BIO 108: Heart Electrocardiogram

__ is a system of specialized cardiac muscle cells (about 1%).

Autorhythmic fibers

__ initiates and distributes electrical impulses that stimulate contraction.

Autorhythmic fibers

Pacemaker produces inherent & rhythmical __ activity, repeatedly generates action potentials.

electrical

__ is a specialized pathway of electrical progression through the heart.

Conduction system

__ is located in right atrium, does not have a stable resting potential.

Sinoatrial (SA) Node

__ is located in the septum between atrium, both atrium contract.

Atrioventricular (AV) Node

__ (bundle of His) transfer signal from atrium to ventricles.

AV Bundle

__ splits signal into L & R, extends signal down interventricular septum to apex.

Left and Right Bundle Branches

__ transfer signal from apex to all ventricular myocardium - both ventricles contract.

Purkinje Fibers

__ are muscle fibers of heart responsible for contraction (99% of myocardium), have a stable resting potential.

Contractile fibers

__ is Na in, action potential, muscle tissue responds by contracting.

Depolarization

The __ maintained depolarization, outflow of Ca = inflow of Ca → this is what makes depolarization last, different from skeletal muscle.

Plateau

__ is the outflow of K, sets up for another action potential.

Repolarization

The __ period is the time after a contraction when another contraction cannot be triggered - This last longer than the contraction - this prevents the heart from cramping (tetanus)

Refractory

The __ refractory period - long, cardiac muscle cells cannot respond.

Absolute

The __ refractory period - short, response depends on degree of stimulus.

Relative

Ca is response for contraction of a __ cell is produced by a(n) __ in calcium ion concentration around myofibrils.

cardiac muscle, increase

__ - atria depolarize

P wave

__ - ventricles depolarize

QRS complex

__ - ventricles repolarize

T wave

__ - end of S to beginning of T (plateau phase)

S-T segment

P-Q interval occurs from start of __ depolarization to start of ventricle __. (total conduction time)

atrial, depolarization.

Q-T interval occurs from __ depolarization to ventricular __. (ventricle contraction)

ventricular, repolarization.

__ = enlarged atrium

Increase P

__ = MI

Increase Q

__ = enlarged ventricle

Increase R

__ = decreased O2 to heart/coronary disease

Flat T

__ = scar tissue in heart

Increase P-Q

__ = acute MI

Raise S-T

__ = decreased O2 to heart

Lowered S-T

__ = myocardial damage or conduction problems

Increase Q-T

In any chamber: blood pressure rises during __ and falls during __.

systole, diastole.

Blood flows from __ to __ pressure by timing of contractions and one-way valves.

high, low

__ - listening to heart sounds.

Auscultation

__ (lubb) - produced by AV valves.

S1

__ (dubb) - produced by semilunar valves.

S2

__ - soft sounds, blood flow into ventricles, and atrial contraction.

S3 & S4

__ - sounds produced by regurgitation through valves.

Murmur

Mitral Stenosis - mitral valve does not __ 100%, trouble filling __.

open, ventricle.

Mitral Insufficiency - mitral valve does not __ 100%, trouble with backflow into __.

close, atrium.

Aortic Stenosis - aortic valve does not __ 100%, trouble forcing blood out of __.

open, left ventricle.

Aortic Insufficiency - aortic valve does not __ 100%, trouble with backflow into __.

close, left ventricle.

__ - adjusted by changes in heart rate or stroke volume.

Cardiac output

__ - adjusted by autonomic nervous system or hormones.

Heart rate

__ - adjusted by changing EDV or ESV.

Stroke volume

__ (Frank-Starling law of the heart) - ventricular stretching during diastole.

Preload

Preload allows duration of ventricle diastole ___ and venous return of __.

more time to fill, more blood.

__ - force produced during contraction, at a given preload.

E(epi) = inc, sedatives = dec.

Contractility

__ - tension the ventricle produces to open the semilunar valve and eject blood.

Afterload

Autonomic regulation of HR in __ center → effects sympathetic &__.

medulla cadio, parasympathetic.

__ - perceived movement

Proprioceptors

__ - chemical changes

Chemoreceptors

__ - blood pressure

Baroreceptors

__ (sympathetic) - triggers release of NE

Cardiac Accelerator Nerves

__ (parasympathetic) - ACh → slows SA node

Vagus Nerves

Increase K & Na = __

decrease Heart Rate & contractility

Increase Ca = __

Increase Heart Rate & contractility