11. Human Body and Organ System
Complete solutions to the Exercises. Maharashtra State Board (Balbharati), Grade Eight General Science.
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Exercises
| Group ‘A’ | Group ‘B’ |
|---|---|
| 1. Heart beats | 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 |
| Organ system | Organs | Functions |
|---|---|---|
| 1. Respiratory system | Nose, trachea, bronchi, lungs, diaphragm | Taking in oxygen and giving out carbon dioxide |
| 2. Circulatory system | Heart, arteries, veins, capillaries | Transport of oxygen, nutrients, hormones and wastes through blood |
(a) Respiratory system
Human respiratory system.
(b) Internal structure of heart
Internal structure of the human heart (diagrammatic). The right side carries deoxygenated blood and the left side oxygenated blood.
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(a) Human blood is red coloured.
RBCs in blood contain haemoglobin. Haemoglobin is a red coloured iron compound. Hence, human blood is red.
(b) Upward and downward movement of diaphragm occurs consecutively.
When the diaphragm moves down, air enters the lungs. When it moves up, air is pushed out. The body needs oxygen continuously. So these movements occur one after the other continuously.
(c) Blood donation is considered to be superior of all donations.
Blood cannot be made artificially. It can save the life of a patient. The body of the donor makes up the lost blood soon. Hence, blood donation is the best of all donations.
(d) Person with ‘O’ blood group is considered as ‘universal donor’.
RBCs of ‘O’ blood group have no A or B antigen. So this blood can be given to a person of any blood group. Hence, ‘O’ group person is called a universal donor.
(e) Food must have limited amount of salts.
Excess salt increases blood pressure. It causes hypertension. The heart and kidneys have to work harder. Hence, food must have limited amount of salt.
(a) Explain the functional correlation of circulatory system with respiratory, digestive and excretory system.
- With respiratory system: Blood takes oxygen from the lungs and carries it to all cells. It brings carbon dioxide back to the lungs.
- With digestive system: Blood absorbs digested food from the intestine and carries it to all cells.
- With excretory system: Blood carries wastes like urea to the kidneys. The kidneys remove them as urine.
Thus, the circulatory system links all these systems.
(b) Explain the structure and function of human blood.
Structure: Blood is a fluid connective tissue. Its pH is 7.4. It has two parts:
- Plasma: A pale yellow fluid. It contains water, proteins and salts.
- Blood cells: RBCs carry oxygen. WBCs protect the body from germs. Platelets help in clotting of blood.
Functions:
- Transport of oxygen, carbon dioxide, food, wastes and hormones.
- Protection of the body from diseases.
- Clotting of blood at the injury.
- Maintaining body temperature.
(c) Explain the importance and need of blood donation.
- Blood is needed in accidents, operations and diseases like anaemia and thalassaemia.
- Blood cannot be made artificially.
- Blood can be stored only for a limited time. So regular donation is needed.
- Donating 350 ml of blood does not harm a healthy person.
- Blood donation can save someone’s life.
(a) Arteries and veins.
| Arteries | Veins |
|---|---|
| They carry blood away from the heart. | They carry blood towards the heart. |
| They carry oxygenated blood (except pulmonary artery). | They carry deoxygenated blood (except pulmonary vein). |
| They are deeply located. | They are mostly superficial. |
| Their walls are thick. | Their walls are thin. |
| They do not have valves. | They have valves. |
(b) External and internal respiration.
| External respiration | Internal respiration |
|---|---|
| It occurs in the lungs. | It occurs in the cells of the body. |
| Exchange of gases takes place between the alveoli and blood. | Exchange of gases takes place between blood and tissue fluid. |
| It can be seen as breathing movements. | It cannot be seen. |
- Age should be above 18 years. Weight should be proper.
- Haemoglobin level.
- Blood pressure, pulse and body temperature.
- Blood group.
- Tests for HIV, hepatitis and malaria.
- Recent illness or surgery.
(a) RBCs of the blood contain haemoglobin, 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.
(a) A, O, K, AB, B K
K is not a blood group.
(b) Blood plasma, platelets, blood transfusion, blood corpuscles Blood transfusion
Blood transfusion is a process. The others are components of blood.
(c) Trachea, alveoli, diaphragm, capillaries Capillaries
Capillaries belong to the circulatory system. The others belong to the respiratory system.
(d) Neutrophils, globulins, albumins, prothrombin Neutrophils
Neutrophils are white blood cells. The others are plasma proteins.
The textbook prints the number 8 twice. This is the ninth question.
The child cries continuously, is weak, has shortness of breath and its nails have turned blue.
The child is suffering from a congenital heart disease (blue baby). In this disease, there is a defect in the heart since birth. Oxygenated and deoxygenated blood get mixed. So the body gets less oxygen and the nails turn blue.
- He should take medicines as advised by the doctor.
- He should check his blood pressure regularly.
- He should eat less salt.
- He should avoid oily and junk food.
- He should exercise daily and control his weight.
- He should avoid tobacco and alcohol.
- He should reduce stress by doing yoga and pranayam.