HLTH cardio system review Flashcards
heart location
located within the mediastinum and the double walled pericardial sac
3 layers of the heart
endocardium, myocardium, and epicardium
atrioventricular valves
bicuspid or mitral valve (left side) and tricuspid valve (right side)
where does the heart conduction pathway begin?
the SA node
sinus rhythm
rhythm established by the SA node
order of flow of heart conduction
SA node > AV node > bundle of His > right and left bundle branches > purkinje fibres
P wave of ECG
is the atrial depolarization
QRS wave
ventricular contraction (and atrial relaxation but this is masked)
T wave
represents repolarization of the ventricles
what detects changes in BP?
the baroreceptors in the aorta and carotid arteries
sympathetic receptors in the heart
beta1-adrenergic receptors
two arteries branching off the aorta
left and right coronary arteries
what does the left coronary artery branch into?
the left anterior descending artery and the left circumflex artery
what does the right coronary artery branch into?
the right marginal artery and the posterior interventricular artery
when is blood flow to the heart the greatest?
during diastole or relaxation
collateral channels
exist between vessels and are important if one gets obstructed; more develop with aerobic exercise
what does the right coronary artery supply?
the right side of the heart, the posterior left ventricle, and the posterior interventricular septum
what does the left coronary artery supply?
the anterior sides of the ventricles, the anterior septum, and the left atrium
lubb sounds
closing of the AV valves
dubb sounds
closing of the semilunar valves
what causes heart murmurs?
defective valves that don’t close completely or a hole in the heart septum
apical pulse
refers to pulse measured at the heart itself
pulse deficit
difference between the radial pulse and the apical pulse
cardiac output
the volume of blood ejected by a ventricle in one minute; SV x HR
cardiac reserve
refers to the heart’s ability to increase output in response to increased demand
preload
refers to the heart at the end of diastole with ventricles at their maximum volume
afterload
the force required to eject blood from the ventricles
blood pressure
refers to pressure against the systemic arterial walls
systolic pressure
is the pressure exerted by the blood during systole of the left ventricle
diastolic pressure
refers to pressure that is sustained during diastole
pulse pressure
difference between systolic pressure and diastolic pressure
peripheral resistance
forces opposing blood flow such as friction
2 ways BP is elevated by the sympathetic system
beta1-andregenic receptors increase HR and vasoconstriction occurs
what is an ECG useful for?
myocardial infarction, infections, and arrhythmias
echocardiography
ultrasound is used to record images of the heart and valve movements; useful for valve defects and congenital defects
nuclear imaging
is done with thallium and can asses the size of an infarction
single-photon emission
can assess cardiac ischemia at rest
troponin blood tests
can measure the level of blood proteins called troponins that are released when the myometrium is damaged
doppler studies
a microphone that assess blood flow or obstruction of a vessel
benefits of exercise for the heart
decreases serum lipid levels, increases high-density lipoprotein levels, and reduces stress
smoking effects on the heart
increases vasoconstriction and heart rate, increases platelet adhesion and thrombus formation, and increases serum lipid levels
vasodilators example and function
decrease peripheral resistance, but may also decrease blood pressure; ex. nitroglycerin or isosorbide
beta-blockers function and example
prescribed for hypertension and dysrhythmias and act on beta1-adrengenic receptors; ex. metoprolol or atenolol
calcium channel blockers
block the movement of calcium into the smooth muscle, thus decreasing contractions
digoxin
slows conduction of heart rate (less frequent but more powerful) and used for atrial dysrhythmias
side effects of antihypertensive drugs
orthostatic hypotension
anticoagulant drugs
aspirin or warfarin, however, hemorrhage can be a risk
cholesterol or lipid lowering drugs
are prescribed when exercise and diet are ineffective and are the statin drugs, ex. simvastatin
what does coronary heart disease include?
angina pectoris or an MI
dangers of coronary heart disease
decreased O2 delivery to the myocardium
cause of angina
a deficit of O2 to the myocardium which can be caused by obstructions, spasms, or hypertrophy of the heart
variant angina
when vasospasm occurs at rest
unstable angina
refers to prolonged pain at rest, perhaps the result of a break of an atheroma
what usually precedes angina?
an increased demand for O2; can be exercise, getting angry, following an infection, or eating a large meal
signs of angina
chest pain that can radiate to the neck or left arm, followed by pallor, diaphoresis (excessive sweating), or nausea
treatment for angina
usually vasodilators like nitroglycerin
myocardial infarction
is a heart attack due to death of myocardial tissue due to ischemia
risk for those surviving an MI
recurrent MI, CHF, or stroke
2 broad types of MIs
ST elevation or non-ST elevation
most common cause of an MI
atherosclerosis with thrombus attached
3 causes of an infarction
thrombus in an artery grows, vasospasm + partial obstruction, or thrombus breaks away and lodges in a smaller artery
what happens to the heart tissue following infarction?
necrosis, inflammation, and fibrous tissue develop, as well enzymes are released
warning signs of an MI
persistent chest pain radiating to the left arm, pallor, and rapid, weak pulse
what treatment can prevent permanent heart tissue damage before an MI?
thrombolytic therapy
what enzymes are elevated during an MI?
LDH-1, aspartate aminotransferase, and creatine phosphokinase with M and B subunits
what causes death during an MI?
ventricular arrhythmias and fibrillation
Cardiogenic shock
occurs if the pumping capability of the left ventricle is greatly impaired
silent MI
no pain is present but gastric discomfort may indicate the infarction
heart block
occurs when conduction fibres in the infarcted area can no longer function due to problems in the AV node or bundle of His
what are major causes interfering with the heart conduction cycle?
damage to the system or electrolyte imbalances (resulting from stress, fever, hypoxia, infection, or drug toxicity)
major problems with irregular heart contractions?
they interfere with normal filling and emptying cycles of the heart
a very rapid heart rate reduces cardiac output because
it reduces ventricular filling