen ovale

An opening in the fetal heart allowing blood to pass from the right atrium to the left atrium.

What are the functional differences between arteries and veins?

Arteries carry oxygenated blood away from the heart, while veins return deoxygenated blood to the heart. Arteries have thicker, more muscular walls to withstand higher pressure, whereas veins have thinner walls and valves to prevent backflow.

How does blood travel from an artery to a vein?

Blood travels from an artery to a vein through a network of capillaries, where oxygen and nutrients are exchanged for carbon dioxide and waste products.

True or False: All arteries carry oxygen-rich blood?

False; pulmonary arteries carry deoxygenated blood.

True or false: Blood vessels are composed of living tissue

True; blood vessels are made of endothelial cells, smooth muscle, and connective tissue, which are all living tissues.

True or False: Veins are usually used to obtain blood samples.

True; veins are more accessible and have larger lumens than arteries, making them preferable for blood draws.