Anatomy and Physiology of the Circulatory System Basic Cardiac Anatomy

Anatomy and Physiology of the Circulatory System

Basic Cardiac Anatomy

Anatomy & Physiology of the Circulatory System


The circulatory system is composed of four main parts:

• Heart—the pump• Blood vessels—transport system• Blood—the circulating fluid• Lymphatic system—an immunological

axillary fluid system

The Heart and Circulation



– Acting as a double pump, its structure is divided into the right and left heart by the septum.

– The heart has four chambered, Rt & Lt Atria, Rt & Lt Ventricles.– Although it is not much bigger than a human fist and weighs less

than a pound, the heart is a very powerful organ. Each day the heart pumps approximately 2,000 gallons of blood through 70,000 miles of blood vessels by beating approximately 100,000 times a day.

Heart



Linings of the HeartEndocardium - inner lining of the heart Myocardium-muscular, middle layer Pericardium-outer membranous sac



Right atrium receives deoxygenated blood from all body parts (except the lungs) through the superior and inferior vena cava as the SA node contracts.

Left atrium receives blood rich in oxygen returning from the lungs via the left and right pulmonary veins and sends it to the left ventricle and out to the aorta to the rest of the body also as the SA node contracts.

Upper Chambers of the Heart - Atria



Right ventricle- receives deoxygenated blood from the right atrium through the tricuspid valve or AV valve and pumps it though a semilunar valve to the lungs to drop off waste product and get oxygenated.

Left ventricle- receives

oxygenated blood from the left atrium through the bicuspid valve or mitral valve where it is pumped through the semilunar valve to the large artery known as the aorta and from there to all parts of the body except the lungs.

Lower Chambers of the Heart - Ventricles



Review-gross anatomy of the heart

Septum

Aorta



– Fuel line and transportation network.– There are approximately 70,000 miles of blood vessels.– (almost 1/3 of the distance from the Earth to the Moon)

• Arteries are the vessels that lead away from the heart; all have a pulse reflecting the rhythmical beating of the heart used to check rate, rhythm and condition of the arterial walls and downsize to arterials (heart to body).

• Veins are thinner walled vessels compared to arteries. They move deoxygenated blood toward the heart from the tissues; they have valves that prevent the backflow of blood (back to heart).

• Capillaries are the smallest vessels. They have singled cell walls that connect arterioles with venules and form the point of exchange for oxygen and nutrients into body cells and waste products coming from body cells.

Blood Vessels and Circulation



Capillaries



Coronary Arteries and Veins



Coronary Arteries and Veins (cont’d)



– Tricuspid valve: also known as the AV valve (cusps are flaps

of the valves): between right atrium and right ventricle.

Major Valves of the Heart



– Pulmonary semilunar valve: between right ventricle and

pulmonary artery; allows blood to flow to the lungs.




– Bicuspid or mitral valve: between left atrium and the left

ventricle; allows blood to flow to the left ventricle




– Aortic semilunar valve: between left atrium and aorta where blood exits out to the body; blood leaving the left ventricle passes through the aortic semilunar valve and into the systemic circuit by way of the ascending aorta.




Pathway of blood through the heart



Pathway of blood through the heart

Superior Vena Cava

Inferior Vena Cava

Right Atrium

Tricuspid Valve

Right Ventricle

Pulmonary Semilunar Valve Pulmonary Arteries

Pulmonary Veins

Left Atrium

Bicuspid Valve

Right Ventricle

Aortic Semilunar Valve

Aorta



• Closure of valves associated with sounds “lub, dub, lub, dub”.

• Lub: closure of the tricuspid and mitral valves at the beginning of systole.

• Dub: closure of the aortic and pulmonary valves at the end of systole.

• Murmur: abnormal heart sound caused by improper valve closure.

Heart Sounds



• Cardiac cycle is controlled by the autonomic nervous system.

• There are two phases of the heartbeat representing blood pressure:

– Systole: contraction phase– Diastole: relaxation phase

• The systole-diastole- cardiac cycle occurs between 60-80 times per minute (over 100,000 times per day).

• The heart pumps 3 ounces of blood with each contraction. This means that about 5 quarts are pumped per minute (75 gallons an hour and about 2000 gallons a day).

Cardiac Cycle



Cardiac Cycle

•ECG or EKG (electrocardiogram): the record used to detect electrical changes in heart muscle as the heart beats.

• The P wave -indicates that the atria are contracting to pump out blood.

• the QRS complex-indicates that the ventricles are contracting to pump out blood. Systole

• The T wave- indicates the resting Diastole

• Rarely you will find a U wave; also indicates resting



• Blood pressure: the force that blood exerts on arterial walls.– Measured using sphygmomanometer and stethoscope. – Usually expressed as a fraction:

systolic pressure/diastolic pressure. – Example: 120/80 mm Hg– Pulse pressure is difference between systolic and

diastolic readings and tone of arterial walls (BP=120/80, then the Pulse Pressure =40)

Blood Pressure



• Nodal Cells

– Sinoatrial node (SA node): pacemaker of the heart located in the upper wall of the right atrium.

