Heart Flashcards
How do the heart muscles contract together like one muscle?
Gap junctions allow them to function as a syncytium
What are gap junctions? How do they relate to cardiac muscle?
Special intracellular connections that allow ions to pass and help send signals to other cells to contract cardiac muscle.
What do desmosomes do in cardiac muscle?
Maintain structural integrity and anchor the cells together.
What are intercalated discs and what do they do in cardiac muscle?
- Specialized structures that connect adjacent cardiac muscle cells together.
- Contain specialized junctions like desmosomes and gap junctions.
How big is the heart?
Approximately the size of a fist.
Where is the heart located?
In the mediastinum
What is the heart enclosed in?
Pericardium
What protects, anchors and prevents overfilling in the heart?
Superficial Fibrous Pericardium
How many layers does the serous pericardium have? What are they? Where are they located?
- 2
- Parietal Layer: lines internal surface of fibrous pericardium
- Visceral Layer: lines external surface of heart
What is the visceral layer also known as? Where is it located?
- Epicardium
- On external surface of heart
What separates the parietal and visceral layer? What is the function of this?
- Pericardial cavity
- Contains serous fluid which lubricates pericardium and reduces friction as heart beats.
What are the layers of the heart (innermost-outermost)? And their functions?
Endocardium - contains endothelial cells for smooth surface that allows blood to flow easily through heart
Myocardium - contain cardiac muscle cells, anchors cardiac muscle fibers, supports great vessels and valves
Epicardium - visceral pericardium, CT for protection and support, contains blood vessels and nerve fibers to supply heart with O2 and nutrients.
What are the chambers of the heart?
2 atrium (left and right), 2 ventricles (left and right)
What encircles the junction of the atria and ventricles?
Coronary sulcus (atrioventricular groove)
What vessels enter the right atrium? Left atrium?
- Superior Vena Cava, Inferior Vena Cava, Coronary sinus
- Right and left pulmonary veins
What vessel leaves the right ventricle? Left ventricle?
- Pulmonary trunk
- Aorta
What is the trabeculae carneae?
Ridges in the walls of ventricles that give structural support and prevent ventricle walls from collapsing during ventricular contraction.
Which side of the heart is the pump for pulmonary circuit?
Right side
Which side of the heart is the pump for systemic circuit?
Left side
What is the pulmonary circuit?
Circulation of blood from the heart to the lungs
What is systemic circulation?
Circulation of blood from the heart to every tissue in the body
Which circuit is high pressure and which is low? Pulmonary circuit or systemic circuit? Why?
- Systemic circuit is high pressure and pulmonary circuit is low pressure.
- It takes a lot more energy and pressure to pump blood to all the bodies tissues compared to pumping blood to the lungs, therefore systemic circuit has higher pressure.
Why are the left ventricle walls thicker than the right ventricle?
It takes a lot of work and energy to pump blood for systemic circulation (which is what left ventricle pumps to), so its walls a thicker to accommodate amount of energy needed to pump.
What is coronary circulation? Why is it important?
- Circulation of blood to the heart
- It’s important for the function of the heart and heart muscle
What are collateral routes and anastomoses? Why do we need them?
Collateral routes - natural connections between adjacent blood vessels
Anastomoses - surgical or natural connections between two blood vessels
- We need them because they allow blood to continue to reach tissues and organs even if a blood vessel is partially or completed blocked
What are the major arteries in the heart? (hint: 6)
(slide 25 CVS1)
- Right/left coronary artery
- Right marginal artery
- Posterior interventricular artery
- Anterior interventricular artery
- Circumflex artery
What are the major cardiac veins?
(slide 26 CVS1)
- Small cardiac vein
- Middle cardiac vein
- Great cardiac vein
What is angina pectoris?
Thoracic pain due to fleeting deficiency in blood delivery and O2 supply to the myocardium
What is myocardial infarction?
Heart attack; prolonged coronary blockage
- areas of cell death can be repaired with non contractile scar tissue
Which is long term and which is short term? Angina pectoris or myocardial infarction? Why?
- Myocardial infarction is long term and angina pectoris is short term
- Angina pectoris is only fleeting deficiency of blood while myocardial infarction is a prolonged blockage of blood supply
What are the atrioventricular (AV) valves?
Tricuspid valve: right
Mitral (bicuspid) valve: left
What are heart valves for?
Ensure unidirectional blood flow through the heart
What are the chordae tendineae and papillary muscles for?
- Chordae tendineae anchor AV valve cusps to papillary muscles
- Papillary muscles pull on chordae tendineae to open and close valves
What are the semilunar (SL) valves?
- Aortic semilunar valve
- Pulmonary semilunar valve
What is the pathway of blood through the heart?
Superior/inferior vena cava —> right atrium —> tricuspid valve —> right ventricle —> pulmonary semilunar valve —> pulmonary trunk —> pulmonary arteries —> lungs —> pulmonary veins —> left atrium —> bicuspid valve —> left ventricle —> aortic semilunar valve —> aorta —> systemic circulation
Why does cardiac muscle have large mitochondria? How much of cell volume do they take up?
- The heart is constantly functioning, therefore they need bigger mitochondria for more energy
- 25-35% of cell volume
What are T-tubules for? Why are they wide?
- Allow rapid and efficient transmission of electrical impulses throughout the cardiac muscle cell
- Synchronize the contraction of the entire muscle cell
- They are wide in order to allow electrical signals to pass through at a higher rate
What are some characteristics of cardiac muscle cells?
Striated, short, fat, branched, interconnected
