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 deoxygenated blood to the heart

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 Aortic Valves

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 Animation

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.• This blood is coming from the lungs

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– Purkinje Fibers (network)

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 branches

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

• Make the heart muscle contract

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!!!

Systemic Circulation

Diseases of the Cardiovascular System

• Hypertension• Stroke• Aneurysm• Coronary Artery Disease (CAD)• Myocardial Infarction (MI, Heart

Attack)• Congestive Heart Failure (CHF)

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 (CVA) or stroke

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

Face Arms & Legs Speech Time

Stroke• Common damage from a stroke

– Thought disorders

– Speech difficulty

– Loss of muscle control

– Some paralysis

– Disorientation

Stroke Animation!!

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

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

CHF Animation!!