Maharashtra Board Textbook Solutions for Standard Eight

Chapter 11 - Human Body and Organ System

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
6. pH of oxygenated blood
f. 5000-6000 per mm³

Ans:

Group 'A' Group 'B'
1. Heart beats
d. 72
2. RBC
e. 50 – 60
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

2. Complete the following table.

Organ systems Organs Functions
1. Respiratory system
2. Circulatory system

Ans: 

Organ systems Organs Functions
1. Respiratory system
Nose
Filters air with the help of hair and mucus
Pharynx
It conducts air to the wind pipe
Wind pipe
Allows passage of air into lungs
Lungs
Carries out exchange of gases
Diaphragm
It lowers and rises up helping in inhalation and exhalation of air
2. Circulatory system
Heart
It pumps blood throughout the body
Blood vessels
It transports blood throughout the body

3. Draw neat and labeled diagrams.

a. Respiratory system 

Ans:

Shaykh Academy Respiratory System Chapter 11 – Human Body and Organ System

b. Internal structure of heart

Ans:

Shaykh Academy Internal structure of heart Chapter 11 – Human Body and Organ System

4. Explain with reasons.

a. Human blood is red coloured. 

Ans:

(i) Human blood contains red-colored cells, i.e., RBCs, that have an iron-containing red-colored pigment called haemoglobin.

(ii) The bright red colour is caused by iron molecules binding to oxygen. Hence, human blood is red-coloured.

 

b. Upward and downward movement of diaphragm occurs consecutively. 

Ans:

(i) The diaphragm is a muscular partition present at the base of the thoracic cage. It is located between the thoracic and abdominal cavities.

(ii) The ribs rise up and the diaphragm lowers, causing a decrease in the pressure on the lungs due to the fact that air moves into the lungs through the nose.

(iii) The ribs return to their original position and the diaphragm rises, due to which the pressure on the lungs increases and the air moves out of the lungs through the nose.

(iv) This continuous upward and downward movement of the diaphragm is required to bring about the process of breathing.

 

c. Blood donation is considered to be superior of all donations. 

Ans:

(i) A blood transfusion is needed in various situations, like when a person meets with an accident that results in heavy blood loss; during surgeries; in the case of patients with anaemia, thalassemia, or cancer; and also after parturition (childbirth).

(ii) Also, there is a constant need for regular blood supply, as blood can only be stored for a limited time before use.

(iii) Regular blood donations will ensure the availability of safe blood wherever and whenever needed.

(iv) A person who donates blood may be a recipient in the future. Thus, blood donation must be done without any expectations.

(v) Blood donated by a healthy person can save the life of a needy person. Hence, it is considered the best donation.

 

d. Person with ‘O’ blood group is considered as ‘universal donor’.

Ans:

(i) A person who donates blood is a blood donor.

(ii) A person with the blood group “O” can donate blood to a person having any other blood group, i.e., O, A, B, and AB.

Thus, a person with blood group “O” is considered a universal donor.

 

e. Food must have a limited amount of salts. 

Ans:

(i) Many people consume foods containing more salt than is normally required.

(ii) Eating foods with high amounts of salt (e.g., sodium) increases the blood pressure, thereby adding strain on the blood vessels.

(iii) This leads to health problems like hypertension.

(iv) In order to stay healthy and prevent such diseases, one should consume foods with a limited amount of salt.

 

5. Answer the following questions in your own words.

a. Explain the functional correlation of circulatory system with respiratory, digestive and excretory system. 

Ans:

(i) The circulatory system performs the function of transporting various substances, like water, hormones, oxygen, soluble nutrients, and waste materials, through different organs.

(ii) Oxygen inhaled during respiration reaches the alveoli and diffuses into the blood. It is then transported to the cells present in various parts of the body for cellular respiration. In cellular respiration, food is broken down in the presence of oxygen to release energy.

(iii) Carbon dioxide, a waste product of cellular respiration, diffuses into the alveoli (i). It is transported into the bronchioles and reaches the trachea through the bronchi (i). From there, it is exhaled out of the body through the nose.

