Circulatory SystemCirculatory System

Function and Parts

Parts of the Circulatory SystemThe circulatory System is divided

into three major parts:The Heart The Blood The Blood Vessels

FunctionFunction

Transport materials needed by cells– Oxygen– Glucose

Remove waste materials from cells– Carbon dioxide– urea

Major ComponentsMajor Components

Heart – Continuously circulates blood

Network of tubes– Arteries- blood away from heart– Veins- blood back to the heart– Capillaries

Blood– Fluid that fills the circulatory system

• Arteries– Arteries are blood vessels that carry oxygen rich

blood AWAY from the heart.

• Capillaries– Capillaries are tiny blood vessels .– Capillaries connect arteries to veins.

Veins– Veins carry blood back toward your heart.

The vascular system is made up of three types of blood vessels:

Photo from U. S. Federal Government courtesy of Wikipedia.

Blood Vessels

In mammals and birds, the heart is divided into a right and left side and each side is divided into an atrium and ventricle.

Therefore, the heart is said to have four chambers (right atrium, right ventricle, left atrium, and left ventricle).

The atrioventricular valves (AV valve) separate the atrium and ventricle on each side of the heart.

The AV valves have flaps of tissues, called leaflets or cusps, which open and close to ensure that the blood flows only in one direction and does not backflow into the atriums.

The AV valve on the right side of the heart is called the tr icuspid valve because it has three leaflets (cusps).

The AV valve on the left side of the heart is called the bicuspid valve (or mitral valve) because it has two leaflets.

The pulmonary valve and the aortic valve prevent blood from back-flowing into their respective ventricles.

The pulmonary valve is located between the right ventricle and the pulmonary artery.

The aortic valve is located between the left ventricle and the aortic artery.

Pulmonary Circulation System

Red portion of heart and red blood vessels carry oxygen-rich blood.

Blue portion of heart and blue blood vessels carry oxygen-poor blood.

Blood that is low in oxygen returns to the heart through two large veins called the superior (or cranial) vena cava and the inferior (or caudal) vena cava.

The un-oxygenated blood enters the right atrium of the heart.

Flow of Blood in Pulmonary Circulation

The blood then passes through the right atrioventricular (tricuspid) valve into the right ventricle.

The right ventricle pumps the blood through the pulmonary valve into the pulmonary artery.

The pulmonary artery quickly divides into two branches.

Each branch of the pulmonary artery carries blood to a lung.

In the lungs the pulmonary arteries branch into capil laries that surround the alveoli .

Through diffusion, carbon dioxide moves from the blood into the alveoli and oxygen moves from the alveoli into the blood.

The oxygenated blood then returns to the heart through the pulmonary vein into the left atrium.

From the left atrium, the blood flows through the left atrioventricular (bicuspid) valve into the left ventricle. The thick-walled left ventricle pumps the blood through the aortic valve into the aorta.

The amount of pressure that is required for pulmonary circulation is much less than what is required for systemic circulation.

Therefore, the muscle mass developed in the right ventricle is much less that of the left ventricle.

Plasma, which makes up 50 – 65% of the total volume of blood, is a straw-colored liquid containing water (90%) and solids (10%).

The solids in plasma include inorganic salts and organic substances such as antibodies, hormones, vitamins, enzymes, proteins, and glucose (blood sugar).

The non-plasma, or cellular, portion of blood is composed of red blood cells, white blood cells, and platelets.

Photo from U. S. Federal Government courtesy of Wikipedia.

From left to right: Red blood cell (erythrocyte); Platelet (thrombocyte); White blood cell (leukocyte).

Red blood cells, called erythrocytes, are responsible for carrying oxygen from the lungs to various body tissues.

Red blood cells contain hemoglobin, which gives them their characteristic red color and helps them carry the oxygen.

Anemia is a condition caused by low levels of red blood cells and hemoglobin.

Anemia can be caused by the following:• Loss of blood due to injury,

• Infestations of blood-sucking parasites, or

• Low levels of red cell production due to poor nutrition.

Blood platelets, or thrombocytes, are oval-shaped discs that are formed in the bone marrow.

Blood platelets help prevent blood loss from injuries to blood vessels by forming clots (white thrombus).

Human ABO Blood Types

Image courtesy of Wikipedia.