Introduction to the Introduction to the Cardiovascular Cardiovascular SystemSystem

Chapter 13Chapter 13

Unit 4: TransportUnit 4: Transport

IntroductionIntroduction

Primary function of the Primary function of the cardiovascular systemcardiovascular system is to is to pump blood throughout the bodypump blood throughout the body– Recall that blood is a transport Recall that blood is a transport

medium for oxygen, nutrients, and medium for oxygen, nutrients, and wasteswastes

CV System is a closed circuitCV System is a closed circuit– Blood is contained in blood vesselsBlood is contained in blood vessels

IntroductionIntroduction

There are two main components to the There are two main components to the CV systemCV system– CardioCardio - refers to the presence of the - refers to the presence of the

heart, which is the major pump for the bodyheart, which is the major pump for the body Transporting 7,000 liters of blood every day.Transporting 7,000 liters of blood every day. Beats 2.5 billion times in a lifetimeBeats 2.5 billion times in a lifetime

– VascularVascular - refers to the vessels that - refers to the vessels that contain bloodcontain blood

Blood is forced from the heart into arteries, Blood is forced from the heart into arteries, arterioles, capillaries, venules, and veins in that arterioles, capillaries, venules, and veins in that orderorder

Each blood cell circulates through the body’s CV Each blood cell circulates through the body’s CV system in about a minutesystem in about a minute

Circuits of the Circuits of the Cardiovascular SystemCardiovascular System The cardiovascular system can be The cardiovascular system can be

divided into two circuits:divided into two circuits:

1.1. Pulmonary CircuitPulmonary Circuit

• Sends deoxygenated blood to lungs to pick up Sends deoxygenated blood to lungs to pick up oxygen and unload carbon dioxideoxygen and unload carbon dioxide

• Involves the right side of the heartInvolves the right side of the heart

2.2. Systemic CircuitSystemic Circuit

• Sends oxygenated blood and nutrients to all Sends oxygenated blood and nutrients to all body cells and removes wastesbody cells and removes wastes

• Involves the left side of the heartInvolves the left side of the heart

Paths of CirculationPaths of Circulation

Pulmonary Circuit:Pulmonary Circuit:– Blood in the right side of the heart is Blood in the right side of the heart is

OO22-poor-poor

– Right side of heart pumps blood into Right side of heart pumps blood into the the pulmonary pulmonary trunk/arteries that trunk/arteries that transport blood to the lungstransport blood to the lungs

– Once blood becomes rich in OOnce blood becomes rich in O2 2 it it returns to the returns to the leftleft side of the heart side of the heart through the through the pulmonary veinspulmonary veins

Paths of CirculationPaths of Circulation

Systemic Circuit:Systemic Circuit:– Blood returning to the heart from the lungs Blood returning to the heart from the lungs

enters the enters the left side left side of the heartof the heart– Heart pumps blood into the Heart pumps blood into the aortaaorta, which , which

branches into smaller and smaller arteries branches into smaller and smaller arteries throughout the bodythroughout the body

– Blood returns to the Blood returns to the right sideright side of the of the heart via the superior and inferior heart via the superior and inferior vena vena cavaecavae after unloading its supply of O after unloading its supply of O22 in in the body’s cellsthe body’s cells

Paths of CirculationPaths of Circulation

Heart AnimationHeart Animation

What would What would happen without happen without circulation in circulation in the body?the body?

Structural Structural Characteristics of the Characteristics of the HeartHeart The heart is:The heart is:

– HollowHollow

– Cone-shapedCone-shaped

– MuscularMuscular

– Found inside the thoracic cavityFound inside the thoracic cavity

– Rests on the diaphragmRests on the diaphragm

Size and Location of Size and Location of the Heartthe Heart Varies in size and shape, but the Varies in size and shape, but the

average adult heart is about 14 average adult heart is about 14 cm long and 9 cm wide.cm long and 9 cm wide.– About the size of your fist.About the size of your fist.

Rests in an opening called the Rests in an opening called the mediastinummediastinum– Bordered laterally by the lungs, Bordered laterally by the lungs,

posteriorly by the vertebral column, posteriorly by the vertebral column, and anteriorly by the sternumand anteriorly by the sternum

Coverings of the HeartCoverings of the Heart

The heart is enclosed in a fibrous The heart is enclosed in a fibrous sack called the sack called the PericardiumPericardium (3 (3 layers).layers).– Consists of an outer bag…Consists of an outer bag…

Two layersTwo layers– Fibrous PericardiumFibrous Pericardium - - outermost layeroutermost layer– Parietal PericardiumParietal Pericardium - - deep to the fibrous p.deep to the fibrous p.

– ……and an inner bagand an inner bag Visceral PericardiumVisceral Pericardium - deepest layer, - deepest layer,

continuous with the outermost layer of continuous with the outermost layer of the heart.the heart.

Coverings ContinuedCoverings Continued

The fibrous pericardium serves as a The fibrous pericardium serves as a point of attachment to:point of attachment to:

– Diaphragm, sternum, vertebral column, and Diaphragm, sternum, vertebral column, and large blood vessels emerging from the heartlarge blood vessels emerging from the heart

The space between the parietal and The space between the parietal and visceral pericardia is called the visceral pericardia is called the pericardial cavitypericardial cavity– Contains Contains serous fluidserous fluid secreted by the secreted by the

visceral pericardiumvisceral pericardium– Fluid serves to reduce friction between the Fluid serves to reduce friction between the

membranes as the heart moves within themmembranes as the heart moves within them

Walls of the HeartWalls of the Heart

The walls of the heart are The walls of the heart are composed of three distinct layers composed of three distinct layers of tissue:of tissue:

– EpicardiumEpicardium

– MyocardiumMyocardium

– EndocardiumEndocardium

EpicardiumEpicardium

The The EpicardiumEpicardium is the outermost layer is the outermost layer of the heart muscle.of the heart muscle.