(iv) The organs of the digestive system need the circulatory system to transport nutrients to the body’s cells. Blood carries simple nutrients like glucose, fatty acids, amino acids, etc. from the wall of the alimentary canal to each cell of the body.

(v) The blood also carries nitrogenous wastes like ammonia, urea, creatinine, etc., released by the tissues for excretion.

(vi) In this manner, different body systems work together to perform body functions.

 

c. Explain the structure and function of human blood. 

Ans:

Structure of blood:

(i) Blood is a connective tissue fluid that is red in color.

(ii) The oxygenated blood is deep red and salty to taste.

(iii) The pH of blood is 7.4 (slightly alkaline).

(iv) Blood is composed of mainly two components: plasma and blood cells.

 

a. Plasma: Plasma is a pale yellow, clear, and slightly alkaline fluid. It contains 90–92% water, 6–8% proteins, 1–2% inorganic salts, and a few other components. Albumins, globulins, fibrinogen, prothrombin, and inorganic salts are the components of plasma.

Functions:

(i) Albumins help maintain osmotic balance.

(ii) Globulins perform a very important role in fighting infections (protection).

(iii) Fibrinogen and prothrombin help in the blood clotting process.

(iv) Inorganic ions like Ca, Na, and K regulate the function of muscles and nerves.

 

b. Blood cells: The major types of blood cells are:

(i) RBCs (Red Blood Cells) or Erythrocytes: They are circular, small, and enucleated (the nucleus is absent). RBCs appear red due to the presence of hemoglobin, an iron-containing protein. There are around 50 to 60 lakh RBCs per mm3 of blood. They are produced in the bone marrow. The average life span of RBCs is 120 days.

Function: Hemoglobin carries oxygen to the body’s tissues.

(ii) White Blood Cells (WBCs)/Leucocytes: WBCs are large, nucleated, and colourless cells. 5000–10,000 WBCs are present per mm of blood. There are five types of WBCs present in the blood: basophils, eosinophils, neutrophils, monocytes, and lymphocytes. WBCs are formed in the bone marrow.

Function: They serve a specific role in the human immune system. WBCs attack pathogens, fight infections, and protect the human body from various diseases.

(iii) Platelets and thrombocytes: Platelets are extremely small and disc-shaped. About 2.5–4 lakh platelets are present per mm of blood.

Function: They are involved in the formation of blood clots in cases of injury.

 

Functions of blood:

(i) Transport of gases: Oxygen is transported via blood from the lungs to body tissues and carbon dioxide from tissues to the lungs.

(ii) Transport of nutrients: The blood transports nutrients like glucose, amino acids, and fatty acids obtained from the wall of the alimentary canal to each cell of the body.

(iii) Transport of waste materials: Nitrogenous wastes like ammonia, urea, and creatinine are released by tissues into the blood, which carries these waste materials to the kidney for excretion.

(iv) Protection: Antibodies formed in the blood protect the body from microbes and other harmful particles.

(v) Transport of enzymes and hormones: Enzymes and hormones are transported by blood from the site of their production to their target sites (organs and tissues) in the body.

(vi) Thermoregulation: It regulates normal body temperature (37 °C) by vasodilation (dilation of blood vessels) and vasoconstriction (narrowing of blood vessels).

(vii) Maintenance of concentrations of minerals like Na, K, etc. in the body.

(viii) Blood platelets and fibrinogen protein form a clot and seal the site of injury to prevent blood loss by bleeding.

 

c. Explain the importance and need of blood donation. 

Ans:

(i) A blood transfusion is needed in various situations, like when a person meets with an accident that results in heavy blood loss; during surgeries; in the case of patients with anaemia, thalassemia, or cancer; and also after parturition (childbirth).

(ii) Also, there is a constant need for regular blood supply, as blood can only be stored for a limited time before use.

(iii) Regular blood donations will ensure the availability of safe blood wherever and whenever needed.

(iv) A person who donates blood may be a recipient in the future. Thus, blood donation must be done without any expectations.

(v) Blood donated by a healthy person can save the life of a needy person. Hence, it is considered the best donation.

