Circulator System Unit 4 - Part 1

parts of the circulator system include

heart, blood, blood vessels

functions of the circulatory system

transportation of oxygen and other nutrients

removal of carbon dioxide and other cellular waste products

regulation of body temperature (vasoconstriction/vasodilation)

transportation of hormones

assistance with immune response

heart chambers

right atrium, left atrium, right ventricle, left ventricle

heart valves

tricuspid, bicuspid, aortic pulmonary

heart blood vessels

aorta, pulmonary vein, pulmonary artery, superior and inferior vena cava

atria (atrium)

upper chambers, thin walled, deliver blood to the ventricles

ventricles

lower chambers, thicker walled, left __ thickest because it pumps blood further and experiences greater resistance.

pulmonary and aortic valves

semilunar valves — allow ejection of blood into arteries

tricuspid and bicuspid valve

atrioventricular valves — valves found between atria and ventricles

pericardium

outer membrane that surrounds and protects the heart

myocardium

thick layer of cardiac muscle making up the walls of the heart

chordae tendinae

tendon-like cords found within the ventricles that help prevent the backflow of blood through the valve

trabeculae carneae

series of ridges caused by raised bundles of cardiac muscles

papillary muscles

cone-shaped trabeculae carneae to which the chordae tendineae are attached

auricles

wrinkled, pouch-like structure found on anterior surface of the atria; increases capacity of atria slightly

apex

inferior portion of the heart that comes to a point

base

broad, superior portion of the heart

septum

muscular partition that prevents blood on two sides from mixing

pericardial fluid

slippery secretion produced by pericardial cells, which reduces friction as heart moves when it contracts

pulmonary trunk

large vessel from the right ventricle, which splits into the pulmonary arteries

coronary arteries

branches from ascending aorta that bring oxygenated blood to the heart

relaxation (diastole)

begins at the end of a cardiac cycle
all 4 chambers are in diastole
initiated by repolarization of ventricles
ventricular pressure goes down, AV valves open, ventricles fill

atrial systole

action potential from SA node causes atrial depolarization
atria contract and complete filling of the ventricles “LUB”. 
AV valves still open, SL valves still closed

ventricular systole

contraction of ventricles, pushes blood against AV valves forcing them to shut “DUB”
ventricular pressure up, both SL valves open, ejection of blood

systemic circulation

left side of the heart pumps through blood vessels to the tissues of the body and back to the right side of the heart

pulmonary circulation

right side of the heart pumps blood through vessels to lungs and back to the left side of the heart

cardiac output

the volume of blood pumped from the heart per minute (mL/min)

stroke volume

amount of blood pumped per ventricle per contraction

heart rate

number of beats/contractions of ventricles per minute

sinoatrial node (SA) (pacemaker)

location: right atrial wall
function: initiates each heartbeat and sets basic pace for heart rate. sends action potential to both atria causing them to contract

atrioventricular node (AV)

location: interatrial septum
function: picks up action potential from SA node and passes it to the atrioventricular bundle

atrioventricular bundle (bundle of his)

location: interventricular septum
function: picks up action potential from AV node and passes it to the right and left bundle branches

right and left bundle branches

location: interventricular septum
function: picks up action potential and passes it to conduction myofibers

conduction microfibers (purkinje fibers)

location: ventricular myocardium
function: picks up action potential from bundle branches and passes it to ventricular myocardial cells, causing ventricles to contract

electrocardiogram (ECG or EKG)

a recording/diagram of the electrical changes that accompany the heartbeat. can be analyzed to determine abnormalities in heartbeat. 

P wave

atrial depolarization

QRS complex

onset of ventricular depolarization

T wave

ventricular repolarization

tachycardia

rapid, resting, heart/pulse rate over 100 bpm

bradycardia

slow, resting heart/pulse rate under 60 bpm

arrhythmia

an irregularity in heart rhythm caused by problem in conduction system of the heart

atrial fibrilation

uncoordinated contraction of atrial muscles, muscle fibers quiver individually rather than contracting together

ventricular fibrillation 

asynchronous, haphazard ventricular muscle contractions. ventricular ejection ceases —> death

heart murmur

faulty heart valves, gurgling, blood back up in chambers, not detectable with ECG (mechanical issue)