– Continuous with the visceral pericardium Continuous with the visceral pericardium and protects the heart by reducing frictionand protects the heart by reducing friction

– Composed of serous membranes Composed of serous membranes (connective tissue), epithelium, and deeper (connective tissue), epithelium, and deeper adipose tissueadipose tissue

Adipose tissue is found predominantly along the Adipose tissue is found predominantly along the paths of coronary arteries and cardiac veins that paths of coronary arteries and cardiac veins that carry blood to the heart muscle itselfcarry blood to the heart muscle itself

MyocardiumMyocardium

The The myocardiummyocardium is the thick is the thick middle layer of heart muscle.middle layer of heart muscle.

– Composed primarily of Composed primarily of cardiac cardiac muscle tissuemuscle tissue..

– Used to pump blood out of the heart Used to pump blood out of the heart chamberschambers

– Myocardial muscle works Myocardial muscle works continuously… needs a good supply continuously… needs a good supply of oxygen and sugarof oxygen and sugar

MyocardiumMyocardium

These muscles are supplied by the These muscles are supplied by the coronary arteriescoronary arteries, NOT THE , NOT THE BLOOD THAT IS IN THE CHAMBERS BLOOD THAT IS IN THE CHAMBERS OF THE HEART!!!!!OF THE HEART!!!!!– Coronary arteries branch off the aorta Coronary arteries branch off the aorta

immediately after leaving the heartimmediately after leaving the heart– This is the #1 site for plaque build-up, This is the #1 site for plaque build-up,

causing causing myocardialmyocardial infarctioninfarction (heart attack)(heart attack)

MyocardiumMyocardium

EndocardiumEndocardium

The The endocardiumendocardium is the innermost is the innermost layer of the heart muscle.layer of the heart muscle.– Consists of epithelium and connective Consists of epithelium and connective

tissue that contains many elastic and tissue that contains many elastic and collagenous fibers (helps it stretch)collagenous fibers (helps it stretch)

– Contains Contains Purkinje FibersPurkinje Fibers (aid in (aid in transmission of muscle impulses in transmission of muscle impulses in heart)heart)

– Continuous with the inner linings of the Continuous with the inner linings of the blood vessels attached to the heartblood vessels attached to the heart

Heart ChambersHeart Chambers

The heart is divided into 4 hollow The heart is divided into 4 hollow chambers-two on the right and two on the chambers-two on the right and two on the left:left:

– The upper chambers are called The upper chambers are called AtriaAtria

Have thin walls and receive blood returning to the Have thin walls and receive blood returning to the heartheart

– The lower chambers are called The lower chambers are called VentriclesVentricles Receive blood from the atria.Receive blood from the atria. Thick walls that contract to force blood out of the Thick walls that contract to force blood out of the

heart into the arteriesheart into the arteries

– The right and left chambers are separated from one The right and left chambers are separated from one another by a solid, wall-like another by a solid, wall-like SeptumSeptum

Heart ChambersHeart Chambers

The right side of the heart is part of The right side of the heart is part of the the pulmonary circuitpulmonary circuit– Only deoxygenated blood passes through Only deoxygenated blood passes through

the right sidethe right side

The left side of the heart is part of the The left side of the heart is part of the systemic circuitsystemic circuit– Only oxygenated blood passes through the Only oxygenated blood passes through the

left sideleft side *O*O22-rich and O-rich and O22-poor blood do not mix -poor blood do not mix

in healthy individualsin healthy individuals

Valves of the HeartValves of the Heart

ValvesValves are flap-like tissue that are flap-like tissue that prevents backflow of bloodprevents backflow of blood– Keeps blood going in one direction onlyKeeps blood going in one direction only

Four valves found in heartFour valves found in heart– Tricuspid valve - b/w R. atrium and R. Tricuspid valve - b/w R. atrium and R.

vent.vent.– Pulmonary valve - at exit of R. vent.Pulmonary valve - at exit of R. vent.– Mitral (bicuspid) valve - b/w L. atrium and Mitral (bicuspid) valve - b/w L. atrium and

L vent.L vent.– Aortic valve - at exit of L. vent.Aortic valve - at exit of L. vent.

Path of Blood Through Path of Blood Through the Heartthe Heart

Blood that is low in oxygen and high Blood that is low in oxygen and high in carbon dioxide enters the right in carbon dioxide enters the right side of the heart and is pumped side of the heart and is pumped into the pulmonary circulation.into the pulmonary circulation.

After blood is oxygenated in the After blood is oxygenated in the lungs and some carbon dioxide is lungs and some carbon dioxide is removed, it returns to the left side removed, it returns to the left side of the heart.of the heart.

Greater DetailGreater Detail

Deoxygenated blood FROM body enters Deoxygenated blood FROM body enters the right atrium through the vena the right atrium through the vena cavae.cavae.

Blood passes through the tricuspid Blood passes through the tricuspid valve and enters the right ventriclevalve and enters the right ventricle

Blood moves through the pulmonary Blood moves through the pulmonary valve and into the pulmonary trunk and valve and into the pulmonary trunk and the pulmonary arteriesthe pulmonary arteries

Blood enters the capillaries (aveoli) of Blood enters the capillaries (aveoli) of the lungsthe lungs

More DetailMore Detail

Blood returns to the heart via the Blood returns to the heart via the pulmonary veins into the left pulmonary veins into the left atriumatrium

Passes through the mitral valve Passes through the mitral valve into the left ventricleinto the left ventricle

Blood moves through the aortic Blood moves through the aortic valve into the aorta and to the valve into the aorta and to the bodybody