Chapter 18: The Heart
atrioventricular (av) valve
A heart valve located between each atrium and ventricle that prevents a backflow of blood when the ventricle contracts.
Why are gap junctions a vital part of the intercellular connection of cardiac muscles?
Gap junctions are a form of electrical synapse that allow action potentials to spread to connected cells. This property allows the signal to spread efficiently through the heart.
stroke volume
The amount of blood ejected from the heart in one contraction.
venous return
The amount of blood returned to the heart by the veins
cardiac skeleton
crisscrossing, interlacing layer of connective tissue -Anchors cardiac muscle fibers -Supports great vessels and valves -Limits spread of action potentials to specific paths
Which of the following is the innermost layer of the heart?
endocardium
coronary sinus
enlarged vessel on the posterior aspect of the heart that empties blood into the right atrium
coronary circulation
flow of blood to and from the tissues of the heart
coronary sulcus
groove that marks border between atria and ventricles
trabecular carnae
muscular ridges and columns on inside walls of ventricles
myocardium
muscular, middle layer of the heart
heart attack
myocardial infarction
Which layer of the heart wall contracts and is composed primarily of cardiac muscle tissue?
myocardium
Which heart chamber receives oxygenated blood from the lungs?
Oxygenated blood from the lungs returns to the left atrium of the heart.
right atrium
receives blood returning from systemic circut
Right side of heart:
receives oxygen poor blood from tissues
Left side of heart:
receives oxygenated blood from lungs
Electrocardiogram (ECG)
recording of the electrical changes that occur in the myocardium during a cardiac cycle
apex
the highest point
ventricles
the two lower chambers of the heart
atria
the two upper chambers of the heart
serous pericardium
thinner, more delicate membrane that forms a double layer around the heart
quiescent period
total heart relaxation
QRS complex
ventricular depolarization
left atrium
receives blood returning from pulmonary circuit
electrocardiogram
record of the electrical activity of the heart
ligamentum arteriosum
remnant of ductus arteriosus
fossa ovalis
remnant of foramen ovale of fetal heart
tricuspid valve
right AV valve separating the right atria and ventricle
auricles
"flaps" on the atria to increase the volume of the chamber
chordae tendineae
"heart strings" are tiny white collagenic cords that anchor the cusps to the ventricular walls. They originate from the papillary muscles.
myocardial infarction
(heart attack) Prolonged coronary blockage Areas of cell death are repaired with noncontractile scar tissue
Base of heart
(posterior surface) leans toward right shoulder
Left ventricular walls are ___ thicker than right
3x
Pulmonary Circuit
Carries blood to and from gas exchange surfaces of lungs
Heart
A hollow, muscular organ that pumps blood throughout the body.
pacemaker potential
A self-initiating action potential that occurs in the conduction system of the heart and triggers action potentials (and thus contraction) in the cardiac muscle cells Tee pacemaker potential is triggered by the regular, spontaneous depolarization of the cells of the conductions system, due to slow inwar leak of positive ions (Na+ and Ca2+). Because the SA node has the fastest leak, it typically reaches the threshold for the pacemaker potential before any other region of the conduction system, and thus sets the pace of the heart.
sinoatrial node
A small mass of tissue that is made up of Purkinje fibers, ganglion cells, and nerve fibers, that is embedded in the musculature of the right atrium, and that originates the impulses stimulating the heartbeat -- called also S-A node, sinus node.
Tachycardia
Abnormally rapid heartbeat
intercalated discs
Attachment sites between the transverse lines between cardiac muscle cells
incompetent valve
Blood backflows so heart repumps same blood over and over
Systole
Contraction of the heart
systole
Contraction of the heart
Autorhymicity
the ability of cardiac cells to beat spontaneously in the absences of input from the CNS. Uses slow leak of sodium
myocardial infarction (MI)
Death of cardiac muscle due to ischemia
Serous pericardium
Deep two-layered
pulmonary veins
Deliver oxygen rich blood from the lungs to the left atrium
pericardium
Double-layered membrane surrounding the heart.
cardiac tamponade
Excess fluid sometimes compresses heart, limited pumping ability
cardiac muscle
Involuntary muscle tissue found only in the heart.
aorta
Largest artery in the body
Systemic circuit
Left atrium->mitral valve->left ventricle->aortic semilunar valve->aorta->systemic circulation
dystole
Relaxation of the heart
visceral layer of serous pericardium
Simple squamous epithelium and areolar connective tissue Attaches directly to heart
valvular stenosis
Stiff flaps that constrict opening Heart needs to exert more force to pump blood
Which chamber of the heart has the highest probability of being the site of a myocardial infarction?
The left ventricle has to pump blood around the entire body and overcome the largest pressures (120/80 mm Hg). This is the largest chamber in the heart and has the most muscle around it compared to the other chambers.
