Cardiovascular Flashcards
Define an artery
Thick-walled, muscular vessels that carry blood away from the heart
Usually carry oxygenated blood; the exception; the pulmonary arteries
They have the ability to dilate and contract due to signals from the nervous system
They help to regulate blood pressure together with contraction of the left ventricle
Smallest arteries are called Arterioles.
Define a vein
Thin walled blood vessels that carry blood to the heart
Usually carry deoxygenated blood; the exception; pulmonary veins
Veins have valves which keeps blood moving in one direction – back up towards the heart.
Valves are necessary as veins operate under low pressure
Define a capillaries
Between the tiny Arterioles and Venules, at tissue level, are a network of blood vessels called Capillaries
•They are the smallest of all blood vessels, microscopic, have thin walls, and are only one cell thick
•They contain less than five percent of the total circulating blood volume at any one time
•About ten billion capillaries lace all body tissues, bringing blood and therefore oxygen and nutrients within reach of every cell.
What is the tunica adventitia
Outer fibrous sheath
What is the tunica íntima
Inner lining
What is the tunica media
Middle - elastic muscle tissue
◦Larger in arteries
Define the lumen
oInner channel of smooth muscle through which blood flows freely
Define the mediastinum
The Mediastinum refers to the space between the lungs that extends from the sternum, back to the vertebral column
Where is the base of the heart
is at the top anatomically, where the main vessels enter and exit the chambers.
Where is the apex of the heart
the point of the heart; lies at the bottom, on the diaphragm (at the 5th intercostal space)
What is the endocardium
The inner lining of the hearts chambers
•Smooth glistening layer of epithelial cells
•Allows for smooth blood-flow through the chambers
•Continuous to the inner lining of the blood vessels.
What is the myocardium
Muscular part of heart
•Allows for the pumping action of the heart
•It makes up most of the bulk of the heart.
•The highest percentage of muscle is around the left ventricle.
What is the pericardium/ epicardium
The outer layer of the heart
•The visceral layer is called the Epicardium
•It secretes the serous fluid.
•Pericardial cavity contains the serous fluid
•Prevents friction during heart contractions.
•Surrounded by the fibrous sac enclosing the heart to which the parietal layer is fixed.
What is the superior vena cava
The largest vein in the body
•Transports deoxygenated blood from the head, arms and upper body into the right atrium
What is the inferior vena cava
Transports blood from the lower body to the right atrium
What is the function of the right atrium
Receives blood from both Vena Cavae.
◦Blood is pushed through the tricuspid valve into the right ventricle
What is the function of the right ventricle
Receives blood from the right atrium and pushes blood through the pulmonary/pulmonic valve into the Pulmonary Arteries
What do the pulmonary arteries
The pulmonary artery carries blood from the right side of the heart to the lungs
•The only artery that carries de-oxygenated blood
•It divides into two branches – one for each lung
•Gaseous exchange occurs in the alveoli.
What is the function of the pulmonary veins
Following metabolic gaseous exchange…
•The pulmonary veins carry blood from the lungs to the left side of the heart
•The only veins that carry oxygen-rich blood
•There are four pulmonary veins, two from each lung
What is the function of the left atrium
Receives blood from the pulmonary veins.
•Blood is then pushed through the Mitral/Bicuspid valve into the left ventricle
What is the function of the left ventricle
The main pump
•Receives blood from the left atrium and pushes blood through the Aortic Valve into the Aorta.
What is the aorta
The body’s largest blood vessel, arches out of the heart and down toward the lower body
•Carries oxygenated blood to the whole body
The aorta is divided into several parts:
•the ascending aorta
•the arch of the aorta
•the thoracic and abdominal portions of the descending aorta
What is the function of the coronary arteries
The exclusive arterial blood supply to the heart muscle and electrical conduction system
•They originate in the aorta just above the aortic valve
•This system of small arteries that branch from the Aorta, cross over the hearts surface, dividing and sending tiny branches into the heart muscle
•There are 2 main coronary arteries
◦The left coronary artery
◦The right coronary artery
What is the function of the left coronary artery
Left Coronary Artery
•Supplies the left ventricle, the intra-ventricular septum, and part of the right ventricle
•Anterior descending branch
•Circumflex branch
What is the function of the right coronary artery
Right Coronary Artery
•Supplies the right atrium and ventricle and part of the left ventricle
•Posterior descending branch
What is the definition of cardiac electrophysiology
An electrophysiology (EP) study is a test performed to assess your heart’s electrical system or activity and is used to diagnose abnormal heartbeats or arrhythmia.”
Define automaticity
Cells can depolarise without any impulse from outside source ( a process called self excitation)
Define excitability
Cells can respond to an electrical stimulus
Define conductivity
Cells can propagate the electrical impulse from cell to cell
Define contractility
The specialised ability of the cardiac muscle cells to contract
What is the SA node
◦60 to 100 bpm
•Heart’s normal pacemaker
◦Located in the wall of the right atrium near where the superior vena cave enters the heart
Define the internodal pathways
The internodal pathways consist of three bands, (anterior, middle, and posterior), that lead directly from the SA node to the next node in the conduction system, the atrioventricular node. The impulse takes approximately 50ms (milliseconds) to travel between these two nodes.
