CBSE Class 10 Science Transportation Notes

TRANSPORTATION

4.1 INTRODUCTION :

All living bodies need nutrients and oxygen in every cell of its various tissues to sustain life. The transport of different material and gases is essential both in plants and animals. Unicellular organisms e.g. Amoeba and Paramecium do not require the transport of any material. These are in direct contact with their surroundings from where they obtain these nutrients. These substances are distributed in the cytoplasm due to the streaming movements of cytoplasm called as cyclosis. They exchange gases from the external environment directly by diffusion due to the difference in the concentration in and outside their body. In higher organisms both plants and animals,  digested food, oxygen, hormones, waste nitrogenous substances etc. are to be carried from one place to the other. So transportation of materials is essential. It is done through circulatory system.

4.1 (a) Transportation in Higher Plants:

The higher plants have specialized system for the transportation of materials inside the body. The transportation of material is carried out by means of vascular tissues of the plants. The vascular tissues act as pipes or vessels. Through these vessels or pipes, water, minerals, salts, food etc. are transported in the plant body. In plants the medium of transportation is water. Water and food flows through the xylem (tracheids and vessels are the constituents of xylem) and phloem (sieve tubes and companion cells) for various metabolic activities. Tracheids and vessels are non-living parts of xylem while sieve tubes and companion cells from the living parts of phloem. The terrestrial (land) plants absorb water and mineral salts through their roots. The area of young roots where most of the absorption takes place is the root hair zone. Root hair are the extensions of the epidermal cells. Root hair are delicate and do not live more than two days. The root hair have sticky walls by which they adhere tightly to soil particles. The root hair absorb water from soil by the process of osmosis but take in mineral salts by diffusion. The water and mineral salts are transported from the roots to the leaves, flowers and other parts of the plant. The upward movement of cell sap (water and minerals) through the xylem is called “ascent of sap”.

4.1 (b) Translocation :

Phloem Translocates the manufactured food (sugar) or starch from the leaves to the leaves to the different parts of the plant including the roots.

4.1 (c) Transpiration :

Most of the water absorbed is lost through the aerial parts of the plant into air by a process called “transpiration”. Two percent of total water absorbed is used up in various metabolic activities in the plant body. Transpiration is the loss of water from the living tissues of the aerial parts of the plant in the form of water vapours. There are three types of transpiration :

(i)  Cuticular transpiration (through cuticle)

(ii) Lentiular transpiration (through lenticels)

(iii) Stomatal transpiration (through stomata)

Importance of transpiration :

(A) It controls the rate of absorption of water from the soil.

(B) It is responsible for ascent of sap.

(C) It regulates the temperature of the plant.

(D) Mostly water absorbed by roots is lost by transpiration without serving any purpose.

The energy spent by the plants in transpiration is wasted. So transpiration is a necessary evil.

4.1 (d) Differences in Function of Xylem and Phloem :

 Xylem                                                                                  Phloem

(i)    Functional xylem ells are dead.                   (i)            Functional phloem cells are alive.

(ii)   It carries mineral salts, water and               (ii)           An organic solution of sugars and amino acids is

        traces of organic molecules                                          translocated.

(iii) The movement is only upward.                   (iii)         The movement can be upward or downward.

4.2 TRANSPIRATION COHENSION THEORY :

The main loss of water is through stomatal transpiration. Turgor pressure in the mesophyll cells of the leaf forces water outwards through the cell wall. Water evaporates from the surface of the cells into the air spaces of the spongy tissues and then passes into the outer atmosphere through the pores or stomata. The cell sap of mesophyll cells becomes concentrated by losing water and causes ad drop in turgor pressure. As a result water is sucked from adjoining mesophyll cells and ultimately from vascular tissues. This tension is transmitted all the way down to the unbroken column of water through the stem to the absorbing parts of the root. The molecules of the water show cohesion (mutual attraction) and molecules of water and vessel wall show adhesion (affinity for water). Due to these adhesive and cohesive forces, water column does not break but pulled upward by the force called as “transpiration pull”. The whole process  can be compared with a person (transpiration pull) pulling a bucket full of water (forces on water column) from a well with a rope (column of water due to cohesion).

