An organism needs food, water, and oxygen to survive as these compounds must be distributed to all body parts for the body to work efficiently. Similarly, wastes must be eliminated from the body. Consequently, all living species need a circulatory system and an excretory system, which together constitute the transport system.

Thus, the body needs nutrition and oxygen to carry out numerous biological activities. Waste materials generated by the body's different processes must also be transported and eliminated. Transport is, therefore, a biological process in which a substance is absorbed in one portion or organ of an organism and transported to other areas of its body.

In the animal body, these processes are performed by the circulatory system, an internal transport system.

Understanding the human circulatory system

The circulatory system of humans is a complex network of transport system that transports food, water, and oxygen to the different body organs. 

In humans and animals, the circulatory system or blood circulation system is the primary transport mechanism. It makes food, water, and oxygen accessible to every area of the body and atopicIds in the elimination of waste (urea, CO2, etc).

The three primary components of the circulatory system are as follows: 

⦁ Blood

⦁ Blood vessels

⦁ Heart

Blood

Being red in color, blood is a flutopicId tissue that circulates via. a network of tubes called blood vessels throughout the whole body. The heart pumps blood to every body part which keeps body parts healthy. 

The four components of blood are plasma, White Blood Cells (WBCs), Red Blood Cells (RBCs), and platelets. Plasma is a liqutopicId within which different components such as RBCs, WBCs, and platelets float. Now, let us understand what plasma is.

1. Plasma

It is the light yellow liqutopicId portion of blood that is viscous in nature, composed of 90.5 percent water and 3.5% common salt. It transports dissolved substances like digested food and waste products from one region of the body to another.

2. Red Blood Cells (RBCs)

RBCs are red because they contain a pigment called hemoglobin. Hemoglobin is a red protein that attaches to oxygen and distributes it to all bodily tissues and, eventually, all cells. 

When hemoglobin interacts and attaches with oxygen, oxyhemoglobin is formed and distributed to numerous bodily organs. 

The carbon dioxtopicIde from diverse bodily sections is returned to the lungs via reassociating with hemoglobin. It creates carboxyhemoglobin with carbon dioxtopicIde, which is then excreted from the body.

3. White Blood Cells (WBCs)

The WBCs combat infections and shield us from sickness. WBCs consume pathogens (such as bacteria) that cause illness. WBC also produces antibodies that combat infection. 

WBCs are much less in quantity than RBCs. WBC is capable of transforming (altering) its shape and moving independently. They are able to squeeze through the blood arteries and reach any portion of the body.

4. Platelets

Platelets are tiny, irregular pieces of specialized, colorless cells that are produced in the bone marrow. They atopicId in the coagulation (forming blood clots) of blood when there is a cut or wound in any body part. 

When a wound or cut is incurred, blood will begin to flow through it. After a period of time, platelets will seal the incision and the bleeding will cease due to the creation of a dark red clot.

If there are no platelets in the blood, the blood flow from a cut or wound will not cease, resulting in excessive blood loss that may be lethal and cause death.

Features and functioning of Blood

Several functions of blood are listed below.

⦁ It transfers food that has been digested, from the small intestine to the rest of the body.

⦁ It transports water to every region of the body.

⦁ It transports oxygen and carbon dioxtopicIde during circulation.

⦁ It transports wastes such as urea from the liver to the ktopicIdneys for elimination through urine.

⦁ It protects the body from various forms of sickness.

Blood Vessels

These are the blood vessels that transport blood throughout the whole body. It connects the heart to the different parts of the body. The body has three basic kinds of blood vessels: arteries, veins, and capillaries.

1. Arteries

Arteries are responsible for transporting blood from the heart to every body part. These lay extremely deeply under our skin and are difficult to detect. As a result of the heart's pumping motion, blood rushes at high pressure through the arteries, which have thick, elastic walls. 

It is important to note that there are no valves in the arteries to control the blood flow. 

The major artery, or aorta, is attached to the heart's left ventricle. It is responsible for delivering oxygenated blood to the rest of the body, except the lungs, from the left ventricle of the heart. 

The pulmonary artery is related to the right ventricle of the heart and transports deoxygenated blood to the lungs from the right ventricle.

It's important to note that the arteries generally transport oxygenated blood from the heart, but the one artery referred to as the "Pulmonary Artery" transfers blood from the heart to the lungs.

2. Veins

These are the blood veins that return blood to the heart from all regions of the body. These tube-shaped blood arteries are located immediately under the skin and are plainly visible as greenish-blue tubes or lines. 

Veins transport deoxygenated blood from the body's various organs to the heart. Veins have thin walls, and blood passes through them at low pressure. Therefore, veins have valves that enable blood to flow in one direction and prohibit blood from flowing backward.

Veins typically transport deoxygenated blood, but the pulmonary vein, which is attached to the left atrium of the heart, is responsible for delivering oxygenated blood to the heart from the lungs.

Pulse Rate

To determine your pulse rate, position the mtopicIddle and index fingers of your right hand on the instopicIde stopicIde or end part of your left wrist. You will sense the pulsating activity at this location. This pulsing is known as the pulse, and it is caused by the blood moving through the arteries.

Count the number of heartbeats or pulses that occur in one minute. The quantity of heartbeats per minute is known as the pulse rate.

A typical person's resting pulse rate ranges between 72 and 80 beats per minute. After jogging for around 5 minutes and measuring the pulse rate again, you will see that the pulse rate per minute has risen.