Which of the following does NOT deliver deoxygenated blood to the heart?
The pulmonary veins deliver oxygenated blood to the left atrium.
The systemic and pulmonary circuits.
The right side of the heart pumps blood through the pulmonary circuit and the left side of the heart pumps blood through the systemic circuit. The arrows indicate the direction of blood flow. For simplicity, the actual number of two pulmonary arteries and four pulmonary veins has been reduced to one each.
The __________ valve is located between the right atrium and the right ventricle.
The tricuspid valve is located between the right atrium and right ventricle.
The presence of an incompetent tricuspid valve would have the direct effect of causing ______.
The tricuspid valve separates the right atrium and the right ventricle. It must remain tightly closed during ventricular contraction so blood can be pumped out of the ventricle and into the pulmonary arteries.
Which valve is located between the right atrium and ventricle?
The tricuspid valve separates the right atrium and ventricle.
four chambers of the heart
Two superior atria, two inferior ventricles
Are there equal amounts of blood pumped to pulmonary and systemic circuits?
Yes
atrioventricular bundle
a bundle of modified heart muscle that transmits the cardiac impulse from the atrioventricular node to the ventricles causing them to contract
atrioventricular (AV) node
a node of specialized heart muscle located in the septal wall of the right atrium; receives impulses from the sinoatrial node and transmits them to the atrioventricular bundle
anastomosis
a surgical connection between two hollow or tubular structures
atrial reflex
a sympathetic reflex initiated by increased venous return
Contractility
ability to shorten forcibly when stimulated
arrhythmias
abnormal heart rhythms
heart murmurs
abnormal heart sounds
Epinephrine
adrenaline
hyperkalemia
alters electrical activity, heart block, and cardiac arrest
heart murmur
an abnormal sound from the heart produced by defects in the chambers or valves
Papillary muscles
anchor chordae tendineae to the ventricular walls; prevent eversion of the cusps
Chorade tendineae
anchor cusps to papillary muscles
anterior interventricular sulcus
anterior position of interventricular septum
be able to identify
arteries
aortic
between left ventricle and aorta
Systemic Circuit
carries blood between the heart and the rest of the body
pulmonary trunk
carries blood from right ventricle to pulmonary arteries
pulmonary trunk
carries blood from the right ventricle to the lungs
fibrillation
chaotic, irregular contractions of the heart, as in atrial or ventricular fibrillation
subendocardial conducting network
complete pathway through interventricular septum into apex and ventricular walls
Ductus ateriosus
connects aorta and pulmonary trunk
foramen ovale
connects the two atria in the fetal heart
ventricular systole
contraction of ventricles
cardioacceleratory center
controls sympathetic neurons that increase the heart rate
p wave
depolarization of SA node and atria
hypcalcemia
depresses heart
cardiac reserve
difference between resting and maximal CO
isovolumetric relaxation
early diastole
Three layers of heart wall
epicardium(outside), myocardium(middle), endocardium(inside)
tachycardia
fast heart rate
hypokalemia
feeble heartbeat, arrhythmia
congestive heart failure (CHF)
heart is unable to pump its required amount of blood
cardiac output
heart rate x stroke volume
atrioventricular node
in inferior intertribal septum
atrial reflex
increased blood in atria stretches walls and results in a sympathetic response to increase rate of firing
hypercalcemia
increased hr and contractility
throxine
increases heart rate
Pericarditis
inflammation of the pericardium
endocardium
inner lining of the heart
heart block
interference with normal conduction of electrical impulses that control activity of the heart muscle
pectinate muscles
internal ridges of myocardium in right atrium and both auricles
trabeculae carneae
irregular ridges of muscle on ventricular walls
arrhythmia
irregularity or loss of rhythm of the heartbeat
intercalated discs
junctions between cells anchor cardiac cells
pulmonary congestion
left side fails, blood backs up in lungs
Which chamber of the heart sends oxygenated blood to the systemic circuit via the aorta?
