pericardium

layer that encloses the heart

left

direction in which the heart points

visceral pericardium

layer also known as the epicardium

parietal pericardium

separated from the epicardium by the pericardial cavity

epicardium

layer that protects the heart by reducing friction

myocardium

thick middle layer of the wall of the heart; composed of smooth, cardiac muscle

endocardium

inner layer of the heart wall consisting of epithelium and connective tissue as well as some specialized muscle tissue

atria

receive blood from lungs and body

ventricles

receive blood from atria and force into body

septum

separates right and left sides of heart

tricuspid valve

between right atrium and ventricle

chordae tendinae

fibers attatched to the tricuspid valve which pull it closed when papillary muscles contract, preventing backwash of blood

papillary muscles

responsible for pulling the atrioventricular valves closed by means of the chordae tendineae

pulmonary valve

link between right ventricle and artery extending from it

bicuspid (mitral) valve

between left atrium and ventricle

aorta

largest artery in the body

aortic valve

between the left ventricle and the largest artery in the body

semilunar valves

pulmonary valve and aortic valve

skeleton of the heart

rings of dense connective tissure surrounding the pulmonary trunk and aorta

coronary arteries

first two branches of the aorta; feed the heart

agina pectoris

extreme chest pain caused by blockage (thrombus) of coronary arteries

coronary thrombosis

blood clot completely blocking a coronary artery, causes a heart attack

myocardial infarction

another name for heart attack

coronary sinus

enlarged vein from junctions of coronary veins which empty into the right atrium

systole

contraction of heart muscle

diastole

relaxation of heart muscle

cardiac cycle

atrial systole/ventricular diastole, ventricular systole/atrial diastole, brief complete diastole

functional syncytium

mass of merging cells that function as a unit

cardiac conduction system

fibers of cardiac muscle tissue which distribute impulses over the entire heart

sinoatrial node

small, elongated mass of specialized cardiac muscle tissue just beneath the epicardium in the right atrium near the opening of the superior vena cava-starts impulses

pacemaker

common name for S-A node

atrioventricular node

only normal conduction pathway between the atrial and ventricular syncytia

A-V bundle

group of fibers which receive impluse from the atrioventricular node; also known as the bundle of His

Purkinje fibers

extend from branches of A-V bundle, stimulate muscle fibers in the ventricular walls

electrocardiogram (ECG)

recording of the electrical changes that occur in the myocardium during a cardiac cycle

waves

deflection in a ECG

P wave

in an ECG corresponds to depolarization of the atrial fibers (leads to contraction

QRS complex

in ECG corresponding to depolarization of ventrical membranes, much stronger!!

T wave

in ECG last wave of cardiac cycle corresponding to repolarization

acetylcholine

decreases S-A and A-V nodal activity; leads to heart rate decrease

baroreceptors

detect changes in blood pressure

auricle

expandable extension of the atruim

coronary sulcus

groove that marks border between atria and ventricles

interatrial septum

separates the two atria

interventricular septum

separates the two ventricles

pectinate muscles

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

foramen ovale

penetrates interatrial septum from fifth week of embryonic development until birth

fossa ovalis

small depression of site of prior foramen ovale

trabeculae carneae

muscular ridges on the internal surface of the ventricles

how big is the heart

approximately the siz of a fist

where is the heart located

in the mediastinum between the 2nd rib and the 5th intercostal space, on the superior surface of the diaphragm, two thirds to the left of the midsternal valve , anterior to the vertibral column, posterior to the sternum

pericarditis

inflamation of the pericardium

pericardium

(peri - around cardi - heart)double walled sac the encloses the heart -

superficial fibrous pericardium

it protects, anchors, and prevents overfilling

deep two layered serous pericardium

parietal layer: lines the internal surface of the fibrous pericardium
visceral layer(epicardium): on external surface of the heart - seperated by a fluid filled pericardial cavity (decreases friction)

label - if you hohld your mouse over the photo it enlarges

A. Fibrous pericardium
B. Parietal layer or serous pericardium
C. Pericardial cavity
D. Epicardium
E. Myocardium
F. Endocardium

epicardium

visceral layer of the serous pericardium

describe the myocardium

(made of muscle) spiral bundles of cardiac muscle cells, fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue

what is the function of the myocardium

anchors cardiac muscle fibers, supports great vessels and valves , limits spread of action potentials to specific parts

endocardium

(inside the heart)is continuous with endothelial lining of blood vessels

what are the four main chambers of the heart

two atria - left and right
two ventricles - left and right

internal structure of the two atria

seperated internally by the interarterial septum, coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles , auricles increase atrial volume

internal structure of the two ventricles

seperated by hte interventricular septum, anterior and posterior interventricular sulci mark the position of the septum externally

