heart

heart

transport pump made of cardiac muscle tissue that delivers nutrients and waste via blood. O, glucose, CO2

lungs

located laterally to heart

heart location

base is ventral to heart, apex points to sternum laterally, dorsal to sternum

auscultation

listening to heart via stethoscope

pericardium

double walled sac enclosing heart. fibrous and serous layer

fibrous pericardium

dense connective tissue that anchors and protects heart. also prevents over filling of the heart

serous pericardium

inner layer of pericardium with two membranes parietal and visceral layer

parietal layer

lines internal fibrous pericardium

epicardium

visceral layer of serous pericardium that is intimately attached to heart, outermost layer of the heart wall

pericardial cavity

surrounds the heart and contains serous fluid that lubricates heart

pericarditis

inflammation of pericardium, decreased serous fluid production causes rubbing and pain beneath sternum. auscultate friction rub

cardiac tamponade

increased fluid or blood in pericardial cavity that compresses heart

heart wall

very vascular and made of 3 layers: epicardium, myocardium, endocardium

epicardium

most superficial, outermost layer of heart. visceral layer of serous pericardium

myocardium

middle, muscular layer (cardiac muscle) of heart. contracts. anchored by crisscrossing connective tissue fibers

myocardium

fibrous skeleton of heart, prevents stretching over time, limits spread of action potential across heart to specific pathways

endocardium

glistening inner layer of heart. made on squamous endothelium, continuous with blood vessels leaving heart

superior chambers

left and right atrium, separated by interatrial septum

inferior chambers

left and right ventricle separated by interventricular septum

coronary sulcus

separates atria from ventricles, atrioventricular groove

interventricular sulci

grooves with blood vessels along septum between ventricles. anterior and posterior

atria

receiving blood chambers with thinner walls. posterior surface is smooth, anterior surface is muscle bundles

auricles

appendages that increase atrial volume

pectinate muscles

prominent muscular ridges along the inner surface of the auricle and across the adjacent anterior atrial wall

crista terminalis

C-shaped ridge landmark used to locate veins entering right atrium

fossa ovalis

remnant of foramen ovale of fetal heart

right atrium

the right upper chamber of the heart that receives blood from the superior and inferior vena cava, coronary sinus

superior vena cava

receives blood superior to diaphragm

inferior vena cava

receives blood inferior to diaphragm

coronary sinus

receives blood from myocardium, coronary veins join together to form this, drains directly into right atrium

left atrium

chamber that receives oxygenated blood from the 4 pulmonary veins and lungs

ventricles

largest part of heart that discharges blood from heart. contains trabeculae carneae and papillary muscles

right ventricle

pumps deoxygenated blood to pulmonary trunk and arteries- lungs. thinner walled w larger cavity

left ventricle

pumps oxygenated blood to aorta- body. thicker walled w smaller cavity

trabeculae carneae

irregular ridges of muscle on ventricular walls

papillary muscles

conelike muscle bundles projecting into ventricular cavity, anchor chordae tendineae

heart pathway

two side by side pumps that create two circuits- pulmonary and systemic circuits

pulmonary circuit

right ventricle is pump- short low pressure. blood to and from lungs, gas exchange

systemic circuit

left ventricle is pump- long high pressure. provide oxygen rich blood and returns oxygen poor CO2 rich blood to heart

pulmonary circuit pathway

O poor CO2 rich blood from vena cava. right atrium to right ventricle to pulmonary trunk to lungs (O rich CO2 poor) to left heart

systemic circuit pathway

O rich CO2 poor blood from pulmonary vein to left atrium to left ventricle to aorta to body tissues to systemic veins to vena cava to right atrium

blood pathway

veins carry blood to heart, arteries carry blood away from heart. heart to arteries to arterioles to capillaries (gas and nutrient exchange) to venules to veins to heart

coronary circulation

circulation of blood to myocardium, myocardium is too thick for diffusion, blood in chambers does NOT supply myocardium

coronary arteries

the two arteries that supply blood to the heart muscle, emerge from aorta

left coronary artery

supplies blood to the left ventricle, left atrium, and interventricular septum. 2 branches: anterior interventricular artery and circumflex artery

anterior interventricular artery

supplies blood to anterior interventricular septum

circumflex artery

supplies left atrium and posterior wall of left ventricle

right coronary artery

supplies right atrium and most of right ventricle. 2 branches: marginal artery and posterior interventricular artery

marginal artery

supplies oxygenated blood to lateral wall of right ventricle

posterior interventricular artery

supplies the posterior surface of the left and right ventricles and apex of heart

arterioles

small vessels that receive blood from the arteries, greatest effect of blood pressure

coronary blood vessels

these branch into myocardium, blood flows during relaxation, decrease in contraction, compressed by myocardium, entrances blocked by open valves

