UNIT NO.2
Human Respiratory and Circulatory System
(Solved Exercise)
2.2 Differentiate between:
1. Aerobic and anaerobic respiration
Aerobic respiration
1. It takes place in the presence of oxygen.
2. Large amount of energy is released in aerobic respiration.
3. Carbon dioxide and water are the products of aerobic respiration.
Anaerobic respiration
1.It takes place in the absence of oxygen.
2. Small amount of energy is released in anaerobic respiration.
3. Lactic acid is produced in muscles. Ethanol and carbon dioxide are produced in yeasts.
2. Oxygen and carbon dioxide
Oxygen
1. Chemical formula of oxygen gas is O2 .
2. Animal use oxygen gas for respiration.
3. It helps in burning.
Carbon dioxide
1. Chemical formula of carbon dioxide is CO2 .
2. Plants use carbon dioxide gas for photosynthesis.
3. Carbon dioxide gas is fire extinguisher.
3. Breathing and respiration
Breathing
1. Breathing is the exchange of gases by inhalation and exhalation of the air.
2. It takes place in alveoli of the lungs.
3. Rib muscles in the chest cavity and diaphragm play key role in inhaling and exhaling the air.
4. Enzymes are not involved in breathing activity.
Respiration
1. Respiration is a process to release energy from food during a series of reactions.
2. It takes place in mitochondria of the cells.
3. Muscles are not involved during the process of respiration.
4. Enzymes are involved in all the reactions of respiration.
4. Arteries and veins
Arteries
1. Carry blood away from the heart
2. Thick walled vessels
3. Facing high blood pressure
4. Having no valves
Veins
1. Carry blood towards the heart
2. Thin walled vessels
3. Facing low blood pressure
4. Veins have valve
5. Capillaries and alveoli
Capillaries
The arterioles divide and become tiny vessels called capillaries. Capillaries provide a large surface area for the
exchange of materials between the blood and the tissues.
Alveoli
Each bronchiole ends in a group of air sacs or alveoli. The lungs look like sponges due to the presence of alveoli. Millions of alveoli are found in the lungs.
2.3 Give short answers.
1. Name the body parts involved in breathing system.
Nasal cavity, Larynx, Trachea, Bronchus, Bronchioles, Alveoli.
2. Name the products of anaerobic respiration which occurs in muscles.
Product of anaerobic respiration in muscles is lactic acid with energy.
3. Name different blood cells.
cells (RBCs), white blood cells (WBCs ) and platelets
4. Where does blood oxygenate?
Blood is oxygenated in lungs.
5. Name different chambers of human heart.
There are four chambers in human hearts. Left atrium, Right atrium, Left ventricle and Right ventricle.
2.4 Answer the following questions.
1. Describe the functions of different valves in human heart and veins.
The flow of blood from atria to ventricles is regulated by valves which prevent the backflow of the blood.
2. How does human heart work?
The right atrium receives deoxygenated blood through veins. The left atrium receives oxygenated blood from the lungs. Both atria contract at the same time and pump the blood from left atrium to left ventricle and from right atrium to right ventricle. The two ventricles contract at the same time. During this contraction, the blood from left ventricle is pumped towards all the body parts (except lungs) through the main artery called aorta and the blood from right ventricle is pumped towards the lungs.
3. Explain the structures and functions of the following
(a) Arteries (b) Veins (c) Capillaries
(a) Arteries
1. Carry blood away from the heart
2. Thick walled vessels
3. Facing high blood pressure
4. Having no valves
5. Carry blood having oxygen and nutrients for the body cells, except pulmonary artery which carries deoxygenated blood.
(b) Veins
1. Carry blood towards the heart
2. Thin walled vessels
3. Facing low blood pressure
4. Veins have valve
5. Return blood carrying carbon dioxide and other wastes, except pulmonary vein which carries oxygenated blood
(c) Capillaries
1. Provide surface area for exchange of materials between the body cells and blood cells
2. Very thin walled
3. Facing low blood pressure
4. No valve
5. Provide oxygen and nutrients to the cells and collect carbon dioxide and other wastes from the cells.
4. Explain the role of chest and rib muscles in breathing system.
When we breathe in, rib muscles contract pulling the ribs up and out and chest cavity expands. At the same time, diaphragm contracts and flattens. The space inside the chest cavity becomes larger. As a result, air enters into the lungs. This is called inspiration. The reverse of this process is called expiration.
5. Describe the composition of blood.
Our blood is 55 % plasma and 45 % blood cells suspended in the plasma. Plasma is 92 % water. Plasma without fibrinogen (blood clotting proteins) and blood cells is called serum.
Blood cells
Blood cells are of three types, i.e., red blood cells (RBCs), white blood cells (WBCs ) and platelets.
Red blood cells (RBCs)
Red blood cells (RBCs) are disc shaped and slightly concave on both sides They contain haemoglobin (a red coloured protein) which gives them red colour. This is the haemoglobin in the red blood cells which carries oxygen from the lungs and supplies it to all the body cells during blood circulation. Haemoglobin also carries carbon dioxide from the blood cells and leaves it at the lungs for its removal from the body. Red blood cells exist for 120 days in the blood stream. They are finally fragmented in the liver.
White blood cells (WBCs)
White blood cells (WBCs) are colourless. They have no coloured pigment. They are part of the body’s immune system. They help the body fight infection and other diseases. There are five types of white blood cells which are different in their structure and function. These are larger in size than the red blood cells. Their main function is to protect the body from disease causing microorganisms (pathogens).
Platelets
Platelets are not complete cells. These are fragments of cytoplasm enclosed by membranes. Platelets play an important role in blood clotting. They also help to slow or stop bleeding and healing wounds.
2.5 Constructed Response Questions
1. Explain the difference between burning and respiration.
Burning
1. Burning take place in open air.
2. Burning depends on amount of oxygen.
3. It is a single step reaction.
4. It is simple chemical process.
Respiration
1. Respiration take place in a cell.
2. This process is controlled by enzymes.
3. It completes in series of reactions.
4. It is a biochemical reaction.
2. Blood circulatory system plays a key role in cellular respiration. Explain how?
Blood circulatory system is important in cellular respiration because blood provides glucose and oxygen that is supplied to each of the cell of human body.
3. Anaerobic respiration occurs when the body cannot get enough oxygen for aerobic respiration to take place. Explain with example of the situation when and where anaerobic respiration takes place in human body.
When we run fast or take exercise or play for long time, we tired. Our muscles respire anaerobically.