T2 U2 Physiology of the heart Flashcards
Which 2 systems regulate heart activity
Autonomic system nerves
Nodal System [ Intrinstic Conduction System]
Muscle depolarization from atria to ___ is caused by___
Ventricle.
Intrinsic conduction
Name the 5 conduction pathways of the conduction system
SA node AV node AV bundle Bundle Branches Purkinje fibres
The SA Node is a pacemaker in ____
The Right atria
What is the function of the AV node
Gap junction of Atria and ventricles. Allows SA Node depolarization to spread to atria and ventricles
Why is there a delay b/w impulses in the AV node
Allow atria / ventricles to contract completely
Another name for AV bundle ?
Bundle of His
Where is Bundle of His loctaed
In interventricular septum
Purkinje fibres spread in muscles of
Ventricle wall
Function of purkinje fibres
Carry impulse f/r L + R bundle branches to Ventricular Myocardium
Name and explain the 2 homeostatic imbalnces that can arise from conduction errors
Tachycardia = Abnormal rapid HR Bradycardia = Abnormal slow HR
ECG stands for
Electrocardiogram
Name the waves seen on an ECG, and what they represent
P Wave - Atrial Depolarization
QRS complex - Ventricular Depolarization
T wave - Ventricular repolarization
Name and explain the 4 homeostatic imbalances that ecg will pick up
Myocardial infarct - Heart attack
Heart block - HB too slow b/c signals are blocked
Ischemia - Not enough blood supplied
Fibrilation - Irregular HB
Define:
Systole
Diastole
Cardiac Cycle
Systole - contraction of ventricles
Diastole - Relax ventricles
Cardiac Cycle - Complete HB
Name and explain the 3 periods of the cardiac cycle
Mid-to-late diastole - Heart relax = PSI low. SL valve closed, AVV open. Atria contract = force blood to ventricles
Ventricular Systole - AVV closed, PSI Increased, SLV open = blood flow out, atria relax and fill w/ blood
Early diastole - Ventricles relaxed. SLV closed, Ventricles closed. Inter Ventricular PSI drops, AVV open and ventricles refill
Abnormal heart sound
Murmur
What is Cardiac output
blood pumped by ventricle per minute
what is stroke volume
vol. blood pumped by ventricle per HB
When would cardiac output incr.?
If SV or HR or both incr.
How is the SV regulated
Starlings law = more stretch = more blood pumped. If one side pumps more = higher venous return to opposite side in order to pump equal amounts
What factors modify the HR?
Neural ANS control - emotional/ physical stress
Adrenaline
Ions - electrolyte imbalances eg: Sodium/ potassium, calcium insufficiency/ overload
Exercise
