Cardio A&P review Flashcards
Venous blood from IVC and
SVC passively empties into
the ______
right atrium
During diastole (relaxation of the ventricles) blood flows through the right atrium,
through the _____ valve, and into the right ventricle
right atrioventricular
When the right ventricle contracts, venous
blood is pushed through the _____ into the pulmonary artery
pulmonary valve
This contraction provides the pressure
that sustains pulmonary blood flow for
ventilation and diffusion
Right ventricle contraction
Considered the “workhorse”, the _____ sustains the systemic blood pressure.
left ventricle
The serous pericardium is further
divided into two layers
■ Parietal Layer
■ Visceral Layer
Cardiac Cell membranes are fused with each other at _____
the intercalated discs and function as communicating gap junctions between cells
Between the visceral and parietal layers, there is a potential space called the _____
Pericardial Cavity
Two main types of cardiac muscle
fibers exist in the heart
○ Excitatory fibers: conduct electrical
current through the tissue of the heart
○ Contractile fibers
What does it mean that cardiac muscle is a syncytium?
cardiac cells are so
interconnected that when one cell
becomes excited, the action potential
rapidly spreads to all of them
Removal of calcium leads to _____
the relaxation of the muscle (bradycardia)
There is an important difference in the action potentials recorded in cardiac
muscle cells compared to skeletal muscle cells, what is it?
Cardiac action potentials include a Plateau: This plateau in cardiac depolarization causes
ventricular contraction to last as much as 15
times longer than skeletal muscle
contractions from a single action potential.
In cardiac cells, the same rapid sodium and potassium channels still exist. However, the presence of______ is mostly
responsible for the difference in action potential tracings
a special L-Type Calcium Channel
T/F L-Type calcium/sodium channels are faster than voltage gated sodium channels
F- L-Type Calcium Channels (also known as Slow Calcium Channels and
Calcium-Sodium Channels) are found in the cell membrane and open rather
slowly (compared to voltage-gated Sodium channels) and remain open
much longer
The cardiac events that occur from the
beginning of one heartbeat to the beginning
of the next beat = ______
“The Cardiac Cycle.”
The first phase of the cardiac cycle is ______
diastole
Ends with atrial contraction- the “Kick.”
Diastole
The pulmonary and
aortic valves are
made of _____
sturdy cusps (leaflets)
During diastole, the pulmonary and aortic valves are _____
closed (dub)
During systole, the AV valves are _____
closed (lub)
During systole, the pulmonary and aortic valves are _____
open
______ is the single largest killer of all people
in the United States.
Coronary artery atherosclerosis
This allows for entry of LDL
cholesterol into the tunica intima
microinflammation or damage to
the intima of the arterial wall.
The earliest pathologic lesion of atherosclerosis
“fatty streaks” of LDL cholesterol in the tunica media
The presence of serum lipoproteins in the tunica intima triggers the
______
gathering of Monocytes (which become tissue macrophages), which phagocytize the LDL cholesterol, becoming “Foam Cells.”
Plaques, also called Atheromas, characteristically occur in regions of
______
branching and/or marked curvature (velocity and direction change)
What happens when a placque becomes unstable?
The fibrous cap can rupture, exposing thrombogenic contents to the blood. This results in thrombus formation, partial or complete occlusion of the vessel, and further progression and growth of the atheroma
_____ is the main event that causes acute presentation of
coronary syndromes
Plaque rupture
By impairing or obstructing normal blood flow, atherosclerotic buildup causes ______
myocardial ischemia or infarction
When functioning normally, the atrial
contraction (kick) occurs about ____ before the strong ventricular contraction
1/6 of a second
The _____ is responsible for
generating the normal rhythmical
impulses for the system
Sinoatrial Node (AKA Sinus
Node or SA Node)
What does it mean that the Cells of the SA node are “less negative” at rest than the hyperpolarized
muscle cells throughout the heart?
○ Specialized L-type Channels are
slowly leaking channels that allow
for the slow influx of Sodium and
Calcium into the cell.
○ This slowly pushes the potential to
the threshold for discharge, which is
the mechanism by which these cells
are capable of self-excitation
Total delay of the AV node and why this is important?
total delay of 0.12-0.13 s)
○ This slowing of the impulse through the AV
node occurs due to a lower numbers of gap
junctions between the excitable cells.
T/F The cardiac impulses can move backward from the ventricles to the atria
F
the atrial muscle is separated from
the ventricular muscle by ____
a continuous fibrous barrier that acts as an insulator to prevent the passage of impulses
other than through the AV bundle.
two branches of Purkinje fibers are
○ The Left Bundle Branch ultimately depolarizes the left ventricle.
