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Ahlulbait University

College of Pharmacy

Human Anatumy

Stage : 1 st

Lab:1

Ass.Lectur:Maryam M. Alhelfy

Functions of the Circulatory System

The many functions of the circulatory system can be grouped into two

broad areas: transportation and protection.

1- Transportation. All of the substances involved in cellular

metabolism are transported by the circulatory system. These

substances can be categorized as follows:

A- Respiratory. Red blood cells called erythrocytes transport oxygen

to the tissue cells. In the lungs, oxygen from the inhaled air

attaches to hemoglobin molecules within the erythrocytes and is

trans-ported to the cells for aerobic respiration. Carbon dioxide

produced by cellular respiration is carried by the blood to the lungs

for elimination in the exhaled air

B- Nutritive. The digestive system is responsible for the mechanical

and chemical breakdown of food to forms that can be absorbed

through the intestinal wall into the blood and lymph vessels. The

blood then carries these absorbed products of digestion through the

liver to the cells of the body.

C- Excretory. Metabolic wastes, excess water and ions, as well as

other molecules in plasma (the fluid portion of blood), are filtered

through the capillaries of the kidneys into kidney tubules and

excreted in urine.

D- Regulatory. The blood carries hormones and other regulatory

molecules from their site of origin to distant target tissues.

2- Protection. The circulatory system protects against injury and

foreign microbes or toxins introduced into the body.

Major Components of the Circulatory System The circulatory system

is frequently divided into the cardiovascular system, which consists of the

heart, blood vessels, and blood, and the lymphatic system, which consists

of lymphatic vessels and lymphoid tissues within the spleen, thymus,

tonsils, and lymph nodes.

Chest Cavity

The chest cavity is bounded by the chest wall and below by the diaphragm. It extends upward into the root of the neck about one fingerbreadth above the clavicle on each side.

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Pericardium

The pericardium is a fibroserous sac that encloses the heart and the

roots of the great vessels. Its function is to restrict excessive

movements of the heart as a whole and to serve as a lubricated

container in which the different parts of the heart can contract. The

pericardium lies within the middle mediastinum.

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Location of the Heart The heart is located in the chest between the lungs behind the

sternum and above the diaphragm. It is surrounded by the

pericardium. Its size is about that of a fist, and its weight is about

250-300 g. Its center is located about 1.5 cm to the left of the

midsagittal plane. Located above the heart are the great vessels: the

superior and inferior vena cava, the pulmonary artery and vein, as

well as the aorta. The aortic arch lies behind the heart.

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Structure of the Heart

The walls of the heart are composed of a thick layer of cardiac

muscle, the myocardium, covered externally by the epicardium and

lined internally by the endocardium. The atrial portion of the heart

has relatively thin walls and is divided by the atrial (interatrial)

septum into the right and left atria. The septum runs from the

anterior wall of the heart backward and to the right. The ventricular

portion of the heart has thick walls and is divided by the ventricular

(interventricular) septum into the right and left ventricles.

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Location of the aorta in the body

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An anterior view the abdominal aorta and principal pranches

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Location of the veins in the body