Cardiovascular System

vein

In animals, a vessel that carries blood toward the heart

venule (ven′-yūl)

A vessel that conveys blood between a capillary bed and a vein

ventricle (ven′-tri-kul)

A heart chamber that pumps blood out of the heart.

pulse

The rhythmic bulging of the artery walls with each heartbeat

vasoconstriction

A decrease in the diameter of blood vessels caused by contraction of smooth muscles in the vessel walls.

vasodilation

An increase in the diameter of blood vessels caused by relaxation of smooth muscles in the vessel walls

Trachea

the portion of the respiratory tract that passes from the larynx to the bronchi; also called the windpipe

systolic pressure

Blood pressure in the arteries during contraction of the ventricles

systemic circuit

The branch of the circulatory system that supplies oxygenated blood to and carries deoxygenated blood away from organs and tissues throughout the body.

surfactant

A substance secreted by alveoli that decreases surface tension in the fluid that coats the alveoli

larynx (lār′-inks)

The portion of the respiratory tract containing the vocal cords; also called the voice box

negative pressure breathing

A breathing system in which air is pulled into the lungs

lymph node

An organ located along a lymph vessel that filter lymph and contains cells that attack viruses and bacteria.

lymphatic system

A system of vessels and nodes, separate from the circulatory system, that returns fluid, proteins, and cells to the blood

diastolic pressure

Blood pressure in the arteries when the ventricles are relaxed.

heart

A muscular pump that uses metabolic energy to elevate the hydrostatic pressure of the circulatory fluid (blood or hemolymph). The fluid then flows down a pressure gradient through the body and eventually returns to the heart

heart rate

The frequency of heart contraction (in beats per minute)

gas exchange

The uptake of molecular oxygen from the environment and the discharge of carbon dioxide to the environment

double circulation

A circulatory system consisting of separate pulmonary and systemic circuits, in which blood passes through the heart after completing each circuit.

electrocardiogram (ECG or EKG)

A record of the electrical impulses that travel through heart muscle during the cardiac cycle

cardiac cycle (kar′-dē-ak)

The alternating contractions and relaxations of the heart.

Blood

A connective tissue with a fluid matrix called plasma in which red blood cells, white blood cells, and cell fragments called platelets are suspended.

bronchiole (brong′-kē-ōl′)

A fine branch of the bronchi that transports air to alveoli.

bronchus (brong′-kus) (plural, bronchi)

One of a pair of breathing tubes that branch from the trachea into the lungs

capillary (kap′-il-ār′-ē)

A microscopic blood vessel that penetrates the tissues and consists of a single layer of endothelial cells that allows exchange between the blood and interstitial fluid.

alveolus (al-vē′-uh-lus) (plural, alveoli)

One of the dead-end air sacs where gas exchange oc- curs in a mammalian lung.

arteriole (ar-ter′-ē-ōl)

A vessel that conveys blood between an artery and a capillary bed.

artery

A vessel that carries blood away from the heart to organs throughout the body.

atrium (ā′-trē-um) (plural, atria)

A chamber of the vertebrate heart that receives blood from the veins and transfers blood to a ventricle

diaphragm (dī′-uh-fram′)

A sheet of muscle that forms the bottom wall of the thoracic cavity in mammals. Contraction pulls air into the lungs.