CHP 17- Cardiovascular System Flashcards
What is the apex of the heart?
The point of the cone, which points toward the left hip
What is the base of the heart?
The heart’s posterior side facing the posterior rib cage
Externally, what is found at the boundary between the atria and ventricles?
An indentation known as the atrioventricular sulcus
What is located between the right and left ventricles?
The interventricular sulcus
What are veins?
Blood vessels that bring blood to the heart
What are arteries?
Blood vessels that carry blood away from the heart
What does the right side of the heart do?
Pumps blood to the lungs
What does the left side of the heart do?
Pumps blood to the rest of the body (systemic)
What takes place between the tiny air sacs in the lungs called the alveoli and the pulmonary capillaries?
Gas exchange- oxygen diffuses from the air in the alveoli into the blood in the pulmonary capillaries, and CO2 diffuses from blood in capillarys to air in alveoli to be expired
What is the difference between pressure in the pulmonary circuit vs the systemic circuit?
Pulmonary is a low pressure circuit whereas systemic is high pressure because it delivers blood to the rest of the body
What is the membranous structure surrounding the heart called?
The pericardium
What are the components of the pericardium?
The fibrous pericardium and the serous pericardium
What is the fibrous pericardium?
A tough outer layer that attaches the heart to the surrounding structures; composed of collagen bundles that make it tough and enable it to anchor the heart to structures such as diaphragm
What is the serous pericardium?
A thin inner serous membrane that produces serous fluid
What are the layers of the serous pericardium?
The parietal pericardium and visceral pericardium or epicardium
What is visceral pericardium?
Considered the most superficial layer of the heart wall
What is between the parietal and visceral pericardia?
The pericardial cavity, which is filled with serous fluid called pericardial fluid that acts as a lubricant, decreasing friction as the heart moves
What is deep to the visceral pericardium?
The myocardium
What are the two components of the myocardium?
Cardiac muscle tissue and a fibrous skeleton
What does cardiac muscle tissue consist of?
Cardiac muscle cells or myocytes and extacellular matrix
What are the functions of the fibrous skeleton?
Giving cardiac muscle cells something on which to pull when they contract, structural support, and acting as an insulator for heart’s electrical activity
What is the deepest layer of hear wall?
Endocardium
What is endocardium composed of?
Endothelium and connective tissue; endothelial cells are continuous with endothelial cells of blood vessels
What supplies blood to the heart?
A set of blood vessels collectively called the coronary circulation
What coronary arteries emerge from left ventricle?
The right and left coronary arteries– both travel to right and left atrioventricular sulci
What are the branches of the right coronary artery?
The right coronary artery gives off several branches that supply the right atrium and ventricle
- Marginal artery
- Posterior interventricular artery
What are the branches of the left coronary artery?
Anterior interventricular artery (supplies interventricular septum) and circumflex artery
What are anastomoses?
Systems of channels formed between blood vessels
What are the coronary veins?
- Great cardiac vein
- Small cardiac vein
- Middle cardiac vein
They all drain into the coronary sinus and then into posterior right atrium
What is CAD?
Coronary artery disease; caused by a buildup of fatty material or plaques in coronary arteries; decreases blood flow to myocardium causing myocardial ischemia
What is the purpose of valves?
To prevent backflow
Superior and inferior vena cava
Drain majority of systemic circuit into right atrium
Superior- drains deoxy blood from veins superior to diaphragm
Inferior- drains deoxy blood from veins inferior to diaphragm
Pulmonary trunk
Receives deoxy blood pumped from right ventricle; splits into right and left pulmonary arteries, which bring deoxy blood to right and left lungs
Pulmonary veins
Oxy blood returned to left atrium
Aorta
Supplies the entire systemic circuit with oxygenated blood
What are the auricles?
Muscular pouch on atrium that expand to give the atria more space to hold blood
What separates two atria?
Interatrial septum
What are the trabeculae carnae?
Both ventricles have a ridged surface created by irregular protrusions of cardiac muscle tissue
What are the papillary muscles?
Each ventricle contains fingerlike projections which attach to chordae tendinae
AV valve between the right atrium and right ventricle?
Tricuspid valve (3 cusps)
AV valve between left atrium and left ventricle?
Bicuspid or mitral valve (2 cusps)
How do the chordae tendinae and papillary muscles work together?
The thin chordae tendinae attach to papillary muscles that contract just before the ventricles begin ejecting blood which creates tension to keep valves closed
Valves between right ventricle and pulmonary circuit?
Semilunar valves— Pulmonary valve
Valve between left ventricle and systemic circuit?
Semilunar valve— Aortic valve
Why do cardiac muscle cells not require stimulation from the nervous system?
