Chapter 20 - The Cardiovascular System: The Heart Flashcards
Where is the Heart?
The Heart is located in the Mediastinum
What is Pericardium?
The heart is enclosed and held in place by the Pericardium
The Pericardium consist of an Outer Fibrous Pericardium and an inner Serous Pericardium
Serous Pericardium has 2 layers:
1- Parietal Layer
2- Visceral Layer
Visceral and Parietal layers are separated by the Serous Cavity, a fluid-filled space
What are the Layers of the Heart?
The wall of the heart has 3 layers:
1- Epicardium (the Visceral layer of the Pericardium)
2- Myocardium (cardiac muscle)
3- Endocardium
What are the Chambers of the Heart?
The Chambers of the heart include 2 upper Atria and 2 lower Ventricles
What is Right Atrium?
Right Atrium:
Receives blood from Superior Vena Cava, Inferior Vena Cava, and the Coronary Sinus
Pumps blood to the Right Ventricle through Tricuspid Valve
What is Right Ventricle?
Right Ventricle:
Receives blood from the Right Atrium
Sends blood to the Lungs through the Pulmonary Valve to the Pulmonary Arteries
What is Left Atrium?
Left Atrium:
Receives blood from the Lungs through the Pulmonary Veins
Pumps blood to the Left Ventricle through the Bicuspid Valve (Mitral Valve)
What is Left Ventricle?
Left Ventricle:
Receives blood from the Left Atrium
Pumps blood through all body through Aortic Valve to Ascending Aorta
Note:
Wall of Left Ventricle is much thicker than wall of Right Ventricle
What is Fibrous Skeleton?
Fibrous Skeleton of the Heart:
1- Forms the foundation for which the heart valves attach
2- Serves as a point of insertion for cardiac muscle bundles
3- Prevents overstretching of the heart valves
4- Acts as an electrical insulator
Pulmonary Valve has Pulmonary Fibrous Ring around it
Aortic Valve has Aortic Fibrous Ring around it
Bicuspid Valve (Mitral Valve) has Left Atrioventricular Fibrous Ring around it
Tricuspid Valve has Right Atrioventricular Fibrous Ring around it
Conus Tendon between Pulmonary Valve and Aortic Valve
Left Fibrous Trigone between Aortic Valve and Mitral Valve
Right Fibrous Trigone between Aortic Valve, Mitral Valve, and Tricuspid Valve
What is Heart Valves and Circulation of Blood?
The valves of the heart open and close in response to pressure changes as the heart contracts and relaxes
Right and left Atrioventricular Valves:
Tricuspid Valve and Mitral Valve
Prevent backflow from the Ventricles into the Atria
Right and left Semilunar Valves:
Pulmonary Valve and Aortic Valve
Prevent backflow from the Arteries into the Ventricles
When one set of Valves is open, the other is closed
Mitral and Tricuspid is a set
Pulmonary and Aortic is a set
What is Heart Valves Structure?
Fibrous Ring around Valve
Cusps (Leaflets)
Chordae Tendineae
Papillary Muscles
When Valve is open:
1- Cusps are open
2- Chordae Tendineae loose
3- Papillary Muscles relaxed
When Valve is closed:
1- Cusps are closed
2- Chordae Tendineae stretched
3- Papillary Muscles contracted
Artery vs Vein?
Artery:
Carry oxygen and nutrients in blood away from heart to body tissues
Vein:
Take oxygen-poor blood back from body tissue to heart
What is Systemic and Pulmonary Circulation?
Blood circulates in this way:
1- Superior Vena Cava, Inferior Vena Cava, and Coronary Sinus
2- Right Atrium
3- Tricuspid Valve
4- Right Ventricle
5- Pulmonary Valve
6- Pulmonary Trunk and Right and Left Pulmonary Arteries
7- In Pulmonary Capillaries, blood loses CO2 and gains O2
8- Right and Left Pulmonary Veins
9- Left Atrium
10- Mitral Valve
11- Left Ventricle
12- Aortic Valve
13- Aorta, Right and Left Coronary Arteries, and Systemic Arteries
14- In Systemic Capillaries, blood loses O2 and gains CO2
15- Superior Vena Cava, Inferior Vena Cava, and Coronary Sinus
What is Coronary Circulation?
