The Heart
LEARNING ITS STRUCTURE
AND HOW IT WORKS
The Heart
 Organ that supplies blood and oxygen to the body.
•Located slightly to the left of
your breast bone (sternum)
• Protected by a fluid filled sac
called the pericardium
• Receives blood from the
vena cavae and pulmonary
veins and sends blood out
through the pulmonary
arteries and aorta.
Non-oxygenated blood
travels to the heart
through the superior
and inferior vena
cavae into the Right
Atrium
Allowed into the Right
Ventricle through
the Tricuspid Valve
Sent through the
Pulmonary Valve
into the Pulmonary
Artery, which feed
blood to the
capillaries
surrounding the
lungs
How the Heart
Works
Oxygenated blood
travels back to the heart
through the Pulmonary
Veins into the Left
Atrium
Allowed into the Left
Ventricle through the
Mitral Valve
Sent through the Aortic
Valve into the Aorta
Blood sent through the
Aorta is sent through all
areas of the body to feed
oxygen and nutrients to
muscles, organs, and
tissues.
Cardiac Conduction
The sinoatrial (SA) node contracts generating nerve
impulses throughout the heart wall.
1.
1.
Both Atria contract
2. The atrioventricular (AV) node is delays the
impulse from the SA node
1.
Allows contents of Atria to empty
3. AV Bundle Impulse Conduction
1.
Impulse travels through atrioventricular bundle to left and
right ventricles
4. Purkinje Fibers
1.
Triggers ventricles to contract
Cardiac
Conduction
SA Node (pacemaker of
the heart)
AV node
AV bundles
Purkinje Fibers
Types of Cardiac Conditions
 Arrhythmia
 A change in the normal sequence of the heart rate

Irregular Heartbeat
 Atrial Fibrillation – upper chambers contract irregularly
 Bradycardia – slow heart rate
 Premature Contraction
 Tachycardia – fast heart rate
 Ventricular Fibrillation – lower chambers contract irregularly
 Atherosclerosis
 A buildup of plaque on the artery walls
Types of Cardiac Conditions
 Congenital Heart Defects
 Structural problems present from birth

Could range from valve to structural to arterial defects
 Myocardial Infarction
 Heart attack
Occurs when the supply of nutrient-rich and oxygenated blood is
cut off from the heart - ischemia
 Atherosclerosis occurring in the coronary arteries leads to
ischemia, which leads to the heart attack
 Heart muscle tissue dies as a result of the stoppage of oxygen and
nutrients

How a Heart Attack Occurs
Types of Cardiac Conditions
 Cardiac Arrest
 NOT a heart attack
 Caused when the electrical system malfunctions
 Arrhythmia can lead to cardiac arrest

Ventricular fibrillation is most common during cardiac arrest
Cardiac Arrest
Types of Cardiac Conditions
 Hypertension
 High Blood Pressure

Heart is working too hard to push blood through the body
 Can be caused by smoking, obesity, high salt intake, lack of
physical activity, stress, genetics, excessive alcohol consumption
 Hypotension
 Low Blood Pressure

Heart isn’t pumping enough blood to the organs and tissues
 Pregnancy, hormonal imbalances, diabetes, low blood sugar,
medications, or heart diseases can cause this
 Serious injury, dehydration, low or high body temperature can
cause sudden hypotension
Types of Cardiac Conditions
 Stroke
 Blood flow to the brain is interrupted
Results from a blockage of oxygen and nutrient rich blood to the
brain
 Deadly if not treated immediately
 Severe headache
 Dizziness
 Numbness on one side of body
 Confusion
 Trouble walking
 Trouble seeing out of one or both eyes

Cardiovascular System
 Responsible for transporting and providing nutrients and





oxygen, carries away wastes, and helps fight disease
Blood – comprised of plasma (55%), red blood cells
(40%), white blood cells and platelets (together ~5%)
Heart – pumps blood
Arteries – transport blood away from heart
Veins – transport blood to the heart
Capillaries – tiny blood vessels that allow nutrients and
oxygen to pass through to organs and skin and waste to
enter the blood stream to be carried away