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What does the cardiovascular system consist
of?
heart (the pump) blood vessels (conducting system) blood (fluid medium - plasma + blood vessels) TERM 2
What is the main function of the heart?
DEFINITION 2 the pump of the cardiovascular system generates pressure to propel blood through the system continually TERM 3
what is the primary function of the
cardiovascular system?
DEFINITION 3 transport of nutrients, water, gases, wastes, and chemical signals to and from all parts of the body TERM 4
effects of loss of blood flow to brain
DEFINITION 4 for 5-10 sec: unconsciousness for 5-10 min: brain damage neurons can't meet metabolic need for ATP with anaerobic pathway TERM 5
functions of the chambers of the heart
DEFINITION 5 Right atrium : collect blood from systemic circuit right ventricle : pumps blood to pulmonary circuit Left atrium : collect blood from pulmonary circuit Left ventricle : pump blood to systemic circuit
pulmonary circulation
from RV pulmonary arteries lungs pulmonary veins back to LA high flow, low blood pressure 10% of total blood volume blood flow through lungs = CO **pulmonary veins are carrying the well oxygenated blood TERM 7
systemic circulation
DEFINITION 7 from LV aorta arteries, arterioles capillaries for change in tissues venous circulation SVC/IVC RA TERM 8
portal systems
DEFINITION 8 2 capillary beds in parallel occurs in liver, brain, and kidneys TERM 9
coronary arteries
DEFINITION 9 first branch from aorta after leaving LV nourishes heart itself empty in RA at coronary sinus TERM 10
hepatic portal vein
DEFINITION 10 blood leaving kidneys goes directly to liver via hepatic portal vein most nutrients absorbed routed directly to liver for processing before release to general circulation
blood flow
proportional to the pressure gradient:Flow P (= P1 P2) Depends on the difference in pressures, not how high the pressure is inversely proportional to resistance (Flow P/R) - as resistance increases, flow rate decreases TERM 17
units of pressure
DEFINITION 17 blood commonly measured in mmHg 1 mmHg = 1 torr 1cm H2O = 0.74 mmHg TERM 18
hydrostatic pressure
DEFINITION 18 pressure exerted by a nonmoving fluid (equal in all directions) TERM 19
components of moving fluid pressure
DEFINITION 19 dynamic/flowing (kinetic energy) lateral (hydrostatic pressure, potential energy) TERM 20
Effects of vessel walls contracting and
relaxing
DEFINITION 20 water is minimally compressible so pressure transmitted through the fluid high pressure blood pushed to areas of lower pressure when smooth muscles contract walls expanding creates lower pressure and blood flows in
flow rate vs. velocity of
flow
Not the same! velocity = flow rate / cross-sectional area flow rate = how much (volume/min) velocity = how fast (distance/min) at a given flow rate, velocity is faster in a smaller tube than in a larger tube TERM 22
flow rate
(Q)
DEFINITION 22 volume of blood that passes one point in the system per unit time units: vol/min avg: 5 L/min TERM 23
velocity of flow (v)
DEFINITION 23 distance a volume of blood travels in a given period of time unit: distance/min V = Q/A TERM 24
location/orientation of the heart
DEFINITION 24 in center of thoracic cavity, to ventral side sandwiched between lungs Base (top, broader part) - just behind sternum apex (pointed tip, bottom) - points down to left side of body, rests on diaphragm TERM 25
pericardium
DEFINITION 25 tough, membranous, double-walled sac enclosing the heart outer layer = parietal pericardium inner layer = visceral pericardium pericardial cavity between the 2 layers contains pericardial fluid to lubricate the heart as it beats
Myocardial infarction (MI)
blood flow to a part of the heart is blocked from long enough to damage/kill part of the heart heart attack TERM 32
purpose of heart valves
DEFINITION 32 ensure one-way flow (prevent backflow) also act as electrical insulators between atria and ventricles to ensure bottom-to-top contraction of ventricles for proper blood flow TERM 33
Atrioventricular (AV) valves
DEFINITION 33 between atria and ventricles - permit flow only A V fibrous flaps (cusps) joined at base to fibrous connective tissue ring move passively when blood pushes chordae tendineae and papillary muscles to keep from being pushed back up into atria during ventricular contraction Bicuspid and tricuspid TERM 34
bicuspid valve
DEFINITION 34 aka mitralvalve Left AV valve - separates left atrium and left ventricle 2 flaps TERM 35
tricuspid valve
DEFINITION 35 Right AV valve - separates right atrium and right ventricle 3 flaps
chordae
tendineae
