L4 Cvs Flashcards
Electrical conduct in heart
SA node
create electrical impulse
Generate automatic rhythm action potential
Stimulate atrial contraction
AV node
Receive signal from SA node
AV delay: allow atria completely contract before ventricle
R / L bundle branches
Extend to apex of heart
Purkinje fibres
Carry signal up to ventricle
Stimulate contraction of ventricle
ECG explanation
P wave: atrial depolarisation
None: atrial repolarisation
QRS wave: ventricular depolarisation
T wave: ventricular repolarisation
Cardiac cycle
- Atrial systole
SA node emit action potention
Atrial contract while ventricle relax
AV valve open, semi lunar valve closed
Blood flow from atrial to ventricle - Ventricular systole
Ventricle contract while atrial return to relax
AV valve close to prevent backflow
Blood eject from ventricle to arteries & aorta - Complete diastol
Atrial pressure < ventricular pressure, blood back-flow into atrial
Semilunar valve closed
Heart refilled, ready for another cardiac cycle
Blood vessels big to small
Artery
Arterioles
Capillary
Venules
Veins
Structure of blood vessel
In to out
Tunica interna
Smooth surface
Tunica media
Compound of smooth muscle & elastic fibre
Contribute on the compliance and elastance of the vessel
Separated by internal elastic membrane and external elastic membrane
Tunica externa
Collagen and elastic fibre
Connective tissue
Vein take 65% of blood
Venous return
Skeletal muscle pump
-contracting muscle massage and to tsqueeze the blood back to the heart
Valve
Prevent backflow of blood, unidirection of blood to heart
Respiratory pump
Thoracic pressure decrease when breathing in, promote blood flow to inferior vena cava
Factors affecting cardiac output
Preload
Larger then greater output
Afterload
Greater then higher resistance
Myocardial contractility
RR
Blood pressure control mechanism
Sensor: Chemoreceptor
Effect: decrease o2 -) increase of rr & hr
Control blood volume & cardiac output
CVD
Hypertension
>130 > 80
Septal defects
1.atrial Septal Defect
2. Ventricular Septal Defect
3. Atrioventricular Septal Defect
Mixing of blood / HT / Heart enlargement
Arrhythmias
1. Hypertension
2. Hypotension
3. Irregular rhythm
Solution: medicine / surgery / implanted device
Pericarditis
Swelling of heart
Valve disorder
Insufficient blood passing through
Angina pectoris
Chest pain due to blockage of coronary blood flow
(Myocardial infarction) full blockage of coronary blood flow
Atherosclerosis
Thicken of artery wall, reducing blood flow -) stroke / heart attack
