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chapter 19 the heart
Terms in this set (207)
heart and blood vessels
transport blood throughout the body. allows exchanges between capillary blood and body cells.
what is delivery of blood per time per gram of tissue? (mL/min/g)
what is sufficient to delivery to maintain cell's health? this requires continual pumping of the heart and open, healthy vessels.
open and unblocked vessels essential to good blood circulation and perfusion
hardened or occluded
if heart fails to pump sufficient blood volumes or vessels become _________ ___ ________, adequate blood may not be delivered to body cells. Could lead to cell death, accumulation of waste, decrease in oxygen and nutrients.
location of the heart is in the thoracic cavity in the __________ and sits in the pericardial cavity.
pericardium (pericardial sac)
the heart is separated from other structures by what?
inferior tip of the heart that projects to the left
where is the heartbeat heard best?
apex projects into the inferior lobe of the left lung in a space known as _____ _____.
great veins and great arteries
what is attached to the base (upper portion) of the heart?
what is the typical size of the heart?
males and athletes
who usually have larger hearts?
what increases cell size but does not increase cell number?
increase in size of its cells, enlargement.
enlarged heart due to factors other than exercise. usually undiagnosed and can cause sudden death
how many chambers of the heart are there?
left and right atria and left and right ventricles
what are the chambers of the heart?
receiving chambers of blood. contracts to propel blood into the ventricles
primary pumping chambers. propel deoxygenated blood to the lungs for oxygenation, and propels oxygenated blood to the rest of the body.
pulmonary and systemic circuits
what are the two circuits of the heart?
transports deoxygenated blood to lungs and returns oxygenated blood from the lungs to the heart
transports oxygenated blood to the tissues of the body and returns deoxygenated blood from the body back to the heart
pathway of blood through the heart
Deoxygenated blood enters the right atrium via the superior and inferior vena cava
Blood moves through the tricuspid valve into the right ventricle
Right ventricle pumps deoxygenated blood through the pulmonary semilunar valve into the pulmonary trunk which bifurcates into the left and right pulmonary arteries
Pulmonary arteries carry deoxygenated blood to the lungs
Pulmonary capillaries exchange oxygen and carbon dioxide
Carbon dioxide leaves and oxygen enters
Freshly oxygenated blood moves from the pulmonary capillaries into the left and right pulmonary veins
Pulmonary veins conduct blood into the left atrium
Oxygenated blood is pumped by the left atrium through the bicuspid valve (Mitral) into the left ventricle
Left ventricle pumps oxygenated blood through the aortic semilunar valve into the ascending aorta
Oxygenated blood flows from the ascending aorta into the aortic arch and is then pumped to the rest of the body
Gas exchanges takes place in the systemic capillaries where oxygen leaves and carbon dioxide enters
Deoxygenated blood enters systemic veins and returns to the right atrium via the superior and inferior vena cava
surrounds the heart and the great vessels. (2 sublayers fibrous and serous)
made of dense connective tissue. protects the heart and maintains the position in the thorax
parietal pericardium and visceral pericardium (endocardium)
fused to the fibrous pericardium
(epicardium) part of the heart wall
filled with pericardial fluid. found between the epicardium and the pericardium
leaf-like extension of the atria, also called atrial appendages
fat filled grooves found on the superior surfaces of the heart
major coronary vessels are located in the _____?
found between the atria and ventricles where the coronary artery is sitting
found between the ventricles.
endocardium, myocardium, epicardium
what are the three layers of the heart composed of?
innermost layer of the pericardium
made of cardiac muscle cells.
what ventricle muscle is thicker due to the amount of pressure that must be generated to pump blood to the systemic tissues?
what ventricle is smaller due to decreased resistance and pressure?
lines the chambers were blood circulates and covers the heart valves. composed of simple squamous epithelium called endothelium
wall that divides the heart into chambers
found between atria, where the fossa ovalis is found.
what is the remnant of the fetal heart after it has been permanently sealed?
found between ventricles. much thicker due to pressure inside of the ventricles
found between the atria and ventricles. valves are located here.
what are the specialized structures that ensures one-way blood flow?
tricuspid valve and bicuspid valve
what are the atrioventricular valves found between the atria and ventricles?
what is the other name for bicuspid?
what are found between right ventricle and pulmonary trunk, between left ventricle and aorta?
pulmonary and aortic semilunar valves
what are the semilunar valves?