Define the Bachmanns bundle
Bachmann’s bundle (BB), also known as the interatrial bundle, is well recognized as a muscular bundle comprising of parallel aligned myocardial strands connecting the right and left atrial walls and is considered to be the main pathway of interatrial conduction.
Define the atrioventricular node
Located near the atrioventricular valves
◦Stimulated by the impulse from the SA node
◦Electrically connects the atria and ventricles
◦Capable of initiating impulses
◦If SA node fails, the AV node should take over the pacemaker function
◦40-60 bpm approximately
Define the bundle of his
Electrical pathway from AV node to the ventricles
◦Divides into left and right bundle branches at top of inter-ventricular septum
Define the right bundle branch
Located in the right ventricular septum
◦Conducts impulses from right Bundle of His to Purkinje fibres in right ventricle
Define the left bundle branch
Located in left ventricular septum
◦Conducts impulses from left Bundle of His to Purkinje fibres in left ventricle
Define the purkinje fibres
Spread from base of septum into the walls of the ventricles
◦If both nodes, (SA and AV), fail to initiate an impulse, the fibres can initiate an impulse, (approximately 20-40 bpm).
Define the isoelectric line
baseline or isoelectric line, is represented as a straight line on the ECG paper where there is no positive or negative charges of electricity to create deflections.
Define depolarisation
Depolarisation is the process or the act by which polarity is eliminated. Depolarisation is essential because it allows the transmission of electrical signals (impulses) within the cell, and in certain instances, from one cell to another.
Define repolarisation
Repolarisation of the heart is the orderly return of each cell to its polarised state, cell by cell, until all are polarized again.
Define systole
Refers to the contraction / active phase of a chamber
•Occurs when the muscle reacts to electrical activity
•Blood will be pushed from the chambers.
Define diastole
Refers to the relaxation phase of a chamber.
•While relaxed, the chambers should fill with blood
How long does the cardiac cycle take to complete in a healthy adult
0.8 seconds
How long does contraction of the atria take
0.1
How long does ventricular systole( contraction of the ventricles ) take
0.3 seconds
How long does relaxation of the atria and ventricles take
0.4 seconds
What is stage one of the heartbeat cycle
Atrial systole (stage 1)- contraction
◦Impulse from the SA node initiates this phase
◦Atria contract, squeezing blood into the ventricles
What is stage two of the heartbeat cycle
Ventricular Diastole (stage 2)- relaxation
◦At the same time as the Atria contract, the ventricles relax and fill with blood from the atria. Most blood is filled passively through gravity, and the remainder through atrial contraction
What is stage 3 of the heartbeat cycle
Ventricular Systole (stage 3)- contraction
◦The ventricles contract
◦Pulmonary and Aortic Valves open and blood is forced into the pulmonary artery and the aorta
What is stage 4 of the heartbeat cycle
Atrial Diastole (stage 4)- relaxation
◦Deoxygenated blood enters the right atrium from Vena Cava
◦Oxygenated blood enters the left atrium from Pulmonary Veins
Define the T wave
Repolarisation of the atria and ventricles.
◦Following the heartbeat and the dual-pumping of blood from the heart’s chambers, the cells need to recharge to facilitate the next cycle.
Define an electrocardiogram
An Electrocardiogram is a recording of the heart’s electrical activity; over a period of time; as series of waves and complexes which is then displayed as a graph to record what has been assessed.
How long is one small square on a ECG
0.04
How long is one large square on a ECG paper
0.2 seconds
How long is 5 large squares on a ECG paper
1 seconds
How long is thirty large squares on a ECG paper
6 seconds
How long is the PR interval
0.12 - 0.2 seconds
How long is the QRS complex
<0.12 seconds ( less than 3 small squares)
Define the P wave
06/04/2022
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•P-Wave
◦Represents depolarisation (electrical activity) of the atria
◦Impulse from the SA node initiates this phase.
◦Is usually followed by contraction of the atria.
Define the PR interval
Depolarisation of the Atria and the delay at the AV Junction
◦This phase is normally 0.12 – 0.20 seconds OR 3 – 5 small squares.
Define the QRS complex
Represents depolarisation (electrical activity) of the ventricles
◦This phase is normally 0.12 seconds OR 3 small squares.
◦Is usually followed by contraction of the ventricles
Define the ST segment
oThe line from the end of the QRS Complex to beginning of the T-Wave
oIt should be at the same level as the iso-electric line
oAn elevated OR depressed ST segment may indicate myocardial ischaemia or injury.
Define the T wave
Repolarisation of the atria and ventricles.
◦The atrial repolarization wave is small and is buried within the QRS complex.
◦The larger ventricular T wave follows the QRS complex, and is visible on the ECG.
Define the RR interval
The time elapsed between two successive R waves of the QRS Complexes
•It represents the interval between two ventricular depolarisations (contractions) and gives an indication of Heart Rate.
