LP #110 Understanding The Mechanics Of Heart Fxn & Coronary Circulation Flashcards
1
Q
Measures difference b/w the volume of blood in one ventricle at the end diastolic volume (EDV) & end systolic volume (ESV)
A
Stroke volume
2
Q
3 frank-starling law of the heart
A
- preload
- contractility
- after load
3
Q
- degreee of heart m stretch before m contracts
- determined by EDV
- critical factor controlling SV
- stretch: at rest: myocardial cells shorter than optimal length for contraction
- stretch applied to heart (diastole):
- myofibres lengthen
- decrease overlap of actin & myosin (optimizes force of contraction)
A
Preload
4
Q
- ability of myocardial cells shorten & compress ventricle
- independent of stretch & EDV
- affected by CA+ released from IF & SR
- increase influx of ca2+= increase contraction force= increase SV & CO
A
Contractibility
5
Q
- increase of stretch on myocardial cells= increase force of contraction= increase bald ejected
- excessive increase BVol in ventricles stretches myocardial cells beyond capacity= ineffective SV & decrease blood ejected -occurs in hypertension
A
Preload
6
Q
- P exerted by bold (aorta or pulmonary trunk) against a SL valve
- valve closes- allows P from incoming atrial blood to build in ventricle
- stretch’s ventricle
- ventricular P must overcome after load to open SL valves & eject blood from heart
A
After load
7
Q
- w/normal BP:
- afterloadis not major factor or SV
- but it is important in increase BP
- w/increase BP:
- increase after load= increase ventricular effort to overcome resistance & open Sl valve
- if afterload cannot be overcome:
- decrease SV & increase ESV
- compensatory effects increase workload= cardiac hypertrophy
A
Afterload
8
Q
- supplies myocardium
- body’s shortest vascular circuit
- begins w/ L & R coronary aa
- branches envelope & invade myocardium
- cardiac vv drain bled into coronary sinus, which drains into R atrium
A
Coronary circulation
9
Q
- group of disorders affecting myocardium
- 1’ (idiopathic), or
- 2’ to CV disease
A
Cardiomyopathies
10
Q
3 types of 1* cardiomyopathies
A
- dilated or congestive myopathies
- hypertrophic myopathies
- restrictive myopathies
11
Q
-fibrosis & atrophy of moycardial cells; dilation of heart chambers
A
Dilated or congestive myopathies
12
Q
- hypertrophy of one or both ventricles
- L ventricular hypertrophy is more common
- enlarged ventricle leads to decrease chamber volume= decrease SV
A
Hypertrophy myopathies
13
Q
-decrease ventricular filling d/t increase ridge Ty of ventricular wall
A
Restrictive myopathies
14
Q
In all myopathies cases s/s are
A
- dyspnea
- fatigue
- chest pn on exertion
15
Q
Structural changes in mardiomyopathies d/t
A
Hearts excessive workload