4.3 TRANSPORTAION IN HUMANS :

In humans there is a circulatory system that uses blood or lymph as carries of materials (fluid exchange medium) and the heart as the pumping organ to help in circulation. Circulatory system consists of blood vascular system (blood as carrier) and lymphatic system (lymph as carrier).

4.3 (a) Blood Vascular System :

The higher multicellular animals with  higher metabolic rates posses a well developed blood vascular system. This system helps in the quicker supply of nutrients and oxygen to the body tissues and also in the rapid disposal of toxics waste material and carbon dioxide. The blood acts as the circulatory fluid. Blood vascular system consist of blood, blood vessels and heart.

(i) Blood : The blood is a specialized kind of living connective tissue which is made to circulate, by the muscular pumping organ called as the heart. In adult human beings there is 5.5 to 6 liter of blood. The blood consists of fluid part, the plasma. The red blood corpuscles (RBSs), white blood corpuscles (WBCs) and blood platelets are present in the plasma. The formation of blood is called “Hempieces”.

(ii) Plasma : The plasma consist of water (90% & above) inorganic substances. In the plasma RBCs, WBCs and blood platelets float. Inorganic salts (09%) are also present. The organic substances are glucose, amino acids, proteins, hormones, digested and waste excretory products. The blood proteins (7%) are fibrinogen, albumin, globulin and prothrombin.

NOTE : Serum is plasma from which fibrinogen is removed.

(A) Red Blood Corpuscles (RBCs) or Erythrocytes : The number of RBCs is about 5.5 million in 1 ml of blood. The total number of RBC is about 30 billion. Each RBC is a biconcave disc-like structure devoid of nucleus. The mammalian erythrocytes do not possess nuclei, mitochondria and endoplasmic reticulum. The erythrocytes contain hemoglobin. Hemoglobin consist of globin (protein) and F²⁺ porphyrin compels (haeme). 100 ml of blood contains 15 mg of hemoglobin. if the amount of hemoglobin in blood is less, the person suffers from anemia The hemoglobin carries oxygen to the different cells of the body and brings carbon dioxide from the cells. The life span of a RBC is 120 days.

(B) White Blood Corpuscles (WBCs) or Leucocytes: The number of leucocytes is comparatively fever i.e. one ml of blood contains 5000 - 10000 leucocytes in humans. The total number of WBCs is about 75 millions. The number of leucocytes increases in infections like pneumonia, blood cancer (Leukemia) etc. These are large in size and contain nucleus. White blood corpuscles are of two types :

1. Granulocytes : In granulocytes the cytoplasm contains granules and the nucleus is multliobed. Bosophils, Eosinophils and Neutrophils are three different types of granulocytes. Eosinophils and neutrophils are phagocytic (engulf and kill harmful microbes ) in nature and this process is called as “phagocytosis”. The function of basophils is to release histamine and Heparin.
2. Agranulocytes : Monocytes and lymphocytes are two different types of agraulocytes. Lymphocytes secrete antibodies which destroy microbes. The monocytes are phagocytic in nature.

(C) Blood platelets : These are small and without nuclei. Their number various from 0.15 to 0.45 million in 1ml of blood. Their normal life span is one week. These help in blood clotting at the site of injury by liberating Thromboplastin.

4.3 (b) Functions of Blood :

Blood performs the following functions :

