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Cardiovascular disease
diease affecting the heart, peripheral blood vessels, or both
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coranary heart disease
A typr of CVD,the signal largest killer of americans
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how mant americans suffer fromCardiovascular disease
more than 60 million
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what risk fators increase the possibilty of having cardiovascular diease
Smoking,older age,Family history, hypertension,hypercholesteroemia, carbohydrate intoerance, cocaine use, male gender, lack of exercise
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What are the risk factors that increase Coranary heart disease
Diet, Obesity, oral contraceptive, Type a personality, psychosocial tensions
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Cardiovascular system Has teo m,ajor parts
Heart and perpheral blood vessels
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anastomosis
communication between two or more vessels
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Poiseuille's law
a law of physiology stating that blood flows through a vessel is directly proportional to the radius of the vessel to the fourth power
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cardiac cycle
the period of time from the end of one cardiac contractionto the end of the next
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diastole
the period of time the myocardium is relaxed and cardiac filling and coranary perfusion occurs
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systole
the period of the cardiac cycle when the myocardium is contracting
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ejection fraction
ratio of blood pumped from the ventricle to the amount remaining at the end of distole
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stroke volume
the amount of blood ejected by the heart in one cardiac contraction
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preload
the pressure within the ventricles at the end of diastole: commonly called the end -diastolic volume
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Starling's law of the heart
law of physiology stating that the more the myocardium is stretched ,up to a certain amount the more forceful the subsequent contraction will be
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afterload
the resistance against which the heart must pump
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Factors that affect stroke volume
Preload, cardiac contractivity, afterload
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cardiac output
the amount of blood pumped by the heart in one minute
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cardiac output
stroke volume (70ml) x Heart rate (bpm) = cardiac output
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blood pressure is
blood pressure= cardiac output x systemic vascular resistance
Blood pressure+ (stroke volume x heart rate) x systemic vascular resistance
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Sympathetic alpha receptors
located in the perpheral blood vessels and are responsible for vasconstriction
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Synpathetic Beta1
primarily in the heart which increase heart rate and contractiliy
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symphetic beta 2
primarily in the lungs and perpheral blood vessels causes bronchodiliation, and perpheral vasodilation
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inotrophy
cardiac contractile force
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dromotrophy
speed of impluse transmission
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sodium
major role in depolarization
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calcium
takes part in myocardium depolarization and mycardium contraction
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Calcium Hypercalcemia, Hypocalcemia
- hyper= increased contractility
- hypo= decreased myocardium contractility
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potassium hyperkalemia, hypokalemia
- hyper = decreases automaticity and conduction
- hypo = increase irritability
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intercalated discs
specialized bands of tissue inserted between myocardial cells that increase the rate in which the action potenial is spread from cell to cell
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syncytium
group of cardiac muscle cells that physiologically function as a unit
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cardiac depolarization
a reversal of charges at a cell membrane so that the inside of the cell becomes postive in relation to the outside, the oppisite of the cells resting state in which the inside of the cell is negative in relation to the outside
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resting potential
the normal electrical state of cardiac cells
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action potential
the stimulation of myocardium cells as evidence by a change in the membrane electrical charges, that subsequently spreads across the myocardium
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repolarization
return of a muscle cell to its preexcitation resting state
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excitability
ability of the cells to respond to an electrical stimulus
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conductivity
ability of the cell to propagate the electrical impulse from one cell to another
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automaticity
pacemaker cells capability of self- depolarization
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contractility
ability of muscle cells to contract or shorten
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SA node intrinsic rate
60-100
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AV node intrinsic rate
40-60
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purkinjie fibers intrinsic rate
15-40
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Name the two types of cardiac cells and tell what type of activity each is responsible for
- electrical: conduction
- mechanical: contraction
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How do these two types of cells work together to produce cardiac activity
electrical cells stimulate muscle cells to contract
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what physical signs are used to reflect the mechanical function of the heart
pluse, B/P, other perfusion parameters
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How do you assess electrical activity in the heart
analyze EKG
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Arrhythmias are manifestations of which type of cardiac activity
electrical
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what happens when postive and negative electrical charges exchange places across the cell membrane of the cardiac cell
it initiates the flow of electrical current
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Explain polarized state
when electrical charges are balanced and in a statee of readiness for discharge
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explain depolarization
the discharge of electrical energy that accompanies the transfer of electrical charges across the cell membrane
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Is depolarization the same as contraction
NO; depolarization is an electrical phenomenon; contraction is mechanical and is expected to follow depolarization
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What is repolarization
The return of the electrical charges to their original state of readiness
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List the area of the conduction system in the order in which the impulses travel through the heart
1. SAnode, 2 intraatrial and internodal pathways; 3 AV node, 4 Bundle of his, 5 Bundle Branches, 6 Purkinje Fibers
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Which site is normally the pacemaker of the heart and why?
the SA Node; it has the fastest inherent rate
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Give the inherent rates for each of the following sites
SA NODE
AV Junction
Ventricles
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What process is responsible for a site speeding up and overriding a higher site, thus taking over as pacemaker
irritability
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What mechanism is in play if a lower site takes over responsibility for the pace-making function following failure of higher site
escape
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Which nervous system has two branches that control the activities of the heart
autonomic
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name the two branches of the nervous system identified in the proceding question
- sympathetic
- parasympathetic
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List three things that will happen to the heart if the sympathetic branch is stimulated
- increased heart rate
- increased AV conduction
- increased irritability
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list three things that will happen to the heart if the parasympathetic branch is stimulated
- decreased heart rate
- decreased AV conduction
- decreased irritability
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what part of the heart does the sympathetic branch innervate
atrias and ventricals
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what part of the heart does the parasympathetic branch innervate
only the atria
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What happens if one branch is blocked
the influence of the opposing branch will control the heart
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