Biomed mod.16 obj.1-6

heart, pump, fist

True

• The heart is close to the midline
•   -the c enter is slightly to the left of the midline
•   -About the same level as the nipples
• About the size and shape of a closed fist
• The pointed apex of the heart is inferior and rests on the diaphragm.
• The base of he heart is superior to the apex

• the heart lies in a cavity called the mediastinum 
• This consists of:
•   -The thoracic cavity minus the pleural cavity (lungs and associated structures)
•   -esophagus
•   -thymus
•   -great vessels of the heart
•   -the heart

Pericardium 

This keeps the heart in place in the mediastinum, but gives it enough freedom to contract and beat.

• an ultrasound (sound wave picture) of the heart
• shows both cardiac anatomy and function
• By placing a transducer in the esophagus, physicians can get a picture of the heart that is unobstructed by tissues that limit conventional echocardiography

• Endocardium
• Myocardium
• Epicardium
• Pericardium

• The deepest layer of the heart wall
• consists of a thin layer of simple squamous epithelium (endothelium)over a thin layer of connective tissue
• This provides a smooth surface for the blood as it glows through the chambers and the valves of the heart.
• This helps prevent friction that may cause blood clots.

• The thick middle layer (muscular layer of the heart)
• Makes up 95% of the heart and is responsible for the pumping action.

• The thin outermost layer of the heart wall
• a delicate membrane of epithelial and connective tissue giving the heat a slippery covering
• This is synonymous with the visceral layer of the pericardial covering

endocardium, heart valves, wall

• heart defects
• degeneration of the valves
• transplanted heart valves
• Rheumatic fever

True.

Patients at risk of endocarditis should receive antibiotics prior to dental work.

• surrounds and protects the heart
• consists of the serous pericardium and the and the outer most Fibrous pericardium
• see slide on p.757

• has two layers
•   -visceral layer: synonymous with the epicardium
•   -parietal layer: fused to the fibrous pericardium
• Pericardial fluid fills the cavity between the visceral and parietal layers

a tough dense connective tissue that precvents the heart from over expanding and anchors to the mediastinum

• and accumulation of excess fluid in the paricardial cavity 
• this may occur due to infection, trauma, or myocardial infraction. 
• The fluid puts pressure on the heart that may become great enough to prevent the it from pumping.
• This is called cardiac tamponade, and is life threatening.

• striated like skeletal muscle
• Unlike skeletal muscle cardiac fibers are shorter, branch, and have on central nucleus
• contain interculated discs for structural strength
• Gap junctions to synchronize muscle cell contraction
• plentiful mitochondria for energy:take up about 25%of the space in the cytosol compared to 2% in skeletal muscle.

• Atria: superior protion of the heart, holding chambers for blood
•   -right atrium
•   -Left atrium
• Ventricles: inferior portion, pumps blood to lungs and body
•   -Right ventricle
•   -Left ventricle

This receives deoxygenated blood from the body

receives oxygenated blood from the lungs

• receives blood from the right atrium
• it pumps deoxygenated blood out to the lungs

• receives oxygenated blood from the left atrium 
• it pumps oxygenated blood out to the body.

• Right atrioventricular valve (AV) tricuspid valve
•   -right atrium --> right ventricle
• pulmonary semilunar valve
•   -regulates blood flow: right ventricle --> pulmonary trunk
• Left atrioventricular valve (AV) mitral valve (bicuspid valve)
•   -left atrium -->left ventricle
• aortic semilunar valve
•   -regulates blood flow: left ventricle-->aorta

• control the flow of blood between the atria and the ventricles.
• these include:
•   -Right atrioventricular or tricuspid valve
•   -Left atrioventricular, bicuspid, or mital vlave

• control the flow of blood leaving the heart from the ventricles.
• these include:
•   -Pulmonary semilunar valve
•   -Aortic semilunar valve

pressure, valve

Valves prevent the backflow of blood.  The are anchored in place by chordae teninae: chordlike tendons that are anchored to papillary muscles.

• right ventricle pumps short distance and against low pressure to the lungs
• Left ventricle pumps long distance and against large pressure to body
• Therefore, left ventricle muscle wall very thick compared to right.

• Valves do not actively open; ratter they are pushed open by increased pressure 
• chordae tendinae help keep valves in place
• Valves mainly act as "backflow preventers"