Chapter 20: The heart Flashcards
Location of the heart
located in the mediastinum
What does the pericardium consist of
- superficial fibrous pericardium
- deeper serous pericardium
Fibrous pericardium
- has one layer
- composed of tough, inelastic dense irregular connective tissue
Fibrous pericardium function
- prevents overstretching of the heart
- provides protection
- anchors the heart to the mediastinum
- Apex of the heart is anchored to the diaphragm
Serous pericardium
- has 2 layers
- parietal pericardium
- visceral pericardium
The parietal and visceral pericardium is separated by
the pericardial cavity, a fluid filled space
- reduces friction between the layers when the heart moves
Layers of the heart wall
- epicardium (visceral layer)
- myocardium (muscle layer)
- endocardium (inner most layer)
Pericarditis
- inflammation of the pericardium
- Acute pericarditis: sudden, no known cause, may be linked to viral infection
- Chronic pericarditis: build up of fluid around the pericardium
Myocarditis
- inflammation of the myocardium, usually complication of viral infection
Endocarditis
- inflammation of the endocardium
- typically due to bacteria and involves heart valves
Chambers of the heart
- 2 atria (single is atrium)
- 2 ventricles
Coronary sinus
major coronary vein located in the rear section of the heart
Right atrium
receives blood from the superior and inferior vena cava and the coronary sinus
Right ventricle
receives blood from the right atrium and sends blood to the lungs through the pulmonary valve –> pulmonary trunk –> pulmonary artery
Left atrium
receives blood from the pulmonary veins
- brings oxygenated blood from the lungs
Left ventricle
receives blood from the left atrium through the left atrioventricular valve
- sends blood all over the body
The left ventricle is much thicker than that if the right ventricle because…
the left ventricle has to pump blood to the rest of the body
Fibrous skeleton of the heart
- 4 dense connective tissue rings that surround the valves of the heart
- forms the foundation in which the heart valves attach
- serves as a point of insertion for cardiac muscle bundles
- prevents overstretching of the heart as blood passes through them
- acts as an electrical insulator between the atria and ventricles
What do the valves of the heart prevent
- they open and close in response to pressure changes as the heart contracts and relaxes
- right and left atrioventricular valves prevent backflow from ventricles into the atria
- right and left semilunar valves prevent backflow from the arteries to the ventricles
Chordae tendineae
- heart strings
- connect valves to papillary muscles
- relaxed when valves are open
- when the valves close heart strings become taught
Damage to the chordae tendineae can lead to
heart problems
Coronary circulation
- blood flows through coronary arteries to deliver oxygenated blood to the myocardium
- the arteries branch from the ascending aorta
- coronary veins remove CO2 and waste
- coronary vein branches converge to the coronary sinus
Myocardial ischemia
- reduced blood flow to the myocardium
- can cause hypoxia and angina pectoris, and pain in the neck, chin, left arm and elbow
Myocardial infarction
- heart attack
- death of tissues due to interrupted oxygen supply
Intercalated discs show
borders of cardiac muscle cells
What type of cardiac cells are self excitable
- autorythmic fibers are self excitable
- not all cardiac myocytes are self excitable
The heart does not need…
nerve impulses however the brain can still send impulses to slow down or speed up the heart
What do autorhythmic fibers do
repeatedly generate spontaneous action potentials that then trigger heart contractions