The Cardiovascular System

- A closed system, meaning, the blood is contained within the heart and vessels.

-It functions to connect organs and systems together by pumping blood throughout the body.

-It plays a major role in homeostasis.

Two components:

-Heart (cardi-): The pump

-Vessels (-vascular): the "tubes" that contain the blood.

Arteries:

-Vessels that take blood AWAY from heart

-Usually contain blood that is oxygenated

Veins:

-Vessels that return blood back TOWARD the heart.

-Usually they contain the Deoxygenated.

-Located between arteries and veins

-Walls are one-celled thick (simple squamous epithelium)

-Exchange occurs across membrane

-Overall blood pressure in capillary beds decreases b/c overall surface area increases.

Blood flows through the cardiovascular system due to differences in pressure between one segment of the blood vessel circuit and the next. Blood continues to move through the circuit because it is moving from an area of high pressure to the next area of low pressure.

-The force of the blood against the walls of the blood vessels is blood pressure.

-Stronger when your heart contracts (systole), and weaker when your heart relaxes (diastole).

-Stronger in your arteries and weaker in your veins.

-Typically measured in the brachial artery.

-A sphygmomanometer measures pressure in millimeters (mmHg) of mercury.

-A stethoscope is used to hear the turbulent sounds made as blood begins to flow again through the artery (Korotkoff sounds).

-Pulmonary Circuit

----Circulation of blood through the LUNGS

-Systemic Circuit:

-----Circulation of blood through the body

A function of the RIGHT side of the heart

-Blood is pumped from the heart, to the lungs, and back to the heart.

A function of the LEFT side of the heart.

-Blood is pumped from the heart, to the body, and back to the heart.

Approximately the size of your fist.

-Base: the TOP, broad, flat surface

-Apex: the BOTTOM, narrow, region

In the center of the thoracic cavity, medial to the lungs and just superior to the diaphragm.

The heart is rotated slightly counterclockwise so that the apex is located approximately two inches left of the xiphoid process.

The heart is enclosed by a two layered serous membrane called the pericardium.

Parietal pericardium (aka PERICARDIUM)

The outermost, loose lining containing the heart and serous fluid.

Visceral Pericardium (aka Epicardium)

The "shrink-wrapped" serous membrane covering the heart wall myocardium.

Myocardium: The thickest portion of the heart wall containing cardiac muscle fibers.

Endocardium: A simple squamous epithelial lining covering the inside of the heart and extending into blood vessels.

The heart has four hollow chambers.

The two SUPERIOR chambers are called: Atria.

The two INFERIOR chambers are called Ventricles.

-Receiving chambers

-Thin-walled

-Separated by the interatrial septum

-Pumping chambers

-Thick-walled

-Separated by inter ventricular septum

-There are four valves in the heart.

-Valves are made from endocardium.

-Valves prevent blood from flowing backward.

-An incomplete closure of a valve is a murmur.

-Located between the atria and ventricles.

-The RIGHT AV valve has THREE cusps: Tricuspid.

-The LEFT AV valve has TWO cusps: Bicuspid (aka Mitral).

-Cusps are anchored by chordae tendineae.

-Chordae tendineae attached to papillary muscles.

-Semi-lunar valves are located at the EXIT of the heart

-As blood is pumped from the ventricle, it passes through the semi-lunar valve into major arteries.

-The RIGHT semi-lunar valve is located at the exit of the right ventricle and the entrance to the pulmonary trunk.

-The LEFT semilunar valve is located at the exit of the left ventricle and the entrance to the aorta.

The Lub-Dub sounds of the heartbeat are caused by the closure of the heart valves.

-The first heartbeat sound is caused by the closure of the atrioventricular (AV) valves.

-Closure of the AV valves is caused by ventricular contraction (systole).

-AV valves are open during ventricular diastole (relaxation) so that blood can fill ventricles.

-The second heartbeat sound is caused by the closure of the semi-lunar valves.

-Closure of the semi-lunar valves is caused by ventricular relaxation (diastole).

-Semi-lunar valves are open during ventricular contraction (systole) so that blood is directed out of the heart.

-Right and left coronary arteries branch from the aorta.

-They deliver fresh, oxygenated blood to cardiac muscle tissue (myocardium).

-They return oxygenated blood from cardiac muscle tissue and combine on the posterior aspect of the heart to form the coronary sinus.

-Blood from the coronary sinus then enters the right atrium.

Heart Attack, Angina pectoris

(Myocardial Infarction; MI)

-If heart tissue does not get enough blood then death of heart tissue may occur (dead tissue =infarct)

-Chest pains accompanied by radiating left arm pain from ischemia (decreased blood supply) to heart muscle.

The heart is auto-excitatory. It produces its spontaneous action potentials at regular intervals from specialized cells called pacemaker cells.

Electrical Conduction Pathway

-Located in the top of the right atrium.

-Sets the tempo for the heart called the sinus rhythm.

-It is the heart's natural pacemaker.

-An electrical impulse is generated in the SA node and spread across BOTH atria causing them to contract.

Electrical Conduction Pathway

-Located in the inferior medial wall of the right atrium.

-Electrical impulse from the SA node is passed to the AV node.

-The AV node conducts the electrical impulse through the atrioventricular bundle (Bundle of His).

-Conduction of impulse is slightly delayed to allow contraction of the atria.

Electrical Conduction Pathway

-Conducts the electrical signal from the AV node downward through the interventricular septum.

-The AV bundle bifurcates (splits in two) into a right and left bundle branch.

Electrical Conduction Pathway

-After the electrical impulse reaches the apex, is sent up the lateral walls of the ventricles through the Purkinje fibers.

-The Purkinje fibers distribute the electrical signals throughout the ventricular myocardium.

Monitoring Electrical Activity

-Every time the heart beats, it sends out an electrical signal.

-The heart's electrical signals can be measured with a machine called an electrocardiogram (ECG or EKG)

Monitoring Electrical Activity

-Electrodes are specifically placed on different parts of the body (one on each arm and leg and six across the chest).

Monitoring Electrical Activity

-Tracings of the heart's electrical activity can be made and permanently recorded on paper or in a computer.

Monitoring Electrical Activity

-Doctors assess a patient's heart by studying the shape and size of the waves, the time between waves, and the rate and regularity of beating.

Monitoring Electrical Activity

-Three major waves of electrical signals appear on the ECG. Each one shows a different part of the cardiac cycle.

-All of the events that occur during one heartbeat.

-Cycle of systole (contraction) and diastole (relaxation).

Phase 1: Cardiac Diastole: Atria and ventricles relax

Phase 2: Atrial Systole: Right and left atria contract

Phase 3: Ventricular systole: Right and left ventricles contract

-P-Wave:

atrial contraction

-QRS Complex

ventricular contraction

-T wave:

ventricles reset

Electrical Conduction Problems

Irregular or abnormal heartbeat

-The SA node doesn't produce the right number of signals

-Another part of the heart takes over as the natural pacemaker

-The electrical pathways are interrupted.

Systolic

Diastolic

Sphygmomanometer

Korotkoff

Brachial

False

Diastolic pressure is not an indicator

Consistent diastolic pressure > 90 indicates hypertension.

1.) Right atrium

2.) Right ventricle

3.) Pulmonary trunk

4.) Pulmonary arteries