A. brachiocephalic trunk
B. superior vena cava
C. right pulmonary artery
D. ascending aorta
E. pulmonary trunk

F. right pulmonary veins
G. right atrium
H. right coronary artery
I. anterior cardiac vein
J. right ventricle

K. right marginal artery
L. small cardiac vein
M. inferior vena cava
N. left common carotid artery
O. left subclavian artery

P. aortic arch
Q. ligamentum arteriosum
R. left pulmonary artery
S. left pulmonary veins
T. auricle of the left atrium

U. circumflex artery
V. left coronary artery
W. left ventricle
X. great cardiac vein
Y. anterior interventricular artery
Z. apex

what are the recieving chambers of the heart

atria

where are the pecinate muscles found

walls of the atria

vessels entering the right atrium are

superior vena cava
inferior vena cava
coronary sinus

vessels entering the left atrium are

right and left pulmonary arteries

what are the discharging chambers of the heart

ventricles

where are the trabeculae carnae found

the ventricles of the heart

where do the papilary muscles project

into the ventricular cavities

vessels leaving the right ventricle are

pulmonary trunk

vessels leaving the left ventricle are

aorta

A. superior vena cava
B. right pulmonary artery
C. pulmonary trunk
D. right atrium
E. right pulmonary veins
F. fossa ovalis

G. pecinate muscles
H. tricuspid valve
I. right ventricle
J. chordae tendineae
K. trabeculae carneae
L. inferior vena cava

M. aorta
N. left pulmonary artery
O. left atrium
P. left pulmonary veins
Q. mitral (bicuspid ) valves

R. aortic valve
S. pulmonary valve
T. left ventricle
U. papilary muscles

V. interventricular septum
W. epicardium
X. myocardium
Y. endocardium

the heart is two side by side pumps, what is the right side the pump for

the pulmonary circuit - vessels that carry blood to and from the lungs

the heart is two side by side pumps, what is the left side the pump for

the systemic circuit - vessels that carry the blood to and from all body tissues

pathway of blood through the heart

Superior & Inferior Vena Cavas and coronary sinus Right atrium  Tricuspid valve  Right ventricle  Pulmonary semilunar valve  Pulmonary trunk  Pulmonary arteries  Lung capillaries  Pulmonary veins  Left atrium  Bicuspid (mitral) valve  Left ventricle  Aortic semilunar valve  Aorta  to the systemic arteries  systemic capillaries  systemic veins  superior & inferior vena cavas and coronary sinus

what occurs when blood reaches the lungs

gas exchange

are equal volumes of blood pumped to the pulmonary and systemic circuits

yes

describe the pulmonary circuit

short, low pressure circulation

describe the systemic circuit

blood encounters much resistance in the long pathways

how does the anatomy of the ventricles reflect these differences

the left ventricle is thicker than the right ventricle

the cornonary circulation is known as what? does what?

the shortest circulation in the body
is the functional blood supply of the heart

what are anastomoses

junctions - collateral routes that provide additional routes for blood delievery

label

A. Anastomosis
B. Left coronary artery
C. Right coronary artery
D. Circumflex artery
E. Posterior interventricular artery
F. Anterior interventricular artery

the major coronary areteries are

1. right and left coronary arteries (in atrioventricular groove)
2. marginal arteries
3. circumflex arteries (wraps around the heart)
4. anterior and posterior interventricular arteries

the major cardiac veins are

1. small cardiac vein
2. anterior cardiac vein
3. middle cardiac vein
4. great cardiac veins

what is the coronary sinus

the blood pooling area into the right atrium

What is angina pectoris and what is it caused by

chest pain
thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium

what is myocardial infarction and what is it caused by

heart attack
prolonged coronary blockage, areas of cell death are repaired with noncontractile scar tissue

what do heart valves do

ensure unidirectional blood flow through the heart

what is the job of the atrioventricular (AV) valves

prevent backflow into the atria when ventricles contract
tricuspid valve - right side
mitral (bicuspid) valve - left side

What do the chordae tendineae do

they anchor AV valve cusps to papillary muscles

what is the function of the semilunar (SL) valves

prevent backflow into the ventricles when the ventricles relax
aortic semilunar valve and the pulmonary semilunar valve

when the AV valves open: atrila pressure is greater than ventricular pressure - what occurs

1. blood returning to the heart fills the atria, putting pressure against the atrioventricular valves; atrioventricular valves are then forced open
2. as ventricles fill, atrioventricular valve flaps hang limply into the ventricles
3. atria contract, forcing additional blood into ventricles

when the AV valves close, atrial pressure is less than ventricular pressure - what occurs

