PART 2 CARDIOVASCULAR SYSTEM Flashcards
four-chambered muscular organ approximately
the size of a fist. It is positioned in the mid-mediastinum of the
chest, behind the sternum
heart
Approximately two-thirds
of the heart lies to the left of the midline of the sternum between what ribs?
2nd and 6th ribs
The apex of the heart is formed by the
____________ and lies above the diaphragm at the level
of the _________ to the left
a.tip of the left ventricle
b.5th intercostal space
The base of the heart is
formed by the atria and projects to the right,___________. Posteriorly, the heart rests at the level of the ____________
a. lying below the 2nd rib
b.5th -8 thoracic vertebrae
Compressions must be done
at a depth of at least___________) for an average adult, avoiding excessive
chest-compression depths.
2 inches (5 cm
Externally, surface grooves called ______ the boundaries
of the heart chambers.
sulci mark
The heart is enclosed in a sac called
pericardium
Tough, loose-fitting and inelastic sac
surrounding the heart
Fibrous pericardium
Consisting of two layers:
Serous pericardium
Inner lining of the fibrous pericardium
parietal layer
Covering the outer surface
of the heart and great vessels
Visceral layer or epicardium
A thin layer of fluid called the __________ separates the
two layers of the serous pericardium.
pericardial fluid
abnormal amount of fluid can accumulate between the layers,
resulting in a
pericardial effusion
compresses the heart muscle, leading
to a serious decrease in blood flow to the body. This, ultimately,
may lead to shock and death.1,4
cardiac tamponade
The heart wall consists of three layers
(1) outer epicardium,
(2) middle myocardium, and (3) inner endocardium.
Support for the four interior chambers and valves of the heart
is provided by ___________, which form a
fibrous “skeleton.”
four atrioventricular (AV) rings
is the backflow of blood through a malfunctioning
leaky valve
REGURGITATION
is a pathologic narrowing or constriction
of a valve outlet, which causes blood to back up and
increased pressure in the proximal chamber and vessels
STENOSIS
______________
causes high resistance to the blood flow into the left ventricle from the left
atrium. This increased resistance causes a backflow into the pulmonary circulation,
leading to pulmonary edema with fluid collecting in the alveoli and interstitial
spaces in the lungs, impairing oxygenation and breathing.
Mitral stenosis
(decreased oxygen supply
Tissue Ischemia
Complete obstruction of a coronary
artery may cause tissue death or infarct, a condition called
Myocardial Infarction
___________ is the name given to three
types of coronary artery diseases (CAD) that are associated with
gradual and/or sudden obstruction of the coronary arteries
a. Acute Coronary Syndrome (ACS)
three
types of coronary artery diseases (CAD)
(1) unstable angina or angina pectoris, (2) Non-ST segment elevation myocardial infarction (NSTEMI) and (3) ST-segment
elevation myocardial infarction (STEMI).
Classic signs of tissue ischemia (decreased oxygen
supply) are chest pain and shortness of breath resulting in a clinical condition
called
angina pectoris
Symptoms of a _________ include tightness
or pain in the chest, neck, back or arms, as well as fatigue, lightheadedness,
abnormal heartbeat and anxiety. Women are more likely to have atypical
symptoms than men
myocardial infarction
Because
the thebesian veins bypass or shunt around the pulmonary circulation
as part of the normal anatomy, this phenomenon is
called an anatomic shunt.
a.thebesian veins
myocardial tissue possesses
the following four key properties:
- Excitability
- Inherent rhythmicity or automaticity
- Conductivity
- Contractility
is the ability of cells to respond to electrical,
chemical or mechanical stimulation
excitability
is the unique ability of
the cardiac muscle to initiate a spontaneous electrical impulse
(depolarization and repolarization).
Although such impulses can
arise from anywhere in the cardiac tissue. This ability is highly
developed in specialized areas called the _____________
a. Inherent rhytmicity or automaticity
b. heart pacemaker or nodal
tissues.
are the heart’s primary pacemakers
The sinoatrial (SA) node and the atrioventricular (AV) node
is the ability of the myocardial tissue to spread
and conduct electrical impulses. This property allows the myocardium
to contract without direct neural innervation (as required by skeletal muscle).
Conductivity
When the electrical signals of a
wave reach the contractile cells they contract _________. When
the repolarization signals reach the myocardial cells they relax
_________ and thus the electrical signals cause the mechanical
pumping action of the heart; mechanical events always follow
the electrical events.
systole
diastole
Abnormal conductivity can affect the timing of
chamber contractions and decrease cardiac efficiency.
True or false?
true
in response to an electrical impulse, is the
primary function of the myocardium. Contrary to the contractions
of other muscle tissues, cardiac contractions cannot be
sustained or tetanized because myocardial tissue exhibits a prolonged
period of inexcitability after contraction
contractility
The period
during which the myocardium cannot be stimulated is called
the _______ and lasts approximately ____, nearly as
long as the heart contraction or systole.
refractory period
250 ms
begins with the aorta on the left ventricle and ends in
the right atrium
systemic circulation
begins with the
pulmonary artery out of the right ventricle and ends in the
left atrium
pulmonary circulation
The systemic circulation has three major components:
1) the
arterial system,
(2) the capillary system, and
(3) the venous system.
consists of large, highly elastic, lowresistance
arteries and small, muscular arterioles of varying
resistance.
arterial system
With their elasticity, the large arteries help transmit
and maintain the head of pressure generated by the heart.