Receiving chamber for deoxygenated blood returning to the heart from systemic circulation
Superior and inferior vena cava and coronary sinus from the heart drain here
anterior surface of the right atrium contains what muscles?
what is the opening between the right atrium and right ventricle?
receives blood from right atrium via tricuspid. ejects blood into the pulmonary trunk.
what are valves anchored by? (aka heart strings)
strings (chordae tendineae) connect the valve to what?
what are the walls of the ventricles lined with? (ridges of cardiac muscle)
blood from the lungs is emptied here via pulmonary veins. does not contain pectinate muscles, but does have an auricle. pumps blood into the left ventricle via bicuspid valve.
major pumping chamber for the systemic circuit. ejects blood into the aorta through the aortic semilunar valve
aka right atrioventricular valve. contains 3 cusps connected to the papillary muscles via the chordae tendineae.
what muscles controls the opening and closing of the valves?
pulmonary semilunar valve
contains 3 flaps. between the right atrium and pulmonary trunk
aka mitral valve or left atrioventricular valve. contains 2 cusps attached to papillary muscle via chord tendineae.
aortic semilunar valve
contains 3 flaps between left ventricle and aorta
first portion of aorta gives rise to these. they supply blood to myocardium and other components of the heart.
left coronary artery
supplies blood to the left side of the heart
arises from the left coronary artery
right coronary artery
supplies blood to the right side of the heart.
arise from the right coronary artery and supply blood specifically to the right ventricle.
what drains the heart? (great cardiac vein, posterior cardiac vein, middle cardiac vein, small cardiac vein)
all veins transporting deoxygenated blood dump into where?
what does occluded mean?
what does cardiac muscle display?
99% of the cells in the atria and ventricles
Conduct impulses and are responsible for contractions that pump blood through the body
Initiate and propagate action potentials that travel through the heart to trigger contraction
display audtorhythmicity. contractile cells, conducting cells, branched fibers, intercalated discs, twitch contractions, and long refractory periods
cells are joined by what that supports synchronized contraction of cardiac muscle?
these have long refractory periods followed by brief relaxation periods.
long refractory periods
what prevents tetany to ensure blood is always being pumped?
sinoatrial node (SA node)
establishes normal cardiac rhythm. specialized conducting cells found in the anterior and posterior walls of the right atrium. highest rate of depolarization known as pacemaker. initiates normal electrical pattern of the heart.
what is the highest rate of depolarization is known as?
impulse moves from the SA node throughout the atria via what pathway?
atrioventricular node (AV node)
Conducting cells located in the inferior portion of right atrium in the atrioventricular septum
Septum prevents impulse from spreading directly to the ventricles without first passing through here.Brief pause occurs before __________ node depolarizes and transmits signal to the AV bundle.
what is critical as it allows atrial cardiac cells to complete contraction pumping blood into the ventricles before impulse moves into the ventricle?
bundle of his
aka atrioventricular bundle. proceeds through the inter ventricular septum before dividing into the atrioventricular bundle branches that are connected by purkinje fibers.
Spread impulse to the contractile cells in the ventricles
Extend throughout myocardium from the apex toward the atrioventricular septum
Electrical stimulus begins at the apex along with the contraction
Contraction begins at the apex and travels toward the base of the heart
Allows blood to be pumped out of the ventricles and into the pulmonary trunk and aorta
what is the time for impuse to take place from SA node to ventricular depolarization?
cardiac cells do not have a stable ___
-60mv to -40mv
(cardiac cells) Sodium ion channels allow a normal and slow influx of sodium ions that causes the MP to rise from
once meeting the threshold -40mv ______ channels open and ______ enters the cell causing depolarization until membrane is at +5mv.
calcium channels close and _________ channels open allowing ________ ions to exit the cell causing repolarization
when membrane reached -60mv again, potassium channels close and ______ channels reopen beginning a new cardiac cycle
what is the RMP for atrial cells?
what is the RMP for ventricular cells?
the action potential causes rapid influx of calcium into the cells depolarizing to +30 mv is called?
membrane potential declines slowly due to opening of slow calcium channels allowing calcium to enter and potassium to exit until MP reaches 0mv is known as what?
When MP is 0mV, calcium channels close and potassium channels open causing potassium to exit the cell
MP returns to -80mV/-90mV
this arrangement (conduction system of the heart) allows for long refractory periods needed for cardiac muscle cells to pump blood effectively before ______ again
Extended refractory period is essential for blood to be pumped effectively
Without the long refractory period, what would occur?
