Chapter 18: The Heart

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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


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