Because their electrical activity is coordinated by a population of cardiac muscle cells called pacemaker cells that rhythmically and spontaneously generate action potentials that trigger the other type of cardiac cells known as contractile cells
Characteristics of cardiac muscle cells
- Striated
- Branched with single nucleus
- Shorter and wider than skeletal muscle cells
- Contain abundant myoglobin
- A lot of mitochondria
- Intercalated discs that join pacemaker cells to cardiac muscle cells
- Desomosomes and gap junctions
What are the sequence of events for CONTRACTILE CELLS
- Rapid depolarization phase
- Initial repolarization phase
- Plateau phase
- Repolarization phase
What does the plateau phase prevent?
Tetany by lengthening the refractory period, which allows the heart to relax and ventricles to refill with blood before the cardiac muscle cells are stimulated to contract again
Which node has the fastest rate of intrinsic depolarization?
The SA node; the rate is subject to influence from the sympathetic and parasympathetic nervous system; 60 APs per minute
Where is the SA node located?
Upper right atrium
Atrioventricular node?
Posterior and medial to the tricuspid valve; slower than SA node; 40 APs per minute
What is the purkinje fiber system?
The slowest group of pacemaker cells; 20 APs per minute; has 3 components including the atrioventricular bundle (AV bundle), right and left bundle branches, and terminal branches
What does autorhythmicity mean?
The heart does not require conscious intervention to elicit cardiac muscle to contract— cardiac muscle sets its own rhythm without a need for input from nervous system
What coordinates cardiac electrical activity?
Cardiac muscle cells called pacemaker cells, which rhythmically and spontaneously generate action potentials that spread to other type of cardiac muscle cells called contractile cells
What is significant about the AV bundle?
It is the only electrical connection between atria and ventricles
How are action potentials spread throughout cardiac muscle cells?
Gap junctions allow action potentials to spread rapidly
What happens at the AV node?
Conduction slows considerably because of less gap junctions and presence of nonconducting fibrous skeleton that surrounds AV node– Known as AV node delay
What is the purpose of the AV node delay?
It allows atria to depolarize and contract before the ventricles, giving the ventricles time to fill with blood. Action pote3ntial then conducted from AV bundle to right and left bundle branches and depolarization spreads along Purkinje fibers to contractile cardiac muscle cells of ventricles
What does the P wave represent?
Depolarization of all cells within atria except SA node
What does QRS complex represent?
Ventricular depolarization; hides atrial repolarization
What does T wave represent?
Ventricular repolarization
R-R interval?
Time between two successive R waves; represents entire duration of generation and spread of action potential; measured to determine heart rate
P-R interval?
Represents time it takes for depolarization generated by SA node to spread through atria to ventricles
Q-T interval?
Duration of ventricular action potential
S-T segment?
Flat, because it is recorded during the plateau phase of ventricles
What drives blood flow through the heart?
Pressure changes!!! Valves prevent backflow of blood.
What phase are the ventricles in during ventricular filling?
Ventricular diastole
What phase are the ventricles in during ventricular ejection?
Ventricular systole
What happens to pressure when ventricles contract?
Their pressures rise above those in right and left atria and in pulmonary trunk and aorta, which cause blood to flow into great vessels. AV valves CLOSE, SL valves OPEN
What happens to pressure when ventricles relax?
Pressures in ventricles fall below those in atria and in pulmonary trunk and aorta. Higher pressures in pulmonary trunk and aorta push semilunars closed. Higher pressures in atria forces AV valves open
When is S1 heard?
When AV valves close
When is S2 heard?
When SL valves close
What is beats per minute known as?
Heart rate
What is the amount of blood pumped into pulmonary and systemic circuits in 1 minute?
Cardiac Output
What is the blood pumped in one heartbear?
Stroke volume
What is the formula for cardiac output?
CO=HR x SV
How is stroke volume determined?
EDV- ESV
What is EDV?
End diastolic volume; amount of blood in ventricle after it has filled during diastole
What is ESV?
End systolic volume; amount of blood in ventricle at end of contraction
What are the three factors that influence stroke volume?
Preload, heart contractility, and afterload
What is ejection fraction?
Percentage of blood ejected with each ventricular systole; value should be equal for each ventricle
What is preload?
Length or degree of stretch of sacromeres in ventricular cells before they contract
What is a main determinant of preload?
End diastolic volume; EDV increases when ventricles spend more time in diastole because there is more time for them to fill with blood
What are two factors that influence EDV?
Length of time ventricles spend in diastole and amount of blood returning to right ventricle from systemic circuit (venous return)
What is the Frank- Starling law?
Relationship between preload and stroke volume. Increased ventricular muscle cell stretch leads to more forceful contraction. Because there is more stretch, there is a higher stroke volume