tendons attached to the AV valves pulled on by papillary muscles to prevent valves from swinging back into atria TERM 37
semilunar valves
DEFINITION 37 crescent-shaped valves between ventricles and major arteries prevent back flow from pulmonary trunk/aorta no muscular support 3 cusps that fill and push valve closed when blood flows back TERM 38
valves during ventricular
contraction
DEFINITION 38 AV valves closed - prevent back flow to atria semilunar valves open - allow flow out to arteries TERM 39
valves during ventricular
relaxation
DEFINITION 39 Semilunar valves close - prevent blood from flowing back from arteries into now lower pressure ventricles AV valves open - allow filling of ventricle TERM 40
myocardium
DEFINITION 40 cardiac muscle, composes most of heart cells linked together by intercalated disks 2 types - contractile and conducting
Calcium-induced calcium release (CICR)
in muscle cells, calcium entry from extracellular (via voltage-gated L-type calcium channels in membrane) triggers release of additional calcium Opens ryanodine receptor (RyR) channels in SR, forming most of calcium signal for contraciton TERM 47
Sodium-Calcium exchanger (NCX)
DEFINITION 47 antiporter helps remove calcium from myocardial cell after contraction signal 1 Ca2+ out of cell & 3 Na+ into cell Na+/K+ ATPase maintains sodium gradient in cell by pushing sodium back out TERM 48
force of contraction
DEFINITION 48 can be graded according to how much Ca2+ enters the cell myocardial cells are not all or nothing like skeletal muscle cells
- single cardiac muscle fiber can vary amount of force it generate force proportional to active # of cross-bridges (determined by amount of Ca binding troponin) longer muscle is when it begins contraction greater force TERM 49
Frank-Starling principle
DEFINITION 49 force of contraction in cardiac muscle cells is greater when a muscle fiber is longer at the beginning of contraction (to a point) longer sarcomeres = more force; sarcomere length determined by amount of blood in heart chamber slow HR = more filling time exercise = more venous blood return TERM 50
differences in cardiac muscle contraction
compared to that of skeletal muscle
DEFINITION 50 synchronistic - from gap junctions autorhythmic - heart has self-excitable cells, don't need neuronal stimulation like skeletal muscle longer absolute refractory period in heart muscle (250ms vs. 2-3ms; lasts almost entire twitch in cardiac cells, prevents summation and tetanus of heart)
action potential phases of myocardial
contractile cells
Phase 0: rapid depolarization from Na+ influx Phase 1 : initial repolarization (Na+ channels close) Phase 2 : plateau phase (Ca2+ influx, fast K+ channels close) Phase 3 : rapid repolarization (K+ efflux as slow K+ channels open and Ca2+ channels close) Phase 4 : resting membrane potential TERM 52
Myocardial contractile AP - Phase 0
DEFINITION 52 rapid depolarizationphase created by Na+ influx Depolarization moves through gap junctions membrane potential becomes more positive & opens Na+ channels membrane potential reaches ~+20mV before Na channels close TERM 53
Myocardial contractile AP - Phase 1
DEFINITION 53 initial repolarization phase Very brief Na+ channels close K+ leaves via open K+ channels TERM 54
Myocardial contractile AP - Phase 2
DEFINITION 54 plateau phase Fast K+ channels close and Voltage-gated Ca2+ channels open Ca2+ influx lengthens duration of myocardial AP - increases refractory period and help prevent summation/tetanus TERM 55
Myocardial contractile AP - Phase 3
DEFINITION 55 steep (rapid) repolarization phase slow K+ channels open and Ca2+ channels close cell quickly returns to resting potential
path of the heart's conducting system
SA node internodal pathways AV node AV bundle (bundle of His) bundle branches Purkinje fibers TERM 62
intrinsic conduction system of the
heart
DEFINITION 62 APs (depolarization) originate at SA node and spread rapidly cell to cell in heart through gap junctions Naps followed by a wave of contraction TERM 63
Sinoarterial (SA) node
DEFINITION 63 in posterior wall of RA contains pacemaker cells - main pacemaker of the heart (begins atrial activation and sets pace of heartbeat) connected to AV node by internodal pathways if malfunctions. AV node or ventricles take control of HR TERM 64
internodal pathways
DEFINITION 64 branched, noncontractile autorhythmic fibers connect SA node to AV node rapid electrical conduction TERM 65
atrioventricular (AV) node
DEFINITION 65 in floor of right atrium receives impulse from SA node via internodal pathways atrial contraction begins delays impulse as passes signal to AV bundle only pathway through which AP can reach contractile fibers of the ventricles (needed for bottom up contraction)