1- Blood flow through Coronary Arteries deliver oxygenated blood and nutrients to the Myocardium
Branches arise from the Ascending Aorta
2- Coronary Veins remove CO2 and wastes from the Myocardium
Branches converge at the Coronary Sinus
Where are the Vessels of the Coronary Circulation?
1- Left Coronary Artery splits to:
Anterior Interventricular Branch (anteriorly)
Circumflex Branch (from anterior to posterior horizontally)
2- Right Coronary Artery splits into:
Marginal Branch (anteriorly)
Posterior Interventricular Branch (from anterior to posterior
3- Coronary Sinus to which all Coronary Veins converge:
Great Cardiac Vein (anterior left + Tributary to Great Cardiac Vein inferior)
Small Cardiac Vein (anterior right superior)
Anterior Cardiac Vein (anterior right inferior)
Middle Cardiac Vein (posterior)
What is Cardiac Muscle Tissue?
1- Nucleus
2- Mitochondria
3- Sarcolemma:
Surrounds cardiac muscle fibers
4- Intercalated Discs:
Connect cardiac muscle cells with Desmosomes
Desmosomes seal the gaps and allow communication
5- Gap Junction
6- Openings of Transverse Tubules
What is Arrangement of Cardiac Muscle Fibers?
Sarcolemma surrounds cell
Nucleus and mitochondria
Transverse Tubules
Sarcoplasmic Reticulum
Sarcomere:
I Band (at each end, between 2 Myosin filaments)
Z Disc (at center of each I Band)
A Band (between I Bands, length of a Myosin filament)
H Zone (inside A Band, between 2 Actin filaments)
M Line (inside H Zone, center of Sarcomere)
What is Conduction System of Heart?
Cardiac muscle cells are self-excitable, therefore, Autorhythmic
Cardiac muscle cells repeatedly generate spontaneous action potentials that then trigger heart contractions
These cells form the Conduction System, which is the route for propagating action potentials through the heart muscle
What is the Conduction System Route of the Heart?
1- Sinoatrial Node (SA Node):
In Right Atrium
Act as pacemaker
2- Atrioventricular Node (AV Node):
In Right Atrium
3- Atrioventricular Bundle (AV Bundle, Bundle of His):
In Interventricular Septum
4- Right and Left Bundle Branches:
In Interventricular Septum
5- Purkinje Fibers:
In Myocardium
Branching all over heart Myocardium
Contract following action potentials
What is Sinoatrial Node (SA Node)?
The autorhythmic fibers in the SA Node are the natural pacemaker of the heart because they initiate action potential most frequently
Signals from the nervous system and hormones (like Epinephrine) can modify the HR and force of contraction but they do not set the fundamental rhythm
What is Action Potential in a Ventricular Fiber?
An action potential in a Ventricular Contractile Fiber is characterized by:
1- Rapid Depolarization:
Due to Na+ inflow when voltage-gated fast Na+ channels open
2- Plateau:
Maintained Depolarization
Due to Ca2+ inflow when voltage-gated slow Ca2+ channels open
And K+ outflow when some K+ channels open
3- Repolarization:
Due to a closure of Ca2+ channels
And K+ outflow when additional voltage-gated K+ channels open
What is ATP Production in Cardiac Muscle?
Cardiac muscle generates ATP via Anaerobic Cellular Respiration and Creatine Phosphate
What is Electrocardiogram (EKG or ECG)?
An EKG is a recording of the electrical changes that accompany each heart beat
1- P Wave
2- QRS Complex
3- T Wave
P-Q Interval (contains atrial contraction)
S-T Segment
Q-T Interval (contains ventricular contraction)
What is Action Potential Propagation Through the Heart?
1- Depolarization of Atrial Contractile Fibers produce the P Wave
Action Potential in SA Node
2- Atrial Systole (contraction)
3- Depolarization of Ventricular Contractile Fibers produce the QRS Complex
4- Ventricular Systole (contraction)
5- Repolarization of Ventricular Contractile Fibers produce the T Wave
6- Ventricular Diastole (relaxation)
