Human Body and Organ System Class 8 Chapter 11 Exercise


Important points to remember :
  1. Group of organs working together to perform a specific function is called as organ system. Various organ systems like digestive, respiratory, circulatory, nervous, excretory, reproductive, skeletal, muscular, etc. are functioning in our body.  
  2. Energy is essential to operate all the life processes in human body. Energy production occurs within the cells. Cells need the supply of soluble nutrients and oxygen for this purpose. 
  3. This supply takes place with the help of respiratory and circulatory systems. 
  4. Exchange of gases between cells and tissue fluid is called as internal respiration. 
  5. A muscular partition is present at the base of thoracic cage. This partition is called as diaphragm. It is present between the thoracic cavity and abdominal cavity.  
  6. In 1628, William Harvey described the mechanism of circulation in the body. He proposed a theory that our heart is a muscular pump by which blood is circulated in the body. 
  7. In case of a healthy person, there are  72 beats of heart per minute. Rate of heart beat increases due to physical exercise and emotions. 
  8. Two types of sounds are heard during heart beat. One is described as 'lubb' and other as 'dub. Blood is required in various situations like accidents, bleeding, parturition, surgical operations, etc. 
  9. Blood donated by healthy person is used to save the life of needful person. Hence blood donation is considered as the best donation. 
  10. Branch of medical science that deals with the study of blood, hematopoietic organs and blood diseases is called as hematology.


Question 1: Find out my partner.
 Group 'A' Group 'B'
 1. Heart beats          a. 350 ml
 2. RBC                          b. 7.4
 3 WBC                          c. 37∘C
 4 Blood donation d. 72
 5 Normal body
Temperature           e. 50-60 lakh/mm3
 6 pH of oxygenated
blood                         f. 5000-6000 per mm3

Answer :
 1. Heart beat - d. 72
 2. RBC. - e. 50-60 lakh/mm3
 3 WBC   - f. 5000-6000 per mm3
 4 Blood donation -  a. 350 ml
 5 Normal body Temperature - c. 37∘C
 6 pH of oxygenated blood - b. 7.4


Question 3. Draw neat and labeled diagrams.
a. Respiratory system


b. Internal structure of heart.


Question 4. Explain with reasons.
a. Human blood is red coloured. 
Answer : Human blood is red because of the protein hemoglobin, which contains a red-colored compound called heme that's crucial for carrying oxygen through your bloodstream. Heme contains an iron atom which binds to oxygen; it's this molecule that transports oxygen from your lungs to other parts of the body.

b. Upward and downward movement of 
diaphragm occurs consecutively.
Answer : The upward and downward movement of diaphragm occurs consecutively during inspiration process. It is because when you inhale the air, diaphragm in your breathing system moves fully upward and while you exhale the air, diaphragm fully moves download.

c. Blood donation is considered to be 
superior of all donations. 
Answer : Blood donation is considered superior of all donations because it can save someome'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.

d. Person with 'O' blood group is considered as 'universal donor'.
Answer : In transfusions of packed red blood cells, individuals with type O Rh D negative blood are often called universal donors. Those with type AB Rh D positive blood are called universal recipients.

e. Food must have limited amount of salts.
Answer :  Having less sodium in your diet may help you lower or avoid high blood pressure. People with high blood pressure are more likely to develop heart disease or have a stroke. Most people eat too much sodium, often without knowing it. The average American eats about 3,400 mg of sodium a day


Question 5. Answer the following questions in your own words.

a. Explain the functional correlation of 
circulatory system with respiratory, 
digestive and excretory system.
Answer :  The circulatory system consists Blood which helps in the transfer of oxygen from lungs to different organs(respiratory), It also helps for the transfer of nutrients and also the elimination of waste material from blood(digestive and excretory system respectively).

b. Explain the structure and function of 
human blood. 
Answer : Blood is important for regulation of the body’s pH, temperature, osmotic pressure, the circulation of nutrients and removal of waste, the distribution of hormones from endocrine glands, and the elimination of excess heat; it also contains components for blood clotting. Blood is made of of several components, including red blood cells, white blood cells, platelets, and the plasma, which contains coagulation factors and serum.
  1. Blood helps maintain homeostasis by stabilizing pH, temperature, osmotic pressure, and by eliminating excess heat. 
  2. Blood supports growth by distributing nutrients and hormones, and by removing waste. Red blood cells contain hemoglobin, which binds oxygen. These cells deliver oxygen to the cells and remove carbon dioxide.
  3. Blood plays a protective role by transporting clotting factors and platelets to prevent blood loss after injury. 
  4. Blood also transports the disease-fighting agents white blood cells to sites of infection. 
  5. These cells—including neutrophils, monocytes, lymphocytes, eosinophils, and basophils—are involved in the immune response.


c. Explain the importance and need of 
blood donation. 
Answer : Along with helping save lives, there are a number of reasons why donating blood is important.
  1. A single donation can save three lives. One blood donation provides different blood components that can help up to three different people.
  2. Blood cannot be manufactured. Despite medical and technological advances, blood cannot be made, so donations are the only way we can give blood to those who need it.
  3. Blood is needed every two seconds. Nearly 21 million blood components are transfused in the U.S. every year.
  4. Only 37 percent of the country’s population is able to donate blood.
  5. Your friends or family may need your blood someday.