left ventricle
parietal layer of serous pericardium
lines internal surface of fibrous pericardium
Parietal layer
lines internal surfaces of fibrous pericardium
posterior interventricular sulcus
marks the boundary between the ventricles posteriorly
Heart's location
mediastinum, between second rib and fifth intercostal space
functional syncytium
merging cells performing as a unit; those of the heart are joined electrically
sinus rhythm
normal heart rhythm
visceral layer (epicardium)
on external surface of heart
three waves
p wave, t wave, qrs complex
apex of heart
points toward left hip
three main factors affect SV
preload, contractility, afterload
Be able to label heart
print out sheet to review
fibrous pericardium
protects anchors to surrounding structures and prevents over filling
semilunar valves
pulmonary and aortic valves located between the right ventricle and the pulmonary artery and between the left ventricle and the aorta
pulmonary circuit
right atrium ->tricuspid valve->right ventricle->pulmonary semilunar valve->pulmonary trunk->pulmonary arteries->lungs->pulmonary valve->left atrium
peripheral congestion
right side of the heart fails
pericardial friction rub
scraping or grating noise heard on auscultation of the heart; suggestive of pericarditis
Interatrial septum
separates atria
interatrial septum
separates the two atria
inter ventricular septum
separates the two ventricles
Ventricular filling
takes place in mid-to-late diastole; AV valves are open; 80% of blood passively flows into ventricles; Atrial systole occurs, delivering the remaining 20%
angina pectoris
thoracic pain caused by fleeting deficiency in blood delivery to myocardium
mitral valve
valve between the left atrium and the left ventricle; bicuspid valve
be able to identify
veins
qrs complex
ventricular depolarization and atrial repolarization
t wave
ventricular repolarization
cardiac cycle
A complete heartbeat consisting of contraction and relaxation of both atria and both ventricles
sinoatrial (SA) node
A specialized area of cardiac tissue, located in the right atrium of the heart, which initiates the electrical impulses that determine the heart rate; often termed the pacemaker for the heart.
mitral valve
A valve in the heart that guards the opening between the left atrium and the left ventricle; prevents the blood in the ventricle from returning to the atrium. Alternative name is bicuspid valve.
tricuspid valve
A valve that is situated at the opening of the right atrium of the heart into the right ventricle and that resembles the mitral valve in structure but consists of three triangular membranous flaps.
Mediastinum
Centrally located space between the lungs
fibrous pericardium
tough, white fibrous connective tissue that is the outer layer of the pericardium
cardioinhibitory center
controls the parasympathetic neurons that slow the heart rate
left coronary artery
one of two arteries from the aorta that nourish the heart; (runs from left side of heart then divides into the circumflex and left anterior descending branches)
Which of these muscles is particularly associated with anchoring the right and left atrioventricular valves?
papillary muscles
What separates the parietal and visceral pericardium?
pericardial cavity
cardiac pacemaker cells
phase 0 depolarization is mediated by an inward flux of calcium. This differs from phase 0 cardiomyocytes and Purkinje cells, which results from an inward sodium current.
extrasystole
premature contraction
circumflex artery
supplies the left atrium and the posterior walls of the left ventricle
left side of heart pumps to body tissues via
systemic circuit
electrocardiography
process of recording the electrical activity of the heart
right side of heart pumps to lungs via what
pulmonary circuit
Which of these vessels returns blood to the left atrium of the heart?
pulmonary veins
Apical Impulse (PMI)
pulsation created as the left ventricle rotates against the chest wall during systole
papillary muscles
responsible for pulling the atrioventricular valves closed by means of the chordae tendineae
Into which chamber of the heart do the superior vena cava, inferior vena cava, and coronary sinus return deoxygenated blood?
right atrium
The right atrioventricular valve prevents backflow of blood from the right ventricle into the __________.
right atrium
interventricular septum
separates ventricles
right marginal artery
serves the myocardium of the lateral right side of the heart
Bradycardia
slow heart rate
Consider the following characteristics of the cells found in muscle tissue. Which feature is shared by both cardiac muscle and skeletal muscle?
striations
epicardium
visceral layer of serous pericardium
inferior vena cava
A vein that is the largest vein in the human body and returns blood to the right atrium of the heart from bodily parts below the diaphragm.
superior vena cava
A vein that is the second largest vein in the human body and returns blood to the right atrium of the heart from the upper half of the body.
coronary veins
Blood vessels that transport deoxygenated blood from the heart toward the right atrium.
diastole
Relaxation of the heart
vagal tone
The constant inhibition provided to the heart by the vagus nerve. Vagal tone reduces the intrinsic firing rate of teh SA node from 120 beats/minute to around 80 beats/minute.
Cardiac tamponade results in ineffective pumping of blood by the heart because the excessive amount of fluid in the pericardial cavity will______.
The heart is wrapped by a double-walled sac called the pericardium. The pericardial cavity lies between the parietal and visceral layers of the serous pericardium. It is filled with a very small amount of serous fluid. If additional fluid fills the pericardial space, it adds pressure on the outside of the heart, preventing it from filling normally.
T/F? The right side of the heart is considered the systemic circuit pump.
The right side of the heart pumps oxygen-poor blood to the lungs to be re-oxygenated. For this reason, the right side of the heart is considered the pulmonary circuit pump. The left side of the heart pumps blood to the body, and is therefore considered the systemic circuit pump.
functional syncytium
mass of merging cells that function as a unit
ectopic focus
any region of spontaneous firing other than the SA node
Blood enters the left and right coronary arteries directly from which vessel or chamber?
aorta
cardiac veins
drain the myocardium of blood
great cardiac veins
drains blood from area of anterior interventricular artery into coronary sinus
