Lecture 4 - Cardio Cycle and Circulation Flashcards
How long does the PQRST process take?
0.51 seconds
What happens to the heart rate during strong sympathetic stimulation?
The T-P interval, which is where the EKG flatlines between peaks, shortens and can disappear (increasing HR).
What happens during sinoatrial block?
Impulses from SA node are blocked, AV node is the new pacemaker, one PQRS-T wave skipped.
What happens during ventricular fibrillation?
Some parts of ventricle contract while others relax, no coordinated contraction, fatal. Circus movements.
How ventricular defibrillation is used to rectify fibrillation:
1000V DC applied for a few thousandths of a second, all heart becomes refractory, 3-5 seconds after a new pacemaker established.
Needs to be used fast, within 1 min of fibrillation.
What is atrial flutter?
Single large impulse travels around atria in one direction, atria can beat 2-3 times faster than the ventricle.
What is atrial fibrillation?
Often caused by atrial enlargement. Long conduction pathway, gives circus movements in atria - irregular and fast movements in atria.
What is the result of atrial fibrillation?
No fatality, efficiency of pumping is however decreased by about 20-30%.
What happens during cardiac arrest, and how can you fix it?
No electrical activity in the heart. Will need new pacemaker or prolonged CPR to reestablish rhythm.
What are the four major functions of the circulatory system?
- Transport nutrients and hormones
- Transport waste away from tissues
- Maintain constant temperature
- Maintain homeostasis generally
Blood flow is controlled in relation to…
Tissue requirements
eg how circulation can increase or decrease in digestion vs running
Cardiac output is controlled by….
Local tissue flow - think Frank-Starling
Arterial pressure is…
Independent of local blood flow control or cardiac output control. It’s all about regulating circulation of the organism as a whole.
Qualities of aorta and large arteries
Blood is under high pressure, high flow volume and velocity, any severe constrictions or aneurisms are fatal.
Qualities of arterioles
They exist within organs, have strong muscular walls, and can constrict to almost no flow - major site of resistance.