Question 6. Explain the differences.
a. Arteries and veins. 
Answer :
  1. One of the major difference between arteries and veins is that the arteries carry oxygenated blood to all body parts, whereas, veins carry the deoxygenated blood to the heart. 
  2. Arteries are thicker due to a higher and more fluctuating blood pressure. Veins are thinner.  
  3. Peripheral veins have valves to keep blood flowing in one direction toward the heart.


b. External and internal respiration.
Answer : 
  1. External respiration occurs in the lungs where oxygen diffuses into the blood and carbon dioxide diffuses into the alveolar air. 
  2. Internal respiration occurs in the metabolizing tissues, where oxygen diffuses out of the blood and carbon dioxide diffuses out of the cells.



Question 7. Which health parameters of blood donor should be checked
Answer : Information about minor illnesses, exposure to communicable diseases, travel to disease endemic areas, pregnancy and lactation and medical and surgical interventions should be elicited so as to determine suitability for blood donation or the need for deferral.

Requirements for Donating Blood
  1. Be at least 17 years old
  2. Weigh at least 110 pounds.
  3. Be in good health generally and feel well on the day of donation.
  4. Bring a current photo ID on the day of donation.


Question 8: Fill in the blanks using appropriant words given in the bracket.
( hemoglobin, alkaline, diaphragm, red bone marrow, acidic, voluntary, involuntary.)

​a. RBCs of the blood conatin hemoglobin, an iron compound.

b. Diaphragm is present between thoracic and abdominal cavity.

c. Cardiac muscles are involuntary.

d. pH of oxygenated blood is alkaline.

e. Production of RBCs occurs in red bone marrow.


Question 9: Find odd one out.

a. A, O, K, AB, B
Answer : K is the odd one out because it is an inorganic ion while rest of the four are types of blood groups.

b. Blood plasma, platelets, blood transfusion, blood corpuscles
Answer : Blood transfusion is the odd one out because it is a techniques for transfer ing of blood from donor to repeient. Rest of the three are components of blood.

c. Trachea, alveoli, diaphragam, capillaries Answer : Capillaries are the odd one out because they are a part of the circulatory system while rest of the three are parts of the respiratory system.

d. Neutrophils, globulins, albumins, prothrombin 
Answer : Neutrophils are the odd one out because they are a type of blood cell. Rest of the three are components of the plasma.       


Question 10: Read the following paragraph and identify the disease.
Today, her child became one and half year old. However, that child does not seem to be healthy and happy. It was continuously crying and gradually becoming weak. It has shortness of breath. Its nails have become blue.
Answer : From the above mentioned symptoms, it seams 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. It is known as cyanosis.
It occurs when enough oxygen is not present in blood, thus making the skin or membrane below the skin turn purplish-blue.

# can you tell
1. Which processes occur in our body during sound sleep? 
Answer : After deep sleep, your brain starts to perk up, and its electrical activity starts to resemble the brain when it is awake.
This is the period of the night when most dreams happen. In this stage of sleeping our eye lids are moving and your lucid dreams occur at this stage and your heart rate and respiration increases.


2. Which life processes occur continuously in our body? 
Answer : These are the life process that occurs continuously in our body, Respiration refers to all the processes, involved in the exchange of oxygen and carbon dioxide between the cells and the external environment. Digestion is the process of breaking down complex ingested foods into simple.

3. Which organs are present in the 
respiratory system? 
Answer : The organs of the respiratory system include the lungs, pharynx, larynx, trachea, and bronchi.

4. One should not talk while eating. Why 
is it so?
Answer :  Sitting is the best posture when it comes to eating your meals as is allows the food to digest properly. Bad posture may cause indigestion and lead to weight gain. Talking and eating: Another rule we are often told is to not talk while eating as it may result in choking of the food pipe.

5. We can feel the pulse behind the ears and near the heel of foot. 
How these pulses occur? 
Answer :Feeling a pulse through the temporal artery can signal a malfunction in the blood vessel is rare.
It can also occur in heart when ur heart moving excess blood with each heart beat.

6. What flows out when we have an injury?
Answer : These and other elements float through blood vessels in a straw-like liquid called plasma. Normally, when a blood vessel is injured (for example, from a cut on the skin or an internal injury), blood starts to flow.

Tags : class 8 science textbook solutions,
what are the 12 organs of the body.
meritnation class 8 science ncert solutions,
human body class 4 byju's, human body system questions and answers pdf, human body system questions answer key,
organ system questions and answers,
human body parts.