Chapter 35 - Assessment: Cardiovascular Sx - Exam 2 Flashcards
(211 cards)
The heart is composed of 3 layers:
- a thin inner layer, ______
- a layer of muscle,_______
- an outer layer, _________
endocardium
myocardium
epicardium
A fibroserous sac called the __________ covers the heart
pericardium
The cusps of the mitral and tricuspid valves are attached to thin strands of fibrous tissue called
chordae tenineae
the p wave represents
depolarization of the atria
(contraction)
the QRS wave represents
depolarization from the av node to the ventricles
(ventricular contraction)
the t wave represents
repolarization of ventricles
(relaxation)
the u wave represents
repolarization of the purkinje fibers,
(relaxation)
a large u wave may represent hypokalemia
During ventricular contraction (depolarization), the tricuspid and mitral (atrioventricular valves) are
closed
During ventricular contraction (depolarization) the pulmonic and aortic (the semilunar valves) are
open
During ventricular relaxation (repolarization) the tricuspid and mitral (atrioventricular) valves are
open
During ventricular relaxation (repolarization) the pulmonic and aortic (semilunar) valves are
closed
Nodal (SA or AV node) and Purkinje electrical cells
Characteristics:
1. automaticity
- they initiate electrical impulse
Nodal (SA or AV node) and Purkinje electrical cells
Characteristics:
2. excitability
- they respond to electrical impulse
Nodal (SA or AV node) and Purkinje electrical cells
Characteristics:
3. conductivity
- they have an ability to transmit electrical impulse
SA node - what is it commonly called? and how many beats/min?
pace maker (primary one)
60-100 b/min
AV node - if the SA node fails, how many b/min can it produce
40-60 b/min
If the SA and AV node fail, how many beats/min can the ventricular cells produce?
30-40 b/min
_______. ________, and calcium contain ions that stimulate myocytes to exchange an electrical charge and contract
sodium, potassium
when the heart contracts this is called
depolarization
Once the myocytes discharge their energy and contract, the then rest and recharge, this is called
repolarization
________ moves through the fast channels to create fast depolarization (contraction) of myocytes
sodium
SA and AV nodes depolarize when ________ enters the electrical cells
calcium
the myocardial cells need to repolarize during ________periods
refractory
heart muscle cells have a compensatory mechanism that makes them unresponsive or _________ to restimulation during action potential
refractory