75
average heartbeats per minute
cardiology
study of the heart
Mediastinum
location of the heart
pericardium
Double-layered membrane surrounding the heart.
dorsal surface
near the bodies of the vertebrae
anterior surface
deep to sternum and costal cartilage
apex
just left of the sternum between the 4th and 5th costal cartilages
anteriorly
the right side of the heart is deflected ________
posteriorly
the left side of the heart is deflected _______
300 grams
weight of heart
4 chambers of the heart
right atrium, right ventricle, left atrium, left ventricle
atria
receives blood from outside of the heart
ventricles
push blood out of the heart to the body
pulmonary and systemic
2 circuits of the heart
pulmonary circulation
transports deoxygenated blood to the lungs to exchange carbon dioxide for oxygen then returns oxygenated blood to the heart from the lungs
systemic circulation
transports oxygenated blood to the entire body and returns deoxygenated blood from the body to the heart
pericardium
Double-layered membrane surrounding the heart that contains 2 layers
outer fibrous pericardium and inner serous pericardium
2 layers of pericardium
outer fibrous pericardium
dense connective tissue that protects the heart
inner serous pericardium
subdivided into parietal and visceral
parietal pericardium
fused to fibrous pericardium
visceral pericardium
(epicardium) fused to the heart and is made of simple squamous epithelium "mesothelium" and secrets serous fluid
pericardial cavity
space between epicardium and parietal pericardium and is filled with serous fluid
serous fluid
provides a frictionless environment for the heart
left and right auricles
ear-like" extensions on the superior surface of each atria
sulcus
#NAME?
epicardium, myocardium, endocardium
3 layers of the heart
epicardium
outermost layer of the heart also called the visceral pericardium
myocardium
muscular, middle layer of the heart that is thicker on the left
epicardium
outermost layer of the heart that lines chambers where blood circulates and covers heart valves, contains simple squamous epithelium, continuous with blood vessels
septum
Divides the right and left chambers of the heart and has physical extensions of the myocardium covered in endocardium
interatrial septum
between the atrium which contains oval shaped fossa ovalis
inter ventricular septum
separates the 2 ventricles
atrioventricular septum
separates atria from ventricles and has 4 openings to allow blood to pass through
atrioventricular valves
between atria and ventricles
semilunar valves
between ventricles and major arteries
right atrium
receives blood returning from systemic circuit
superior and inferior vena cava
2 major veins that empty into the right atrium
pectinate muscles
smooth inner walls with some areas of prominent ridges (left atrium does not have these)
tricuspid valve
valve between the right atrium and the right ventricle
superior vena cava
brings blood from above the diaphragm
inferior vena cava
brings blood from below the diaphragm
right ventricle
receives blood from the right atrium through the tricuspid valve
-attached to papillary muscles by chordae tendineae
-walls are lined with trabeculae carneae
trabeculae carneae
ridges of cardiac muscle covered in endocardium
moderator band
arises from inferior inter ventricular septum and attaches to inferior papillary muscle and reinforces the right ventricle
-plays a role in cardiac conduction
left atrium
Receives blood from the pulmonary circulation after it has been oxygenated in the lungs
-Does not have pectinate muscle but its auricle does
-blood passes into the left ventricle through the bicuspid (mitral) valve
left ventricle
#NAME?
Tricuspid
_________ the right atrioventricular (AV) valve
-Tri = 3 flaps which are leaflets of endocardium
-Connected by chordae tendineae to papillary muscles
-Closes when right ventricle contracts to keep blood from flowing back to atrium
Pulmonary semilunar (SL) valve
- 3 small flaps with no chordae tendineae nor papillary muscles
- Closes when right ventricle stops contracting to keep blood from flowing back into ventricle
Bicuspid or Mitral
_______ is the left atrioventricular (AV) valve
-Bi = 2 flaps instead of 3
- Connected by chordae tendineae to papillary muscles
- Closes when left ventricle contracts to keep blood from flowing back to atrium
Aortic semilunar (SL) valve
-aortic valve
-3 small flaps with no chordae tendineae nor papillary muscles
-closes when left ventricle stops contracting to keep blood from flowing back into ventricle
coronary arteries
#NAME?
left coronary artery
Bifurcates into Circumflex Artery and Anterior Interventricular Artery
right coronary artery
Branches into Posterior Interventricular Artery and several small marginal arteries
coronary veins
generally parallel to large surface arteries
-5 veins
great cardiac vein
Follows anterior interventricular artery, then circumflex artery
posterior cardiac vein
Follows marginal arteries that branched from circumflex artery
middle cardiac vein
Follows posterior interventricular artery
small cardiac vein
Follows right coronary artery
anterior cardiac veins
Drain directly into right atrium
cardiac muscle
Muscle of the heart
has 2 major types
-striated and organized into sacromeres
-shorter than skeletal muscle
-has mitochondria
-often mononucleated but can be multinucleated
myocardial contractile cells
-99% of cells in the atria and ventricles
-Contract to pump blood
myocardial conducting cells
-1% of heart cells
-Forms conduction network of the heart, similar to neurons
branching of cardiac muscle
#NAME?
