8.5 The Heart Flashcards
What are the atria?
upper chambers of the heart
Describe the muscular walls of the atria:
THIN
LITTLE PRESSURE/FORCE required
to push blood over short distance into ventricles
What are the ventricles?
lower chambers of the heart
Describe the muscular walls of the ventricles:
RIGHT: thinner»_space; less pressure/force required to push blood over shorter distance to lungs.
LEFT: thicker»_space; more pressure/force required to push blood over longer distance to body.
What are the valves in the heart and what are their functions?
BICUSPID: LA ⟶ LV
TRICUSPID: RA ⟶ RV
SEMILUNAR: V’s ⟶ out
What is the function of the tendinous cords?
anchors valves
preventing them from inverting
What is the function of septum?
SEPARATES oxygenated + deoxygenated blood
What veins are involved with the heart?
PULMONARY: lungs ⟶ heart
VENA CAVAE:
superior: upper body ⟶ heart inferior: lower body ⟶ heart
What arteries are involved with the heart?
PULMONARY artery: heart ⟶ lungs
AORTA: heart ⟶ body
CORONARY ARTERIES: supply heart muscle
What is the cardiac cycle?
series of events
in 1 heart beat
diastole + systole
What is diastole?
PHASE of cardiac cycle
when heart muscle RELAXES
What is systole?
PHASE of cardiac cycle
when heart muscle CONTRACTS
split into atrial systole + ventricular systole
What occurs during diastole?
muscle are relaxed
chambers FILL with blood
What occurs during atrial systole?
atria contract
PRESSURE pushes blood through atrioventricular (bi/tricuspid) valves ⟶ ventricle
Which systole occurs first?
atrial
What occurs during ventricular systole?
ventricles begin to contract
- pressure builds, closes AV valves, not enough pressure to open semilunar valves. All valves closed @ this point.
pressure builds enough to open semilunar valves
atria + ventricles relax
- semilunar valves shut.
The left and the right side of the heart fill and empty…
together
Describe the rhythm of the heart in term of electrical impulses:
- Electrical impulse originates in SAN.
- atria contact
- layer of conducting tissue prevents signal passing to ventricles.
- Electrical impulse travels to AVN
- slight PAUSE to allow atria to finish contracting.
- Bundle of his carries electrical impulse ⟶ APEX, branches into walls
- ventricles contract from bottom
What is the normal heart rate?
70bpm
What heart rate is tachycardia?
> 100bpm
What is an ectopic heartbeat?
extra beat outside rhythm
What is atrial fibrillation?
atria constantly relaxing + contracting
blood circulates less efficiently
What is an ecg trace of a single heartbeat made from?
P wave
Q R S complex
T wave
What does the P wave of a heartbeat ecg indicate?
electrical impulse travelling through atria
What is the QRS complex?
electrical impulse travelling through ventricles
What does the T wave of a heartbeat ecg indicate?
dissipation of electrical impulse / recovery wave
What does an ecg measure to create a trace of the heartbeat?
changes in SKIN’S ELECTRICAL CONDUCTIVITY
as a result of HEART ACTIVITY.
