Chapter 5A Flashcards
The heart has four chambers: the two superior (on top) receiving chambers are the A and
the two inferior pumping chambers are the B.
atria
ventricles.
The paired atria receive blood from blood vessels returning blood to the heart,
called X, while the ventricles eject the blood from the heart into blood vessels
called X
veins
arteries
This atrium forms the right surface of the heart and receives blood from three
veins: the superior vena cava, inferior vena cava, and coronary sinus.
right atrium
Blood passes from the right atrium into the right ventricle through a valve that is
called the tricuspid valve
true/false
true
- Blood passes from the right ventricle through the pulmonary (semilunar) valve into a
large artery called the pulmonary trunk, which divides into right and left pulmonary
arteries and carries blood to the X.
lungs
The X atrium receives blood from the lungs through four pulmonary veins
left
Blood passes from the left atrium into the left ventricle through the bicuspid (mitral)
valve which has two cusps
ok
The left ventricle is the thickest chamber of the heart and forms the apex of the
heart.
true/false
true
- Blood passes from the left ventricle through the aortic semilunar valve into the
ascending aorta
true/false
true
Some of the blood in the aorta flows into the coronary arteries, which branch from
the ascending aorta and carry blood to the heart wall.
- The remainder of the blood passes into the arch of the aorta and descending aorta
(thoracic aorta and abdominal aorta). - Branches of the arch of the aorta and descending aorta carry blood throughout
the body
ok
systemic vs pulmonary circulation: which goes to the lungs?
pulmonary = to the lungs
Exchange of nutrients and gases occurs across the
thin capillary walls.
true/false
true
Blood unloads O2 (oxygen) and picks up CO2 (carbon
dioxide)
true/false
true
In most cases, blood flows through only one capillary
and then enters a systemic venule.
* Venules carry oxygen-poor/-rich blood
away from tissues and merge to form larger systemic
veins.
poor
The …. side of the heart is the pump for
pulmonary circulation.
* It receives all of the dark-red
deoxygenated blood returning from the
systemic circulation.
* Blood ejected from the right ventricle
flows into the pulmonary trunk, which
branches into pulmonary arteries that
carry blood to the right and left lungs.
* In pulmonary capillaries, blood unloads
CO2, which is exhaled, and picks up O2
from inhaled air.
* The freshly oxygenated blood then flows
into pulmonary veins and returns to the
….. atrium.
right side
left atrium
There are two types of cardiac fibers or cardiomyocytes:
Autorhythmic cardiac cells
Contractile cardiac cells
Explain
Autorhythmic: specialized cells, form a specialized excitatory and conductive (conduct electrical signals) system of the heart. self-excitable. Generate action potentials that trigger heart contractions.
> Controls cardiac contractions
Contractile: ventricular or working cells
What are the two important functions of autorhythmic cardiac cells?
- pacemaker, setting the rhythm
- cardiac conduction system: provide a path for each cycle of cardiac excitation
True/false:
SA node cells have a stable resting potential
False
SA node cells do not have a stable resting potential. Rather, they repeatedly
depolarize to threshold spontaneously.
* The spontaneous depolarization is a pacemaker potential (!!)
Membrane potential of sinus nodal fibers are similar to ventricular muscle fibers
false: the “resting membrane potential” of the sinus nodal fiber is more positive than ventricular muscle fiber
The cause of this lesser negativity of nodal fibers vs ventricular muscle fibers is that the cell membranes of the sinus fibers are
naturally …. to sodium and calcium ions, and positive charges of the entering
sodium and calcium ions neutralize some of the intracellular negativity.
leaky
Na+ leaks into SA nodal cells through “funny” channels
Between heartbeats, influx of positively charged sodium ions causes a slow
decline/rise in the resting membrane potential in the positive/negative direction
rise, positive
SA node sets the rhythm for contraction of the heart
true/false
true, is the pacemaker of the heart
Nerve impulses from the …..nervous system (..NS) and blood-borne hormones
(such as epinephrine) modify the timing and strength of each heartbeat (see section
“regulation of heart rate”), but they do not establish the fundamental rhythm.
autonomic
Put in right order of transmission of electrical signal:
- Right and left bundle branches
- AV bunde (bundle of HIS)
- Purkinje fibers
- SA node
- AV node
- SA node
- AV node
- AV bundle
- Right and left
- Purkinje fibers
at the SA, there are/are not contractile muscle filaments
are virtually not
At the AV node, the action
potential slows to provide time for..
the two atria contract at the same time and empty their
blood into the ventricles.
only site where action potentials can
conduct from the atria to the ventricles = ?
AV bundle
Purkinje fibers -> ventricles contract -> pushing blood upwards
true/false
true
Can you see if the heart is enlarged with an ECG?
yes
Can you determine the cause of chest pain with an ECG?
Yes
ECG: Lead …. is the most common, most popular, and generally the best view.
2
Why is lead 2 the best? Because…
By setting the ECG monitor to Lead II, we are essentially viewing the impulse as it
travels from the …. atria toward the …. ventricle.
right atria
left ventricle
Three clearly recognizable waves appear with each heartbeat: …. wave, … complex
and … wave
P wave, QRS complex
and T wave
Analysis of an ECG also involves measuring the time spans between waves, which are
called intervals or segments
See p.51
P wave: is a small upward deflection on the
ECG. The P wave represents atrial
depolarization/repolarization, which spreads from the SA node
through contractile fibers in both atria.
depolarization
P–R interval: the time from the beginning of the
P wave to the beginning of the …. It
represents the conduction time from the
beginning of atrial excitation to the beginning
of …. excitation: time required for the
action potential to travel through the atria,
atrioventricular node, and the remaining fibers
of the conduction system.
QRS complex
ventricular
QRS complex: begins as a downward deflection,
continues as a large, upright, triangular wave,
and ends as a downward wave. The QRS
complex represents rapid ventricular
de/repolarization, as the action potential spreads
through ventricular contractile fibers
depolarization
T wave: is a dome-shaped upward deflection. It
indicates ventricular de/repolarization and occurs
just as the ventricles are starting to relax. The T
wave is smaller and wider than the QRS complex
because repolarization occurs more slowly than
depolarization
depolarization
Q–T interval: extends from the start of the QRS
complex to the end of the T wave. It is the time
from the beginning of …..
depolarization to the end of ……
repolarization
ventricular
ventricular