1. Transportation of hormones : Hormones are produced by endocrine glands. These hormones have target organs (p lace to act). These are carried by the plasma of blood and bring about the coordination in the working of the body.
2. Transportation of excretory products : Different wastes from the different parts of the body are collected by the blood and then taken to the organs (kidneys, lungs, skin and intestine) from where they are exerted.
3. Transportation of respiratory gases: The respiratory gases (oxygen, carbon-dioxide) are transported by the blood. Oxygen is transported from the respiratory surface (lung, skin and buccal cavity) to the tissues and carbon dioxide from the tissues is taken to the respiratory organ for its removal.
4. Transpiration of nutrients: The digested and absorbed nutrients like glucose, amino acids, fatty acids are first transported to the liver and then to all the tissues for their storage, oxidation and synthesis of new substance.
5. Maintenance of pH: the plasma proteins act as buffer system and maintains required pH of the body tissues.
6. Regulation of body temperature : The blood flows in all the parts of body, so it equalizes the body temperature. It carries heat from one place to another place in the body.
7. Transportation of metabolic intermediates : The blood carries metabolic intermediates from one tissue to another for further metabolism. In the muscle cells due to anaerobic respiration lactic acid is produced. This lactic acid is carried to the liver for further oxidation.
8. Water balance : The blood maintains water balance to constant level by distributing it uniformly in the body.
9. Protection from diseases : The WBCs (eosinophils, neutrophils, monocyts) engulf the bacteria and other disease causing organisms by phagocytosis. The lymphocytes produce antibodies to neutralize the action of toxins produced by pathogens.
10. Clotting of blood : Blood forms a clot at the site of injury and thus prevents the further loss of blood.
11. Support : Blood flows under pressure in arteries. Due to this tissues become stiff as in the case of erection of nipples, clitoris and penis.

4.3 (c) Blood Clotting :

At the site of injury of the blood vessels, the platelets induce blood coagulation through the release of thromboplastic (thrombokinase). Thromboplastin changes prothrombin of blood plasma into thrombin. Thrombin converts soluble protein fibrinogen to insoluble fibrin. Fibrin forms a network which entangles RBCs and blood platelets to form plug or clot over the inured area. Blood clotting is usually completed within 2-3 minutes.

4.3 (d) Blood Groups :

Land Steiner discovered that blood of different individual did not match each other but there were biochemical differences. He discovered Antigens A and B and blood groups (ABO systems). Antigen (agglutinogen) is a glycoprotein present on RBCs. For each antigen there is a corresponding antibody. Thus there are two antibodies (agglutinin) and b occurring in the blood plasma. There are four types of blood groups depending on the presence or absence of these antigens.

Blood is a life saving fluid. It is often needed during accident and operation. The transfusion of blood is only done when blood group is known. These groups are A,B, AB and O. Blood of O group is a universal donor i.e. it an donate blood to any group (a, AB, B and O) but it can receive blood from O blood group. A B group is universal recipient (receiver). It an receive blood from any group (A, B, AB, O) but it can donate to AB group only.

4.3 (e) Blood Transfusion :

The transfusion of blood from a healthy person to a patient suffering from blood loss due to injury or surgical operation is called a “blood transfusion”. For this all major hospitals have blood banks where blood is collected from voluntary and professional donors. Before preservation the blood is tested for its blood group and Rh factor. Though theoretically a patient may be able to receive blood of two or more types, it is always advisable to have the donor blood of the same group as that of the recipient. Rather the blood of donor is always cross matched before transfusion to exclude any change of incompatibility. When blood from a donor is added is added to blood of the recipient, it is necessary to avoid bringing together corresponding antigen and antibody. This causes clumping of RBCs. Thus antigen A in RBCs of group A individuals reacts with antibodies of plasma of group B individuals. This phenomenon is called “agglutination”.

Rh factor (in blood) can be genetically determined. Most of the people (more than 85%) are Rh positive (Rh+) while a few are Rh negative (Rh-). Both people lead normal life. If an Rh-  woman marries with an Rh+ man then Its pregnancy is normal but in 2nd pregnancy the mother with Rh- blood may lose the baby due to incompatibility of Rh factor. By new techniques and procedures now the child can be saved.

Heart is a hollow muscular organ that lies obliquely in the thoracic region in a cavity between the two lungs that is pericardial cavity. It is lined by 2 layers outer and inner pericardial membranes. These are filled with a fluid called “pericardial fluid”. It protects the heart from shock and injury.

