Copyright © 2010 Pearson Education, Inc. Cardiovascular System components The heart Blood vessels Blood

Copyright © 2010 Pearson Education, Inc.

Cardiovascular System components

• The heart

• Blood vessels

• Blood



Heart Anatomy

• Approximately the size of a fist

• Location

• In the mediastinum between second rib and fifth intercostal space

• On the superior surface of diaphragm

• Two-thirds to the left of the midsternal line

• Anterior to the vertebral column, posterior to the sternum

• Enclosed in pericardium, a double-walled sac


Coverings of the Heart: Anatomy• The heart is enclosed in a double-walled sac called the

pericardium.

• Superficial fibrous pericardium

• Protects, anchors, and prevents overfilling

• The outer parietal pericardium consists of a tough fibrous layer of dense connective tissue.

• The inner thin, smooth, moist serous layer turns in at the base of the heart, forming the visceral pericardium/epicardium covering the heart surface.

• Between the parietal and visceral pericardia is a space called the pericardial cavity.

• It contains pericardial fluid that lubricates the membranes and allows the heart to beat almost without friction.


Layers of the Heart Wall myocardium

• Spiral bundles of cardiac muscle cells to allow “twisting” when contracting

• Fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue

• Supply structural support for the heart

• Anchors cardiocytes and give them something to pull against

• Limits spread of action potentials to specific paths


Heart Chambers

Atrium – singleAtria - pleural

Ventricle/s

http://mtsu32.mtsu.edu:11259/heart3.jpg


Atria of the Heart

• Atria are the receiving chambers of the heart – entering veins

• Blood enters right atria from superior and inferior venae cavae and coronary sinus

• Blood enters left atria from pulmonary veins

• Each atrium has a auricle that increase atrial volume

• Separated internally by the interatrial septum

• Coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles

• Pectinate muscles mark the anterior atrial wall


Ventricles of the Heart

• Ventricles are the discharging chambers of the heart

• Right ventricle pumps blood into the pulmonary trunk

• Left ventricle pumps blood into the aorta

• Papillary muscles that attached to the valves

Copyright © 2010 Pearson Education, Inc.Figure 18.4e


Heart Valves

• Heart valves ensure unidirectional blood flow through the heart (prevent backflow)

• Atrioventricular (AV) valves lie between the atria and the ventricles

• AV valves prevent backflow into the atria when ventricles contract

• Chordae tendineae anchor AV valves to papillary muscles

• Semilunar valves prevent backflow of blood into the ventricles

• Aortic semilunar valve lies between the left ventricle and the aorta

• Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk


1.mitral (bicuspid)2.tricuspid 3.Pulmonary semilunar 4.aortic semilunar

http://mtsu32.mtsu.edu:11259/heart.htm


Figure 20-8a Valves of the Heart

Aortic valve(closed)

LEFTATRIUM

Left AV (bicuspid)valve (open)

Chordaetendineae (loose)

Papillary muscles(relaxed)

LEFT VENTRICLE(relaxed and fillingwith blood)

Pulmonaryveins

Frontal Sections through Left Atrium and Ventricle

Rel

axe

d v

entr

icle

s


Figure 20-8b Valves of the Heart

Co

ntr

acti

ng

ven

tric

les

Aortic valve open

RIGHTVENTRICLE

Right AV(tricuspid) valve

(closed)

Cardiacskeleton

Left AV(bicuspid) valve

(closed)LEFTVENTRICLE

Aortic valve(open)

Pulmonaryvalve (open)

When the ventricles are contracting, the AV valves are closed and the semilunar valves are open. In the frontal section notice the attachment of the left AV valve to the chordae tendineae and papillary muscles.


Figure 20-8b Valves of the Heart

Co

ntr

acti

ng

ven

tric

les

Aorta

Aortic sinus

LEFTATRIUM

Aortic valve(open)

Left AV (bicuspid)valve (closed)

Chordae tendineae(tense)

Papillary muscles(contracted)

Left ventricle(contracted)

Copyright © 2010 Pearson Education, Inc. Figure 18.9

1 Blood returning to theheart fills atria, puttingpressure againstatrioventricular valves;atrioventricular valves areforced open.

1 Ventricles contract, forcingblood against atrioventricularvalve cusps.

2 As ventricles fill,atrioventricular valve flapshang limply into ventricles.

2 Atrioventricular valvesclose.

3 Atria contract, forcingadditional blood into ventricles.

3 Papillary musclescontract and chordaetendineae tighten,preventing valve flapsfrom everting into atria.

(a) AV valves open; atrial pressure greater than ventricular pressure

(b) AV valves closed; atrial pressure less than ventricular pressure

Direction ofblood flow

Atrium

Ventricle

Cusp ofatrioventricularvalve (open)

Chordaetendineae

Papillarymuscle

Atrium

Blood inventricle

Cusps ofatrioventricularvalve (closed)

Copyright © 2010 Pearson Education, Inc. Figure 18.10

As ventriclescontract andintraventricularpressure rises,blood is pushed upagainst semilunarvalves, forcing themopen.

As ventricles relaxand intraventricularpressure falls, bloodflows back fromarteries, filling thecusps of semilunarvalves and forcingthem to close.

