Solutions-Class 8-Science-Chapter-11-Human Body and Organ System-Maharashtra Board

Respiratory system

Internal structure of heart

Human blood is red in colour due to the presence of the respiratory pigment haemoglobin. Haemoglobin is a red coloured conjugated protein with iron that is present on the red blood cells. Thus imparts red colour to the blood.

Diaphragm is a muscular partition which is present between the thoracic cavity and abdominal cavity. During the process of breathing, the upward and downward movement of diaphragm occurs simultaneously. The rib muscles also help in these movements.

• When the ribs rise and diaphragm is lowered at the same time, then there is a decrease in pressure on lungs.
• This causes movement of air into the lungs at the time of inhalation.
• On the other hand, when ribs come back to their normal position and diaphragm is risen, then pressure on the lungs increases.
• This causes movement of the air out of the body through the nose in the form of exhalation.
• These movements are possible only due to consecutive upward and downward movement of the diaphragm.

Blood donation is considered superior of all donations because Blood cannot be manufactured by any artificial chemical process. The only way to obtain blood is by donations of blood from a live donor. Blood is needed at times of emergency, it can save someone's life. Most of the lives are lost due to blood loss during surgeries, accidents or cases where regular blood transfusion is required. These lives can be saved, if adequate amount of blood is available.

Person with 'O' blood group does not have any antigen on his/her RBCs. The ‘O’ type blood thus cannot cause clotting reactions in the body of the recipients. Such persons with ‘O’ blood group can donate blood to any person having any blood group therefore they are considered as ‘universal donor’.

Food must have limited amount of salts as we require limited amounts of these in our body. Excessive salts in food can cause rise in blood pressure. Such condition is called hypertension. This condition can be dangerous and fatal in some cases. Therefore, one must keep control over sodium content of the food.

Three systems viz. respiratory, digestive and circulatory always work in coordination.

• Digestive system helps in breaking down complex food molecules into simple soluble nutrients at the end of the digestion process. The soluble nutrients are absorbed in the circulating blood in the villi of the intestine. The blood carries these nutrients to each cell during its circulation.
• Respiration exchange of gases occurs in the lungs. The respiratory system causes the diffusion of oxygen into the blood and the diffusion of CO₂out of the blood. The oxygen is then transported to cells of the body via the circulatory system. 
• The excretory system is responsible for the elimination of waste products from the body. These waste products are transported by blood to the excretory system.

Blood is a fluid connective tissue that flows in blood vessels. It is composed of two components- plasma and blood cells. 

Plasma is a yellowish colour fluid, made up of water (~90%) and some dissolved nutrients, proteins, hormones and waste products. 

Blood Cells consists of three types of blood cells. These are

1. Red Blood Cells (RBC):They contain a red pigment called haemoglobin, which transports oxygen to all body cells.
2. White Blood Cells (WBC):They fight against germs that enter the body. Thus, they protect the body from diseases.
3. Platelets: When we get injured, bleeding stops after some time. This happens because of the activity of platelets, which help in the clotting of blood.

Functions of blood:

• It transports nutrients and oxygen to the different parts of the body.
• It also carries waste materials (from the different parts of the body) to be removed by the excretory organs.
• Chemical messengers like hormones are transported by the blood.
• Protects the body from disease carrying germs.
• Helps to maintain a constant body temperature.

Blood donation is one of the biggest donations of an individual towards their society. Blood loss can occur under circumstances of accidents, during surgeries or in case of diseases which require blood transfusion. Adequate amount of available blood can save many lives. It does not harm or effect the body of the donor and the amount of blood which is donated is recovered within 24 hrs.
This donated blood can be stored and used as and when the requirement arises.

The following parameters of blood donors have to be checked prior blood donation:

• Blood donor should be healthy.
• He or she should have good haemoglobin content.
• The RBC and WBC count should also be normal.
• They should not carry any parasites in their blood such as malarial parasite or dengue virus.
• The donor should not be HIV positive or should not have any infectious diseases.
• He should not have any addictions such as drug-abuse or alcohol consumption.

i. RBCs of the blood containhemoglobin, an iron compound.

ii. Diaphragmis present between thoracic and abdominal cavity.

iii. Cardiac muscles are involuntary.

iv. pH of oxygenated blood is alkaline.

v. Production of RBCs occurs in red bone marrow.

 K is the odd one out because it is an inorganic ion while rest of the four are types of blood groups.

Blood transfusion is the odd one out because it is a techniques for transferring of blood. Rest of the three are components of blood.

Capillaries are the odd one out because it exists throughout the body, while rest of all are the parts of the respiratory system.

Neutrophils are the odd one out because they are a type of blood cell. Rest of the three are proteins present in the plasma.         

From the above mentioned symptoms, it seems like the child is suffering from some kind of respiratory disorder/circulatory disorder. He has problem in breathing and his nails have become blue which means there is low level or lack of oxygen circulating in the red blood cells, thus the baby may be suffering also from respiratory problems.

Hypertension has many causes. Try to find out what is the exact cause. Is it lack of exercise, obesity, lots of fast and junk food consumption, over-intake of salt, mental tension, etc?

The following methods can be adopted to keep the blood pressure within normal range:

• loose the extra weight
• exercise or do yoga regularly
• eat a healthy balanced diet containing fruits and vegetables
• reduce the amount or salt in food
• avoid alcohol and smoking
• reduce the amount of stress by indulging in your favourite activities

regular monitoring of blood pressure