Heart Flashcards
What is the function of the heart?
4-sectioned pump
Continuously pumps blood around the body
Hub of the body’s transportation system
What forms the heart?
Muscle tissue
Stimulated by electrical activity
What does the electrical activity of the heart ensure?
Heart pumps in the right sequence, rate, and power for the body’s needs
Briefly describe the mechanism of the heart pumping…
Deoxygenated blood arrives into right atrium from the inferior vena cava
Oxygenated blood arrives into the left atrium via pulmonary veins from the lungs
Atria contract-eject blood into ventricles via tricuspid valve (right) and mitral valve (left)
Ventricles contract- eject deoxygenated blood to lungs via pulmonary artery (on right) and oxygenated blood to the body via aorta (on left)
What initiates the heartbeat?
Initiated by the sinoatrial node (SAN)
What is the cause of a P wave?
Electrical impulse from SAN to AVN
Atria contract
What is the cause of the QRS wave?
Corresponds to electrical impulses in ventricular muscles and proceeds ventricular contraction
Electrical stimulus passes from bundle of His into bundle branches and purkinje fibres
More voltage required to cause ventricular contraction so wave is much bigger
What is the cause of T waves?
Repolarisation
How does adrenaline affect electrical activity of heart?
Released by the sympathetic system or given as a drug
Increases HR by increasing number of electrical impulses per min from the SAN
Speed of atrioventricular impulses
What is the effect of nicotine in electrical activity?
Increases HR by stimulating secretion of adrenaline
What is the effect of caffeine on electrical activity?
Increases HR by blocking certain enzymes that keep HR controlled
Affect repolarisation rate in certain parts of heart
Induces arrhythmias
What is the effect of digoxin on electrical activity?
Slows down AV conduction
Reduced ventricular rate
