Cardiovascular
System
Functions
• Body’s delivery service
• Heart:
– Pumps blood through the body
• Blood Vessels:
– Carry oxygen-rich blood to all the body’s cells and return
The Heart
• Average adult heart- fist-sized
– Lies in thoracic cavity, between the lungs
– Two-thirds of the heart actually lies to the left of the sternum
• Amazingly powerful muscle
– Beats an average of 72 times per minute, 100,000 times a day and 3000 million times (3 trillion) in the average lifetime
Parts of the Heart
• The Pericardium:
– A protective sac that covers
the heart
– Has two layers:
• Visceral pericardium: innermost layer next to the heart
• Parietal pericardium: outer layer
Parts of the Heart
• The Heart:
– Three layers of tissue:
• Epicardium: outer layer
• Myocardium: middle layer, muscular tissue
• Endocardium: inner layer, forms membrane lining the chambers and valves
The Heart
• The heart is divided into right and left sides
• Each side has two chambers • Right Side:
– Right Atrium: upper chamber – Right Ventricle: lower chamber
• Left Side: same as right
• Two sides are separated from each other by a partition called the septum
The Heart
• Valves of the Heart:
• Control blood flow to and from the heart • Valves that control blood between atria
and ventricles:
– Bicuspid (mitral) valve: Valve between left atrium and ventricle
– Tricuspid valve: Between right atrium and ventricle
• Valves that control blood leaving the heart (preventing backflow): Pulmonary and
Blood Flow
• Blood flows through the chambers of the heart in only one direction
• The flow is regulated by the valves of the heart
• Arteries: carry blood AWAY from the heart
– Usually carry blood rich in oxygen
– EXCEPTION: Pulmonary Artery, which
carries blood low in oxygen AWAY from the heart, toward the LUNGS to pick up
OXYGEN from the ALVEOLI
Blood Flow
• Veins: carry blood TOWARD the heart
– Usually carry blood low in oxygen
– EXCEPTION: Pulmonary Veins, which returns blood that is rich in oxygen
TOWARD the heart.
Cardiac Conduction System
• The heart muscle works like a pump.
• Electrical impulses control the pumping cycle of the heart muscle.
• Electrical impulses begin in one part of the heart and travel all through the
heart.
• The special tissues in the heart that produce electrical impulses form the cardiac conduction system
Cardiac Conduction System
• The Cardiac Conduction
System contains:
– The Sinoatrial (SA) node
– The Atrioventricluar (AV) node – Bundle of His (AV Bundle)
– Bundle Branches
SA Node
• Small round structure
• Located in upper part of right atrium
• Natural pacemaker-makes the heart start to beat
• Fires at about 60-100 times per minute
– Fire: transmit a nervous impulse or electrical signal
• Conduction begins in the SA node (which means that each heartbeat begins here as well)
AV Node
• Also small and round structure
• Located along the floor of the right atrium
• Receives impulses traveling through the heart (from the SA node) and can delay or slow down the impulse
• If SA node is not working, AV node can also act as the pacemaker
• Usually fires at a rate of 40-60 times per minute
Bundle of His
• Located next to the AV node
• Transfers electrical energy from the atria to the ventricles
• When impulses reach the ventricles, they are divided into the bundle
Bundle Branches
• Located along the left and right side of the septum separating the left and right ventricles
• Impulses travel through the left and right bundle branches to the left and right ventricles
• Fork in the Road: Some impulses go right, others left
Purkinje Network
• Spreads the impulses throughout the ventricles, through a system of fibers called the Purkinje fibers
• Fibers provide an electrical pathway for each of the cardiac cells
• Electrical impulses speed up here
– Activate right and left ventricles at one time, causing them to contract
– Electrical impulse produces an electrical wave, which can be recorded using an Electrocardiogram (ECG)
Cardiac Conduction Animation!!
