2 week 9 Flashcards
the heart = muscular pump that drives the flow of blood through _______
blood vessels
what is vasculature?
blood vessels carry blood from heart to organs to heart again (“closed system”)
diff bw superior and inferior vena cava?
superior: carries blood from above diaphragm
inferior: carries blood from below diaphragm
aorta is related to which ventricle/circuit?
aorta = left = systemic circuit
pulmonary artery is related to which ventricle/circuit?
pulmonary artery = right = pulmonary circuit
order of cardiac cycle?
- right atrium
- tricuspid valve
- right ventricle
- pulmonic valve
- pulmonary arteries
- pulmonic veins
- left atrium
- mitral valve
- left ventricle
- aortic valve
- aorta
in ___ capillary beds, oxygen ENTERS blood and carbon dioxide EXITS
pulmonary
in ___ capillary beds, oxygen EXITS blood and carbon dioxide ENTERS
systemic
the heart muscle obtains most of its nourishment from blood via the _____
coronary arteries
what are the 2 advantages of the parallel arrangement of organs in the systemic circuit?
- each organ is fed by a separate artery (fresh blood!)
- blood flow can be independently regulated (to match the changing metabolic needs of organs!)
when atrial pressure is higher than ventricular pressure, the AV valves; when ventricular pressure becomes higher than atrial pressure, the valves .
open
close
atrioventricular (AV) valves control blood flow between ___ and ___
atria and ventricles (duh!)
left AV valve is ___cuspid while right AV valve is ___cuspid
left = bicuspid (mitral)
right = tricuspid
when ventricles relax, the AV valve is ___.
when blood enters the atria, valve cusps are in the ___.
open
ventricles
when ventricles contract, the AV valve is ___.
contraction of ____ muscles tightens _____, preventing prolapse.
closed
papillary muscles
chordae tendineae
aortic semilunar (SL) valve connects the ___ and ___
aorta
left ventricle
pulmonary SL valve connects the ___ and ___
pulmonary artery
right ventricle
when ventricles contract, the aortic SL valve is ___.
blood enters the _ and _.
open
aorta and pulmonary artery
when ventricles relax, the aortic SL valve is ___.
closed
what happens in mitral valve disease? therapies for it?
heart must work harder to deliver the same amount of oxygenated blood (changes shape)
therapies = drugs to inhibit calcification, valve replacement surgery
many valve designs exist but all enable ____
one-way flow
what determines the heart rate?
depolarization of SA node
whats the pathway of depolarization in the heart? (4)
- SA node
{internodal pathways}
- AV node (atria)
{0.1 second delay}
- bundle of His (separate to right and left ventricles)
- purkinje fibers (electrical conduits, spreads upward)
what does “the AV node is slave to the SA node” mean?
- once AV is activated by SA, it goes into refractory period, preventing the AV from initiating an extra beat.
- SA has higher beating frequency, so it depolarizes first (“override”).
what if SA node malfunctions? what if Plan B malfunctions?
Plan A = SA
Plan B = AV
Plan C = idioventricular pacemakers
define: autorhythmicity and myogenic
autorhythmicity = automatic contraction
myogenic = initiated by heart
pacemaker cells are ___ while cardiac myocytes are ___
electrical
contractile
T or F: pacemaker potentials are steady
false – unsteady *
describe the ions involved in pacemaker potentials
- funny channels open = sodium enters, depolarize to threshold
- calcium channels open = calcium enters, depolarization to peak
- calcium channels start to close and potassium channels open = potassium exits, repolarization
- potassium channels close, stops repolarizing
- funny channels open, depolarize to threshold and process repeats
what happens to heart rate during sympathetic vs parasympathetic stimulation?
sympa (F or F) = increased heart rate
parasympa (R + D) = decreased heart rate
how are pacemaker and contractile cells a “mass of connected cells that act as one” ? what does this mean?
gap junctions!!!
means they contract as one
T or F: cardiac myocytes have a higher resting potential and shorter APs than pacemaker cells
F – lower* and longer*
describe phases of cardiac myocyte’s potential (0-4)
- 0: sodium channels open = sodium enters (30-40mV)
- 1: sodium channels close = only slight drop in mV bc potassium channels close and calcium channels open
- 2: “plateau phase” since calcium influx is greater
- 3: potassium channels open = repolarize, makes calcium channels close
- 4: all channels at resting values, mV is negative bc more permeable to potassium
which cells does excitation-contraction coupling occur in?
myocytes
describe the process of myocyte excitation-contraction coupling
- AP enters from adjacent cell
- calcium channels open = calcium enters (via L-type channel)
- calcium-induced calcium release
- calcium sparks occur
- sparks = calcium signal
- calcium binds to troponin, allowing crossbridge cycle to begin
- relaxation occurs when calcium unbinds from troponin
- calcium pumped back into SR for storage (via ATPase or Na-Ca exchanger)
- calcium is exchanged with sodium via NCX antiporter
- sodium gradient maintained by Na-K ATPase
what does an ECG measure?
patterns of AP firing in the entire population of cells that make up the heart muscle
what is the P wave?
atrial depolarization
what is the QRS complex?
ventricular depolarization + atrial repolarization
what is the T wave?
ventricular repolarization
what is sinus tachycardia?
- double heart rate
- injury to SA node
what is sinus bradycardia?
- slow heart rate
- blockages in conducting fibers, dysfunction/absence of SA node, OR could be healthy i.e., in athletes!
what is ventricular fibrillation?
- ventricular muscle cells depolarize independently
- ventricles can no longer efficiently pump blood
