Cardiovascular Systemheart and blood vessels

Systemic Circulation – delivers blood to all body cells and carries away wastePulmonary Circulation – eliminates carbon dioxide and oxygenates blood (lung pathway)

Structure of the HeartHeart Size – about 14 cm x 9 cm (the size of a fist).

Located in the mediastinum (space between lungs, backbone, sternum), between the 2nd rib and the 5th intercostal space. The distal end of the heart is called the apex.

Pericardium encloses the heart (like a bag) and has 2 layers

Pericardial cavity – contains fluid for the heart to float in, reducing frictionWall of the Heart Epicardium – outer layer, reduces friction Myocardium – middle layer, mostly cardiac muscle Endocardium – thin inner lining, within chambers of the heart

Heart Chambers & Valves• Your heart is a double pump/loop.

Circulation is a double circuit: Pulmonary (lungs only) and systemic (rest of the body)

• Heart has 4 chambers: o 2 Atria – thin upper chambers that receive blood

returning to the heart through veins.. Right and Left Atrium

o 2 Ventricles – thick, muscular lower chambers. Receive blood from the atria above them. Force (pump) blood out of the heart through arteries. Right and left ventricle.

• Septum – separates the right and left sides of the heart

• Valves of the Heart – allow one-way flow of blood. 4 total

• (2 Atrioventricular Valves (AV)Right Atrioventricular valve – also called the tricuspid valve. Between right atrium and ventricle

o Left Atrioventricular valve – also called the bicuspid valve or mitral valve. Between left atrium and ventricle

•Superior Vena Cava: vein that carries deoxygenated blood from the upper half of the body to the heart's right atrium.

•Inferior Vena Cava: vein that carries de-oxygenated blood from the lower half of the body into the right atrium of the heart.

•Coronary Sinus collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart. It delivers deoxygenated blood to the Right atrium in conjunction with the superior and inferior vena cava.

•Chordae tendinae/ Papillary muscles also known as the heart strings, are cord-like tendons that connect the papillary muscles to the tricuspid valve and the mitral valve in the heart.

•Pulmonary Trunk/arteries: Carries deoxygenated blood from the heart to the lungs. They are the only arteries (other than umbilical arteries in the fetus) that carry deoxygenated blood.

•Begins at the base of the right ventricle then branches into two pulmonary arteries (left and right), which deliver de-oxygenated blood to the corresponding lung.

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• Pulmonary Semilunar, or just pulmonary valve. Between the left ventricle and the aorta

• Pulmonary Veins: Large blood vessel that carries oxygenated blood from the lungs to the left atrium of the heart. In humans there are four pulmonary veins, two from each lung

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• Aorta- is the largest artery in the body which orginates from the left ventricle. Distributes oxygenated blood to the body.

• Aortic Semilunar – or just aortic valve. Between the left ventricle and the aorta

Mitral = bicuspid (left side)Tricuspid (right side)

Aortic and Pulmonary are both semilunar valves

Path of Blood Flow

*This is a good time to watch some of the heart animations and tutorials.

Label the heart diagram on your

notes!

Check your labels!

1 Pulmonary Valve2 Tricuspid Valve3 Mitral (Bicuspid) Valve4 Aortic Valve5 Heart Apex

Heart Actions• Cardiac Cycle: One complete heartbeat.

The contraction of a heart chamber is called systole and the relaxation of a chamber is called diastole.

Regulation of Cardiac Cyclecontrolled by the cardiac center within the medulla oblongata. The cardiac center signals heart to increase or decrease its rate according to many factors that the brain constantly monitors.

Muscle ActivityBody TemperatureBlood ion levels (potassium & calcium)

ECG – electrocardiogram – a recording of the electrical events (changes) during a cardiac cycle

• P Wave – depolarization of the atria (atrial contraction – systole)

• QRS Complex – depolarization of the ventricles (ventricular contraction, systole)

• T Wave – Repolarization of the ventricles

Heart Sounds – opening and closing of the valves, flow of blood into and out of the chambers, vibrations in muscle

SADS  = (Sudden Arrhythmia Death Syndromes  or  Sudden Adult Death Syndrome)

Routine ECG Screening may help prevent deaths in young people

Heart Sounds - Opening and Closing of Valves, "Lub Dub"

Stethoscope - instrument to listen and measure heart sounds

Interpreting ECGsAn ECG is printed on paper covered with a grid of squares.Notice that five small squares on the paper form a larger square. The width of a single small square on ECG paper represents 0.04 seconds.  A common length of an ECG printout is 6 seconds; this is known as a "six second strip."

Analyze an ECG

Each one of the figures represents an ECG pattern displaying three types of abnormal rhythms: Tachycardia, Bradycardia, and Arrhymthmia. Identify each.

Factors affecting blood pressure:           Average is 120/80   (higher number is the systolic pressure)1.        Cardiac Output2.       Blood volume (5 liters for avg adult)3.       Blood Viscosity4.       Peripheral Resistance

Control of Blood Flow:Precapillary sphincters – circular, valve-like muscle at arteriole-capillary junction.Vasoconstriction – narrowing  blood vessel’s lumen (“passageway”)Vasodilation – explanding blood vessel’s lumen

Blood flow through veins – not very efficient.  Slow, weak “pushing” by arterial blood pressure is not much of a factor at all.  Important factors include:   1.  Contraction of the diaphragm.  2.  Pumping action of the skeletal muscles.  3. Valves in the veins.

13.4  BLOOD VESSELS

Blood Vessels:  arteries, veins, capillariesArteries :  strong elastic vessels which carry blood moving away from the heart.   Smallest ones are arterioles which connect to capillaries. VEINS - Thinner, less muscular vessels carrying blood toward the heart.  Smallest ones are called venules which connect to capillaries.  Contain valves. Capillaries:  Penetrate nearly all tissues.  Walls are composed of a single layer of squamous cells – very thin.  Critical function: allows exchange of materials (oxygen, nutrients) between blood and tissues.

Disorders of the Circulatory System

1. MVP - mitral valve prolapse, the mitral valve does not close all the way; this creates a clicking sound at the end of a contraction.

2. Heart Murmurs – valves do not close completely, causing an (often) harmless murmur sound. Sometimes holes can occur in the septum f the heart which can also cause a murmur

3. Myocardial Infarction (MI) - a blood clot obstructs a coronary artery, commonly called a “heart attack”

4. Atherosclerosis – deposits of fatty materials such as cholesterol form a “plaque” in the arteries which reduces blood flow. Advanced forms are called arteriosclerosis. Treatment: Angioplasty, where a catheter is inserted into the artery and a balloon is used to stretch the walls open. A bypass can also treat clogged arteries, a vein is used to replace a clogged artery. Coronary bypass refers to a procedure where the coronary artery is bypassed to supply blood to the heart. (The phrase “quadruple bypass” means that 4 arteries were bypassed.)

Video Showing a Stent and Angioplasty (Mayo Clinic)

5. Hypertension – high blood pressure, the force within the arteries is too high. A sphygmomanometer can be used to diagnose hypertension