3.1.2 e,f,g and h the heart Flashcards
what is the heart made of?
cardiac muscle
what supplies blood to the cardiac muscle?
coronary arteries
what is the heart surrounded by and why is it there?
inelastic pericardial membranes which help prevent the heart from over-distending with blood
where does the blood go after the right atrium?
slight pressure builds as blood flows in until the atrioventricular valve/ tricuspid valve opens to let blood flow into the right ventricle
where does deoxygenated blood enter the heart?
right atrium from the superior vena cava and the inferior vena cava
what happens when both the right atrium and ventricle are filled?
atrium contracts forcing all the blood into the right ventricle and stretching the ventricle walls
what happens when right ventricle starts to contract?
tricuspid valve closes to prevent any back flow of blood into the right atrium
what do the tendinous cords do?
make sure the valves are not turned inside out by the pressures exerted when the ventricles contract
what happens when the right ventricle contracts fully?
deoxygenated blood is pumped through the semilunar valves into the pulmonary artery which transport it to the capillary beds of the lungs
where does blood from the lungs go?
enters the left atrium from the pulmonary vein
what happens when pressure in the left atrium builds?
bicuspid valve opens so left ventricle fills with oxygenated blood
what happens when both left atrium and left ventricle are full?
atrium contracts forcing all the oxygenated blood into the left ventricle
what happens when the left ventricle contracts?
oxygenated blood is pumped through the semilunar valves into the aorta and around the body
what side of the heart has a thicker muscular wall?
left side has to produce sufficient force to overcome the resistance of the aorta and the arterial systems of the whole body and move blood everywhere in the body
what is the septum?
inner dividing wall of the heart which prevents the mixing of deoxygenated and oxygenated blood
what does the cardiac cycle describe?
the events in a single heartbeat which lasts about 0.8 seconds in a human adult
what does the heart do in diastole?
heart relaxes and the atria and the ventricles fill with blood
volume and pressure of the blood in the heart build as the heart fills but the pressure in the arteries is at a minimum
what does the heart do in systole?
atria contract and ventricles contract so pressure inside the heart increases and blood is forced out of the heart
volume and pressure of blood is low at the end of systole and blood pressure in arteries is at its maximum
what is atria contraction called?
atrial systole
what is ventricular contraction called?
ventricular systole
what is cardiac muscle?
myogenic
what does myogenic mean?
muscle is able to contract without an external stimulus
what is the basic rhythm of the heart maintained by?
wave of electrical excitation
where does the wave of electrical excitation begin and what happens?
begins in the pacemaker area called the Sino-atrial node causing the atria to contract which initiates the heartbeat
what separates the atria and the ventricles in terms of electrical conduction?
layer of non-conducting tissue
what picks up the wave of electrical activity from the SAN and what happens?
atrio-ventricular node picks it up and AVN imposes slight delay before stimulating the bundle of His
what is the bundle of His made from and what does it do?
made from a bundle of conducting tissue made up of Purkyne fibres which penetrate through the septum between the ventricles
splits into two branches and conducts the wave of excitation to the apex of the heart
what happens at the apex?
Purkyne fibres spread out through the walls of the ventricles on both sides and the spread of excitation triggers the contraction of the ventricles starting at the apex
what is the recording of electrical activity of the heart called?
electrocardiogram
what is tachycardia?
heartbeat is very rapid, over 100 bpm
may be caused by problems in the electrical control of the heart
treatments for tachycardia?
relaxation therapy
beta-blockers
what is bradycardia?
heart rate slows down to below 60 bpm
many people have it because they are fit or caused by drugs
severe may need a pacemaker
what is ectopic heartbeat?
extra heartbeats that are out of the normal rhythm
what is heart block?
separation of the p wave and the qrs complex
delay in conduction between atria and ventricles
what is hypertrophy?
p wave and atrial contraction is normal
qrs complex is distorted due to hypertrophy of one side of the heart
hypertrophy means enlargement
could be caused by high blood pressure
what is ventricular fibrillation?
cardiac muscle is contracting normal
ventricles contract but it is not coordinated
what is a flat line?
no electrical activity in the heart
what is a hole in the heart?
have it at birth between atria or ventricles
allows mixing of oxygenated and deoxygenated blood
dangerous if not treated as pressure is reduced and less O2 is carried so less respiration
