Chapter 11

Chapter 11 – The Cardiovascular System

Applied Learning Outcomes

Use the terminology associated with the cardiovascular system

Learn about the following:• Blood vessel function and

structure• Circulatory system pathways• Heart function and structure• Electrocardiography principlesUnderstand the aging and

pathology of the cardiovascular system

Overview

Chapter 11 – The Cardiovascular System

Cardiovascular System: Refers to the heart and blood vessels

Heart: The hollow muscular organ that pumps blood throughout the body

Blood Vessels: A part of the cardiovascular system that carries blood throughout the body

Overview

Cardiovascular system refers to the heart and blood vessels.Circulatory system pertains to the blood circulation, blood vessels,

and the heart.Blood presssure is the force of the blood pushing against blood

vessel walls.Pulse is a throbbing of the blodd vessels produced by the heart beat.

Cardiovascular system formation is present at the beginning of the third week of embryological development.

•Derived from same type of mesoderm that forms bone and muscle.

Circulatory System VesselsThree major types of blood vessels:

1. Arteries2. Veins3. Capillaries

Arteries:muscular, carry blood away from the

heartnot visible through the skin

Veins:flexible vessels, carry blood from the

body back to the heart.often visible under the skin

Capillaries:smallest vessels, connect arteries to

veinsform networks that exchange materials

between the blood and cells

Circulatory System Vessels

Arteries and Veins:major conduits for moving blood around the body

Both composed of three layers:1. Tunica adventitia: the outer layer

it contains collage fibers for strength

it contains elastin fibers for flexibility

fibroblasts assists with healing and main-

tenance of this layer.2. Tunica media: middle layer

primarily composed of smooth muscle

interspersed with collagen and elastin fibers.

• Tunica intima: composed of simple squamous cells

attached to a layer of loose connective tissue.

Lumen: space within the interior of the blood vessel.

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Circulatory System Vessels

Comparison of Arteries and Veins:

Arteries1. Stronger and thicker2. Under pressure 3. More elastin in the tunica adventitia

Tunica media is thicker because it has smooth muscle that provides strength and permits the arteries to control blood pressure.

Constriction or Vasoconstriction: Narrowing of the diameter of a blood vessel.Dilation or Vasodilation: Widening of the diamter of a blood vessel.

Circulatory System Vessels

Veins: Respiratory activity and

contraction of skeletal muscles contribute to blood flow in

the veins.Many veins contain special one-way

valves that prevent the backflow of blood. Arterioles and venules branch off

arteries and veins.

Capillaries are very small, just large enough to allow the passage of blood cells.Two types of capillaries:

1. Continuous most common, tightly connected to each other, limits the type of material that can pass into and out of the bloodmost often found in CNS, lungs, muscles, and skin2. Fenestratedhave openings, materials are readily exchanged through themcommonly found in digestive, endocrine, and urinary system

Circulatory System Vessels

Two types of Capillaries

Continuous:most found in the CNS, lungs,

muscles, and skinFenestrated:

commonly found in the digestive, endocrine, and urinary systems. Capillaries and Venules are the major vessels which materials are exchanged between the blood and tissues.

Circulatory System Vessels

Chapter 11 – The Cardiovascular System

The circulatory system is composed of three major types of blood vessels: arteries, veins, and capillaries.

Hydrostatic pressure—the pressure of the water that is circulated in the blood and tissues—permits the exchange of materials.

Structure of the Human Heart

Chapter 11 – The Cardiovascular System

The heart is composed of four chambers that are separated by a septum into two halves.

The left half of the heart controls systemic circulation [circulation that supplies blood to all parts of the body except the lungs]

The right half controls pulmonary circulation [circulation that supplies blood to the lungs].

It is separated from the lungs by the cavity membrane called the pericardium (membranous sac that encloses the heart).

Structure of the Heart

Structure of the HeartLayers of the heart:Epicardium- the outer layer of the heart.

Formed by the visceral layer of the pericardium.Myocardium- the muscle of the heart wall that contracts to

pump blood.Endocardium- the inner lining of the heart.Blood supply to the heart muscle:Coronary arteries-vessels that supply oxygenated blood to the heart muscle (myocardium).Coronary veins- collect blood from the heart muscle. Blockage of the coronary vessels can lead to

•cardiac infarction (death of heart muscle due to lack of oxygen from the blood)•cardiac ischemia (a lack of sufficient oxygen for normal heart function of heart muscle).

The Adult HeartFour heart chambers

Top chambers: atriaBottom chambers:ventricles

Septum- separates the left side of the heart from the right sideHeart valves

Left side- mitral (bicuspid) separates left atria from

left ventricle aortic semilunar closes off

the aorta from the left ventricle

Right side- tricuspid separates right atria from right ventricle

pulmonary semilunar closes off the

pulmonary artery from the right ventricle.

The Adult HeartFive major blood vessels direct blood flowing into and out of the heart.

Superior and inferior Vena cavaBrings deoxygenated blood from the body to right atrium.Pulmonary arteryCarries deoxygenated blood from right ventricle to the lungs.Pulmonary veinBrings oxygenated blood from the lungs back to the left atriumAortaCarries oxygenated blood from left ventricle to the body

Blood Flow through the heart

The Adult Heart

The electrical conduction systemComposed of special cardiac muscle cells

that act like a miniature nervous system.They produce electrical signals that

stimulate the heartto contract.

Composed of:Sinoatrial (SA) node called the

pacemakerAtrioventricular (AV) node Bundle of HisPurkinje system

The SA node initiates the heart beat with contraction of atria.The SA node then stimulates the AV node to make the ventricles contract. The AV node stimulates the bundle of His and Purkinje system to carry out the contraction of ventricles.