Together, the large arteries are called ____
conductance vessel
_______ provide this
control by varying their flow resistance; they play a major role
in the distribution and regulation of blood pressure and are
referred to as resistance vessels.
arterioles
maintains a
constant exchange of nutrients and waste products for the cells
and tissues of the body. For this reason, the ______ are commonly
referred to as exchange vessels.
capillary
____maintains a
constant exchange of nutrients and waste products for the cells
and tissues of the body. .
The vast capillary system, or microcirculation
the capillaries are commonly
referred to as ____
exchange vessel
Direct communication
between these vessels is called an
arteriovenous anastomosis
Contraction of _________
decreases blood flow locally, whereas relaxation increases local
perfusion. In combination, these various channels, sphincters
and bypasses allow precise control over the direction and amount
of blood flow to a given organ or area of tissue.
precapillary sphincter
consists of small, expandable venules and
veins and larger, more elastic veins. Besides conducting blood
back to the heart, these vessels act as a reservoir for the circulatory
system.
venous system
At any given time, the veins and venules hold
approximately _________ of the body’s total blood volum
three-quarter
Vascular space decreases when
vasoconstriction (constriction of the smooth muscles in the
peripheral blood vessels) occurs, which causes blood pressure
to _______ even though blood volume is the same
increase
Vascular
space increases when _____ (relaxation of the smooth
muscles in the arterioles) occurs, which causes blood pressure to
______ even though blood volume has not changed (e.g., during
septic shock).
a.vasodilation
b. decreases
The following four mechanisms aid the venous
return to the heart:
(1) sympathetic venous tone;
(2) skeletal
muscle pumping or “milking” (combined with one-way venous
valves);
(3) cardiac suction;
(4) thoracic pressure differences
caused by respiratory efforts.5
The right side of the heart generates a systolic pressure
of approximately ___ to drive blood through the
low-resistance, low-pressure pulmonary circulation
25mmhg
The left side
of the heart generates systolic pressures of approximately ____ to propel blood through the higher pressure, high-resistance
systemic circulation.
120 mmhg
regulates blood flow mainly by
altering the capacity of the vasculature and the volume of blood
it holds.The goal is to maintain adequate perfusion to all tissues according
to their needs
cardiovascular system
____ plays only a secondary role in regulating
blood flow; the ____ tells the heart how much blood
it needs, rather than the heart dictating what volume of blood
the vascular system will receive.
heart
vascular system
____operate independently
without central nervous system control. It
alters perfusion under normal conditions to meet metabolic needs.
Intrinsic control
involves both the central nervous
system and circulating humoral agents. It
maintain a normal level of vascular tone; however, central
control mechanisms take over when the competing needs of local
vascular beds must be coordinated.
Central or Extrinsic control
Smooth-muscle relaxation and vessel dilation is caused by
stimulation of either _____ _____
cholinergic or specialized β-adrenergic receptors.Release of norephinephrine
involves the relationship between vascular,
smooth-muscle tone and the level of local cellular metabolites.
High amounts of carbon dioxide (CO2) or lactic acid, low pH
levels, low partial pressures of O2 levels, histamines (released during
an inflammatory response), endothelium-derived relaxing factor,
and some prostaglandins all cause relaxation of the smooth muscle
and vasodilation, increasing blood flow to the affected area.
Metabolic control
mainly affects the highresistance
arterioles and capacitance veins.
central control
In a healthy person at rest, the EDV ranges from _____.
110 to 120 mL
a healthy heart ejects approximately ___ of its
stored volume ____.
two-thirds(60% to 66%)
the force the ventricle can
generate results from the length (or stretch) of the myocardial
fibers just before contraction. As the ventricle fills with blood,
the myocardial fibers are stretched and as the stretch increases,
the tension (force) within the walls of the heart increases (analogous
to stretching a rubber band).1
Frank Starling Law
can be described as the combined
force of all the factors that the left ventricle encounters
and must overcome when stimulated to contract and achieve
the end of systole.
afterload
Increases in afterload can decrease _____, especially in
the failing heart by increasing the ___
Stroke volume
End diastolic volume
represents the amount of systolic force exerted
by the heart muscle at any given preload
contractility
A higher SV for a given preload
(increased slope) indicates a state of increased contractility, often referred to as
positive inotropism
A
lower SV for a given preload indicates decreased contractility,
referred to as
negative inotropism
is the resistance the ventricle must overcome or the forces that
oppose ejection of blood pressure generated as the heart works to eject its
SV.
Afterload
blood rushes in from the atria to fill the ventricles
diastole
respond to pressure changes
baroreceptors
respond
to changes in blood chemistry.4
chemoreceptors
SV is affected primarily by intrinsic control of these 3 factors
preload, afterload, contractility
