6 - Cardiovascular system Flashcards
What are the three basic components of the cardiovascular system?
- Heart
- Blood vessels (passageway from heart to rest of body)
- Blood (medium that transports dissolved materials)
What is the difference between pulmonary and systemic circulation?
Pulmonary: vessels between heart and lungs
Systemic: vessels between heart and other body systems
Describe the basic anatomy of the heart
- Divided into right and left halves
- Four chambers:
- Atria (upper chambers, receive blood)
- Ventricles (lower chambers, pump blood from the heart)
What’s the difference between arteries and veins?
- Arteries: carry blood away from ventricles
2. Veins: return blood from tissues to atria
Describe the blood flow through the heart
- Right atrium receives blood from body, transfer to right ventricle, pumps into pulmonary circulation
- Left atrium receives blood from pulmonary system, transfers to left ventricle, pumps to the body.
Why is the left ventricular wall thicker than the right ventricular wal?
Because the right pumps to pulmonary, which is low-pressure, low resistance system
Because the left pumps to systemic circulation, which is high-pressure, high resistance system
Which ventricle pumps more blood?
They both pump the same volume! but at different pressures against different resistances
What are the four heart valves?
- Right atrioventricular valve
- Left atrioventricular valve
- Aortic valve
- Pulmonary valve
*They ensure that blood only flows in 1 direction (forward pressure: open, backward pressure: closed)
How does cardiac muscle pump blood? What is is made of?
- Arranged spirally around ventricle
- Contracts and causes wringing motion
- Contains skeletal, cardiac and smooth muscle
- Cardiac muscle cells are interconnected by desmosomes and gap junctions
- connection points called intercalated discs
What is the functional syncytium?
- When one cardiac cell undergoes an action potential, the impulse spreads to all other cells joined by gap junctions
- They all become excited through this process and contract as a single muscle mass (aka functional syncytium)
What is autorhythmicity?
- setting its own rhythm by generating potentials by itself (heart does this)
What are the two types of specialized cardiac muscle cells?
- Contractile cells (99% of cardiac muscle cells)
- Autorhythmic cells (initates action potentials) aka non contractile cells
- When the membrane potential reaches a threshold “pacemaker potential”, the membrane fires
Where are non-contractile cells found?
- SA node
- AV node
- Atrioventricular bundle
- Purkinje fibers
Describe the process of Cardiac excitation
- Impulse starts at SA node
- Action potential spreads through right and left atria
- Impulse passes from atria into ventricles through AV node
- Action potential briefly delayed at AV node
- Impulse travels fro interventricular septum by means of bundle of His
- Impulse disperses through myocardium by means of Purkinje fibres,
- Rest of ventricular cells activated by spread of impulses through gap junctions
What is the SA node?
- Known as pacemaker of the heart
- Heart beats at pace set by fastest rate of autorhytmicity (aka rate set by SA node)
What is the refractory period?
The time it takes for response after impulse
Na+ channel inactivation is the chief factor responsible for prolonged refractory period
The Na+ channel cannot be activated again until the membrane has repolarized to resting
What’s an ECG?
Electrocardiogram: record of overall spread of electrical activity through the heart during depolarization & repolarization
(comparison of voltage detected at diff points on body surface, not direct recording of actual electric activity of heart)
What are the three waveforms in an ECG record?
- P wave: atrial depolarization
- QRS complex : ventricular depolarization
- T wave: ventricular repolarization
What some examples of abnormalities in heart rate?
- Tachycardia: Rapid heart rate (>100 beats per minute)
- Bradycardia: Slow heart rate (<60 beats per minute)
- Rhythm: spacing of ECG waves
- Arrhythmia: variation from normal rhythm (atrial flutter, atrial fibrillation, ventrical fibrillation, heart block)
