A&P II ~ Exam 1

anterior mediastinum

• small space in front of the heart

• composed mainly of CT, fat, lymph nodes, & thymus (in children)

middle mediastinum

heart, pericardium, roots of the great vessels

posterior mediastinum

esophagus, descending aorta, thoracic duct, azygos & hemiazygos veins (drain the wall of the chest & abdomen), and the sympathetic trunk

dextrocardia

• a congenital defect of the heart where the apex sits on the right side instead of the left

• also called situs inversus

epicardium (outer layer)

• a thin, smooth membrane that reduces friction between the beating heart and the surrounding structures

• contains CT, fat, blood vessels, lymphatics, and nerves

• also called the visceral layer of the serous pericardium

myocardium (middle layer)

• a thick, muscular layer made of specialized cardiac muscle cells (cardiomyocytes)

• responsible for pumping action of the heart

endocardium (inner layer)

• a thin, smooth lining of the heart chambers and valves

• made up of endothelium & connective tissue

• wall of the heart

pericardium

• double-walled sac that surrounds & protects the heart

serous fluid

• thin film of fluid that enables the heart to move and beat in a frictionless environment

fibrous pericardium (outermost layer)

• connective tissue that keeps the heart from expanding too much

desmosomes

anchor cardiac cells together

intercalated discs

part of sarcolemma

gap junction

allow quick propagation of APs

endocarditis

inflammation of one of the heart valves

auricles

• wrinkled, flap-like extensions of the atria

• act as reservoirs which increase volume capacity of the atrium

crista terminalis

separates the ridged muscular part from the smooth part of the atrium

moderator band

• a prominent trabecula in the right ventricle

• helps obstetrician identify the right vs. left ventricle in the developing fetus

hypoxia

insufficient oxygen reaching the tissue

hypoxemia

• abnormally low level of oxygen in the blood and cause hypoxia as the blood is not supplying enough oxygen to tissues in the body

• due to respiratory disorders such as pneumonia or blood disorders such as iron deficiency anemia

ischemia

• insufficient blood flow to the tissue

• such as coronary artery disease where there is blockage of a coronary artery preventing blood flow to heart muscle

necrosis

tissue death

infarction

when necrosis is due to hypoxia

ventricular systole

when ventricles are contracting and pumping blood

ventricular diastole

when ventricles are relaxed and filling with blood

stenosis

thickening/narrowing of a heart valve that restricts blood flow

insufficiency

failure of a valve to close completely

prolapse

valve leaflets balloon upward as the ventricle contracts

regurgitation

valve leaflets do not properly close, forcing blood back into the atrium

cardiac cycle

from one heartbeat to the next heartbeat

automaticity

can generate own action potential

cardiac pacemaker cells

found in SA node, AV node, and purkinje fibers

cardiac conducting fibers

• 1%, intrinsic conduction system of the heart

• initiate and spread APs through the heart, triggering each contraction

• demonstrate automaticity

cardiac contractile fibers

• 99%, make up most of the myocardium

• responsible for heart contractions that pump blood through the heart into the rest of the body

• do not demonstrate automaticity

sinus rhythm

electrical impulses initiated in the SA node coordinate your heart beats at regular intervals

arryhthmia/disrhythmia

irregular heart rhythm

EDV

volume of blood in the ventricle at the end of ventricular diastole

SV

volume of blood pumped out of each ventricle after each contraction

ejection fraction

% of EDV that was ejected with each contraction

p wave

atrial depolarization

qrs complex

ventricular depolarization

t wave

ventricular repolarization

pq interval

delay of AV node to allow filling of ventricles

ST elevation

acute myocardial infarction

peaked t waves

• hyperkalemia

inverted (flipped) t waves

• myocardial ischemia/onset of myocardial infarction

long qt syndrome

• certain medications can cause

phase 4

potassium leakage channels maintain the inside of the membrane at a relative negative charge

phase 0

rapid sodium influx due to opening of voltage-gated channels

phase 1

sodium channels begin to close & potassium voltage-gated channels open, allowing potassium to efflux out of the cell

phase 2

• calcium channels open

• calcium influx into cell

• potassium channels still open

• potassium effluxing out of the cell balances calcium influxing into the cell

  • plateau phase

phase 3

• calcium channels are closed

• potassium channels remain open with continued efflux of potassium out of the cell

phase 4 (after phase 3)

once excitation reaches the ventricles through the cardiac conduction system, the electrical signal passes from one contractile cell to another contractile cell via gap junction