Advanced and Integrated Physiology

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3^RD YEAR BACHELOR OF BIOMEDICAL SCIENCES

Advanced and Integrated Physiology

PP3101 SEMESTER 1 2017 LECTURE NOTES

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The Cardiovascular System

Revision from PP2201

The cardiovascular system is made up of the heart and a series of blood vessels, ie. The pump and tubes.

Functions

- Transport of nutrients e.g. CO2 and glucose, to site of use - Transport of wastes to the excretive organs

- Homeostasis e.g. hormones, body temperature - Meeting the demands of the nutrients

Gross Anatomy of the Heart

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The heart has four chambers, and it pumps blood through two different circuits; the systemic circulation that pumps blood around the body (ie. To the various other systems of the body) and the pulmonary circulation that pumps the blood to the lungs.

The heart is located in the mediastinum, the central compartment of the thoracic cavity. It is superior to the diaphragm

anterior to the vertebral column posterior to the sternum.

flanked by the lungs

Flanked = to be in the middle of or surrounded by The Membranes Covering the Heart

The heart is enclosed by a double-walled sac, called the pericardium, made up of dense CT.

Functions of the pericardium:

- protect the heart

- anchor the heart in place to stop it from moving around - prevent the overfilling of the heart with blood

Fibrous pericardium = the outer layer of dense CT

serous (parietal) pericardium = the layer directly beneath, it is a thin and slippery membrane.

Epicardium = the visceral layer, directly in contact with the heart, may have some fat in this layer as well if the person is older

The Walls of the Heart

The wall of the heart has 3 layers:

The epicardium, discussed above

myocardium = the muscle that contracts.

Cardiac muscle cells are connected to one another by CT that forms spiral and circular networks.

Fibrous skeleton = the CT that connects the muscle cells of the myocardium

Endocardium = the endothelium that rests on thin layers of connective tissue. It lines the heart chambers and covers the fibrous skeleton of the valves.

The Action Heart

The heart is a four-chambered double pump. Each pump consists of an atria and a ventricle.

Atria = thin-walled receiving chambers. They are thin because they don’t have to pump the blood very far, just to the ventricle below it.

Ventricles = pumping chambers, thick muscular walls that have to pump blood to the lungs and around the body

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The right ventricle pumps blood from the Right atrium to the lungs

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7 Valves

 The blood only flowing in one direction

There are two semi-lunar valves and two atrioventricular valves.

The right atrioventricular valve is tricuspid and the left is bicuspid.

Papillary Muscles = muscles located in the ventricles of the heart that attach to the cusps of the atrioventricular valves via the chordae tendineae and contract to prevent the closure of these valves during a systole.

The semilumar valves prevent backflow into the ventricles. One is the pulmonary valve and the other one is the aortic valve. The three pockets are shaped like a crescent moon.

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Coronary Circulation

The myocardium is too thick for enough blood to diffuse from the heart chambers to myocardial cells so the heart needs its own blood supply. Also, the heart is a muscle and like any other muscle, it requires nutrients and oxygen.

Coronary circulation supplies the cells of the heart wall.

The left and right coronary arteries arise from the aorta and encircle the heart in the atrioventricular groove. Anterior interventricular artery supplies the interventricular septum and the anterior was of both ventricles. The circumflex artery supplies the interventricular septum and the anterior walls of bother ventricles. The circumflex artery supplies the Left atrium and the posterior walls of the left ventricle.

Branches of the right coronary artery supply the right atrium and nearly all of the right ventricle.

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Venous blood is collected by the cardiac veins. Ther path roughly folloes the cardiac arteries. There are small, middle and great arteries. They join to form the coronary sinus on the posterior side of the hear. The coronary sinus empties the blood into the right artery. Anterior cardia veins drain directly into the right artery.

Conditions

Atherosclerosis = when deposits of cholesteral accumulate at an injured area in the inner lning of an artery.

as the deposits harden and narrow the arteries, blood flow to the tissues decreases and a clot may form, completely blocking the artery.

Advanced and Integrated Physiology