The heartbeat Flashcards
What does myogenic mean?
has its own intrinsic rhythm…
prevents the body wasting resources maintaining the basic heart rate
What is the pacemaker of the heart?
sino-atrial node.
.. emits a wave of electrical excitation that causes the atria to contract… this initiates the heart beat..
. a layer of non-conducting tissue prevent the excitation passing directly to the ventricles
How is the signal relayed to the ventricles? part 1
the signal from the SAN is picked up my the atrio-ventricular node..
. the AVN imposes a slight delay before stimulating the purkyne fibres (bundle of His) which penetrate through the septum, between the ventricles…
collagen tissue prevents the wave of electrical activity from being passed directly
How is the signal relayed to the ventricles? part 2
bundle of His splits into two branches and conducts a wave of excitation at the bottom of the heart..
. the purkyne fibres are spread thorugh the walls at the apex of the ventricles on both sides.
.. contraction starting at the apex allows more efficient emptying of the ventricles…
Why is there a delay?
to make sure the atria have stopped contracting before the ventricles start…
What is an electrocardiogram?
a recording of electrical activity in the heart.
.. measures electrical differences in your skin which result from electrical activity of the heart…
usues electrodes…
What is tachycardia and bradycardia?
tachy - when the heart is very rapid, over 100bpm.
.. brady - when the heart rate slows down to 60bpm …
What is a ectipopic heartbeat?
are out of normal rhythm …
can be linked with serious conditions when frequent…
What is atrial fibrillation?
an example of an arrhythmia.
.. rapid electric impulses generated in the atria…
they can fibrillate up to 400 times a minute…
they dont contract properly and only some impulses are passes to the ventricles which contract much less often..
. very uneffective
wHAT ARE the parts of the ECG trace? Where are the sounds?
- P waved caused by contactopm (depolarisation) of the atria
- QRS complex
- main peak of heartpeat
- together with dipos at either side
- caused by the contraction (depolarisation) of the ventricles
- T wave is due to the relaxation (repolarisation) of the ventricles
he information from Fig. 16.4, what conclusions can you draw about the way in which this person’s heart is functioning abnormally?
- no distinct, P curve / atrial depolarisation irregular / weak,
- atrial contraction insufficient blood forced into ventricles
- although ventricles contract there is less blood forced from the heart
The most obvious feature of tachycardia is an increased heart rate. Using the information in Fig. 16.1, Fig. 16.2 and Fig. 16.3, what are other key features of tachycardia?
- lower (Q)R(S) peak
- P and T equal in height
- width of T wave greater
What are the letter of the ecg trace?
Where is the sino-atrial node located
wall of right atrium
What does the heigh of the ECG wave indicate?
- how much charge is passing through the heart
- a bigger wave means more electrical charge
- this means there is a stronger contaction
