15. Distinguish between arteries and veins.
| Arteries | Veins |
| The wall of arteries is thick and non collapsible. | The wall of the vein is thin and have a larger lumen. They can be easily stretched. |
| Arteries carry blood away from the heart | Veins bring blood from different parts of the body to the heart. |
| All arteries carry pure blood except the pulmonary artery. | All veins carry de oxygenated blood except the pulmonary veins. |
| Arteries have no valves. | Veins have valves to prevent back flow of blood. |
| The blood flows in arteries with great pressure. | The flow of blood in the veins is under low pressure |
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16. Distinguish between open and closed circulation.
| Open Circulatory system | Closed circulatory system |
| Blood is pumped by the heart into the blood vessels that open into blood spaces (Sinuses) called haemocoel. | The blood is pumped by the heart into closed blood vessels |
| Blood is in direct contact with tissue cells. | Blood is not in direct contact with tissue cells |
| Exchange of respiratory gases, nutrients and waste products occurs directly between the blood and tissues | Tissue fluids helps in exchange of respiratory gases, nutrients and waste products between blood and tissues |
| Respiratory pigments are absent | Respiratory pigment (Haemoglobin) is present in the RBC of the blood. |
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17. Distinguish between mitral valve and semi lunar valve.
| Mitral valve | Semilunar valve |
| It guards the opening between left auricle and left ventricle | It guards the opening between Ventricles, pulmonary artery and aorta. |
| It has two flaps or cusps. | Each valve is made up of three half-moon shaped cusps. |
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18. Right ventricular wall is thinner than the left ventricular wall. Why?
1.The right ventricle pumps deoxygenated blood into the pulmonary artery which carries blood to the lungs only
2.whereas the left ventricle pumps blood into the aorta which distributes oxygenated blood to all parts of the body.
3.Hence the wall of the left ventricle is thicker and right ventricle has a thinner wall
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1.Iron is necessary for the formation of haemoglobin pigment.
20. Describe the mechanism by which
the human heart beat is initiated and
controlled.
2. A person whose diet is deficient in iron will not have sufficient haemoglobin production in his body.
3.Haemoglobin plays a major role in transport of oxygen in the blood.
4.Since haemoglobin is a component of RBC, production of RBC will decrease leading to anaemia.
5.An anaemic person feels tired since oxygen supply in the body will be less because of the reduced number of RBC's in the blood.
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The heart in human is myogenic (cardiomyocytes can produce spontaneous rhythmic depolarisation that initiates contractions). The sequence of electrical conduction of heart is shown below.
1.The cardiac cells with fastest rhythm are called the Pacemaker cells, which are located in the right sinuatrial (SA) node/ Pacemaker.
2. On the left side of the right atrium is a node called auriculo ventricular node (AV node).
3. Two special cardiac muscle fibres originate from the auriculo ventricular node and are called the bundle of His which runs down into the interventricular septum and the fibres spread into the ventricles. These fibres are called the Purkinjie fibres.
4.Pacemaker cells produce excitation through depolarisation of their cell membrane. Early depolarisation is slow and takes place by sodium influx and reduction in potassium efflux.
5. Minimum potential is required to activate voltage gated calcium(Ca) channels that causes rapid depolarisation which results in action potential. The pace maker cells repolarise slowly via K+ efflux.
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About 90% of fluid that leaks from capillaries eventually seeps back into the capillaries and the remaining 10% is collected and returned to blood system by means of a series of tubules known as lymph vessels or lymphatics. The fluid inside the lymphatics is called lymph.
Functions of lymph :
1. The narrow passages in the lymph nodes are the sinusoids that are lined with macrophages. The lymph nodes successfully prevent the invading microorganisms from reaching the blood stream.
2.Fats are absorbed through lymph in the lacteals present in the villi of the intestinal wall
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22.What are the heart sounds? When and how are these sounds produced?
1.Rhythmic contraction and expansion of heart is called heart beat.
2. The contraction of the heart is called systole and the relaxation of the heart is called diastole.
3. The heart normally beats 70-72 times per min in a human adult.
4. During each cardiac cycle two sounds are produced that can be heard through a stethoscope.
5. The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves whereas second heart sound (dub) is associated with the closure of the semilunar valves. These sounds are of clinical diagnostic significance.
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23. Select the correct biological term.
Lymphocytes, red cells, leucocytes, plasma, erythrocytes, white cells, haemoglobin, phagocyte, platelets, blood clot.
a. Disc shaped cells which are concave on both sides.
Ans: erythrocytes
b. Most of these have a large, bilobed nucleus.
b. Most of these have a large, bilobed nucleus.
Ans: Leucocytes
c. Enable red cells to transport blood.
d. The liquid part of the blood.
c. Enable red cells to transport blood.
d. The liquid part of the blood.
Ans:plasma
e. Most of them move and change shape like an amoeba.
e. Most of them move and change shape like an amoeba.
Ans:phagocyte
f. Consists of water and important dissolved substances.
f. Consists of water and important dissolved substances.
Ans:plasma
g. Destroyed in the liver and spleen after circulating in the blood for four months.
g. Destroyed in the liver and spleen after circulating in the blood for four months.
Ans:Erythrocytes
h. The substances which gives red cells their colour.
h. The substances which gives red cells their colour.
Ans:haemoglobin
i. Another name for red blood cells.
i. Another name for red blood cells.
Ans:Erythrocytes
j. Blood that has been changed to a jelly.
j. Blood that has been changed to a jelly.
Ans:blood clot
k. A word that means cell eater.
k. A word that means cell eater.
Ans:phagocyte
l. Cells without nucleus.
l. Cells without nucleus.
Ans:RBC/platelets
m. White cells made in the lymphatic tissue.
m. White cells made in the lymphatic tissue.
Ans:Lymphocytes
n. Blocks wound and prevent excessive bleeding.
n. Blocks wound and prevent excessive bleeding.
Ans:blood clot
o. Fragment of cells which are made in the bone marrow.
o. Fragment of cells which are made in the bone marrow.
Ans:RBC
p. Another name for white blood cells.
p. Another name for white blood cells.
Ans:Leucocytes
q. Slowly releases oxygen to blood cells.
q. Slowly releases oxygen to blood cells.
Ans:haemoglobin
r. Their function is to help blood clot in wounds.
r. Their function is to help blood clot in wounds.
Ans:platelets
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24. Name and Label the given diagrams to show A, B, C, D, E, F, and G
Answer:
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