Chapter 20/21 The Heart Flashcards
Where is the heart located?
Mediastinum
The heart is enclosed and held in place by what?
The pericardium
The pericardium consist of what?
- outer fibrous pericardium
- inner serous pericardium
The serous pericardium has 2 layers what are they?
- Visceral
- Parietal
What is the parietal and visceral layer separated by?
A serious cavity and a fluid filled space
What is the right atrium?
Receives blood from the superior and inferior vena cava
What is the right ventricle?
Receives blood from the right atrium and sends the blood to the lungs
What is the left atrium?
Receives blood from the pulmonary veins
What is the left ventricle?
Receives blood from the the left atrium and pumps blood to the entire body
Which ventricle has the thicker wall?
The left one does because it needs to pump blood to the whole body
What is the fibrous skeleton?
- forms the foundation for which the heart valves attach
- serves as a point of insertion for cardiac muscle
- prevents overstretching of the heart values
- acts as an electrical insulator
What are the three walls of the heart?
- Epicardium
- Myocardium
- Endocardium
The valves of the heart open and close in response to what?
Pressure changes as the heart contracts and relaxes
What does the right and left atrioventricular valves do?
Prevent back flow form the ventricles into the atria
What does the right and left semilunar values do?
Prevent back flow from the arteries into the ventricles
Blood flows through the coronary arteries to delivery what to where?
Oxygenated blood and nutrients to the myocardium
Coronary veins remove what?
Carbon dioxide and wastes from myocardium
What is myocardial ischemia?
Reduced blood flow to the myocardium
What is myocardial infarction?
Heart attack. Infarction refers to death of tissues due to interrupted blood supply
What can myocardial ischemia cause?
Hypoxia (reduced oxygen supply) and angina pectoris (severe pain in the chest) and pain in the neck, chin, left arm and elbow
Cardiac muscles are self excitable and therefore what?
Autorhythmic
Cardiac muscle cells repeatedly generate what?
Spontaneous action potentials that then trigger heart contractions
Cardiac muscle cells form what?
The conduction system, which is the route for propagating action potentials through the heart muscle
The autorhythmic fibers in the SA (sinuatrial) node are what?
The natural pacemaker of the heart because they initiate action potentials most frequently
Signals from the nervous system and hormones (like epinephrine) can do what?
Modify the heart rate and force of contraction but they do not set the fundamental rhythm
What is the pathway of the conduction system?
- SA node
- AV node
- AV bundle
- Right and left bundle branches
- subendocardial conducting network
What is a electrocardiogram (EKG or ECG)?
Recording of the electrical changes that accompany each heart beat
What is the cardiac cycle?
One cardiac cycle consists of
1. contraction (systole) of both atria
2. relaxation (diastole) of both atria
3. rapidly followed by systole and diastole of both ventricles
What are the elements of the cardiac cycle?
- Electrical events
- Pressure changes
- Heart sounds
- Volume changes
- Mechanical events
What is cardiac output?
The volume of blood ejected from the left or right ventricle into the aorta or pulmonary trunk each minute
Stroke volume (SV) is what?
The amount of blood pumped out of the ventricle in one beat
What is the Cardiac output formula?
CO = SV x HR
What are some of the several factors that regulate heart rate?
- Autonomic nervous system
- Hormones
- Ions
- Age
- Gender
- Physical fitness
- Temperature
What are some homeostatic imbalances?
- Coronary artery disease
- Atherosclerotic plaques
- Congenital heart defects
- Arrhythmia
- Congestive heart failure
In the Cardio vascular system what does aging result in?
- Loss of compliance of the aorta
- Reduction in cardiac muscle fiber size
- Progressive loss of cardiac muscular strength
- Decline in maximum heart rate
- Increased systolic blood pressure
