312
a hollow, muscular organ loated in the center of the thorax
heart
it occupies the space between the lungs and rest on the diaphragm.. weighs approximately 300g
Mediastinum
inner layer consists of endothelial tissue and lines the inside of the heart and valves
Endocardium
middle layer made up of the muscle fibers and responsible for the pumping action.
Myocardium
the exterior layer of the heart
Epicardium
relaxation phase
Diastole
refers to the events in the heart during contraction of the two top chambers (atria) and two bottom chambers (ventricles)
Systole
the pulsation created during normal ventricular contraction. Also called the Point of Maximal Impulse
Apical Pulse
composed of thin leftlets of fibrous tissue, open and close in response to the movement of blood and pressure changes within the chambers.
Heart Valves
separate the atria from ventricles
Atrioventricular Valves
composed of three cusps or leaflets, separate the right atrium from the ventricle
Tricuspid Valve
lies between the left atrium and the left ventricle
Mitral or Bicuspid Valve
composed of three leaflets which are shaped like half moon, its is also a valve that are. losed during diastole
Semilunar Valves
these arteries originate from the aorta just above the aortic valve leaflets
Coronary Arteries
the heart has high metabolic requirements, extracting approximately ___ to ___ of oxygen delivered
70% to 80%
ability to initiate an electrical impulse
Automaticity
ability to respond to an electrical impulse.
excitability
ability to transmit an electrical impulse from one cell to another
Conductivity
primary pacemaker
Sinoatrial Node
secondary pacemaker
Atrioventricular Node
refers to the events that occur in the heart from one heartbeat to the next
Cardiac Cycle
refers to the amount of blood pumped by each ventricle during a given period
Cardiac Output
specialized nerve cells located in the aortic arch and in both right a d left internal carotid arteries
Baroreceptors
cells increase their rate of discharge, transmitting impulses to the cerebral medulla. Initiates parasympathetic activity and inhibits sympathetic response, lowering the heart rate and the BP
Hypertension
the resultant vasoconstriction and increased heart rate elevate the BP
Hypotension
refers to the degree of stretch of the ventricular cardiac muscle fibers at the ened of diastole commonly reffered tomas left ventricular end diastolic pressure (LVEDP)
Preload
within limits, the greater the initial length or stretch of the cardiac muscle cells (sarcomeres), the greater the degree of shortening that occurs
Frank Starling Law
resistance to ejection of blood from the ventricle, is the second determinant of stroke volume
Afterload
resistance of the BP to left ventricular ejection
Systemic Vascular Resistance
resistance of the pulmonary BP to the right ventricle ejection
Pulmonary Vascular Resistance
refers to the force generated by the contracting myocardium
Contractility