cardiac veins

these empty into coronary sinus which then empties into right atrium. great, middle, and small

atrioventricular valves

these separate atria and ventricle, prevents backflow of blood into atria while ventricles are contracting

right av valve

tricuspid valve, 3 cusps that are flaps of endocardium with connective tissue

left av valve

bicuspid valve, 2 cusps, mitral valve

both valves

these are one way and are anchored to ventricular wall with papillary muscles and chordae tendinae

semilunar valves

half moon, controls blood flow out of ventricles and into arteries. ventricular pressure forces valves open, backflow of blood closes valves

pulmonary valve

right semilunar valve, blood from right ventricle flows through this into lung circuit

aortic valve

left semilunar valve, blood from left ventricle flows through this into systemic circulation

incompetent valve

heart has to re pump same blood over and over, can be replaced surgically- synthetic, pig heart, cadavers

murmur sound

sound of blood being shot backward

stenosis

valve is stiff from scar tissue from endocarditis or calcium deposits, heart works harder and may cause the heart to weaken

cardiac muscle cells

striated, paler, branched, shorter than skeletal. 1-2 central nuclei. intercalated discs- desmosomes, gap junctions prevent separation of adjacent cells

functional syncytium

mass of merging cells that function as a unit. ions pass so myocardium contracts in unison

mitochondria

cardiac muscle has large ____ and a high resistance to fatigue. also has less elaborate sarcoplasmic reticulum

cardiac contraction

some myocardial cells can initiate depolarization automatically, self excitable. heart dose this as a unit

250 ms

length of cardiac muscles absolute refractory period (where Na channels are open) and the contraction duration

skeletal muscles contraction

1-2 ms refractory period. 20-100 ms period of contraction

contraction

1. voltage, Na channels open, depolarization -90mV to +30mV. 2. action potential travels through t tubules, sr releases Ca ions. 3. cross bridge activation

Ca

10-20% for muscle contraction is extracellular. stimulates of 80% release from sr. action potential opens slow channels

action potential

1. Na dependent membrane depolarization 2. Ca channels open 3. Ca from sr released 4. Ca channels close 5. K flows outward, restores resting membrane potential

200 ms

duration of cardiac muscle action potential and contraction

skeletal duration

1-5 ms for action potential. 15-100 for contraction

cardiac muscle

more dependent on aerobic respiration, cannot contract for long periods in anaerobic conditions. better at using different nutrients

oxygen

the most important factor for myocardium

intrinsic cardiac conduction system

cardiac muscle can initiate depolarization and distribute impulses throughout heart, may still beat even when disconnected from nerves

coordinated contraction

the heart can do this because of the gap junctions at intercalated disc and function syncytium

autorhythmic cells

are also called pacemakers because they set the rate of the heartbeat. continually depolarize and slowly approach threshold

autorhythmic cells

these initiate action potential through rest of myocardium

autorhythmic cell location

these are found at the sinoatrial node, atrioventricular node and bundle, right and left bundle branches, and purkinje fibers

sa node

on right atrial wall, generates impulses 75 times per min. fastest depolarization rate

sa node

pacemaker, produces sinus rhythm, determines heart rate

av node

receives wave of depolarization through internodal pathway from sa node. located in interatrial septum by tricuspid valve. impulse is delayed- allows atria to contract

av bundle

bundle of his, located on superior interventricular septum. the only electrical connection between atria and ventricles

bundle branches

branches of the AV bundle that divide to the right and left sides of the interventricular septum, travel towards apex

purkinje fibers

fibers in the ventricles that transmit impulses to the right and left ventricles, causing them to contract

purkinje fibers

penetrate myocardium and are more elaborate in left ventricle. directly supply papillary muscles and allows them to contract before the ventricles

arrhythmias

irregular heart rhythms; uncoordinated atrial and ventricular contractions

ectopic focus

defective sa node, abnormal pacemaker, av node may take over- junctional rhythm

extrasystole

premature contraction, atria or ventricle contracts before sa node initiates impulse

heart block

damaged AV node releases the ventricles from control of the SA node; result is a slower heart rate as ventricles contract at their own rate. partial or total

sympathetic

increases heart rate, medulla oblongata

parasympathetic

decreases heart rate, vagus nerve x

electrocardiogram

recording of the electrical activity of heart, composite of all action potentials. recoded on electrocardiograph

lead

electrodes that detect electrical current, limb leads I, II, III, up to 12

p wave

first deflection, depolarization from sa node through atria, atria contracts shortly after

qrs complex

largest deflection, depolarization of ventricles, ventricles contract shortly after

t wave

follows qrs complex, represents repolarization of ventricles

p q interval

beginning of atrial contraction to beginning of ventricular excitation, atrial depolarization through rest of conduction system