The Fetal HeartBy the 8th week of fetal development, the heart is fully functional.The fetal heart differs from the adult heart by two structures:

Ductus arteriosusForamen ovale

Ductus arteriosis Usually diverts blood from the pulmonary artery to the aorta. This keeps large amounts of blood from entering the fetus lungs.Lungs not needed until after birthDuctus arteriosis usually closes a day after birth

Foramen ovaleA flap like opening within the septum between atria.It directs blood flow from right atrium to left atrium.Reduces blood flow to the lungs.

Ductus arteriosus Foramen Ovale

Heart Function

Chapter 11 – The Cardiovascular System

One pumping action of the heart is called the cardiac cycle. Diastole is the filling of the atria and ventricles; systole is the emptying of the ventricles.

Heart Function

Cardiac Cycle means a single cycle of cardiac activity.Two basic stages:Diastole the ventricles fill with blood delivered by contractions of the atria.Systole the contraction and discharge of blood from the ventricles.

Heart rate refers to the number of ventricular contractions per minute.

Omit Electrocardiography Basics Pages 427-429

Wellness and Illness over the Life Span

Chapter 11 – The Cardiovascular System

• Diseases of the cardiovascular system affect either blood vessels or the heart. Common vascular diseases disrupt blood flow; common heart diseases prevent the chambers and/or valves from working properly.

• The heart becomes more susceptible to damage as a person ages. Arterial stiffening is a common event associated with cardiovascular system aging.

Pathology of the Cardiovascular System

Cardiovascular diseases divided into two categories:1. Vascular disorders -diseases of arteries, capillaries, veins2. Cardiac disorders- affect heart function, muscle,

pericardium, valves.

Major Cardiovascular conditions in North America and Western Europe

1. Aneurysm-bulging of wall of a blood vesselusually form in large arteriestreated with surgery

2. Angina pectoris-pain in the chest areausually felt when heart needs more bloodno treatment-it is an indicator of disease

3. Arrhythmia-any deviation in normal heartbeat rhythmsome require no treatment, severe conditionstreated with medicines

4. Atherosclerosis-when plaque builds up on inner liningof an artery (usually used when fat or cholesterolbuild up)treatment-change in life style, surgery

5. Arteriosclerosis- used when calcium deposits form in the vessels, gradual stiffening of arterial walls dueto age

6. Endocarditis-caused by bacterial infection, inflames thelining of the heart, can cause damage to heart valves and produce irregular blood flow

7. Congenital heart disease- defect in heart or blood vessels

near the heart before birthcaused by many genetic conditions

8. Congestive heart failure-describes the heart’s loss of

pumping ability. Blood enters the heart faster than it canbe pumped outCaused by diabetes, high blood pressure, and lung disease.Treatment- change in lifestyle (stop smoking, diet changes)

9. Enlarged heart-caused by thickening or hypertrophy of heart

muscleCauses- vascular disorders that overwork

the heart, obesity, excessive exercise also overwork heart No treatment available

10. Fibrillation-rapid contraction of either atria or ventricles Atrial fibrillation- most likely occurs with age Rapid beating causes improper emptying of atria

Leads to pooling of blood and formation of blood clots Ventricular fibrillation-more serious condition

can lead to rapid heart failureReduces blood flow to body, ventricles don’t fill with adequate amount of bloodTreatment-defibrillator devices

11. Heart Murmurs-usually result of defective heart valvescan be caused by fevers, pregnancy

• Hypertension-high blood pressurecan be caused by congenital cardiovascular conditionand diseases of the kidneys and lungslinked to improper diets, obesity, smoking

13.Pericarditis-inflammation of the pericardiumcause-sometimes unknown, could be

bacterial, heart attack, heart surgeryCan last for weeks or monthsProduces chest pain and fever

13. Rheumatic heart disease-result of a bacterial infection

usually starts out as infection in the throat (strep)if left untreated it can enter blood stream and damage organsmainly heart valves

14. Sudden cardiac death- caused by abrupt loss of heart function.

Sometimes referred to as cardiac arrest or heart attack

Symptoms appear only minutes before death, making it

difficult to prevent.Atherosclerosis is believed to be most

common factor.

15. Thrombosis - blood clot that forms in blood vessels or the heartclots are plugs of proteins and blood cells that form at a wound siteDeep vein thrombosis occurs in people over 40 years oldusually form in leg, cause pain

16. Prolapse- mostly results in reduced blood-pumping capacity by the heart, can cause thickening of affected ventricle This occurs because of incomplete closure of the valve.Mitral valve prolapse affects almost 20% of American population. Occurs more in females, may be linked to hormonal differences.Surgery may be used to repair the heart valve.

Aging of the Cardiovascular System

Aging of cardiovascular system is caused more by interactions between age, disease, and lifestyle.

Some conditions of an aging cardiovascular system:1. Arterial stiffness-arteries lose elastin with age2. Varicose veins-veins become stretched out3. Maximal heart rate decreases with age4. Ventricles thicken with time5. Enlarged atria with time-makes them more subject to atrial

fibrillation

Summary

Chapter 11 – The Cardiovascular System

The cardiovascular system is responsible for distributing such resources as nutrients and oxygen to the other organ systems. Its ability to do this depends on the proper functioning of blood vessels and the heart.

The heart relies on nervous system impulses and coordinated signals from the heart’s conduction system.

Some cardiovascular degeneration is due to changes that occur with age; however, lifestyle is the major contributing factor to cardiovascular system aging.