6. Explain the differences.

a. Arteries and veins. 

Ans:

Arteries Veins
(i) They are blood vessels which carry blood away from the heart.
(i) They are blood vessels which carry blood towards the heart.
(ii) It carries oxygenated blood, except pulmonary artery.
(ii) It carries deoxygenated blood except pulmonary vein.
(iii) These blood vessels do not have valves.
(iii) These blood vessels have valves.
(iv) They are deeply situated.
(iv) They are superficially located.
(v) They are thick walled.
(v) They are thin walled.

2. External and internal respiration.

Ans:

External respiration Internal respiration
(i) It occurs in the lungs.
(i) It occurs in cells of the body.
(ii) Oxygen from lungs moves into the blood.
(ii) Oxygen brought by blood is given to cells and tissues.
(iii) Carbon dioxide from various parts of the body is transported through blood.
(iii) The exchange of gases takes place between blood and tissues of the body.
(iv) The exchange of gases takes place between the blood and surrounding medium.
(iv) Carbon dioxide from cells and tissues is transported through blood.

7. Which health parameters of blood donor should be checked? 

Ans: The different parameters of a blood donor that need to be checked are as follows:

(i) Haemoglobin content: For blood donation, females must have a minimum haemoglobin level of 12.5 g/dL and males must have a minimum level of 13.0 g/dL.

(ii) Illness: The donor should not be suffering from any communicable disease.

(iii) Age: The donor’s age must be between 16 and 70 years old.

(iv) Weight: The donor’s weight should be a minimum of 45 kg.

(v) Pulse: The pulse rate should be 60 to 100 beats per minute.

(vi) Blood pressure: The blood pressure of an individual should be near normal (i.e., 120/80 mm Hg), indicating that the donor is healthy.

(vii) Body temperature: The body temperature should not exceed 37.5 °C.

 

8. Fill in the blanks using appropriate words given in the bracket. 

(haemoglobin, alkaline, diaphragm, red bone marrow, acidic, voluntary, involuntary) 

 

a. RBCs of the blood contain ________ , an iron compound. 

Ans: hemoglobin

 

b. ________ is present between thoracic and abdominal cavity. 

Ans: diaphragm

 

c. Cardiac muscles are ________.

Ans: involuntary

 

d. pH of oxygenated blood is ________.

Ans: alkaline

 

e. Production of RBCs occurs in ________.

Ans: red bone marrow

8. Find an odd one out.

a. A, O, K, AB, B. 

Ans:

A, O, AB and B are the main blood groups of the human blood group system.

 

b. Blood plasma, platelets, blood transfusion, blood corpuscles. 

Ans: Blood transfusion

Blood transfusion is the process carried out to compensate for the shortage of blood in the body, whereas rest all are the components of blood.

 

c. Trachea, alveoli, diaphragm, capillaries. 

Ans: Capillaries

Capillaries are the part of the circulatory system and are present throughout the body rest all are the parts of the human respiratory system.

 

d. Neutrophils, globulins, albumins, prothrombin. 

Ans: Neutrophils

Neutrophils are the types of WBCs and rest all are proteins in blood plasma.

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. 

Ans: Asthma (Respiratory disease)

 

11. Your neighboring uncle has been diagnosed with hypertension. What should he do to keep his blood pressure within normal range?

Ans: 

(i) High blood pressure increases the risk of a heart attack. Making lifestyle adjustments is a key to maintaining normal blood pressure.

(ii) Blood pressure can be controlled in the following ways:

a. Eating a healthy diet: In order to manage blood pressure, one should limit the amount of salt in the diet and consume less fat-containing food.

b. Regular exercise: Regular exercise can help in maintaining weight and lowering blood pressure. Also, brisk walking is beneficial.

c. Managing stress: Learning to manage stress can improve mental and physical health. It will help in controlling high blood pressure. Techniques like meditation, listening to music, etc., can help in managing the stress.

d. Avoiding alcohol and smoking: Both of these habits can increase blood pressure and the risk of heart attack and stroke. Thus, they should be avoided.