Electrcal Control Flashcards
1
Q
Heart muscle is…
A
Myogenic
- can generate its own impulse/ contraction
- does not need to be stimulated by a nerve to make it contract
2
Q
ECG stands for…
A
ElectroCardioGram
3
Q
Sino-Atrial node
A
- Stimulus to contract originates in it
- Acts as pacemaker and in wall of right atrium
- Generates electrical impulse/ wave of excitation
- Transmitted across atria
- Causes depolarisation of atria and atrial systole
- May be stimulated by hormones, exercise, temp…
4
Q
Connective tissue
A
Prevents impulse/ stimulus form passing to ventricles and causing them to contract downwards
5
Q
AtrioVentricular Node
A
- At the bottom of the wall separating the atria
- Receives wave of excitation/ impulse from SAN
- Allows 0.1 second delay before wave passed to ventricles
- Prevents aria and ventricles contracting at the same time
- Allows ventricles to fill with blood before contraction
- Complete atrial systole - Passes impulse onto the Bundle of His in the septum
6
Q
Bundle of His and Purkyne/ Purkinje fibres
A
- Carries impulse from AVN to the apex of the heart
- Purkinje fibres spread cardiac impulse through walls of ventricles (conveyed upwards) to the top
- Causes ventricular systole
- They contract from bottom/ apex upwards
- No more conductive tissue and impulse terminates
- Heart goes into diastole
7
Q
Septum role
A
- Prevents direct transfer of wave of excitation to ventricles
- Atria and ventricles don’t contract at the same time
- Allows time for ventricles to fill
8
Q
P Wave
A
- SAN generates electrical impulse
- Depolarisation of atria
- Atrial systole
9
Q
PR Interval
A
Time taken for excitation to spread form atria to ventricles through AVN
10
Q
QRS Complex
A
- AVN passes on electrical impulse
- Through Bundle of His in the septum
- Depolarisation of ventricles
- Ventricular systole
11
Q
T Wave
A
- Repolarisation of ventricles
- Ventricular diastole/ relaxation of ventricles
12
Q
Exercise effect (2)
A
- Shorter distance between consecutive P waves
- Shorter PR interval/ segment
