Chapter 19 pt. 1: heart

circulatory system

blood, blood vessels, and heart

systemic circulation

supplies blood to body and organs

pulmonary circulation

supplies blood to lungs

red

oxygenated blood

blue

deoxygenated blood

what’s the reason for the left side of circulatory system?

systemic circulation

what’s the reason for the right side of circulatory system?

pulmonary circulation

location of heart

inside pericardial cavity, located inside mediastinum inside the thoracic cavity

what are the layers of the heart?

epicardium, myocardium, and endocardium

epicardium

superficial layer; aka visceral pericardium, contains cardiomyocytes and areolar tissue; produces thin watery serious fluid around the heart to prevent friction

myocardium

middle layer; cardiac muscle tissue; contains cardiomyocytes and connective tissues

endocardium

deepest layer; lines inside of heart; contains endothelium and areolar tissue

4 chambers of the heart?

L/R atria; L/R ventricles

pulmonary trunk

branches into L and R pulmonary arteries that go to the lungs

aorta

pumps blood throughout rest of the body

superior vena cava

brings in from upper part of the body and empties into the right atrium

coronary sinus

short lengthened skeletal muscle, branched, cardiac muscles; striated and has smaller sarcoplasmic reticulum

striated muscles

cardiomyofibrils with sarcomeres

intercalated discs

• connection points of cardiomyocytes; branched relatively shortRely on aerobic respiration (not lactic acid fermentation)

• lots of mitochondria and myoglobin

• many fuel sources like fatty acids, glucose, amino acids, lactic acid

• critical for O2- → fuel

is fuel or oxygen more important in cardiomyocytes?

oxygen

gap junctions

allow direct flow of AP throughout the heart; little tubes that makes a little passageway into cells

desmosomes

strong anchors points between cells to hold them strongly connected together in the filaments

fascia adherens

special adherens junctions that connect sarcomere from one cell to sarcomere in next cell; connects myofibrils together

cadherins

transmembrane proteins; connecting between cells

connector proteins

special adherens structure that attaches to thin actin filaments in sarcomere

intermediate filaments

strong, rope-like protein fibers forming part of the cell's cytoskeleton; provides strength and support of cell shape

cardiac muscle

aka the heart; has myogenic contraction, no nerves needed; autorhythmicity; has pacemaker cells

pacemaker cells

where the heartbeat starts; stored in sinoatrial valve

what are the 2  atrioventricular valves?

tricuspid (R) and bicuspid (L)

tricuspid valve

right

bicuspid/mitral valve

left

what are the 2 semilunar valves?

aortic valve and pulmonary valve

functions of the semilunar valves?

allows blood to come out of ventricle

cardiac cycle

cycle of contraction and relaxation during a heartbeat

systole

contraction

diastole

relaxation

what makes the “Lubb” sound?

AV valves snapping shut

what makes the “Dubb” sound?

semilunar valves snapping shut

cardiac conduction system

specialized conducting cardiomyocytes; players → SA and AV nodes, tracts, bundles, and fibers

SA node

located in right atrium,autorhythmicity (beats automatically), contains pacemaker cells

pacemaker cells

create spontaneous action potentials; the start of heartbeat

From SA to AV node

APs goes through the 3 internodal tracts (anterior, middle, and posterior internodal tracts) to get to AV node

Interatrial Band/Bachmann’s bundle

goes from SA node to left atrium; synchronizes contractions between atria

The atrioventricular (AV) Node

only signal pathway to ventricles ; delays signals due to slower speed in the AV node; Connective tissue barrier between atria and ventricles, blocking the other paths

The Bundle of His/atrioventricular bundle

from AV node to interventricular septum, switching back to fast speed, then shoots down to apex

Purkinje fibers

signal to ventricle walls; from apex towards base shoot down septum, then up the sides; aka subendocardial conduction network

Cardiac AP Steps:

SA node → spreads through 3 internodal tracts → AV node → interatrial band (Bachmann’s bundle) → atrioventricular node → bundle of his (atrioventricular bundle) → purkinje fibers