Cardiovascular Systemheart and blood vessels

Tainted Love…?

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

Function

▫Transports nutrients and oxygen to the body

▫Removes metabolic waste and carbon dioxide from cells

▫Distributes hormones and antibodies throughout the body

▫Helps control body temperature and electrolyte balance

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.

The Heart• Is a two-sided, hollow organ about the size of a fist.

• Located in the mediastinal cavity

• Has three layers of tissue:▫Pericardium – outer layer, reduces friction as the heart beats ▫Myocardium – middle layer, pumps blood through the system▫Endocardium – inner layer, allows the blood to flow smoothly

Fibrous Pericardium encloses the heart (like a bag) and has 2 layers • visceral pericardium (inner) • and parietal pericardium (outer, attached

to diaphragm, sternum and vertebrae)

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. 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) & 2 Semilunar valves) o Left Atrioventricular valve – also called the

bicuspid valve or mitral valve. Between left atrium and ventricle

o Right Atrioventricular valve – also called the tricuspid valve. Between right atrium and ventricle

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

• Pulmonary Semilunar, or just pulmonary 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!

Name the valves

(#5 is not a valve)

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.

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

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

Stethoscope - instrument to listen and measure heart sounds

1 Sinoatrial node (Pacemaker)2 Atrioventricular node3 Atrioventricular Bundle (Bundle of His)4 Left & Right Bundle branches5 Bundle Branches (Purkinje Fibers)

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)

Cardiac Output

Cardiac Output = Stroke Volume x Heart Rate

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."

Defibrillator

common treatment for life-threatening cardiac arrhythmia

The device shocks the heart and allows it to re-establish its normal rhythm

The device can also be used to start a heart that has stopped. 

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.

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.

Blood Clots can occur if blood does not flow properly through the veins - can occur if a person does not move enough

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

Cardiac output =

stroke volume xheart rate

Major Blood Vessels Aorta  -  Ascending Aorta, Aortic Arch, Descending Aorta, Abdominal Aorta.  The aorta is the largest artery. (leaves  left ventricle) Pulmonary Trunk – splits into left and right, both lead to the lungs (leaves left ventricle) Pulmonary Veins – return blood from the lungs to the heart (connects to left atrium)   Superior and Inferior Vena Cava – return blood from the head and body to the heart (connects to right atrium)

Systemic Circulation

• Carries blood through out the body

• Same in all tissues and organs

Pulmonary Circulation

• Carries blood to the lungs to et oxygenated

• Path goes from right ventricle through pulmonary artery, large pulmonary vein to left atrium

Hepatic Circulation

• Unique blood route through the liver

• Assists with homeostasis of blood glucose

• Nutrient rich blood flows form small intestine to liver

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

Congested Heart Failure

• Enlarged heart.

• Irregular heart sounds.

• Abnormal sounds in the lungs.

• Swelling or tenderness of the liver.

• Fluid retention.

• Elevation of pressure in the veins of the neck.