The _____ is a strong, muscular _____ just a little over the size of a _____.
heart, pump, fist
True or false
The heart pumps about 3,600 gallons of blood through the body in one day, and beats 100,000 times.
What is the position of the heart?
- 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
Position of the the heart:
- the heart lies in a cavity called the mediastinum
- This consists of:
- -The thoracic cavity minus the pleural cavity (lungs and associated structures)
- -great vessels of the heart
- -the heart
The _______ is a membrane that covers and protects the heart.
This keeps the heart in place in the mediastinum, but gives it enough freedom to contract and beat.
Transesophageal Echocardiography (TEE)
- 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
What are the layers of the Heart wall?
- 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
The __________ can develop chronic infections with microorganisms that can lodge on the _____ _____ or the ____ of the heart. This is called endocarditis
endocardium, heart valves, wall
Risk factors for endocarditis
- heart defects
- degeneration of the valves
- transplanted heart valves
- Rheumatic fever
True or false
Dental cleaning can allow a small amount of bacteria to enter the blood stream.
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.
Histologic features of Cardiac muscle tissue
- 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.
What are the four chambers of the heart?
- 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.
What are the four valves of the heart?
- 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
Atrioventricular valves (AV)
- control the flow of blood between the atria and the ventricles.
- these include:
- -Right atrioventricular or tricuspid valve
- -Left atrioventricular, bicuspid, or mital vlave
Semilunar (outflow) valves
- control the flow of blood leaving the heart from the ventricles.
- these include:
- -Pulmonary semilunar valve
- -Aortic semilunar valve
The valves of the heart operate _______. When enough pressure builds up behind a _____, it forces the valve open.
Valves prevent the backflow of blood. The are anchored in place by chordae teninae: chordlike tendons that are anchored to papillary muscles.
Functions of the Chambers:
Ventricles are pumping chambers
- 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.
Function of Valves
- 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"