Cardio - System overview and the Heart Flashcards
What are the components of the circulatory system?
heart
blood vessels
blood
Blood = ___ ___ (cells and cell fragments) + ___ (plasma).
formed elements; liquid
What cells are found in the blood?
red blood cells, white blood cells. (neutrophils, B and T cells, monocytes, eosinophils, basophils), and platelets
What makes up the buffy coat?
leukocytes and platelets
The ___ is a rapid assessment of blood composition. It is a percent of the blood volume that is composed of RBCs.
hematocrit
Total volume = ___ + ___ ___ + ___.
plasma; buffy coat; erythrocytes
Estimate the hematocrit of a person with a plasma volume of 3L and a total blood volume of 4.5L?
Total volume = plasma + buffy coat + erythrocytes
4.5L = 3L + X
X=1.5L erythrocyte volume
Hematocrit = Erythrocyte volume / total volume
1.5L / 4.5L = Hematocrit (33%)
The ___ is a pump that propels the blood through the systemic and pulmonary circuits.
heart
T/F. Arteries carry blood back to the heart and veins carry blood away from the heart.
False, Arteries carry blood AWAY to the heart and veins carry blood BACK TO the heart.
T/F. The red color indicates that blood is fully oxygenated. The blue color indicates that blood is only partially oxygenated.
True.
Blood flows from arteries to ___ to ___ to ___.
arterioles; capillaries; venules
What is microcirculation?
Arterioles + capillaries + venules
At what level is oxygen, carbon dioxide, nutrients and metabolic end products exchanged in the circulation?
capillaries blood and the interstitial fluid by diffusion
What does flow equal?
F = change in P / R
If you decrease the R but keep the change in P the same, what happens to F?
It will increase.
by increasing the radius (vasodilation)
How can you change the resistance?
by changing the radius (vasodilate or vasoconstrict)
In addition to changing the radius, what else can alter resistance?
blood viscosity
What is the function of intercalated discs?
they have gap junctions which are electrically coupled to cause cells to contract
these junctions allow proteins to diffuse through them
Parasympathetic (vagus) neurons synapse on ___ cell receptors found in the ___ and release ___.
muscarinic; atria; acetylcholine
Sympathetic ___ fibers from the ___ spinal nerves release the neurotransmitter ___. The hormone, ___, travels in the ___ from the adrenal ___. Both molecules bind to _-___ 1 receptors on both the ___ and ___.
postganglionic; thoracic; norepinephrine; epinephrine; blood; medulla; Beta-adrenergic; atria; ventricles
What coronary artery do we need to know for this class?
left anterior descending coronary artery
What is the pacemaker of the heart?
SA node because it initiates each wave of excitation with atrial contraction
The ___ _ ___ delivers the excitation to the ___ of the heart so that the ventricular contraction occurs in an ___ sweep.
Bundle of His; apex; upward
What does the P wave represent?
current flow during atrial depolarization (atrial contraction)
What does the QRS wave represent?
ventricular depolarization (contraction of the ventricles)
What does the T wave represent?
ventricular repolarization (relaxation of the ventricles)
What happened to atrial repolarization?
It is not evident on a ECG because it occurs at the same time as the QRS complex.
On a myocardial ventricular cell, what is responsible for the rapid depolarization phase seen when recording membrane potential?
the rapid opening of voltage gated Na+ channels
The prolonged “___” of depolarization is due to the slow but prolonged opening of voltage-gated ___ channels PLUS the closure to ___ channels.
plateau; Ca2+; K+
T/F. Voltage-gated calcium channels open faster than voltage-gated sodium channels in a myocardial ventricular cell.
False, Voltage-gated calcium channels open SLOWER than voltage-gated sodium channels in a myocardial ventricular cell.
The opening of ___ channels results in the repolarization phase.
potassium
T/F. The action potentials of atrial muscle cells are similar in shape to those for ventricular cells, but the duration of their plateau phase is shorter.
True.
T/F. The SA node cell has a steady resting potential.
False, the SA nodes does NOT have a steady resting potential, but instead, undergoes a slow depolarization due to funny channels. This depolarization is known as the pacemaker potential.
What causes a threshold graded depolarization in the SA node?
- sodium ions “leaking” in through the F-type [funny] channels
- calcium ions moving in through the T [calcium] channels
In the SA node, the rapid depolarization phase is due to the rapid opening of voltage-gated ___ channels.
calcium
What two process are involved in the repolarization phase?
- Reopening of potassium channels
2. closing of calcium channels
What does a purkinje cell action potential have?
it has funny channels therefore it looks like a nodal graph, but it is not as fast as the SA node
Describe a second degree (partial) block.
The atria and ventricles are not communicating because the AV node is in refractory. Damage to the AV node permits only every other atrial impulse to be transmitted to the ventricles. Not every P wave is followed by a QRS and T.
Describe a third degree (complete) block.
The atria and ventricles are completely separate. There is no synchrony between atrial and ventricular electrical activities and the ventricles are being driven by a very slow pacemaker cell in the bundle of His. The QRS comes from the purkinje fibers because the AV node is dead
What happens in patients who have a lethal defect of ventricular muscle where the current through the voltage-gated K+ channels is delayed or reduced? How does the electrical signal transfer to contractile force?
This delays the repolarization of ventricular muscle cell action potentials. Thus, the T wave is delayed relative to the QRS. This is known as long QT syndrome.
this leads to arrythmias
Explain Excitation-Contraction Coupling, which links the cardiac muscle cell action potentials to contraction via control of calcium within the myocardium.
- Excitation (depolarization of the plasma membrane) opens Ca2+ channels in T-tubules
- Ca2+ flows into the cytosol (TRIGGER calcium)
- Calcium induced calcium release from the sarcoplasmic reticulum
- Muscle contraction
The plateau phase depends on ___ Ca2+ causing contraction PLUS a ___ period, which allows the ventricles to fill with blood and prevents ___ of cardiac muscle.
trigger; refractory; tetanus
