Chapter 31: The Circulatory System

angina

pain caused by partial blockage of the coronary arteries by the buildup of plaque and lack of oxygen to the heart muscle

aorta

major artery of the body that takes blood away from the heart

arteriole

small vessel that connects an artery to a capillary bed

artery

blood vessel that takes blood away from the heart

atherosclerosis

buildup of fatty plaques in the coronary arteries in the heart

atrioventricular valve

one-way membranous flap of connective tissue between the atrium and the ventricle in the right side of the heart; also known as tricuspid valve

atrium

(plural: atria) chamber of the heart that receives blood from the veins and sends blood to the ventricles

bicuspid valve

(also, mitral valve; left atrioventricular valve) one-way membranous flap between the atrium and the ventricle in the left side of the heart

blood pressure (BP)

pressure of blood in the arteries that helps to push blood through the body

capillary

smallest blood vessel that allows the passage of individual blood cells and the site of diffusion of oxygen and nutrient exchange

capillary bed

large number of capillaries that converge to take blood to a particular organ or tissue

cardiac cycle

filling and emptying the heart of blood by electrical signals that cause the heart muscles to contract and relax

cardiac output

the volume of blood pumped by the heart in one minute as a product of heart rate multiplied by stroke volume

cardiomyocyte

specialized heart muscle cell that is striated but contracts involuntarily like smooth muscle

closed circulatory system

system in which the blood is separated from the bodily interstitial fluid and contained in blood vessels

coronary artery

vessel that supplies the heart tissue with blood

coronary vein

vessel that takes blood away from the heart tissue back to the chambers in the heart

diastole

relaxation phase of the cardiac cycle when the heart is relaxed and the ventricles are filling with blood

double circulation

flow of blood in two circuits: the pulmonary circuit through the lungs and the systemic circuit through the organs and body

electrocardiogram (ECG)

recording of the electrical impulses of the cardiac muscle

endocardium

innermost layer of tissue in the heart

epicardium

outermost tissue layer of the heart

gill circulation

circulatory system that is specific to animals with gills for gas exchange; the blood flows through the gills for oxygenation

hemocoel

cavity into which blood is pumped in an open circulatory system

hemolymph

mixture of blood and interstitial fluid that is found in insects and other arthropods as well as most mollusks

inferior vena cava

drains blood from the veins that come from the lower organs and the legs

interstitial fluid

fluid between cells

lymph node

specialized organ that contains a large number of macrophages that clean the lymph before the fluid is returned to the heart

myocardial infarction

(also, heart attack) complete blockage of the coronary arteries and death of the cardiac muscle tissue

myocardium

heart muscle cells that make up the middle layer and the bulk of the heart wall

open circulatory system

system in which the blood is mixed with interstitial fluid and directly covers the organs

ostium

(plural: ostia) holes between blood vessels that allow the movement of hemolymph through the body of insects, arthropods, and mollusks with open circulatory systems

pericardium

membrane layer protecting the heart; also part of the epicardium

peripheral resistance

resistance of the artery and blood vessel walls to the pressure placed on them by the force of the heart pumping

plasma

liquid component of blood that is left after the cells are removed

platelet

(also, thrombocyte) small cellular fragment that collects at wounds, cross-reacts with clotting factors, and forms a plug to prevent blood loss

precapillary sphincter

small muscle that controls blood circulation in the capillary beds

pulmocutaneous circulation

circulatory system in amphibians; the flow of blood to the lungs and the moist skin for gas exchange

pulmonary circulation

flow of blood away from the heart through the lungs where oxygenation occurs and then returns to the heart again

red blood cell

small (7–8 μm) biconcave cell without mitochondria (and in mammals without nuclei) that is packed with hemoglobin, giving the cell its red color; transports oxygen through the body

semilunar valve

membranous flap of connective tissue between the aorta and a ventricle of the heart (the aortic or pulmonary semilunar valves)

serum

plasma without the coagulation factors

sinoatrial (SA) node

the heart’s internal pacemaker; located near the wall of the right atrium

stroke volume

the volume of blood pumped into the aorta per contraction of the left ventricle

superior vena cava

drains blood from the jugular vein that comes from the brain and from the veins that come from the arms

systemic circulation

flow of blood away from the heart to the brain, liver, kidneys, stomach, and other organs, the limbs, and the muscles of the body, and then the return of this blood to the heart

systole

contraction phase of cardiac cycle when the ventricles are pumping blood into the arteries

tricuspid valve

one-way membranous flap of connective tissue between the atrium and the ventricle in the right side of the heart; also known as atrioventricular valve

unidirectional circulation

flow of blood in a single circuit; occurs in fish where the blood flows through the gills, then past the organs and the rest of the body, before returning to the heart

vasoconstriction

narrowing of a blood vessel

vasodilation

widening of a blood vessel

vein

blood vessel that brings blood back to the heart

vena cava

major vein of the body returning blood from the upper and lower parts of the body; see the superior vena cava and inferior vena cava

ventricle

(heart) large inferior chamber of the heart that pumps blood into arteries

venule

blood vessel that connects a capillary bed to a vein

white blood cell

large (30 μm) cell with nuclei of which there are many types with different roles including the protection of the body from viruses and bacteria, and cleaning up dead cells and other waste