Transportation in Humans: CBSE / NCERT Notes


All livings beings need food, water and oxygen for survival and to perform various activities. Food gets digested in the food canal or in the alimentary canal.The nutrients are transported from there to other parts of the body in the form of glucoseamino acidsfats,etc. This function is performed by the circulatory system. 
Transportation in Humans, CBSE / NCERT Notes, CTET Exam Notes
Unwanted harmful substances and excess water in the body cells are removed by the excretory system.

Circulatory System
This is also known as the cardiovascular system. It consists of the heart, blood vessels and blood.

Functions of the Circulatory System

Blood helps transport food, water and oxygen to all parts of the body. The fluid part of blood is known as plasma.

Blood consists of three types of cells


1.Red Blood Cells

These cells perform a specific function. Red blood cells, also called RBCs, have iron pigments known as hemoglobin that combines with oxygen and transports it to all parts of the body. The presence of hemoglobin gives red color to blood. On an average, there are five million RBCs per cubic mm of blood.

2.White Blood Cells

White blood cells, or WBCs, defend the body against infections.

3.Platelets

When a blood vessel is cut, blood comes out immediately. After some time, a dark red clot is formed on the cut. This is formed by cells called platelets in blood. When the platelet count decreases, excessive bleeding takes place and may even cause death.

Blood Vessels

Blood flows through narrow pipe-like structures in the body, known as blood vessels. These blood vessels transport food, oxygen and waste within the body.

Blood vessels are of two types


1.Arteries

transport oxygen-rich blood from the heart to the other parts of the body. The blood in the arteries is bright red in colour. Blood flows through the arteries at high pressure, because of which the arteries have thick elastic walls. When an artery is cut, blood rushes out immediately. The arteries divide into smaller vessels when they enter an organ, and further divide into thin tubes called capillaries. These capillaries supply oxygen and nutrients to the tissues and also collect waste and carbon dioxide.

2.Veins

carry blood low in oxygen content. Veins have valves that allow blood to flow in one direction – towards the heart – only. Veins have thin walls. That is why when a vein is cut blood comes out slowly and continuously. A number of capillaries together form a vein.

Heart

The heart pumps blood through our body. It is located in the chest cavity with its lower parts towards the left. Its size is that of the person’s fist. The pumps blood rich in carbon dioxide to the lungs, and oxygen-rich blood to the other parts of the body. It also prevents blood rich in oxygen from mixing with blood rich in carbon dioxide. It has four chambers. The two upper chambers are the atria and the two lower chambers are the ventricles. The partition between the two chambers is called the septum. Blood rich in oxygen is pumped out from the left ventricle to all parts of the body. Blood rich in carbon dioxide is pumped out from the right ventricle to the lungs through the pulmonary artery. It is the only artery in the human body that carries carbon dioxide-rich blood. The pulmonary vein is the only vein in the body that carries oxygen-rich blood.                   
The walls of the heart are made up of the most powerful muscles. The muscles of the heart contract and relax, which constitutes a heartbeat. The device that amplifies the sound of a person’s heart beat is called a stethoscope and consists of a chest piece that holds a sensitive diaphragm. The flow of blood in an artery over a bone is called the pulse. The normal pulse rate is 70 to 80 per minute.

Excretory System

The cells in the body perform various activities. Waste products such as urea, uric acid and excess water are formed and have to be removed from the body. The removal of waste products is termed excretion. The organs that help in the process of excretion constitute the excretory system, and include the kidneys, the ureters, the urinary bladder and the urethra.
The useful and harmful substances in blood enter the kidneys, where the capillaries filter it. The useful substances are reabsorbed, but the harmful substances are removed along with water in the form of urine. The urine from the kidneys comes down through long tubes called the ureters, which open into the urinary bladder where the urine is stored temporarily. When the bladder fills, the urine is disposed.
Dialysis
The functioning of the kidneys stops when there is an infection. This is known as kidney failure. As a result, waste products remain in the blood. When blood is not filtered, survival becomes difficult, so it is filtered through an artificial kidney. The process is called dialysis.  The artificial kidney is called a dialysis machine.

Points To Remember

  • Sweat is an excretory product and it consists of water and salt. Sweat cools the body and it helps to maintain normal temperature
  • The circulatory system helps in the transport of glucose, amino acids and fats to different parts of the body. The removal of waste from the body is carried out by the excretory system.
  • The circulatory system is also known as the cardiovascular system. The cardiovascular system consists of the heart, blood vessels and blood.
  • Blood helps transport food, water and oxygen to all parts of the body. It also helps transport harmful and unwanted waste to the excretory organs. The fluid part of blood is plasma.
  • Blood consists of red blood cells, white blood cells and platelets. Each of these cells performs a specific function.
  • Red blood cells transport oxygen to different parts of the body.
  • Red blood cells have an iron pigment called hemoglobin that combines with oxygen, and transports the oxygen to all parts of the body. The presence of hemoglobin gives blood its red colorWhite blood cells or WBC’s defend the body against infections. Whenever there is a cut or a wound, a clot is formed by cells called platelets present in blood.
  • Blood flows through narrow pipe-like structures, known as blood vessels. These blood vessels transport food, oxygen and waste within the body.
  • Arteries have thick elastic walls and transport bright red oxygen-rich blood from the heart to the other parts of the body.
  • Veins have valves on their inner lining that allow blood to flow only in one direction. They carry carbon dioxide-rich blood to the heart from different parts of the body.
  • Arteries divide into fine vessels or tubes known as capillaries. A number of capillaries join together to form a vein.
  • Blood capillaries distribute oxygen and nutrients to tissues.
  • The heart is located in the chest cavity, and pumps blood throughout the body.
  • The heart consists of four chambers. The two upper chambers of the heart are known as the atria.
  • The lower two chambers of the heart are the ventricles.
  • The walls of the heart are made up of the most powerful muscles. Their rhythmic contraction and relaxation constitute heartbeats.
  • Heartbeat can be recognized by placing the palm on the left side of the chest.
  • The stethoscope is a device that amplifies the sound of your heartbeat.
  • The pressure applied by blood on the walls of an artery at a particular part is the pulse. The number of times the heart beats in a minute is the same as the pulse rate.
  • The best place to check pulse rate is the wrist. The ideal pulse rate is 70 to 80 per minute.
Excretory system
The process of the removal of waste produced in the cells in living organisms is called excretion. The organs that help in the process of excretion constitute the excretory system. The excretory system consists of the kidneys, the ureters, the urinary bladder and the urethra. The kidneys are the major organs of the excretory system.

  • Urine trickles down from the kidneys into the urinary bladder through tubes called the uretersUrine consists of 95 per cent water, and a small percentage of urea and other waste products.
  • The ureters open into the urinary bladder. The urinary bladder stores urine temporarily.
  • Urine is expelled through the urethra. Waste substances are removed from the body in the form of urine.
  • Blood is carried through blood capillaries to the kidneys for filtration.
  • Sweat is also an excretory product released from the body. It contains water and salts. Sweating helps maintain the temperature of your body.
  • The impairment of the functioning of the kidneys is known as kidney failure.
  • The filtration of blood regularly by a kidney machine is known as dialysis, and the dialysis machine is also known as an artificial kidney.

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