Exam 3: Circulatory System 2: The Heart Flashcards
Size and Shape of Heart
- essentially a muscular “pump”
- normal heart is about the size of your clenched fist
- enlarged hearts are sick hearts
- located behind sternum and left ribs
- enclosed in pericardium
Endocardium
- endothelium covering a CT layer
- lines the inside of the heart & covers its valves
Myocardium
- cardiac muscle
- thickest layer
Epicardium (Visceral layer of Serous Pericardium)
-thin serous membrane and some fat
Pericardium
-made up of fibrous pericardium and serous pericardium and pericardial cavity
Fibrous Pericardium
- outermost layer
- dense CT
- functions: prevents heart from overfilling with blood
- restricts heart movements
Serous Pericardium
- serous membrane that secretes serous fluid for lubrication
- parietal layer-adheres to fibrous pericardium
- visceral layer-adheres to heart wall (same as epicardium)
Pericardial Cavity
- space between visceral and parietal layers
- serous fluid secreted in here
Right Atrium
- receives venous (deoxgenated) blood from superior and inverior venae cavae
- blood will flow from right atrium to right ventricle through the right atrioventricular (tricuspid) valve
Right Ventricle
- receives blood from right atrium
- 3 papillary muscles-conical muscle bulges
- chordae tendineae
- blood runs from right ventricle through pulmonary semilunar valve and into pulmonary trunk
Chordae Tendineae
- from papillary muscles to 3 flaps of right AV valve
- function: prevent R AV valve from turning inside out (everting/prolapsing) into R atrium when the ventricles contract
Pulmonary Semilunar Valve
- 3 semilunar cusps
- prevents backflow into R ventricle
- blood will now travel into pulmonary arteries to lungs
Left Atrium
- receives oxygenated blood form lungs via 3 or 4 pulmonary veins
- blood will flow from left atrium to left ventricle via the left atrioventricular (mitral/bicuspid) valve
Left Ventricle
- pumps oxygenated blood into aorta
- papillary muscles and chordae tendineae
- blood is pushed from left ventricle through aortic semilunar valve
Pulmonary Trunk and Pulmonary Arteries
-blood is deoxygenated here
Overall Heart Blood Flow
- blood LOW in oxygen enters right atrium
- blood from right atrium goes to right ventricle
- blood from the right ventricle goes through pulmonary trunk
- pulmonary trunk branches into pulmonary arteries, which carry blood to lungs
- exchange of gases occurs in the lungs
- oxygenated blood travels through pulmonary veins to left atrium
- blood from left atrium goes to left ventricle
- blood from left ventricle is pumped through the aorta
- body travels through the blood vessels, will return to right atrium of the heart, and the cycle repeats!
Blood Supply to Heart
- arterial Circulation: transports blood high in oxygen to heart wall
- right coronary artery
- left coronary artery
- venous circulation:returns blood low in oxygen back to right atrium (most of these veins unite/drain into coronary sinus which drains into right atrium)
Condicution System of Heart
- the heart exhibits autorhythmicity, which means the heart itself (and not external nerves) are responsible for initiating the heartbeat
Process of Conduction
- Sinoatrial (SA) Node: “pacemaker” initiates heart beat in wall of RA, makes atria contract and sends nerve impulse to AV node
- Atrioventricular (AV) Node): in RA, sends nerve impulse to AVB
- Atrioventricular bundle: in wall between ventricles, splits into L and R bundle branches
- Purinje fibers: special muscle cells that transmit nerve impulses throughout ventricles, make ventricles contract
ANS Innervation of Heart
- ANS doesn’t initiate heartbeat only makes it faster or slower
- sympathetic innervation increases heart rate
- parasympathetic innervation decreases heart rate
Pericarditis
-inflammation of pericardium
