Sections
Key Terms
Key Terms
- 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