Influx through slow ___________ channels allows for prolonged plateau phase and refractory period
Combines with troponin to allow tropomyosin to be shifted aside exposing myosin binding sites on actin
SA node reaches threshold faster that any other component of conduction system
conduction pathway to the heart
SA node > slight pause > atrioventricular node (AV node) > bundle of His > bundle branches > purkinje fibers
tracing of electrical signals through the heart using surface electrodes on the body. identifies normal and abnormal heart function. clinical diagnostic tool (ECG)
3, 5, or 12
the standard ECG uses how many leads?
the more leads used the more __________ is provided.
how many prominent points on an ECG?
depolarization (contraction) of the atria.
depolarization of the ventricles > ventricle contraction > repolarization of the atria
ventricles begin to contract at this wave peak
repolarization of the ventricles
interruption in the normal conduction pathway. SA and AV blocks.
first degree block
delay between SA node and AV node
Abnormally long PR interval
second degree block
some impulses from SA node reach the AV while some do not
Some P waves not followed by QRS complex while others appear normal
third degree block
no correlation between atrial and ventricular activity
In this case, AV node will act as pacemaker in order to maintain consciousness
AV and infra-hisian blocks
what are the most common types of blocks?
period of time beginning with atrial contraction and ending with ventricular relaxation
period of contraction
period of relaxation
pressures and flow
Move from areas of high pressure to low pressure
When in diastole blood flows into atria from veins
as blood enters the _____ pressures rises so blood will passively move into the ventricles
when action potential triggers contraction (systole), pressure rises in atria pumping blood into the ________.
during systole, pressure rises in the ventricles pumping blood to the ________ _____ from the right ventricle and into the aorta from the left ventricle
in the beginning phases of cardiac cycle atria and ventricles are ______ (diastole_)
blood flows into the atria and tricuspid and mitral valves are ____ allowing for ventricular filling (during cardiac cycle)
both semilunar valves are closed preventing ________ of blood into the ventricles from the pulmonary trunk and aorta (during cardiac cycle)
remaining filling of ventricules takes place here
systole lasts until ventricular systole ______.
atrial diastole takes place as _________ _______ occurs. represented by the QRS complex
end diastolic volume
aka preload. amount of blood contained in the ventricles just before atrial contraction. 130 mL of blood
initial phase of ventricular contraction. as pressure within the ventricles rise, tricuspid and mitral valves are closed.
ventricular ejection phase
Pressure within ventricle is now greater than pressures in the pulmonary trunk and aorta
Pressure generated in the ventricles pushes open the semilunar valves
Pressure in the left ventricle is significantly greater than that of the right ventricle
Both ventricles eject the same amount of blood
both ventricles eject the same amount of blood 70-80mL this is known as
end systolic volume
ventricular systole began with a preload of 130 mL of blood with only 70-80 mL of blood being ejected. remaining blood is the ___ ________ ______ about 50-60 mL of blood.
Represented by the T wave
Ventricular pressure begins to fall causing the semilunar valves to close
Isovolumetric ventricular relaxation phase
AV valves remain closed
No change in blood volume
Ventricles relax causing pressure to drop below atrial pressure
Causes AV valves to open and ventricular filling to occur
heart sounds are detected using __________ via a stethoscope
sound created by the closing of AV valves during ventricular contraction
sound created by the closing of semilunar valves during ventricular relaxation
unusual heart sounds due to turbulent flow of blood
Amount of blood pumped by each ventricle in 1 minute
Calculated by multiplying stroke volume by heart rate
Average cardiac output based on SV of 70mL and resting HR of 75bpm
5250mL (5.25L) blood ejected by each ventricle per minute
exercise and maximum cardiac output
In healthy young adults HR may increase to 150bpm during exercise
SV can increase to 130mL due to increased strength of contraction
Increases cardiac output to approximately 19.5L/minute
Difference between maximum and resting cardiac output
Residual capacity of the heart to pump blood
what varies with exercise and fitness levels along with age?
newborn HR is typically ___
HR ________ until adolescence and then begins to gradually increase again with age.
what is the maximum HR?
what is the resting HR?
what is the average HR?
conditions that cause HR to increase also causes __ _______.
nervous control is controlled by the cardiac centers in the ______.
stimulate sympathetic stimulation
decrease heart activity via parasympathetic stimulation/ vagus nerve
network of nerve fibers that sympathetic and parasympathetic stimulations flow through
Causes release of neurotransmitter norepinephrine
Increases rate of depolarization and contraction/decreases repolarization period
Leads to increased HR
NE binds to beta 1 receptors
what prevents NE from binding to beta 1 receptors in order to decrease heart rate and blood pressure?
Originates in Cardioinhibitory center with impulses traveling via the vagus nerve
Vagus nerve sends branches to the SA and AV node
Causes release of acetylcholine at the neuromuscular junction
ACh slows HR
receives input from visceral receptors (cardiac reflex)
increased physical activity
Stretch receptors found in carotid bodies and aortic sinus
Detect blood pressure, level of physical activity, distribution of blood
Increased stretch causes
Decreased sympathetic activity/increased parasympathetic activity
Increased carbon dioxide, hydrogen ions, lactic acid, low oxygen levels
Innervated by glossopharyngeal and vagus nerves
Information on increased or decreased blood flow based on levels
stress and anxiety
stimuli from limbic system
increase in cortisol levels
slow breathing or mediation may alleviate
epinephrine, norepinephrine, thyroid hormones, ion levels, body temperature, hypoxia, and pH balance
what are factors that increase HR?