AV bundle (bundle of His)
in septum carries impulse to left and right bundle branches at apex of heart TERM 67
AV node delay
DEFINITION 67 slower conduction through nodal cells slows conduction of APs slightly allows atria to complete contraction before ventricles contract TERM 68
Purkinje fibers
DEFINITION 68 small divisions of bundle branch fibers at heart apex spread outward among contractile cells - distribute impulse through ventricles ventricular contraction begins (after atrial contraction complete) can act as pacemakers in some conditions, but don't normally since rhythm is slower than that of AV node TERM 69
electrical conduction of the
heart
DEFINITION 69 SA node depolarizes electrical activity goes rapidly to AV node via internodal pathways depolarization spreads more slowly across atria; conduction slows through AV node depolarization moves rapidly through ventricular conducting system to apex of the heart (bundle of His Purkinje fibers) depolarization wave spreads upward from apex TERM 70
Heart
rate
DEFINITION 70 SA node generates 80-100 APs per minute normal HR ~70 BPM (tonic parasympathetic influence) measured from either beginning of one P wave to beginning of next P wave or from peak of one R wave to peak of next
Tachycardia
abnormally fast HR TERM 77
Ectopic pacemaker
DEFINITION 77 abnormal cells generate high rate of APs bypass conducting system disrupt ventricular contractions TERM 78
nodal rhythm
DEFINITION 78 when AV node takes over pacemaker functions 40-60 APs/min TERM 79
Extrasystole
DEFINITION 79 when outside influence (ex: drugs) lead to premature contractions TERM 80
heart
block
DEFINITION 80 when AV node or bundle of His isn't transmitting sinus rhythm to the ventricles causes ventricular autorhythmic cells to take over ( BPM, may be too slow to maintain adequate blood flow)
Electrocardiogram (ECG)
surface recording of electrical events in the heart recording represents summed electrical potentials generated by all cells of heart obtained by electrodes as specific body locations use abnormal patterns to diagnose heart damage TERM 82
ECG
features
DEFINITION 82 waves: parts of trace going above/below baseline segments: sections of baseline between 2 waves intervals: combinations of waves and segments TERM 83
P wave of ECG
DEFINITION 83 arterial depolarization arterial contraction occurs soon after start of P wave TERM 84
QRS complex of ECG
DEFINITION 84 progressive wave of ventricular depolarization, arterial repolarization conduction through bundle branches (Q), purkinje fibers (R), and ventricle myocardium (S) TERM 85
T wave of ECG
DEFINITION 85 ventricular repolarization
systole
contraction phase TERM 92
diastole
DEFINITION 92 relaxation phase TERM 93
late diastole of cardiac cycle
DEFINITION 93 both sets of chambers relaxed, ventricles fill passively most blood enters ventricles while atria are relaxed (AV valves open, blood flow by gravity A V) ventricles expand to accomodate blood TERM 94
atrial systole of cardiac
cycle
DEFINITION 94 atrial contraction begins (depol. across atria, blood pushed into ventricles) only ~20% of ventricular filling due to contraction - rest is passive AV valves are open to allow blood to ventricles small amount of blood is pushed back into veins (no valve to block, but narrow during contraction) TERM 95
isovolumetric ventricular contraction of
cardiac cycle
DEFINITION 95 early ventricle contraction - 1st phase that pushes AV valve closed S1 sound associated not enough pressure created to open semilunar valves ventricles contain max blood volume - EDV
ventricular ejection of cardiac cycle
heart pumps semilunar valves open as ventricular contraction creates enough pressure blood pushed into arteries (pulmonary and aortic trunks) stroke volume = 60% of EDV AV valve still closed and atria filling TERM 97
isovolumic ventricular relaxation of cardiac
cycle
DEFINITION 97 ventricles repolarize and relax ventricular pressure falls (higher than atrial pressure but falling) blood flows back into cusps of semilunar valve and push closed (S2) Ventricles now contain ESV (~40% of EDV) all heart valves closed TERM 98
opening of all heart valves
DEFINITION 98 occurs when ventricular relaxation causes ventricular pressure to become less than atrial pressure TERM 99
dicrotic notch
DEFINITION 99 brief increase in aortic pressure after ventricular contraction TERM 100
total cardiac cycle time
DEFINITION 100 0.8 second = 7 BPM atrial systole = 0.1 sec ventricular systole = 0.3 sec diastole = 0.4 sec
