Module 3: The Heart

Chapter 19 The Heart

pulmonary circuit

what circuit is on the right side of the heart

systemic circuit

what circuit is on the left side of the heart

pulmonary circuit

what circuit carries blood to lungs for gas exchange and back to heart

systemic circuit

supplies oxygenated blood to all tissues of the body and returns it to the heart; delivers oxygen and nutrients while removing waste products

mediastinum

space between lungs where the heart is located

pericardium

double-walled sac that encloses the heart

parietal pericardium

outer tough fibrous layer of connective tissue

visceral pericardium (epicardium)

inner, thin, smooth, serous membrane covering heart

pericardial cavity

space inside the pericardial sac falled with 4 to 30 mL of pericardial fluid

pericarditis

painful inflammation of the membranes

myocardium

middle muscle layer (cardiac muscle)

endocardium

lines inner heart; inner

right and left atria

receive blood returning to heart from the body and lungs, respectively.

auricles

enlarge chamber

right and left ventricles

pump blood into arteries

interatrial septum

wall that separates atria

pectinate muscles

internal ridges of myocardium in right atrium and both auricles

interventricular septum

muscular wall that separates ventricles

trabeculae carneae

internal muscular ridges; help chambers expand and refill more easily

coronary sulcus

separates atria above from ventricles below; encircles heart near base

anterior and posterior interventricular sulci

separate right and left ventricles

atrioventricular (AV) valves

control blood flow between atria and ventricles

right AV valve

tricuspid valve

left AV valve

mitral valve/bicuspid valve

chordae tendineae

strings of connective tissue that attach the AV valves cusps to papillary muscles on floor of ventricles

semilunar valves

control flow into great arteries; open and close because of blood flow pressure

pulmonary semilunar valve

in opening between right ventricle and pulmonary trunk

aortic semilunar valve

in opening between left ventricle and aorta

valvular insufficiency (incompetence)

any failure of a valve to prevent reflux (regurgitation), the backward flow of blood

valvular stenosis

cusps are stiffened and opening is constricted by scar tissue

mitral valve prolapse (MVP)

insufficiency in which one or both mitral valve cusps bulge into atria during ventricular contraction

coronary circulation

heart has its own supply of vessels to deliver blood to myocardium

angina pectoris (heart attack)

chest pain caused from partial obstruction of coronary blood flow

myocardial infarction

complete obstruction causes death of cardiac cells in affected area

cardiomyocytes

striated, short, thick branched cells, one central nucleus

mechanical junctions

tightly join cardiomyocytes

electrical junctions

gap junctions which form channels that allow ions to flow from the cytoplasm from one cell directly into the next

depolarization

exciting the cell

repolarization

relaxation (not systole)

SA (sinoatrial) node

modified cardiomyocytes

pacemaker

intitiates each heartbeat and determines heart rate

right and left bundle branches

Divisions of AV bundle that enter interventricular septum

purkinje fibers

Nerve-like processes spread throughout ventricular myocardium

systole

contraction

diastole

relaxation (of chamber or ventricles)

sinus rhythm

normal heartbeat triggered by SA node

70-80

adult at rest is typically _______ bpm

ectopic foci

region of spontaneous firing other than the SA node

electrocardiogram

Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes (leads) on arms, legs, and chest

p wave

what wave is Atrial systole

pq segment

wave that represents time required for signals to pass from the SA node to the AV node

qrs complex

wave where Ventricular depolarization occurs

st segment

wave that represents ventricular systole

t wave

Ventricular repolarization and relaxation

cardiac cycle

One complete contraction and relaxation of all four chambers of the heart

s1

Louder and longer “lubb” occurs with closure of AV valves

s2

Softer and sharper “dupp” occurs with closure of semilunar valves

stroke volume

amount of blood ejected, 70 ml at rest

end systolic volume

amount of blood left in heart

congestive heart failure (CHF)

results from the failure of either ventricle to eject blood effectively

pulse

Surge of pressure produced by heart beat that can be felt by palpating a superficial artery (radial or carotid)

infants

who has HR of 120 bpm or more

young adult females

who average 72-80 bpm

young adult males

who average 64-72 bpm

tachycardia

Persistent, resting adult HR above 100 bpm

bradycardia

Persistent, resting adult HR < 60 bpm

cardioacceleratory center

Stimulates sympathetic cardiac nerves to SA node, AV node and myocardium

cardioinhibitory center

Stimulates vagus nerves

chemoreceptors

respiratory control

coronary artery disease (CAD)

A constriction of the coronary arteries

major risk factor for coronary artery disease (CAD)

excess of low-density lipoprotein (LDL) in the blood