1. Heart is made up of 4 chambers: upper 2 chambers are auricles and the lower 2 chambers are ventricles. Auricles are the receiving chambers and ventricles are the pumping chambers. Walls of ventricles are thicker as they have to pump the blood.
2. Partition between right and left auricle is called “interauricular septum” and between right and left ventricles is “inter ventricular septum”.
3. Four pulmonary veins enter into left auricle, two from each lung bring oxygenated blood. There is one auriculoventricular aperture with a bicuspid or mitral valve in left auricles which opens into left ventricle.
4. Left ventricle has aortic valve having 3 semilunar cusps for large artery i.e. dorsal aorta which takes the oxygenated blood to all body parts.
5. Right auricle has openings for superior venacava that brings deoxygenated blood from head, neck and upper limbs, inferior venacava receives deoxygenated blood from rest of the body and lower limbs. Blood enters into right ventricle through tricuspid valve. A coronary sinus that drains venous blood from heart muscles.
6. Right ventricle has pulmonary valve having 3 semilunar cusps for pulmonary artery carrying deoxygenated blood to lungs.
7. The series of events which occur during one heart beat is called as cardiac cycle.

NOTE : During foetal condition a flap valve called “foramen ovale” is present at interauricular septum having a depression called as fossa ovalis. If it remains after birth it results “a hole in the heart”.

5.1 (a) Blood Pressure :

It is the pressure of the flow of blood in the aorta and its man arteries. The blood pressure varies according to the contraction and relaxation of the heart. In the condition of contraction or systolic phase (Lubb sound) it is about 120 mm of Hg. This is called “systolic pressure”. In the relaxation or diastolic phase (Dub sound) it is about 80 mm of Hg and is called “diastolic pressure”. The normal blood pressure of man (20 years) is 120/80. Fats and anxiety increase the blood pressure, the maximum normal blood pressure should into exceed 150 in males and 140 in females. The blood pressure is measured by “sphygmomanometer”.

5.1 (b) Detection of Normalcy of Heart Beat :

The muscle fibres of heart are specialized at certain parts generate tiny electrical currents which cause the normal heart heats. The “electrocardiograph” (E.C.G.) is the device to record these electrical changes. Electrocardiogram is a record of electrical behaviour of heart and remains constant in a normal man. Doctors use the E.C.G. for detection of various heart diseases. Sometimes the sinoatrial node (SA node or pacemaker) gets damaged and fails to generate cardiac impulses at normal rate it becomes abnormally slow and irregular and ventricles fail to pump the required  amount of blood. It can be corrected by the surgical grafting of an artificial pacemaker instrument in the chest of the patient. This instrument stimulates the heart electrically at regular intervals to maintain the beats.

5.2 LYMPHATIC SYSTEM :

The lymphatic system comprises the lymph, lymphatic capillaries (simply lymphatic), lymphatic vessels and nodes. Lymph severs as the middle man between the blood and organ for exchange of any material. The lymph is the tissue fluid present in the intercellular spaces in the tissues. So it is also called as “extracellular fluid”. The lymph resembles the blood except that the lymph is devoid of R.B.Cs, blood platelets and some plasma proteins. Lymphatic system runs parallel to the veins. The lymphatic capillaries are present in the form of network under epithelial surface. The ends of lymphatic capillaries are blind. The lymphatic capillaries unite to form lymphatic vessels and these vessels resemble with the veins. The lymphatic vessels posses the valves which prevent back flow of lymph. Neighbouring body muscles help in the flow of lymph. The small lymphatic vessels unite to form large vessels. Larger lymphatic vessels unite to form large ducts i.e. right lymphatic duct and thoracic duct. Right lymphatic duct opens into right subclavian vein and left thoracic duct open in to left subclavian vein. Before the lymph reaches the blood, it always passes through the lymph nodes. The lymph’s nodes are enlargements of the lymphatic vessels. Lymphocytes and other plasma cells are present in the lymph nodes. The lymp  is cleaned or filtered by lymph nodes. These cells also kill the germs and produce antibodies.

5.2(a) Functions of Lymph :

(i)  It provides immunity through lymphocytes.

(ii) Fats are absorbed through lymph vessels in the intestine

(iii) It supplies digested food and oxygen to various parts of the body.

(iv) It helps in removal of waste products like parts of dead cells.

(v)  It returns proteins and excess tissue fluid to the blood from the tissue spaces.