epinephrine and norepinephrine
Secreted by adrenal medulla
Fight or flight mechanism
Bind to beta 1 receptors
No parasympathetic stimulation
Increase heart rate and contractility
Excessive levels can lead to tachycardia
Calcium, potassium, sodium
Calcium levels effect HR and contractility
As calcium increases so does HR and contractility
Extremely high Ca levels can lead to cardiac arrest
caffeine and nicotine
Excite body membranes and stimulate the cardiac center
Causes increase in HR
Nicotine stimulates sympathetic neurons
sodium and potassium levels, hypoxia, acidosis, alkalosis, hypothermia
what are factors that decrease HR?
sodium and potassium levels
Electrolyte balance is critical for normal depolarization
Potassium abnormalities are critical
causes arrhythmias. Low blood potassium
causes heart to become weak and leads to heart failure. High blood potassium
leads to bradycardia and arrhythmias
leads to tachycardia
Duration of ventricular diastole where filling occurs
More rapid contractions decrease filling time which effects the ________.
______ increases as ventricular filling increase.
Force of heart contraction is directly proportional to the length of the muscle fiber
The greater the stretch of the ventricles, the more powerful the contraction is
Increasing the preload causes increased contractility
Force of contraction of the heart muscle
Less forceful contractions produce lower SV and increased end systolic volume
positive inotropic factors
Sympathetic stimulation releases epinephrine and NE
Bind to alpha and beta receptors to increase metabolic rate and force of contraction
Hypercalcemia, thyroid hormone, glucagon
(factors that increase contractility)
negative inotropic factors
Parasympathetic stimulation releases Ach
Decreases strength of contraction and stroke volume
Hypoxia, acidosis, hyperkalemia
(factors that decrease contractility)
__________ ________ change heart rate.Alter the activity of nodal cells (SA and/or AV node)
Often work via autonomic nervous system or hormones
positive chronotropic agents
increase heart rate. sympathetic nerve stimulation, thyroid hormone, caffeine, nicotine, cocaine.
sympathetic nerve stimulation
Causes norepinephrine (NE) release on heart
Causes adrenal medulla to release epinephrine (EPI) and NE
NE and EPI bind to nodal cells and increase their firing rate
Receptors are beta 1 adrenergic receptors
Increases number of β1-adrenergic receptors on nodal cells
increases release of norepinephrine
inhibits repute of norepinephrine (more remains in cleft longer)
change stroke volume
Alter contractility (force of contraction)
Generally due to a changes in Ca2+ available in sarcoplasm
Positive inotropic agents increase available Ca2+
EPI and NE work via beta-one receptors to increase Ca2+
Thyroid hormone increases number of β1 receptors
Certain drugs, e.g., digitalis, boost cardiac output by increasing contractility
Negative inotropic agents decrease available Ca2+ and thus lower contractility
Electrolyte imbalances such as increased K+ or H+
Certain drugs, e.g., Ca2+ channel-blocking blood pressure drugs
negative chronotropic agents
decrease heart rate by parasympathetic activity
Parasympathetic axons release acetylcholine (ACh) onto nodal cells
ACh binds M2 muscarinic receptors
beta blocker drugs
Interfere with EPI and NE binding to beta receptors
Used to treat high blood pressure
Tension that ventricles must develop to pump blood effectively against the resistance in the vascular system
increased resistance requires an _________ ________.
damage to the valves will increase afterload.
________ in resistance decreases after load.
what is the first functional organ to develop?
day 21-22, 3 weeks after fertilization
when does the heart being to beat?
prominent bulge on anterior surface of embryo
what is the heart formed from?
what allows fetal blood to be shunted from right atrium to left atrium?
Inflammation of the pericardium
Caused by viruses, bacteria, or fungi
Increased capillary permeability
Fluid accumulation in pericardial cavity
May restrict heart's movement and keep chambers from filling
Results in cardiac tamponade, heart unable to pump
crackling sound heard with stethoscope as pericardial layers rub
(coronary artery disease): plaques narrow coronary arteries. coronary spasm, angina pectoris. treatments induce vascular dilation (nitroglycerin)
sudden narrowing of vessels
pain. usually on left side of chest, left arm, or jaw. usually referred pain when performing a strenuous activity
heart attack.Sudden and complete occlusion of coronary artery
Myocardium deprived of oxygen, possible tissue death
Excruciating chest pain radiating down left arm/left jaw
Weakness, shortness of breath, nausea, anxiety, and sweating
Persistently low resting heart rate in adults
Below 60 beats/minute
Normal change in athletes
Abnormal due to: hypothyroidism, electrolyte imbalance, and congestive heart failure
Persistently high resting heart rate
Over 100 beats/minute
Caused by heart disease, fever, and anxiety
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