ECG--Med surg 716-723 Anatomic and physiological overview Flashcards
does the mitral valve have oxygenated or deoxy blood flowing past it
tricuspid?
during diastole are they open or closed. What closes them?
mitral is oxy (bet left ventricle and atrium)
tricuspid is deoxy between right atrium and venricle
. During diastole they are open. With ventricular systole the ventricles contract and blood flows up into the cusps of the tricuspid and mitral valvesclosing. The chordae tendineae and papillary muscles maintain closure as P increases (the papillary muscles keep the tendineae taut) which prevents backflow of blood.
how much fluid is there in the pericardial sac
what is diastole
20ml
- Diastole-relaxation ohase when all 4 chambers relax simultaneously-ventricular filling occurs
- atrial systole occurs first and then ventricular systole
how many pulm veins empty into L atrium
• L atruum receives oxy blood from 4 pulm veins
wat is the pressure that the left and right venticles must overcome to eject the blood (separate values for each)
• During ventricular systole the R and L ventricles must overcome resistance to blood flow from pulm and systemic circ. Right sided P is 15-25mmHg and L is 110-130.
how does venous blood from coronary veins get returned to heart
through coronary sinus in Rt atrium
how does the atria contracting first contribute to cardia output inc
• Contraction of atria before ventricles allows the Vs to fill completely to maximize CO
what are the 3 characteristics of the nodal and purkinje cells that lead to synchronization of the cardiac electrophysiology
Automaticity (ability to initiate an electrical impulse). Excitability (ability t respond to an electrical impulse). Conductivity (ability to transmit an electrical impulse from one cell to another)
where are the AV and SA nodes
how does the signal travel between the two
- SA—located at junction of superior vena cava and R atrium–and AV ndes are made of nodal cells
- SA signal is conducted along myocardial cells via intermodal pathways that stim contraction and transmit impulse to the AV node, in the R atrial wall near tricuspid valve
how does SA travel through the rest of the heart (which structures/nodes)
• SA node to AV node to bundle of his (a bundle of specialized conducting tissue) that divides into L and R bundle branches that then transmit impulses to L ventricle via the L posterior and L anterior bundle branches. It terminates in the Purkinje fibres then leads to V contraction
which area normally determines the rate.
what do the other pacemakers run at
• HR determined by myocardial cells w fastest firing rate
SA Node - Dominant pacemaker with an intrinsic rate of 60 – 100 BPM
AV Node - Back-up pacemaker with an intrinsic rate of 40 – 60 BPM
Ventricular cells - Back-up pacemaker with an intrinsic rate of 20 – 40 BPM
what is atrial kick when does it occur
and is it good or bad
the priming force contributed by atrial contraction immediately before ventricular systole that acts to increase the efficiency of ventricular ejection due to acutely increased preload
(this occurs during the delay that occurs when the impulse travels from the AV node to the bundle of His)
it inc the amount in the ventricles by 15-25%
which vessel supplies blood mainly to the right side of the heart
The right coronary artery supplies blood mainly to the right side of the heart.
what does the left coronary artery branch into
The left coronary artery, which branches into the left anterior descending (LAD) artery and the circumflex artery, supplies blood to the left side of the heart
what lytes are involved in cardiac action potential
which are normally intracellular and which are extra
which goees through slow channels and which goes through fast channels
Na, K , Ca2+.
K intra and Na extra
Ca has slow channel and Na is fast
During relative refractory period the cell may depolarize prematurey if…?
what can this lead to
if the stimulus is greater than normal
dysrhtyhmia