○ The Right Bundle Branch ultimately depolarizes the right ventricle.
T/F The AV Node and Purkinje fibers
are able to self-excite if not stimulated by the SA node
T
Rhythmic rate of AV node is about _____
40-60 bpm (Purkinje- 15-40 bpm).
SA node is the normal pacemaker because its rate is _____
70-80 bpm
_____ are pacemakers
somewhere other than the SA node.
Ectopic Pacemakers
Ectopic pacers result in ____
an abnormal sequence of muscle contraction in the heart (ex: A-fib)
How does an EKG work?
● When the cardiac impulse travels through the heart, electrical current also spreads from the heart into the adjacent tissue just enough that
we can trace it from the surface.
● Electrodes placed on the skin can
measure this changing electrical
current.
The P wave
Caused by electrical potentials generated
during atrial depolarization
The QRS Complex
Caused by potentials generated with
ventricular depolarization
The T wave
Caused by potentials generated during
ventricular REpolarization
Time from when the SA node first fires until the Purkinje fibers
fire (about 0.15-0.16 seconds). The delay caused by the AV node
PR Interval
Essentially the time between each impulse (tells us the HR).
RR Interval
The length of time the ventricle muscle
cells are depolarized
QT Interval
The time between ventricular
depolarization and repolarization.
ST Segment
As the ventricles contract, this causes a rapid
_____ in the intraventricular pressure
increase
As intraventricular pressure exceeds the intra-
atrial pressure, what happens?
the pressure exceeds pulmonary artery pressure, and aortic (systolic) pressure, the AV valves are pushed closed and the aortic and pulmonic valves are pushed open.
About ____% of the End-Diastolic Volume is
ejected during Ventricular Ejection
60
The fraction of the End-Diastolic
Volume that is ejected is called
the _____
Ejection Fraction
The actual volume of blood that
is ejected during ventricular
contraction is called
the Stroke
Output Volume (stroke volume)
The degree of tension on the muscle walls of the ventricles
when they begin to contract
Preload
The load or pressure against which the ventricles
(especially the left ventricle) exert their contractile force and must
overcome in order to eject the stroke volume
Afterload
Essentially the pressure in the aorta
The systolic blood pressure
Frank-Starling Mechanism says that
The greater the heart muscle is stretched
during filling, the greater the force and volume of contraction
What causes the atrial kick/increased preload?
When an extra amount of blood flows into the ventricles, the cardiac
muscle is stretched to a greater length
_____ is the amount of blood (the volume) that the heart ejects with
each ventricular contraction.
Stroke volume
What factors can affect the rate at which the heart beats?
○ Increase (Positive chronotrope)-
■ Sympathetic input (endogenous/exogenous)
■ Hormones, such as thyroid hormone
○ Decrease (Negative chronotrope)-
■ Parasympathetic input
Total Peripheral Resistance is a product of three factors:
○ Blood Viscosity- The higher the viscosity, the higher the resistance
○ Total Blood Vessel Length - Which is always a constant…
○ Vessel Diameter (the main factor)
Cardiac Output (CO) is the product of
Heart Rate and Stroke Volume
○ In other words, CO = HR x SV
four main factors that affect the CO:
○ Heart Rate
○ Contractility
○ Preload
○ Afterload
For the most part, increased ____ will
increase the CO too, but only to a
certain extent
HR
Rapid monitoring of CO
■ Neural control of vessel diameter,
heart rate, stroke volume
Intermediate to long-term monitoring of CO
■ Renin-Angiotensin II system
■ Renin-Aldosterone system
■ Antidiuretic Hormone (ADH)
Parasympathetic stimulation of the heart can
_____ the CO by as much as 20-30%.
decrease
This Baroreceptor Reflex results in _____
decreased blood pressure by decreasing sympathetic outflow and increasing parasympathetic outflow from the CNS.
Cells that are sensitive to low oxygen, carbon dioxide excess, and H+
excess are located in chemoreceptor organs at the carotid and aorta
chemoreceptors
Review the RAAS system at the end of the slides
:)
act as “control conduits” through which blood is released into the capillaries at a rate that meets the needs of that tissue.
Arterioles
This blood pressure progressively
falls throughout systemic circulation and is about _____ by the time the blood re-enters
the right atrium
0 mmHg
By far, the ____ are the most distensible of the
vasculature, making the ____ a great reservoir for extra blood when needed
veins; veins
What is Delayed Compliance?
When a large amount of fluid is added to a
vein, there is a sudden increase in pressure
due to the elasticity of the vein. However, the vein then immediately starts
adjusting to the new volume by relaxing.
the pressure in the right atrium is called the _____
Central Venous Pressure
