AP - exam 2 (cardiovascular, part 2)

crossing of ions across membrane

what does the membrane potential of cells depend on?

negative

what is always the charge of the resting membrane potential?

Ca influx through slow channels

what causes the plateau phase during a cardiac muscle action potential?

Na influx through fast channels

what causes the depolarization phase during cardiac muscle action potential?

Ca channels close and K channels open

what causes the repolarization phase during cardiac muscle action potential?

longer

when compared to skeletal muscle, cardiac muscle's action potential has a __________ absolute refractory period

pacemakers

what cell generates the rhythm of the heart?

autorythmicity

what do pacemaker cells have, where they do not need nervous system stimulation and can depolarize entire heart?

never

peacemaker potential is never flat line because Na channels ________ close completely

sinoatrial node

what is the normal pacemaker located in the right atrial wall, which generates impulses at about 75/minute?

atrioventricular node

what is in the inferior interatrial septum, which fires at rate of 50/minute in absence of SA node input?

atrioventricular bundle

what contains the bundle of His and is in the superior interventricular septum?

right and left bundle branches

what are two pathways within the interventricular septum and carry impulses toward apex of heart?

30x/minute

what is the depolarization rate of AV bundle and PF in absence of AV node input?

fibrillation

______ defines rapid, irregular contractions

(pumping blood becomes useless -> circulation can cease, which leads to brain death)

ectopic focus

______ defines when abnormal pacemakers take over

premature contraction

what is an extrasystole referred to as?

medulla oblongata

where are the cardiac centers that modify heartbeat via ANS located?

(hint: "alive" center in brain)

increases

activation of the sympathetic nervous system ______ rate and force of heart

decreases

activation of the parasympathetic nervous system ______ heart rate

vagus nerve

parasympathetic nervous system decreases heart rate via the _______, which is known as the cardioinhibitory center in the medulla

ECG or EKG

what is a composite of all action potentials generated by pacemaker + contractile cells called?

P wave

within an ECG, what is the depolarization of the SA node and represents the electrical activity of the atria known as?

QRS complex

within an ECG, what represents ventricular depolarization and atrial repolarization?

T wave

within an ECG, what represents ventricular repolarization?

PR interval

within an ECG, what interval represents beginning of atrial excitation to beginning to ventricular excitation?

ST interval

within an ECG, what interval represents entire ventricular myocardium depolarized?

QT interval

within an ECG, what interval represents beginning of ventricular depolarization through ventricular repolarization?

systole

what is it called when atrioventricular valves close during the "lub-dup" and "tum-ta" sounds?

diastole

what is it called when SL valves close during the "lub-dup" and "tum-ta" sounds?

heart murmurs

_________ are defined as abnormal heart sounds, usually indicating incompetent or stenotic valves

contraction

systole is associated with _________ during the cardiac cycle

relaxation

diastole is associated with _________ during the cardiac cycle

ventricular filling

what is the first phase of the cardiac cycle, which involves. . .

1. low pressure with open AV valves

2. passive blood flow into ventricles (80&)

2. atrial systole (20%)

end diastolic volume (EDV)

_____________ is the volume of blood in each ventricle at end of ventricular diastole

isovolumetric contraction phase

during the second phase of the cardiac cycle, what is the phase called where all valves are closed?

ejection phase

during the second phase of the cardiac cycle, what is the phase called where ventricular pressure exceeds pressure in large arteries which forced SL valves open?

end systolic volume (ESV)

__________ is the volume of blood remaining in each ventricle after systole

isovolumetric relaxation

what is the third phase of the cardiac cycle, which occurs during early diastole and involves . . .?

1. ventricles relax -> atria relax and fills with blood

2. backflow of blood in aorta + pulmonary trunk closes SL valves

cardiac output (CO)

_________ is the volume of blood pumped by each ventricle in one minute

( = heart rate (HR) x stroke volume (SV))

5.25 L/min

what is considered a normal cardiac output?

preload

what is the volume of blood the heart is receiving referred to as, which can be considered the same as EDV and depends on venous return?

venous return

more ______ means more intense cardiac muscle stretching, equaling a stronger contraction

Frank-Starling Law

__________ states that more stretching + distension of cardiac muscle = stronger contraction

longer time for ventricles to fill with blood

what does a slower heartbeat allow?

positive inotropic agents

__________ examples include thyroxine, glucagon, epinephrine, digitalis, high extracellular Ca2+

negative inotropic agents

________ examples include acidosis, increased extracellular K+, Ca channel blockers

afterload

what is the pressure/force that ventricles must overcome to eject blood known as?

hypertension

what increases afterload, which results in increased ESV and reduced SV?

norepinephrine

what causes pacemakers to fire more rapidly, therefore increasing contractibility?

acetylcholine

what hyperpolarizes pacemaker cells, therefore opening K+ channels and slowing HR?

fetus

generally, what age is HR considered to be fastest?

female

generally, which gender was found to have a faster HR?

pulmonary congestion

_________ refers to the left side of the heart failing, leading to blood backing up in the lungs

peripheral congestion

__________ refers to right side failing, leading to blood pooling in body organs (ex. edema)

foramen ovale

in a fetal heart, what connects the two atria?

fossa ovalis

in adults, the _______ is a remnant of the foramen ovale found in a fetus

ductus arteriosus

what connects the pulmonary trunk to the aorta in a fetus?

ligamentum arteriosum

in adults, the _________ is a remnant of the ductus arteriosus found in fetus