Sinoatrial (SA) Node
-Located in the posterosuperior wall of the right atrium
-Known as the "pacemaker of the heart"
-initiates sinus rhythm
-Signal spreads through atria via internodal pathways to the Atriventricular (AV) node
-This takes about 50ms
- Causes atria to contrac
Atrioventricular (AV) Node
-Located in the inferior portion of the right atrium within the atrioventricular septum
-Septum prevents direct transfer of impulses without the AV node
-signal pauses for ~100ms before spreading
-Maximum transmission rate of 220 signals per minute
Atrioventricular Bundle (Bundle of His)
#NAME?
purkinje fibers
-Conductive fibers that reach to myocardial contractile cells in the ventricles
-Extend from apex toward AV septum and base of the heart
- Reaches ventricular muscles in ~75ms
~225ms since the start at SA node
electrocardiogram
record of the electrical activity of the heart and produces a graph that represents important electrical events of the heart
p-wave
depolarization of the atria
qrs complex
depolarization of the ventricles
t wave
repolarization of ventricles
segments
regions between 2 waves
intervals
segments + one or more waves
cardiac cycle
Period of time that begins with atrial contraction and ends with ventricular relaxation
systole
Period of contraction that the heart undergoes while it is pumping blood into circulation
diastole
Period of relaxation that occurs as the chambers are filling with blood
phases of cardiac cycle
1- starts with all chambers in diastole
2- atrial systole and diastole
3- ventricular systole
4- ventricular diastole
chambers in diastole
-1st phase of cardiac cycle
- blood is flowing into the right and left atria
- av valves are open and SL valves are closed
atrial systole and diastole
2nd phase of cardiac cycle
-Contraction follows P wave and lasts ~100ms
-pumps blood through AV valve
-70-80% passive filling of ventricles, 20-30% from atrial systole
ventricular systole
-3rd phase of cardiac cycle
-Follows depolarization represented by QRS complex and lasts ~270ms
- Pressure inside increases as ventricles contract
-Forces AV valves closed
-Pressure builds until SL valves are forced open when pressure exceeds that in the
ventricular diastole
-4th phase of cardiac cycle
-Corresponds with T wave and lasts ~430ms
-Pressure begins to fall immediately after systole
-SL valves close when pressure drops below aorta/pulmonary trunk
-Continues to fall until AV valves open when pressure drops below the
ausculation
Act of listening to heart, lungs, or other organs, usually with a stethoscope
s1 and s2
two audible sounds in a healthy heartbeat
s1
first heart sound "Lub"
-closing of the SL valves at the start of ventricular systole
s2
second heart sound "dub"
-closing of SL valves at the start of ventricular diastole
s3
kentucky gallop"
heart sound of blood rushing in to the atria (occurs after s2)
s4
Tennessee Gallo" heart sound
-Contraction of atria into a stiff or hypertrophic ventricle
Occurs before S1
murmurs
any unusual heart sounds caused by turbulent blood flow
Cardiac Output (CO)
Measurement of the amount of blood pumped by each ventricle in 1 minute
-stroke volume x heart rate
Stroke Volume (SV)
Amount of blood pumped by each ventricle in one cardiac cycle
-how hard the heart is beating
Heart Rate (HR)
Heartbeats per minute, abbreviated as BPM
-how fast the heart is beating
End Diastolic Volume (EDV)
Amount of blood in ventricles after they fill during
diastole
-130 ml
End Systolic Volume (ESV)
Amount of blood in the ventricles at the end of systole
Ejection Fraction (EF)
Portion of blood pumped with each ventricular contraction
stroke volume divided by end diastolic volume (58% at rest)
sympathetic
increases heart rate
Parasympathetic
rest and digest
vagus nerve
-decreases heart rate
sinus rhythm from SA node
-100 BPM without
any nervous input
- Indicates that parasympathetic system is normally in
control to reduce resting HR
-Parasympathetic system releases ACh to slow
contractions
to increase heart rate:
-parasympathetic system must first be inhibited to raise HR to 100 BPM
-Sympathetic system activates to increase HR above 100 BPM
-Uses Norepinephrine (NE) to shorten the repolarization period and makes it easier to depolarize
- Binds to Beta-1 receptor
proprioceptors
Muscles, joints, tendons
- Increased activity warrants increased blood flow
Baroreceptors
#NAME?
baroreceptor reflex
#NAME?
Chemoreceptors
-Monitor waste level in blood (CO2, H+, lactic acid, low O2)
- Increase HR to get rid of wastes
inputs to the cardiovascular centers
#NAME?
influences of heart rate
#NAME?
epinephrine and norepinephrine
#NAME?
thyroid hormones
increases heart rate and contractility
calcium
increases heart rate and contractility
-extreme levels can lead to cardiac arrest
stoke volume
Affected by preload (EDV), contractility, and afterload (ESV)
Preload (EDV)
Stretch of ventricles prior to contraction
Longer ventricular diastole
________ _______ _______ =longer filling time
-Decreases as HR increases, causing lower preload
starlings law of the heart
as stretch increases, the force of contraction increases
contractility
#NAME?
Afterload
#NAME?