–Atrioventricular node (AV node): this sends the excitation wave to a bundle of specialized fibers called atrioventricular bundle or Bundle of His.

• Conducting Cells–Bundle of His (pronounced “hiss”): helps form conduction

myofibers that extend to ventricle walls and stimulate them to contract, beginning systole. A short rest period follows.

–Bundle Branches-Separate the impulses to Left and Right ventricles

–Purkinje fibers: Distribute SA impulses to contractile cells in the ventricle walls

Conduction System of the Heart



Conducting System of the Heart

Bundle of His

Bundle Branches

Purkinje fibers



Conducting System of the Heart



– Blood• Age related changes include:

– Decreased hematocrit.– Constriction or blockage of peripheral veins by formation of

thrombus.– Pooling of blood in veins of lower legs due to ineffective valves.

– Heart• Major related heart changes are:

– Reduction in maximum cardiac output.– Changes in the activities of nodal and conducting cells.– Replacement of damaged cardiac cells by scar tissue.– Progressive changes in blood vessels that restrict coronary circulation.

• The Blood Vessels– Age related changes in blood vessels:

» Changes are often related to arteriosclerosis or atherosclerosis.» May lead to coronary artery disease.

Aging and the Cardiovascular System



– Hypertension—high blood pressure; higher than 140/90.– Hypotension—low blood pressure; less than 90/60.– Myocarditis—inflammation of the heart muscle.– Mitral Stenosis—a condition of narrowing of the mitral valve.– Phlebolith—a calcification within a vein.– Thrombosis—a condition in which there is a blood clot within

the system.– Tachycardia—fast heartbeat (>100 BPM).– Bradycardia—slow heartbeat (<60 BPM).

Common Diseases and Disorders



– Ischemia—a condition in which there is a lack of blood supply to a part, caused by constriction or obstruction of a blood vessel.

Common Diseases and Disorders



– Congestive Heart Failure (CHF): the heart is unable to pump the required amount of blood.

• In U.S., this is primarily the result of high blood pressure and coronary artery disease.

• Results in pulmonary edema.• Fatal if untreated.

– Coronary Artery Disease (CAD): disease of the arteries surrounding the heart.

• Atherosclerosis– thrombotic occlusion – ischemia– necrosis– infarction

Common Diseases and Disorders (cont’d)



– Varicose

Veins

Common Diseases and Disorders (cont’d)



– Lipid tests such as cholesterol and triglycerides.

– Lipoprotein electrophoresis– Serum enzyme tests– Cardiac enzymes

• Performed to determine cardiac damage in an acute myocardial infarction

• The only TRUE way of telling of a previous MI (EKG won’t always show an inversion of a T wave or elevated ST segment.)

Laboratory Tests



- Angiogram: test used to determine size and shape of arteries, veins and organs.

- Doppler ultrasound: Measurement of sound-wave echoes as they bounce off tissues and organs. Can assist in determining heart and blood vessel damage. Also called Echocardiogram (ECHO).

Common Diagnostic Tests



- Cardiac catheterization: test used in diagnosis of heart disorders using a catheter inserted into an artery in the groin area and fed to the heart.

Common Diagnostic Tests (cont’d)



- Electrocardiography (ECG, EKG) – graphic recording of the heart.

- Holter monitoring: method of recording a patient’s portable EKG for 24 hours worn during all activities.

- Stress tests: method of evaluating cardiovascular fitness utilizing a treadmill or ergo meter.

Common Diagnostic Tests (cont’d)



• Treatment procedures • Cardioversion (defibrillation): Converting a cardiac arrhythmia

(irregular heart action) to a normal sinus rhythm using a cardioverter (defibrillator) to give countershocks to the heart

• Endarterectomy: The surgical removal of material that is wholly or partially obstructing blood flow in an artery

• Extracorporeal circulation: Circulation of blood outside the body

• Heart transplantation: Transfer a heart from one body to another

• Thrombolytic therapy: The use of drugs that degrade blood clots in the treatment of acute myocardial infarction, pulmonary embolism, or stroke

Treatment Procedures



Coronary artery bypass graft (CABG): Open-heart surgery in which a shunt is created to permit blood to travel around the constriction of a coronary blood vessel




Pacemaker




- What are the layers of the heart wall?- Name the valves of the heart.- What are the coronary vessels and what is

their purpose?- Describe the pathway through the heart.- What is Myocarditis?- What is arrhythmia?

Questions

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Anatomy and Physiology of the Circulatory System Basic Cardiac Anatomy