Circulation
• There are three types of circulation:
– Coronary – Pulmonary – Systemic
Coronary Circulation
• Circulation of blood within the heart
• Coronary Arteries: branch off the aorta to supply blood to the heart muscle
• AORTA: main artery through which blood exits the heart
• Fun Fact: the heart needs more oxygen to function than any other organ (except the brain)
Pulmonary Circulation
• Flow of blood between the heart and
the lungs
• Pulmonary arteries: carry blood LOW in oxygen from the right ventricle of the heart to the lungs, where it will pick up oxygen from the alveoli
• Blood RICH in oxygen flows back to the
left atrium through vessels called the Pulmonary veins
Systemic Circulation
• Flow of blood between the heart and
the cells of the body
• The heart pumps blood through the
arteries to the cells of the body
• The muscular contraction of the heart pushes the blood through the arteries
• Blood going from the heart to the cells of the body is RICH in oxygen
Special Arteries
• Specialized arteries are those that carry oxygen-rich blood to specific areas of the body
• Carotid Artery: supplies blood to the head and neck • Femoral artery: supplies blood to the thigh
• Arterioles: smaller divisions of arteries • Capillaries: smallest blood vessel
– Deliver nutrients and oxygen to cells – Remove waste products from cells
Systemic Circulation
• After flowing through the capillaries, blood begins the trip back to the heart through venules, which are small
veins
• The Veins take blood that is LOW in oxygen back to the heart
• The blood from the upper part of the
body is collected and returns to the heart through the Superior Vena Cava
• Blood from the lower part of the body
collects and returns to the heart through the Inferior Vena Cava
• Both vessels return blood to the Right
Atrium
Animation!!!
Diseases of the
Cardiovascular System
• Hypertension • Stroke
• Aneurysm
• Coronary Artery Disease (CAD) • Myocardial Infarction (MI, Heart
Attack)
Hypertension: high blood
pressure
• Blood Pressure: the force of the blood surging against the walls of the arteries • No symptoms
• Usually the result of lifestyle factors • Medication is available to keep high
blood pressure at a normal level, but it needs to be taken every day
• Untreated, it may cause major damage to the liver, blood vessels and kidneys • Can lead to a cerebrovascular accident
Stroke
• Can occur when a blood clot blocks
the flow of blood in a vessel, or when a blood vessel bursts in the brain
Stroke
• May experience mild symptoms before a major stroke
– Sudden numbness or weakness of the face, arm or leg especially on one side of the body
– Facial droop
– Sudden confusion
– Difficulty speaking or understanding – Trouble seeing in one or both eyes – Sudden difficulty in walking, loss of
balance, coordination or dizziness – Sudden, severe headache
Stroke
• Short incidents of blood flow loss (transient ischemic attacks-TIAs)
• Can recover completely from a mild stroke
• Severe stroke damage may be permanent
Stroke
• Common damage from a stroke
– Thought disorders – Speech difficulty
– Loss of muscle control – Some paralysis
– Disorientation
Arteriosclerosis
• Hardening of the arteries
• Arteries lose elasticity (their ability to stretch) and their ability to contract
• Commonly occurs as a result of aging • Can lead to high blood pressure or an
Aneurysm
• Occurs when a disease or defect at birth weakens the walls of an artery
• May also be the result of trauma
– Trauma: a physical injury caused by external force or violence
• Ballooning out of an artery wall • Common sites:
– Aorta
– Abdominal artery – Cerebral artery
Aneurysm
• May cause pain and pressure, but usually there are no symptoms
• If found before it ruptures (pops), most must be surgically removed
• If they do rupture, they can cause severe bleeding and death
Coronary Artery Disease (CAD)
• Narrowing of the coronary arteries that supply blood to the heart
• Usually caused by atherosclerosis, which is a buildup of fatty plaque inside the blood vessels
• Can lead to angina or myocardial infarction
Myocardial Infarction (MI)
• Also known as a heart attack • Blood flow to the heart is cut off
• Can result in permanent damage to the heart tissue
• Without a supply of fresh blood, deprived heart tissue begins to die
• If a large portion of the heart is affected , patient may die
Myocardial Infarction (MI)
• Angina: temporary loss of blood supply to the heart
– May cause same symptoms as heart attack
• Symptoms of a Heart Attack:
– Chest discomfort, feeling of fullness in the chest, or pain or pressure in the center of the chest that lasts for more than 3-5 minutes
– Light-headedness or dizziness
– Sweating or breaking out in a cold sweat – Fainting
– Nausea, vomiting – Shortness of breath
– Pale or grayish skin color – Generalized weakness
Congestive Heart Failure (CHF)
• Occurs when heart cannot pump at its usual capacity
• Vital organs do not receive enough blood
• May occur as a result of atherosclerosis and/or MI
Congestive Heart Failure (CHF)
• Heart is weakened and cannot pump at its usual force
• If the right side of the heart is
weakened, blood backs up in the organs and builds up
• If left side of heart is weakened, blood builds up in lung tissue