(a) Semilunar valves open

(b) Semilunar valves closed

Aorta

Pulmonarytrunk


Heart Sounds

• Two sounds (lub-dup) associated with closing of heart valves

• First sound occurs as AV valves close and signifies beginning of systole

• Second sound occurs when SL valves close at the beginning of ventricular diastole

• Heart murmurs: abnormal heart sounds most often indicative of valve problems


Heart valves problems

• Valvular heart disease (VHD)

• When valve function has deteriorated to where heart cannot maintain adequate blood flow

• Can be due to:

• Congenital (present at birth) malformations

• Heart swelling (carditis)

• In severe cases, replacement with a prosthetic valve may be necessary

• Bioprosthetic valves come from pigs or cows


Vessels that Supply/Drain the Heart - coronary circulation

Figure 18.7


Risk factors that can lead to heart diseases

• Coronary artery disease• High blood pressure• Diabetes• Smoking• High cholesterol• Obesity• Excessive alcohol use• Drug abuse• Stress• Family history of heart disease• Advancing age


Arteriosclerosis and coronary artery disease

• Arteriosclerosis (arterio-, artery + sclerosis, hardness)

• Thickening or toughening of artery walls

• Related complications account for about half of all U.S. deaths


Arteriosclerosis and coronary artery disease

• Atherosclerosis (athero-, fatty degeneration)

• Formation of lipid deposits

• Most common form of arteriosclerosis

• Often associated with elevated cholesterol

• May form fatty tissue mass (plaque) in vessel that restricts blood flow

• Most common in older men

• Treatment can be removing damaged vessel or compressing plaque with balloon angioplasty


Heart Disease - Coronary Artery Disease (CAD)

• Areas of partial or complete blockage of coronary circulation

• Reduction in blood flow to heart muscle produces a corresponding reduction in cardiac performance

• Reduced circulatory supply causes coronary ischemia

• One of the first symptoms of CAD is commonly angina pectoris – pain in the middle of the chest, left neck, left shoulder, or left arm


Myocardial infarction (MI), or heart attack

• Part of the coronary circulation becomes blocked, and cardiac muscle cells die from lack of oxygen

• The death of affected tissue creates a nonfunctional area known as an infarct

• Heart attacks most commonly result from severe coronary artery disease (CAD)



• Consequences depend on the site and nature of the circulatory blockage

• If it occurs near the start of one of the coronary arteries:

• The damage will be widespread and the heart may stop beating

• If the blockage involves one of the smaller arterial branches:

• The individual may survive the immediate crisis but may have many complications such as reduced contractility and cardiac arrhythmias



• Pain does not always accompany a heart attack

• therefore, the condition may go undiagnosed and may not be treated before a fatal MI occurs

• A myocardial infarction can usually be diagnosed with an ECG and blood studies

• Damaged myocardial cells release enzymes into the circulation, and these elevated enzymes can be measured in diagnostic blood tests

• The enzymes include:

• Cardiac troponin T,

• Cardiac troponin I,

• A special form of creatinine phosphokinase, CK-MB


CAD and Myocardial Infarction prognosis

• About 25% of MI patients die before obtaining

medical assistance

• 65% of MI deaths among those under age 50 occur

within an hour after the initial infarction


Treatment of CAD and Myocardial Infarction

• Risk Factor Modification

• Stop smoking

• High blood pressure treatment

• Dietary modification to lower cholesterol and

promote weight loss

• Stress reduction

• Increased physical activity (where appropriate)


Treatment of CAD and Myocardial Infarction

• Drug Treatment

• Drugs that reduce coagulation and therefore the risk of thrombosis, such as aspirin and coumadin

• Drugs that block sympathetic stimulation (propranolol or metoprolol) – for hypertension

• Drugs that cause vasodilation, such as nitroglycerin

• Drugs that block calcium movement into the cardiac and vascular smooth muscle cells (calcium channel blockers)


Coronary Artery Bypass Surgery (CABG)

• In a coronary artery bypass graft, a small section is removed from either a small artery or a peripheral vein and is used to create a detour around the obstructed portion of a coronary artery


Pathway of Blood Through the Heart

• The heart is two side-by-side pumps

• Equal volumes of blood are pumped to the pulmonary and systemic circuits

• Right side is the pump for the pulmonary circuit

• Vessels that carry blood to and from the lungs

• Pulmonary circuit is a short, low-pressure circulation

• Left side is the pump for the systemic circuit

• Vessels that carry the blood to and from all body tissues

• Systemic circuit blood encounters much resistance in the long pathways


Pathway of Blood Through the Heart and Lungs

• Vessels carry the blood through the circuits

• Arteries carry blood away from the heart

• Veins carry blood to the heart

• Capillaries permit exchange

• Right atrium tricuspid valve right ventricle

• Right ventricle pulmonary semilunar valve pulmonary arteries lungs

• Lungs pulmonary veins left atrium

• Left atrium bicuspid valve left ventricle

• Left ventricle aortic semilunar valve aorta

• Aorta systemic circulation

Figure 18.5

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Copyright © 2010 Pearson Education, Inc. Cardiovascular System components The heart Blood vessels Blood