1. the ventricles contract forcing blood against atriventricular valve cusps
2. atriventricular valves close
3. papillary muscles contract and chordae tendinae tighten, preventing valve flaps from everting into atria

what occurs when the semilunar valves open

as ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them to open

what occurs when the semilunar valves close

as ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close

anatomy of cardiac muscle

cells are striated, short, fat, branched, and interconnected, the connective tissue matrix(endomysium) conects to the fibrous skeleton, t tubules are wide but less numerous, SR is simpler than in skeletal muscle, contain numerous large mitochondria (25-35 % cell volume), intercalated discs - junctions between cells which anchor cardiac cells,

what types of junctions are found in cardiac muscle

desmosomes - prevent cells from seperating during contraction
gap junctions- allow ions to pass; electrically couple adjacent cells

what does it mean that the heart behaves as a functional syncytium

that is contracts all at once

facts about cardiac muscle contraction

depolarization of the heart is rhythmic and spontaneous
•About 1% of cardiac cells have automaticity—(are self-excitable)
•Gap junctions ensure the heart contracts as a unit
•Long absolute refractory period (250 ms)
•Depolarization opens voltage-gated fast Na+channels in the sarcolemma
•Reversal of membrane potential from –90 mV to +30 mV
•Depolarization wave in T tubules causes the SR to release Ca2+
•Depolarization wave also opens slow Ca2+channels in the sarcolemma
•Ca2+surge prolongs the depolarization phase (plateau)
•Ca2+influx triggers opening of Ca2+-sensitive channels in the SR, which liberates bursts of Ca2+
•E-C coupling occurs as Ca2+binds to troponin and sliding of the filaments begins
•Duration of the AP and the contractile phase is much greater in cardiac muscle than in skeletal muscle
•Repolarization results from inactivation of Ca2+channels and opening of voltage-gated K+channels

which side of the heart are the SA and AV nodes found

the right side

Sinoatrial (SA) Nodeis also known as what

pacemaker

properties of the SA node

generates impulses about 75 times/minute (sinus rythm)
depolarizes faster than any other part of the myocardium (has to get the signal out)

sequence of electrical excitation -

1. the SA node generates impulses about 75 times a minute (depolarizes faster than any other part of the myocardium)
2. the impulses pause at the AV node (for about 0.1 second) smaller diameter fibers and fewr gap junctions, depolarizes 50 times per minute in the absence of SA node input
3. the atrioventricular bundle (bundle of His) connects the atria to the ventricles (only connection between the atria and the ventricles)
4. the bundle branches conduct the impulses through the interventricular (two pathways )septum (the right and the left bundle branches - carry the impulses toward the apex of the heart
5. the perkinje fibers depolarize the contractile cells of both ventricles (complete the pathway into the apex and ventricular walls)

in the absence of AV node how many times a minute do the AV bundles and perkinje fibers depolarize

the AV bundles and perkinje fibers depolarize only 30 times per minute in the absence of AV node imput

defects in the intrinsic conduction system of the heart may result in what?

1. arrythmias- irregular heart rythms
2. uncoordinated atrial and ventricular contractions
3. fibrilation- rapid, irregular contractions, useless for pumping blood

A defective SA node may result in what

ectopic focus - abnormal pacemaker takes over
if AV node takes over, there will be a junctional rythm (40-60 bpm)

A defective AV node may result in what

partial or total heart block, few or no impulses from SA node reach the ventricles - wont pump blood

heartbeat is modified by which system

the ANS autonomic nervous system

Where are cardiac centers located

in the medula oblongata

role of sympathetic neurons

cardioaccelaratory center inervates SA and AV nodes, heart muscles, and coronary arteries through sympathetic neurons

role of parasympathetic fibers

cardioinhibitory canter inhibits SA and Av nodes through parasympathetic fibers in the vagus nerves

what is an electrocardiogram

ECG or EKG - a composite of all the action potentials generated by nodal and contractile cells at a given time

what are the three waves of an EKG

P wave: depolarization of SA node
QRS wave: ventricular depoolarization
T wave: ventricular repolarization

explain the sequence of depolarization and repolarization of the heart related to the deflection waves of an EKG tracing

1. atrial depolarization - initiated by the SA node carries the P wave
2. with atrial depolarization complete the impulse is delayed at the AV node
3. ventricular depolarization begins at apex, causing the QRS complex - atrial repolarization occurs
4. ventricular depolarization is complete
5. ventricular repolarization begins at apex, causing the T wave
6. ventricular repolarization is complete

what are the two sounds associated with the closing of the heart valves

lub dup

when does the first sound lub occur

first sound occurs as AV valves close and signifies begining of systole

when does the second sound dup occur

second sound occurs when semilunar valves close at the begining of ventricular diastole

