Cardiovascular System

Defibrillators

• Found in airports, malls, and other public places

• Can save the life of a person going into cardiac arrest

• Saved 64% of the people they were used on when without it only 5 to 7% survive

• Implantable cardioverter defibrillator

Introduction

• Heart pumps 7,000 liters of blood through the body each day!

• Contracts 2.5 billion times in an avg. lifetime• Heart-arteries-arterioles-capillaries-venules-veins-

heart• Pulmonary circuit – sends deoxygenated blood to

the lungs to pick up oxygen and unload carbon dioxide

• Systematic circuit – sends oxygenated blood and nutrients to all body cells and removes wastes

Structure of the Heart• Adult heart is about 14 cm long

and 9 cm wide• Pericardium encloses heart • Outer wall of heart (beneath

pericardium) is the epicardium which contains serous fluid which protects the heart by reducing friction

• Myocardium consists of cardiac muscle tissue

• Endocardium – consists of epithelium and connective tissue that contains elastic and collagenous fibers

Pericarditis is inflammation of the pericardium due to viral or bacterial infection. It produces adhesions that attach the layers of the pericardium to each other. How do you think this affects the functioning of the heart?

Heart Chambers and Valves

• 2 upper atria (receive blood returning to the heart)

• 2 lower ventricles (receive blood from atria and contract to force blood out into the arteries)

• Separated by septa

Video

• Tricuspid valve (right) and mitral valve (left) prevent blood moving backwards into atria

• Pulmonary valve prevents backflow into right ventricle

• Aortic valve prevents backflow into left ventricle

Mitral Valve Prolapse

• When the mitral valve doesn't open and close properly, the flaps may "billow" backward slightly into the upper chamber during the heart's contraction

• In MVP, sometimes small amounts of blood may leak backward into the upper chamber of the heart because the valve does not close normally. This causes a "heart murmur."

Path of Blood Through the Heart

1. Vena cavae

2. Right atrium

3. Tricuspid valve

4. Right ventricle

5. Pulmonary valve

6. Pulmonary trunk

7. Pulmonary arteries

8. Lungs

9. Pulmonary veins

10. Left atrium

11. Mitral valve

12. Left ventricle

13. Aortic valve

14. Aorta

Blood Supply to the Heart

• Provided by right and left coronary arteries• A thrombus or embolus that blocks or narrows a coronary

artery branch deprives myocardial cells of oxygen, producing a condition called angina pectoris.

• May causes a sensation of heavy pressure, tightening, or squeezing in the chest

• A blood clot completely obstructing a coronary artery or one of its branches kills part of the heart.

• This is called a myocardial infarction or heart attack.• Cardiac veins drain blood and join the coronary sinus

which empties into the right atrium

Heart Actions

• Coordinated so that atria contract while ventricles relax; then ventricles contract while atria relax

• Series of events constitutes a complete heartbeat, or cardiac cycle

• Opening and closing of valves and movement of blood through the heart is controlled by pressure

• Heartbeat through a stethoscope sounds like lubb-dupp

• Sounds due to vibrations in the heart tissues associated with the closing of the valves

• Cardiac muscle fibers contract as a unit and is a type of functional synctium

• S-A node initiates one impulse after another• A-V node provided conduction pathway between

the atrial and ventricular syncytia• ECG is a recording of the electrical changes

Blood Vessels

• Arteries are strong, elastic vessels that are adapted for carrying blood away from the heart under high pressure

• Arteries subdivide into progressively thinner tubes and eventually give rise to finer, branched arterioles

• Vasoconstriction – reduction of vessel diameter• Vasodilation – increase of vessel diameter

• Capillaries are the smallest in diameter; connect arterioles to venules

• Gases, nutrients, and metabolic by-products are exchanged between the blood in capillaries and the tissue fluid surrounding body cells

• Venules continue from capillaries and merge to form veins

• Veins have thinner walls and less elastic tissue than arteries, but their lumens are wider.

Blood Pressure

• The force blood exerts against the inner walls of blood vessels

• FYI: The human heart creates enough pressure to squirt blood 30 feet.

• Arteriol bp rises and falls in a pattern corresponding to the phases of the cardiac cycle

• Max. pressure during ventricular contraction is systolic pressure

• Lowest pressure that remains in the arteries before the next ventricular contraction is diastolic pressure

• Normal is 120/80• measured via a sphygmomanometer

Factors that affect blood pressure

• Heart action– Stroke volume– Cardiac output

• Blood volume• Black licorice• Peripheral resistance (friction between the

blood and walls of blood vessels)• Blood viscosity

Varicose Veins

• enlarged, twisted, painful superficial veins resulting from poorly functioning valves

• affecting mostly women

• Prolonged standing and increased pressure within the abdomen may increase susceptibility to the development of varicose veins or aggravate the condition.

Arteriosclerosis

• too much pressure in your arteries can make the walls thick and stiff — sometimes restricting blood flow to your organs and tissues

• develops gradually• usually no signs or symptoms until an artery is so

narrowed or clogged that it can't supply adequate blood to your organs and tissues

• The damage may be caused by various factors, including:– High blood pressure – High cholesterol – An irritant, such as nicotine – Certain diseases, such as diabetes

Aneurysm

• bulge in a blood vessel, much like a bulge on an over-inflated inner tube

• can be detected by X-ray or by imaging techniques such as echocardiography or MRI

• The larger an aneurysm becomes, the more likely it is to burst

• Can be treated surgically: a patch or artificial piece of blood vessel is sewn where the aneurysm was