Studied by 3 people
Heart
A transport system consisting of 2 side-by side pumps
Right side pump
receives oxygen-poor blood from tissues
pumps blood to lungs to get rid of CO2, pick up O2 via pulmonary circuit
Left side pump
receives oxygenated blood from lungs
pumps blood to body tissues via systemic circuit
How does blood move?
from areas of high pressure to areas of low pressure
Mediatsinum
Between second rib and fifth intercostal space
Epicardium
Visceral layer of serous pericardium
Myocardium
Circular or spiral bundles of contractile cardiac muscle cells
Cardiac skeleton
crisscrossing, interlacing layer of connective tissue
anchors cardial muscle fibers
supports great vessels/valves
limits spread of action potential to specific paths
Coronary Sulcus
Encircles junction of atria and ventricles
Anterior interventricular sulcus
anterior potions of interventricular septum
Posterior interventricular sulcus
landmark on posteroinferior surface
Heart has a double blood supply
pumped blood
blood feeds the heart O2 and nutrients
Desmosomes
hold cells together’ prevent cells from separating during contraction
Gap Junctions
allow ions to pass from cell to cell; electrically couple adjacent cells
Which has a slower contraction? heart muscles or skeletal muscles
heart muscles
What does a slow contraction prevent?
Tetanus
Contractile cells
responsible for contraction
Pacemaker cells
noncontractile cells that spontaneously depolarize
Angina pectoris
thoracic pain caused by fleeting deficiency in blood delivery to myocardium
cells are weakened
Myocardial infarction (heart attack)
prolonged coronary blockage
areas of cell death are repaired with noncontractile scar tissue
Hystemia
low blood flow
Cardiac muscle cells
striated, short, branched, fat, interconnected
Intercalated discs
connecting junctions between cardiac cells that contain desmosomes and gap junctions
Functional syncytium
single coordinated unit
Intrinsic conduction system
network of noncontractile cells
initiate and distribute impulses to coordinate depolarization and contraction of the heart
Where does parasympathetic division occur?
Vagus Nerve
Where does sympathetic division occur?
Cardiac accelerator nerve
Cardiac cycle
Blood flow through heart during one complete heartbeat
takes 0.8 seconds
Electrocardiograph
Can detect electrical currents generated by heart
Electrocardiogram
A graphic recording of electrical activity
Systole
period of heart contraction
Diastole
period of heart relaxation
End diastolic volume
volume of blood in each ventricle at the end of the ventricular diastole
average is 130mL
End systolic volume
blood volume remaining in each ventricle after contraction
average is 60mL
70mL is ejected from EDV
How to find Stroke volume
subtract EDV from ESV
Heart murmur
abnormal heart sounds heard when blood hits obstructions
Cardiac output
amount of blood pumped out by each ventricle in 1 minute
HR times SV
Cardiac reserve
Difference between resting and maximal CO
Stroke Volume
volume of blood pumped out by one ventricle with each beat
Three factors that affect SV
preload
contractility
afterload
Preload
Stretch of a chamber
increased SV
Contractility
increase contractile strength with Na+. Ca2+, T3/T4, etc..
decrease contractile strength with K+ etc.
increase or decrease SV
Afterload
decrease SV
back pressure exerted by arterial blood
Hypocalcemia
depresses heart
decrease Ca2+
Hypercalcemia
increase HR and contractility
increase Ca2+
Hyperkalemia
alters electrical activity which can lead to heart block and cardiac arrest
increase K+
Hypokalemia
results in feeble heartbeats; arrhythmias
decrease K+
Factors that influence HR
age
gender
exercise
body temperature
Tachycardia
abnormally fast HR
Bradycardia
slower HR than normal
P wave
Depolarization of SA node and atria
QRS complex
Ventricular depolarization and atrial repolarization
T wave
Ventricular repolarization
P-R interval
Beginning of atrial excitation to beginning of ventricular excitation
S-T segment
entire ventricular myocardium depolarized
Q-T interval
beginning of ventricular depolarization through ventricular repolarization
Arrhythmias
Irregular heart rhythms
Fibrillation
rapid, irregular contractions
Sinoatrial node (SA)
pacemaker of the heart in right atrial wall
depolarizes faster than rest of myocardium
impulses spread across atria to AV node
Atrioventricular node (AV)
in inferior interatrial septum
delays impulses approximately 100ms
Atrioventricular bundle
in superior interventricular septum
only electrical connection between atria and ventricles
Right and left bundle branches
two pathways in interventricular septum
carry impulses toward apex of heart
Sequence of excitation
sinoatrial node
atrioventricular node
atrioventricular bundle
right and left bundle branches
subendocardial conducting network (purkinje fibers)
Coronary sinus
empties into right atrium formed by merging cardiac veins
Cardiac veins
Collect blood from capillary beds
Left coronary artery
supplies interventricular septum, anterior ventricular walls, left atrium, and posterior wall of left ventricle.
Two branches of the left coronary artery
anterior interventricular artery
circumflex artery
Right coronary artery
Supplies right atrium and most of right ventricle
Two branches of the right coronary artery
right marginal artery
posterior interventricular artery
Semilunar valves
prevent backflow from major arteries back into ventricles
open and close in response to pressure change
each valve consists of three cusps
Pulmonary semilunar valve
located between right ventricle and pulmonary trunk
Aortic semilunar valve
located between left ventricle and aorta
Tricuspid valve
in the right AV valve
made up of three cusps and lies between right atria and ventricle
Mitral valve
in the left AV valve
made up of two cusps and lies between left atria and ventricle
Chordae tendineae
anchor cusps of AV valves to papillary muscles
Right ventricle
most of the anterior surface
Left ventricle
posteroinferior surface
Papillary muscles
project into ventricular cavity
anchor chordae tendeneae that are attached to heart valves
Atria
the receiving chambers
small thin walled chambers; contribute little to propulsion of blood
Auricles
appendages that increase atrial volume
Right atrium
Receive deoxygenated blood from the body
Superior vena cava
returns blood from body regions above the diaphragm
Inferior vena cava
Returns blood from body regions below the diaphragm
Left atrium
Receives oxygenated blood from lungs
Pericardium
double walled sac that surrounds heart
Where is the base of the heart loacted
leans towards right shoulder
Where is the apex of the heart located
points toward left hip
Note 
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