What are heart murmurs

abnormal heart sounds most often indicitive of valve problems

what is the cardiac cycle

all events associated with blood flow through the heart during one complete heartbeat

systole

contraction, higher pressure - ventricular contraction

diastole

relaxation - ventricles are relaxed because they are filling - lower pressure

how is blood pressure read (units of measure)

mm HG (mercury)

phase 1 of the cardiac cycle

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%
END DIASTOLIC VOLUME(EDV) volume of blood in each ventricle at the end of ventricular diastole

phase 2 of the cardiac cycle

ventricular systole
-atria relax and ventricles begin to contract
-risinf ventricular pressure results in closing of AV valves
-isovolumetric contraction phase (all valves are closed - breif moment)
- in ejection phase, ventricular pressure exceeds pressure in the large arteries, forcing the Semilunar valves to open = stroke vilume

stroke volume

the amount of blood ejected from the heart per beat

phase 3 of the cardiac cycle

isovolumetric relaxation occurs in early diastole
- ventricle relax
- backflow of blood in aorta and pulmonary trunk closes semilunar valves and causes breif rise in aortic pressure
-END SYSTOLIC VOLUME (ESV) volume in blood in each ventricle at the end of ventricular systole

do you want more blood at EDV or at ESV

EDV

CO =(HR) x (SV)
what is CO
what is HR
what is SV

CO: cardiac output - volume of blood pumped by each ventricle in one minute
HR: heart rate - number of beats per minute
SV: stroke volume - volume of blood pumped out by a ventricle with each beat

SV = EDV - ESV

stroke volume = end diastolic volume - end systolic volume

what are the three main factors tha taffest stroke volume

preload
contractility
afterload

preload

degree of stretch of cardiac muscle cells before they contract (Frank - Sterling law of the heart)
cardiac muscle exhibits a length- tension relationship, at rest, cardiac muscle cells are shorter than optimal length, slow heartbeat and exercise increase venous return, increased venous return distends (stretches) the ventricles and increases contraction force

contractility

contractile strength at a given muscle length, independent of muscle stretch and EDV

what do positive inotropic agents do

increase contractility,
- hormones (thyroxine, glucagon, and epinephrine)

how do negative inotropic agents decrease contractility

acidosis
increased extracellular K+
calcium channel blockers

afterload

pressure tha must be overcome for ventricles to eject blood

what increases afterload, reulting in what?

hypertension
increased ESV and reduced SV

sympathetic nervous system is activated by what

emotional or physical stressors
norepinephrin causes the pacemaker to fire more rapidly (and at the same time increases contractility)

parasympathetic nervous system opposes sympathetic effects how

acetylcholine hyperpolarizes pacemaker cells by opening K+ channels - the heart at rest exhibits vagal tone (parasympathetic)

what is the atrial (bainbridge) reflex

a sympathetic reflex initiated by increased venous return
stretch of the atrial walls stimulates the Sa node
also stimulatse atrial stretch receptors activacting sympathetic reflexes

explain heartrate and exercise

1. exercise - fright- anxiety
2. sympathetic activity increases, parasympathetic activity decreases, contractility increases and venous return increases
3. EDV (preload) increases ESV decreases
4. heart rate increases, stroke volume increases
5. cardiac output increases

chemical regulation of heart rate: hormones

epinephrine - from adrenal medula enhances heart rate and contractility
thyroxine- increases heart rate and enhances the effects of norepinephrine and epinephrine

chemical regulation of heart rate: intra and extracellular ion concentration

Ca+ and K must be maintained for normal heart function - changes in ion concentration affect heart excitability

other factors that influence heart heart (besides hormones and intra and extracellular ion concentration)

age
gender
exercise
body temperature

tachycardia

abnormally fast heart hear over 100 beats per minute
- if persistant, may lead to fibrillation

bradycardia

heart rate slower than 60 beats per minute
may result in grossly inadequate blood circulation
maybe desirable result if endurance training

congestive heart failure - what is is it? what are causes?

progressive condition where the CO is so low that blood circulation in inadequate to meet tissue needs
caused by
*coronary artherosclerosis
*persistant high blood pressure (hypertension)
*multiple myocardial infarcts
*dialated cadiomyopathy DCM)

age related changes affecting the heart

sclerosis and thickening of valve flaps
decline in cardiac reserve
fibrosis of cardiac muscle
atherosclerosis