Chapter 18: Heart Flashcards
What are chordae tendinae?
the strings attached to the heart valves that keep the valve from reversing (heart strings)
What is the foramen ovale botalli?
An inter-atrial opening to bypass the lungs in a fetus (because the lungs are filled with liquid)
When does the foramen ovali botalli close?
when the baby is born
What is the bypass between the pulmonary artery and aorta called?
ductus arteriosus
What does the ductus venosus do?
it is an umbilical vein that brings blood to the vena cava (in a fetus)
The heart pumps blood to the rest of the body, but the heart also needs its own blood supply which is provided by _______ via the ________
Coronary arteries via the right atrium
What are the three layers of the heart wall?
epicardium, myocardium, and endocardium
Define epicardium:
the outermost layer, the visceral layer (space without friction)
Define myocardium:
muscle of the heart, cardiac muscle
Define endocardium:
white sheet of endothelium resting on CT layer, it lines the inside of the heart wall
Plasma membrane of cardiac cells interlock via __________.
intercalated discs
Intercalated discs contain anchoring __________ and ______.
desmosomes and gap junctions
The atria and ventricle cells are _______ by gap junctions because ___________________________.
not connected, if they were, the whole heart would contract at the same time and blood wouldn’t flow through properly (atria cells are connected to other atria cells via gap junctions, but atria cells are not connected to ventricle cells by gap junctions)
_______ are what hold the intercalated discs together during contraction.
desmosomes
Syncytial:
one cell depolarizes, the signal gets transmitted to others
Where is the calcium (used in a cardiac action potential) stored?
the sarcoplasmic reticulum
What happens in stage 0 of the cardiac action potential?
cell is at -90mV, depolarizes, Na opens and goes inside (to make more positive)
What happens in stage 1 of the cardiac action potential?
~35+, Na closes, K opens, K goes out (more positive)
What happens in stage 2 of cardiac action potential?
Ca is released (plateau)
What happens in stage 3 of cardiac action potential?
Ca closes
What happens in stage 4 of cardiac action potential?
K closes
You could simplify the stages of a cardiac action potential to three stages: ________, __________, and _________
- Depolarization (due to Na influx) 2. Plateau phase (due to Ca influx, few K channels open) 3. Repolarization (Ca channels close, K opens until -90mV is reached)
How long does a cardiac action potential take?
~200 milliseconds