apex
pointed end of the heart
visceral pericardium
serous membrane that adheres directly to the surface the heart
parietal pericardium
serous membrane that adheres to the the diaphragm and the sternum
serous fluid
lubricates the organs and allows them glide without friction
epicardium
the outermost layer of the heart
myocardium
thick middle muscle layer of the heart
endocardium
membrane lining the cavities of the heart
atrium
upper chamber of the heart that receives blood
ventricle
each of the two lower chambers of the heart that pumps blood out of the heart
atrioventricular valve
either of two heart valves through which blood flows from the atria to the ventricles
bicuspid valve
also known as the mitral valve; located between the left atrium and left ventricle
tricuspid valve
valve between the right atrium and the right ventricle
pulmonary semilunar valve
lies between the right ventricle to the pulmonary artery
aortic semilunar valve
lies between the left ventricle and the aorta
chordae tendinae
fibrous tissue cords that anchor the flaps of the A-V valves to the ventricles
papillary muscles
attache to the chordae tendinae to limit movement of valve cusps and prevent backflow of blood
regurgitation
backflow of blood through a defective heart valve
aorta
largest artery in the body; conducts freshly oxygenated blood from the heart to the tissues
pulmonary arteries
arteries that carry deoxygenated blood from the right ventricle to the lungs
inferior vena cava
carries deoxygenated blood from lower limbs and abdominal organs to right atrium
superior vena cava
carries deoxygenated blood from the head and arms and chest and empties into the right atrium
pulmonary circuit
carries blood to the lungs for gas exchange and returns it to the heart
systemic circuit
carries oxygen-rich blood to all body organs and then returns oxygen-poor blood to the right atrium via the veins
coronary arteries
blood vessels that branch from the aorta and carry oxygen-rich blood to the heart muscle
cardiac veins
collects deoxygenated blood from heart muscle tissue empty into right atrium
coronary sinus
enlarged vein from junctions of all cardiac veins which empty into the right atrium
sinoatrial node
the heart's pacemaker, located in the wall of the right atrium
atrioventricular node
located in the lower wall of the right atrium; delays impulses from the SA node to allow the atria to completely empty before the ventricles contract
septum
divides the right and left sides of the heart
atrioventricular bundle
a.k.a. Bundle of His; transmits impulse from the AV node to the ventricles through the septum
Purkinje fibers
extend from branches of AV bundle, stimulate muscle fibers in the ventricular walls
electrocardiogram
the graphic record/representation of the heart's electrical activity
sphygmomanometer
instrument for measuring arterial blood pressure
P wave
atrial depolarization
QRS complex
ventricular depolarization
T wave
ventricular repolarization
systole
ventricular contraction
diastole
relaxation of the ventricles
medulla oblongata
part of the brainstem that controls heart rate, breathing, blood pressure
Rh factor
antigen found in red blood cells; used in blood typing
ABO Blood group
blood type determined by the hereditary presence or absence of antigens A and B on red blood cells
coagulation
blood clotting
hemostasis
the stoppage of bleeding
hematopoiesis
formation of blood cells in bone marrow
agranulocytes
lymphocytes, monocytes
granulocytes
neutrophils, eosinophils, basophils
platelet
cell fragment released by bone marrow that helps in blood clotting
leukocyte
cells that fight infection, also called white blood cells
erythrocyte
red blood cell that transports oxygen and carbon dioxide within the bloodstream
formed elements
cellular portion of blood
plasma
colorless watery fluid of blood in which cells are suspended
shock
condition characterized by profound hypotension and reduced tissue perfusion
arteriosclerosis
thickening, loss of elasticity, and hardening of arterial walls
hypertension
elevated blood pressure
hypotension
abnormally low blood pressure
viscosity
a liquid's resistance to flow
peripheral resistance
opposition to blood flow caused by friction of the blood vessel walls
tissue perfusion
blood flow through the body tissues
vasodilation
widening of the blood vessels that allows for increased blood flow
vasoconstriction
rapid constriction of the blood vessels to decrease blood flow to the area
lumen
opening of a blood vessel
tunica externa
outer layer of a blood vessel which connects it to surrounding tissues
tunica media
middle layer of a blood vessel; made up of smooth muscle fibers and thick layer of elastic connective tissue
tunica intima
innermost layer of a blood vessel
vein
vessel that returns blood to the heart
venule
tiny vein that drains blood from capillaries
capillary
tiny blood vessel where substances are exchanged between the blood and the body cells
arteriole
tiny artery that takes blood into capillaries
artery
blood vessel that carries blood away from the heart
Starling's Law of the Heart
cardiac muscle fibers will contract more forcefully when fibers are stretched (the more you fill it with blood the stronger force of contraction)
stroke volume
measurement of amount of blood ejected from a ventricle in one contraction
cardiac output
volume of blood pumped by one ventricle per minute; stroke volume x heart rate
acetylcholine
neurotransmitter that slows heart rate
vagus nerve
parasympathetic nerve of the heart; activation slows heart rate
parasympathetic nervous system
division of the autonomic nervous system that calms the body, conserving its energy
norepinephrine
hormone stimulates the sympathetic nervous system; speeds up heart rate
sympathetic nervous system
division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations
cardiac cycle
one complete contraction and relaxation of all four chambers of the heart
blood pressure
the pressure that is exerted by the blood against the walls of blood vessels
baroreceptor reflex
reflex that maintains appropriate blood pressure; responds to changes in pressure in the aorta and carotid arteries
Type O blood
no A or B antigens, makes A & B antibodies; universal donor
Type AB blood
both A & B antigens, does not make A or B antibodies; universal recipient
hemoglobin
specialized protein containing iron that carries oxygen on red blood cells
depolarization
the electrical impulse that initiates a chain reaction resulting in a contraction
repolarization
recharging of the cell back to a resting state
atrial natriuretic peptide
hormone released by cells of the heart, lowers blood pressure
angiotensin II
a hormone that causes vasoconstriction and stimulates of aldosterone release, raising blood pressure