HLTH cardiovascular system review Flashcards
where is the heart located?
in the mediastinum between the lungs, and is enclosed in the double-walled pericardial sac
3 layers of the heart
epicardium (visceral), myocardium, and endocardium
what forms the heart valves?
endocaridum
mitral valve
on the left side; aka bicuspid valve
tricuspid valve
on the right side
what causes heart contractions?
the myocardial fibres
desmosomes
discs that connect the muscle cells of the heart to prevent them from separating during contractions
gap junctions in the heart
permit ions from passing from cell to cell, thus facilitating rapid transmission of impulses
conduction pathway for the heart
SA node to AV node, down the bundle of his, through the left and right bundle branches, and then the purkinje network of fibres
where is the SA node located?
in the right atrium
what creates the sinus rhythm?
the SA node, as it is the pacemaker
where is the AV node located?
the floor of the right atrium, near the septum
P wave of an ECG
measures the depolarization of the atria
QRS wave of an ECG
shows the ventricular depolarization; also is where atrial repolarization occurs but this is masked
T wave of an ECG
shows the repolarization of the ventricles
what do ECGs test for?
arrhythmias or dysrthythmias, systemic problems, or electrolyte imbalance
infarction
death of a tissue resulting from failure of blood supply, often from an obstruction of a vessel
what and where is heart rate controlled?
by the cardiac control centre in the medulla
what detect changes in blood pressure?
baroreceptors in the wall of the aorta and the internal carotid arteries
beta-adrenergic receptors
often a site of actions for drugs such as beta blockers; work to prevent normal SNS stimulation and thus block any increases in heart rate
factors that may increase heart rate
elevated body temperature through fever or increased environmental temperatures, exercise, smoking, stress, pregnancy, pain, medication, glycogen levels, and dehydration
what does the left coronary artery branch into?
left anterior descending artery or the interventricular artery
what does the right coronary artery branch into?
the right marginal artery and the posterior interventricular artery
when is coronary blood supply to the heart the greatest?
during diastole; greatly reduced during systole
anastomoses
direct connections between the small branches of the left and right coronary arteries; these have the potential to open up and provide another source of blood to an area
cardiac cycle
alternating sequence of systole and diastole
what cause heart murmurs?
defective valves that leak or do not completely close
apical pulse
a pulse measured at the heart itself and is more certain of HR
cardiac output
the volume of blood ejected by a ventricle in one minute; HR x SR
stroke volume
the volume pumped from one ventricle in a single contraction
cardiac reserve
the ability of the heart to increase output in response to increased demand
preload
the mechanical state of the heart at the end of diastole with the ventricles at their maximum volume
afterload
the force required to eject blood from the ventricles
blood pressure
the pressure of blood against the systemic arterial walls; normal is 120/70 mm Hg; BP = CO x PR
what is blood pressure measured in
systolic pressure over diastolic pressure
peripheral resistance
the force opposing blood flow or the amount of friction
systolic pressure
pressure exerted by the blood when ejected from the left ventricle
diastolic pressure
the pressure that is sustained when the ventricles are relaxed
pulse pressure
the difference between systolic pressure and diastolic pressure
variables affecting blood pressure
blood volume, blood viscosity, venous return, rate and force of contractions, and elasticity of the arteries
how does the SNS increase blood pressure?
through acting on beta-adrenergic receptors to increase contraction and by causing vasoconstriction
